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Enterobacterales as opportunistic pathogens are commonly associated with nosocomial infections. With increasing frequency, Gram-negative bacilli, especially Klebsiella pneumoniae strains, are mul- tidrug-resistant or pandrug-resistant. Carbapenems were used as the drugs of choice for the treat- ment of infections caused by multidrug-resistant Gram-negative bacilli. The aim of this study was to assess the usefulness of the RESIST-4 O.K.N.V. K-SeT for the rapid detection and identification of the most important carbapenemases (OXA-48, KPC, NDM, VIM) in Enterobacterales bacilli. The study involved the isolates of 97 Enterobacterales strains. The ability to produce carbapenemases was determined by the immunochromatographic RESIST-4 O.K.N.V. K-SeT test. This test detected carbapenemases OXA-48, KPC, NDM, and VIM. For the RESIST-4 O.K.N.V. K-SeT test, a positive result was obtained for 93 strains (95.9%). Four strains negative in the RESIST-4 O.K.N.V. K-SeT were positive in the Eazyplex®SuperBugCRE and PCR. These strains produce VIM enzymes. RE- SIST-4 O.K.N.V. K-SeT test is rapid, simple to perform and can be used for fast detection of the most important carbapenemases (OXA-48, KPC, NDM, VIM) among Gram-negative bacilli.

Introduction: The normal vaginal microbiota (mainly Lactobacillus spp.) affects the health of these areas. Bacterial vaginosis is a serious health problem among many women, especially dangerous for pregnant women. The study aimed to assess the impact of Lactobacillus spp. strains on the population of Listeria monocytogenes isolated from women. Materials and methods: The research material consisted of reference strains of Lactobacillus spp.: L. acidophilus (LAC), L. fermentum (LFE), L. gasseri (LGA), L. plantarum (LPL), the strain L. monocytogenes ATCC 19111 and 7 L. monocytogenes strains isolated from the vagina. Results: The highest antagonistic activity was shown for the mixed culture of all Lactobacillus strains (LACTO MIX) used in the experiment. Among the individual strains of Lactobacillus spp. strains, L. plantarum turned out to most effectively reduce L. monocytogenes number (reduction of 5.74 log CFU × ml-1). The least effective in inhibiting the growth of L. monocytogenes was the L. acidophilus strain (reduction of L. monocytogenes of a number of 2.21 log CFU × ml-1). Conclusions: The presence of Lactobacillus spp. in the genital tract limits the development of bacterial infections, which is an important aspect especially for pregnant women.

Objectives: This study evaluated the diagnostic performance of the eazyplex® SuperBug CRE (eSBCRE) system, based on a loop-mediated isothermal amplification (LAMP), for the detection of the most co...

Wstęp Bakterie Gram-ujemne są istotnym czynnikiem etiologicznym szerokiego zakresu zakażeń szpitalnych. Rozpowszechnienie szczepów bakterii wielolekoopornych, zarówno należących do rzędu Enterobacterales, jak i niefermentujących pałeczek z gatunku Pseudomonas aeruginosa, stanowi poważne wyzwanie dla współczesnej medycyny. Badanie nowych opcji terapeutycznych oraz monitorowanie antybiotykowrażliwości drobnoustrojów jest ważnym elementem działań zapobiegających rozwojowi i utrzymywaniu się zakażeń z udziałem szczepów wielolekoopornych. Celem pracy było porównanie aktywności in vitro połączenia ceftazydymu z awibaktamem z najczęściej stosowanymi w Polsce antybiotykami, mającymi zastosowanie w leczeniu zakażeń bakteriami Gram-ujemnymi z rzędu Enterobacterales oraz P. aeruginosa, w ramach programu badawczego ATLAS. Materiał i metody W pracy analizowano wrażliwość 1677 szczepów rzędu Enterobacterales oraz 500 niefermentujących pałeczek P. aeruginosa, izolowanych w latach 2014–2018 w ośrodkach biorących udział w programie, na ceftazydym z awibaktamem oraz inne antybiotyki stosowane w leczeniu zakażeń pałeczkami Gram-ujemnymi. Wyniki Niemal 99% (98,9%) szczepów rzędu Enterobacterales, w tym 96,9% szczepów wytwarzających beta-laktamazy typu ESBL, było wrażliwych na ceftazydym z awibaktamem. Notowano wysoki odsetek szczepów Escherichia coli oraz Klebsiella pneumoniae wrażliwych na ceftazydym z awibaktamem, odpowiednio: 99,8% i 98,9%, w tym także szczepów ESBL-dodatnich tych samych gatunków, odpowiednio: 98,5% i 98,7%. Wrażliwość szczepów P. aeruginosa na ceftazydym z awibaktamem była niższa niż badanych szczepów Enterobacterales, niemniej jednak kształtowała się na poziomie 91,7%, co czyniło ceftazydym z awibaktamem drugim, po kolistynie, najlepiej działającym antybiotykiem wobec tych bakterii. Wnioski Przedstawione dane w połączeniu z dotychczas opublikowanymi wynikami farmakokinetycznymi, farmakodynamicznymi, klinicznymi i bezpieczeństwa wskazują, że połączenie ceftazydymu z awibaktamem może stanowić cenną opcję leczenia zakażeń wywoływanych przez Enterobacterales oraz P. aeruginosa, w tym zakażeń szczepami wielolekoopornymi.

Aim: Escherichia coli is one of the Gram-negative bacteria, known to cause many nosocomial infections. Multi-drug (MDR) and extensively-drug resistant (XDR). E. coli are of particular note, due to significant limitations in antibiotic therapy. Ceftolozane-tazobactam and ceftazidime-avibactam are novel therapeutic options against Gram-negative bacteria; hence the aim of this study was to evaluate and compare the in vitro activity of ceftolozane-tazobactam and ceftazidime-avibactam against MDR and XDR clinical E. coli isolates. Material/Methods: The study included 100 non-replicate E. coli isolates derived from clinical samples of patients hospitalized in teaching hospitals. Bacteria were identified by applying mass spectrometry in the MALDI Biotyper system (Bruker). ESBL (blaCTX-M-1group, blaCTX-M-9group) and carbapenemase (blaKPC, blaVIM, blaNDM, blaOXA-48, blaOXA-181) genes were detected using the eazyplex® SuperBug CRE test, based on a loop-mediated isothermal amplification (LAMP). The in vitro susceptibility to ceftolozane-tazobactam and ceftazidime-avibactam was tested using validated MIC Test strips (Liofilchem). Results: All 84 extended-spectrum β-lactamase-producing (ESBL) E. coli isolates were susceptible to ceftazidime-avibactam and 83 to ceftolozane-tazobactam. Among 17 E. coli isolates with resistance to at least one of the carbapenems, three (17.6%) were susceptible to ceftolozane-tazobactam and ceftazidime-avibactam. All 14 blaVIM gene-positive E. coli isolates were resistant to both ceftolozane-tazobactam and ceftazidime-avibactam. Both antibiotics were active against blaCTX-M-9group and blaOXA-48 gene-positive E. coli isolates, but they were not active against blaCTX-M-1group and blaVIM gene-positive isolates. Conclusions: Ceftolozane-tazobactam and ceftazidime-avibactam are alternative, non-carbapenem therapeutic options for ESBL-positive E. coli strains, and they are promising in the treatment of carbapenem-resistant E. coli strains, but not for those carrying the metallo-β-lactamase enzymes. Both drug combinations have comparable activity against ESBL, however, lower MIC values were found for ceftazidime-avibactam.

Stress and anxiety are common phenomena that contribute to many nervous system dysfunctions. More and more research has been focusing on the importance of the gut–brain axis in the course and treatment of many diseases, including nervous system disorders. This review aims to present current knowledge on the influence of psychobiotics on the gut–brain axis based on selected diseases, i.e., Alzheimer’s disease, Parkinson’s disease, depression, and autism spectrum disorders. Analyses of the available research results have shown that selected probiotic bacteria affect the gut–brain axis in healthy people and people with selected diseases. Furthermore, supplementation with probiotic bacteria can decrease depressive symptoms. There is no doubt that proper supplementation improves the well-being of patients. Therefore, it can be concluded that the intestinal microbiota play a relevant role in disorders of the nervous system. The microbiota–gut–brain axis may represent a new target in the prevention and treatment of neuropsychiatric disorders. However, this topic needs more research. Such research could help find effective treatments via the modulation of the intestinal microbiome.

Pseudomonas aeruginosa is an opportunistic pathogen encoding several virulence factors in its genome, which is well-known for its ability to cause severe and life-threatening infections, particularly among cystic fibrosis patients. The organism is also a major cause of nosocomial infections, mainly affecting patients with immune deficiencies and burn wounds, ventilator-assisted patients, and patients affected by other malignancies. The extensively reported emergence of multidrug-resistant (MDR) P. aeruginosa strains poses additional challenges to the management of infections. The aim of this study was to compare the incidence rates of selected virulence-factor-encoding genes and the genotype distribution amongst clinical multidrug-sensitive (MDS) and MDR P. aeruginosa strains. The study involved 74 MDS and 57 MDR P. aeruginosa strains and the following virulence-factor-encoding genes: lasB, plC H, plC N, exoU, nan1, pilA, and pilB. The genotype distribution, with respect to the antimicrobial susceptibility profiles of the strains, was also analyzed. The lasB and plC N genes were present amongst several P. aeruginosa strains, including all the MDR P. aeruginosa, suggesting that their presence might be used as a marker for diagnostic purposes. A wide variety of genotype distributions were observed among the investigated isolates, with the MDS and MDR strains exhibiting, respectively, 18 and 9 distinct profiles. A higher prevalence of genes determining the virulence factors in the MDR strains was observed in this study, but more research is needed on the prevalence and expression levels of these genes in additional MDR strains.

Among the diseases that pose a serious threat to public health, those caused by viruses are of great importance. The Nipah virus (NiV) belonging to the Paramyxoviridae family was reported in Malaysia in 1998/1999. Due to its high mortality in humans, its zoonotic nature, the possibility of human-to-human transmission, and the lack of an available vaccine, the World Health Organization (WHO) has recognized it as a global health problem. Depending on strain specificity, neurological symptoms and severe respiratory disorders are observed in NiV infection. In most confirmed cases of NiV epidemics, the appearance of the virus in humans was associated with the presence of various animal species, but generally, bats of Pteropus species are considered the most important natural animal NiV reservoir and vector. Consumption of contaminated food, contact with animals, and “human-to-human” direct contact were identified as NiV transmission routes. Due to the lack of vaccines and drugs with proven effectiveness against NiV, treatment of patients is limited to supportive and prophylactic.

The main purpose of micro-organisms elimination from the air and surfaces is to ensure microbiological safety in health care facilities or food production plants. Currently, many disinfection methods are used, both physical, chemical and, increasingly, biological. Scientists seek new solutions with high antimicrobial effectiveness (especially against the drug-resistant strains of bacteria), low production and operating costs, and, above all, the safety of patients and food consumers. The limitation of the methods used so far is primarily the micro-organisms acquire the resistance, mainly to antimicrobial agents. One of the new and alternative methods of disinfection is radiant catalytic ionization (RCI). RCI is an active method of air and surface purification. The technology proved high efficiency against viruses, Gram-positive and -negative bacteria, and fungi, both in the air and on surfaces (planktonic forms and biofilm). RCI has many advantages as well as some minor limitations. This overview summarizes the current knowledge about RCI technology.

BACKGROUND: Listeria monocytogenes is a cause of listeriosis, dangerous especially for elderly, immunocompromised people and pregnant women. Ability to colonize biotic and abiotic surfaces and form biofilm by these pathogens poses a serious threat for the hospitalized, catheterized patients. METHODS: The study was conducted on 29 L. monocytogenes strains isolated from clinical materials (blood, cerebrospinal fluid, swabs from vagina) and the reference strain L. monocytogenes ATCC 1911. Ability to form biofilm in 96-well plates and drug susceptibility (disk diffusion method) of tested strains was determined. RESULTS: All strains formed biofilm though it’s intensity was correlated with source of isolation. The strong biofilm formed 72.73 % of isolates from cerebrospinal fluid ((A570 0.421 – 1.3), 75.0 % of blood isolates 9 (A570 0.389 – 1.063) and 50.0 % of isolates from vaginal swabs (A570 0.457 – 0.487). The strongest biofilm was formed by strains derived from cerebrospinal fluid whereas isolates from vaginal swabs, which strongly formed a biofilm accounted for 50.0% of the studied population (absorbance 0.457 - 0.487). It was found that 93.1 % (n=27) of strains were susceptible to all drugs tested. Two strains (6.9 %) were resistant to cotrimoxazol and 1 strain (3.45 %) to erythromycin. CONCLUSIONS: Diverse ability to form biofilm by clinical L. monocytogenes strains is an important aspect in prophylaxis in catheterized patients.

Introduction. Raoultella spp. representatives are Gram-negative rod-shaped bacteria of the Enterobacteriaceae family. These bacteria are commonly found in the natural environment. Aim. The aim of the study was to indicate the reliable method for Raoultella spp. strains identification, evaluate the susceptibility of Raoultella spp. strains to selected antimicrobials and to detect their resistance mechanisms to beta-lactams. Methodology. Susceptibility of the strains to chosen antimicrobials was determined using the automatic method. The presence of particular antimicrobial resistant mechanism and genes encoding ESBLs and MBLs was determined respectively with double-disc synergy test and commercially available kit – eazyplex SuperBug CRE test (Amplex Diagnostics) and standard PCR. For the selected strains, DNA sequencing was performed. Results. Amongst 105 of the examined Raoultella spp. strains, majority were sensitive to: imipenem (99.0 %), meropenem (98.1 %), gentamicin (93.3 %) and ciprofloxacin (92.4 %). Of the tested Raoultella strains, thirteen (12.4 %) produced ESBLs and one strain simultaneously ESBLs and MBLs. The DNA sequencing results were as follows: for all the reference strains the correct species identification was achieved, for the analysed strains two were identified as R. planticola and one as R. ornithinolytica . Conclusion. Although Raoultella spp. strains remain sensitive to antibiotics, there is a constant need to monitor the sensitivity of these bacteria to selected antimicrobials. Isolation of a multi-drug resistant R. ornithinolytica strain indicates that even the less frequently isolated species of Enterobacteriaceae family should be precisely identified because they might be of clinical importance and the particular strain can also produce enzymes that pose the greatest threat today.

The multi-drug resistance of Gram-negative rods is one of the most important issues of present medicine. In recent years, more and more strains resistant to the majority or to all possible therapeutic options have been isolated—especially Klebsiella spp. and Pseudomonas spp. representatives. It is very important to detect strains with these phenotypes as quickly and reliably as possible. The aim of the study was to evaluate the usefulness of eazyplex® SuperBug CRE test (Amplex Diagnostics) for the detection of the most important beta-lactam resistance genes. eazyplex® SuperBug CRE test is based on the loop-mediated isothermal amplification (LAMP) method, and detects genes for the following beta-lactamases: KPC, NDM-1, VIM, OXA-48, CTX-M1, CTX-M9 and OXA-181. The study involved 87 strains. For all of the positive strains in the LAMP method, additional PCR were performed to increase the spectrum of ESBLs detected by the genes encoding for enzymes belonging to TEM and SHV families. The results obtained by the tested method and standard PCR were consistent for all Klebsiella spp. strains. The discrepancy between the evaluated test and PCR results was observed for one P. aeruginosa strain. The eazyplex® SuperBug CRE test can be used for quick detection of the most important beta-lactam resistance mechanisms amongst Gram-negative rods.

Due to increasing antibiotic resistance Klebsiella pneumoniae is a serious threat for the hospitalized patients. The aim of this study was the assessment of radiant catalytic ionization (RCI) efficacy on K. pneumoniae reduction in the air and on selected surfaces. Four K. pneumoniae NDM and ESBLs-producing strains were included in the study. Three types of surface were tested: cotton-polyester, terry and PVC. It was found that RCI significantly reduced the number of bacteria from all types of surface (terry: 0·56-1·22 log CFU m2 , cotton-polyester: 2·15-3·71 log CFU per m2 , PVC: 4·45-4·92 log CFU per m2 ) as well as from the air (1·80 log CFU per m3 ). The RCI technology may be a useful disinfection method in hospitals. SIGNIFICANCE AND IMPACT OF THE STUDY: Microbial contamination of air and surfaces in hospitals play an important role in healthcare-associated infections. The aim was the assessment of Klebsiella pneumoniae elimination using radiant catalytic ionization (RCI). K. pneumoniae are aetiological agent of nosocomial infections, such as: pneumonia, infections of urinary tract, blood, e.t.c. The strains producing the New Delhi metallo-β-lactamases are one of the greatest epidemiological threat. The use of RCI eliminate the tested bacteria from the hospital environment, but can also be effective in food processing plants or public facilities, ensuring the safety of people and products. This research is scarce in references and has a large innovation and application potential.

Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating - (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood - hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment. Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating – (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood – hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment.

Background: Listeria monocytogenes is a Gram-positive, foodborne pathogen. Biofilms formed by this bacterium are a serious problem in the food industry. Bacteria in biofilms are much more resistant to cleaning and disinfection agents posing a risk of food recontamination. The aim of this study was the assessment of the influence of initial sonication on disinfectant efficacy, based on QAC, against L. monocytogenes biofilm on the stainless steel. Methods: The biofilm formed on the stainless steel by the reference strain L. monocytogenes ATCC 19111 was sonicated for 1 and 5 minutes (500W/ 20kHz/ 100% amplitude). Then disinfection with quaternary ammonium compounds (0.5% working solution) was applied for 1 and 5 minutes and the number of bacteria recovered from the biofilm was assessed. Results: It was found that disinfection was more efficient than sonication (p ≤ 0.05). However, the combination of sonication and disinfection significantly improved biofilm eradication compared to the use of one of these methods separately (p ≤ 0.05). The greatest reduction of bacteria number was achieved after 5 minutes of sonication combined with 5 minutes of disinfection (6.42 log CFU × cm-2), whereas the lowest reduction was observed after 1 minute-sonication (2.03 log CFU × cm-2). Conclusions: Combination of sonication and disinfection based on quaternary ammonium compounds is an effective method allowing biofilm eradication from the food production surfaces.

Background Fluoroquinolones are a group of antibiotics used in urinary tract infections. Unfortunately, resistance to this group of drugs is currently growing. The combined action of fluoroquinolones and other antibacterial and anti-biofilm substances may extend the use of this therapeutic option by clinicians. The aim of the study was to determine the effect of selected fluoroquinolones and therapeutic concentrations of ascorbic acid and rutoside on biofilm formation by Proteus mirabilis. Materials and methods The study included 15 strains of P. mirabilis isolated from urinary tract infections in patients of the University Hospital No. 1 dr A. Jurasz in Bydgoszcz (Poland). The metabolic activity of the biofilm treated with 0.4 mg/ml ascorbic acid, 0.02 µg/ml rutoside and chemotherapeutic agents (ciprofloxacin, norfloxacin) in the concentration range of 0.125–4.0 MIC (minimum inhibitory concentration) was assessed spectrophotometrically. Results Both ciprofloxacin and norfloxacin inhibited biofilm formation by the tested strains. The biofilm reduction rate was correlated with the increasing concentration of antibiotic used. No synergism in fluoroquinolones with ascorbic acid, rutoside or both was found. The ascorbic acid and rutoside combination, however, significantly decreased biofilm production. Conclusions Our research proves a beneficial impact of ascorbic acid with rutoside supplementation on biofilm of P. mirabilis strains causing urinary tract infections.

Multi-drug resistant pathogens are a global problem. Flies are a potential vector of multi-drug resistant pathogens, which can be particularly dangerous in the hospital environment. This study aimed to evaluate flies as vectors of alert pathogens. The research material consisted of 100 flies (

The outbreak of Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2). Thus far, the virus has killed over 2,782,112 people and infected over 126,842,694 in the world (state 27 March 2021), resulting in a pandemic for humans. Based on the present data, SARS-CoV-2 transmission from animals to humans cannot be excluded. If mutations allowing breaking of the species barrier and enhancing transmissibility occurred, next changes in the SARS-CoV-2 genome, leading to easier spreading and greater pathogenicity, could happen. The environment and saliva might play an important role in virus transmission. Therefore, there is a need for strict regimes in terms of personal hygiene, including hand washing and surface disinfection. The presence of viral RNA is not an equivalent of active viral infection. The positive result of the RT-PCR method may represent either viral residues or infectious virus particles. RNA-based tests should not be used in patients after the decline of disease symptoms to confirm convalescence. It has been proposed to use the test based on viral, sub-genomic mRNA, or serological methods to find the immune response to infection. Vertical transmission of SARS-CoV-2 is still a little-known issue. In our review, we have prepared a meta-analysis of the transmission of SARS-CoV-2 from mother to child depending on the type of delivery. Our study indicated that the transmission of the virus from mother to child is rare, and the infection rate is not higher in the case of natural childbirth, breastfeeding, or contact with the mother. We hope that this review and meta-analysis will help to systemize knowledge about SARS-CoV-2 with an emphasis on diagnostic implications and transmission routes, in particular, mother-to-child transmission.

The share of Klebsiella pneumoniae in infections has been recently increasing. Multidrug-resistant strains that produce more than one antibiotic resistance mechanism are also increasingly isolated. Contamination of the organs preservation fluid occurs quite often, but the isolated microorganisms are mainly saprophytic bacteria that are part of the skin microbiota (coagulase-negative Staphylococcus, Corynebacterium spp). The following case describes a K. pneumoniae blood infection in a patient after liver transplantation. Susceptibility of the strains to chosen antimicrobials was determined using the automated method. For strain isolated from blood, it was confirmed by loop-mediated isothermal amplification of genetic material.

The skin is the largest organ of the human body and it protects the body from the external environment. It has become the topic of interest of researchers from various scientific fields. Microorganisms ensure the proper functioning of the skin. Of great importance, are the mutual relations between such microorganisms and their responses to environmental impacts, as dysbiosis may contribute to serious skin diseases. Molecular methods, used for microorganism identification, allow us to gain a better understanding of the skin microbiome. The presented article contains the latest reports on the skin microbiota in health and disease. The review discusses the relationship between a properly functioning microbiome and the body’s immune system, as well as the impact of internal and external factors on the human skin microbiome.

Pseudomonas aeruginosa is one of the most commonly isolated bacteria from clinical specimens, with an increasing isolation frequency in nosocomial outbreaks. The hypothesis tested was whether carbapenem-resistant P. aeruginosa strains display an altered carriage of the virulence factor genes, depending on the type of carbapenem resistance. The aim of the study was to investigate, by PCR, the frequency of 10 chosen virulence factors genes (phzM, phzS, exoT, exoY, exoU, toxA, exoS, algD, pilA and pilB) and the genotype distribution in 107 non-duplicated carbapenem-resistant P. aeruginosa isolates. P. aeruginosa genes involved in phenazine dyes and exoenzyme T synthesis were noted with the highest frequency (100%). Fimbriae-encoding genes were detected with the lowest incidence: 15.9% and 4.7% for pilin A and B, respectively. The differences observed between the exoS gene prevalence amongst the carbapenemase-positive and the carbapenemase-negative strains and the pilA gene prevalence amongst the strains of different origins were statistically significant. Virulence genes’ prevalence and the genotype distribution vary amongst P. aeruginosa strains resistant to carbapenems, especially in terms of their carbapenemase synthesis ability and the strain origin.

Summary Background Streptococcus agalactiae (group B streptococcus: GBS) is a leading cause of early- and late-onset diseases in neonates. Reliable results of GBS carriage investigation among pregnant women may decrease the incidence of neonatal infection and mortality. Aim To compare the results of conventional culture investigation with those of the US Food and Drug Administration-approved nucleic acid amplification test (BD Max GBS (Becton Dickinson)), and to establish our own protocols of standard polymerase chain reaction (PCR). Methods A total of 250 vaginal–rectal swabs from three different hospitals in Bydgoszcz, Poland, were used to evaluate GBS carriage. Standard laboratory technique (overnight culture in broth enrichment media) results were compared with those of BD Max GBS assay (Becton Dickinson) and two standard PCR protocols, established to detect the cfb and 16S rRNA S. agalactiae genes, from the overnight cultures of the samples in the liquid enrichment media. Findings The overall GBS carriage was estimated as 16.4–23.2%, depending on the applied detection method. The highest percentage of positive results, from each lab-oratory was obtained with the application of BD Max GBS assay. The differences in the number of positive results obtained with this particular method were statistically significant. Overall, 27 discrepancies were noted for the results obtained with the application of the methods compared. Conclusions The methods applied for GBS detection differ in sensitivity. A culture technique, though very specific, appears to be less sensitive at detecting S. agalactiae compared with the commercially available BD Max GBS assay or in-house PCR protocols established for this purpose.

Pseudomonas aeruginosa is one of the most commonly isolated bacteria from clinical specimens, with increasing isolation frequency in nosocomial infections. Herein, we investigated whether antimicrobial-resistant P. aeruginosa strains, e.g., metallo-beta-lactamase (MBL)-producing isolates, may possess a reduced number of virulence genes, resulting from appropriate genome management to adapt to a changing hospital environment. Hospital conditions, such as selective pressure, may lead to the replacement of virulence genes by antimicrobial resistance genes that are crucial to survive under current conditions. The study aimed to compare, using PCR, the frequency of the chosen enzymatic virulence factor genes (alkaline protease-aprA, elastase B-lasB, neuraminidases-nan1 and nan2, and both variants of phospholipase C-plcH and plcN) to MBL distribution among 107 non-duplicated carbapenem-resistant P. aeruginosa isolates. The gene encoding alkaline protease was noted with the highest frequency (100%), while the neuraminidase-1 gene was observed in 37.4% of the examined strains. The difference in lasB and nan1 prevalence amongst the MBL-positive and MBL-negative strains, was statistically significant. Although P. aeruginosa virulence is generally more likely determined by the complex regulation of the virulence gene expression, herein, we found differences in the prevalence of various virulence genes in MBL-producers.

The new coronavirus SARS-CoV-2, first identified in Wuhan (China) in December 2019, represents the same family as the Serve Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1). These viruses spread mainly via the droplet route. However, during the pandemic of COVID-19 other reservoirs, i.e., water (surface and ground), sewage, garbage, or soil, should be considered. As the infectious SARS-CoV-2 particles are also present in human excretions, such a non-droplet transmission is also possible. A significant problem is the presence of SARS-CoV-2 in the hospital environment, including patients' rooms, medical equipment, everyday objects and the air. Relevant is selecting the type of equipment in the COVID-19 hospital wards on which the virus particles persist the shortest or do not remain infectious. Elimination of plastic objects/equipment from the environment of the infected person seems to be of great importance. It is particularly relevant in water reservoirs contaminated with raw discharges. Wastewater may contain coronaviruses and therefore there is a need for expanding Water-Based Epidemiology (WBE) studies to use obtained values as tool in determination of the actual percentage of the SARS-CoV-2 infected population in an area. It is of great importance to evaluate the available disinfection methods to control the spread of SARS-CoV-2 in the environment. Exposure of SARS-CoV-2 to 65–70% ethanol, 0.5% hydrogen peroxide, or 0.1% sodium hypochlorite has effectively eliminated the virus from the surfaces. Since there are many unanswered questions about the transmission of SARS-CoV-2, the research on this topic is still ongoing. This review aims to summarize current knowledge on the SARS-CoV-2 transmission and elucidate the viral survival in the environment, with particular emphasis on the possibility of non-droplet transmission., Graphical abstract Unlabelled Image, Highlights • SARS-CoV-2 may spread via a non-aerogenic route via surfaces and sewage. • SARS-CoV-2 is more resistant to environmental factors than other enveloped viruses. • Sewage can be a source of SARS-CoV-2 in soil. • Municipal waste from people infected with SARS-CoV-2 or people in contact with patients with COVID-19 may be a hazard. • It is imperative to distinguish the detection of viral RNA from the detection of complete virions.

Background: Currently, natural food preservation methods are explored, one of which includes the use of herbs and spices. Methods: The study assessed the effect of herbs and spices; either opened directly before the test or opened and stored for three months; on the survival of L. monocytogenes and S. Enteritidis bacilli, isolated from meat. Moreover, the microbiological purity of the investigated herbs and spices was evaluated. The research consisted of the analysis of inhibition zone patterns around the wells with spice pulp after the incubation period. Results: Varied influence of herbs and spices on the survival of bacilli was reported, depending on the species. The strongest impact against L. monocytogenes, among freshly opened spices, had: granulated garlic (38.63 mm), whole cloves (28.87 mm), savoury (22.25 mm), ground cinnamon (22.13 mm), ground ginger (18.75 mm). As for S. Enteritidis, in the group of freshly opened spices, the strongest effect was found for: granulated garlic (37.25 mm), whole cloves (31.50 mm), and ground cinnamon (18.16 mm). It was reported that the storage of open spices caused a decrease in antimicrobial activity against L. monocytogenes, except for cloves, oregano, hot pepper, chilli, sage and turmeric. In the case of S. Enteritidis, the following stored spices were not effective: cinnamon, ground black pepper, sage, oregano, basil, tarragon, marjoram, rosemary, coriander, green mint, hot pepper, chilli, curry. Conclusions: It was confirmed, that herbs and spices, because of its antimicrobial activity can be used, e.g. for food preservation, minimizing the amount of chemical additives applied to the product and extending its shelf-life.

L. monocytogenes poses a serious threat to public health, since most cases of listeriosis are connected with eating contaminated food. L. monocytogenes is often detected both in fresh and frozen vegetables. The aim of this study was to evaluate the antibiotic susceptibility and ability to form biofilm of L. monocytogenes strains isolated from frozen vegetable mixtures in Poland. Ninetynine genetically different strains were found among 100 isolates of L. monocytogenes. Among the 99 strains, 80 (80.8%) were susceptible to all tested antibiotics. Nineteen (19.2%) strains were resistant to one or more antibiotics. From this group of L. monocytogenes strains, most strains were resistant to erythromycin (16; 16,1%), penicillin (15; 15.1%), meropenem (12; 12.1%), cotrimoxazole (12; 12.1%), and ampicillin (3; 3.1%). According to the obtained results, differences in intensity of biofilm, both between those isolated in successive years and in the particular year, were observed. Performed analysis showed statistically insignificant faint negative correlation (r=–0.088) between the number of antibiotics to which strains were resistant and the intensity of biofilm formation by them. Food contamination with L. monocytogenes poses a threat to consumers, therefore it is necessary to monitor their antibiotic susceptibility, ability to form biofilm, and genetic similarity, in order to evaluate the strains persistence time in plant.

The aim of this study was to perform the phenotypic and genotypic evaluation of Listeria monocytogenes strains isolated from fish and equipment used in fish processing plants. The prevalence of selected gene-encoding virulence factors among L. monocytogenes strains was assessed by multiplex PCR. The genetic (PFGE method) and protein similarities (MALDI-TOF MS technique) of isolates were determined. Their drug resistance (disk-diffusion method and MIC values), serogroup classification (multiplex-PCR), and the ability to co-aggregate with Salmonella enteritidis were also evaluated. Among 37 L. monocytogenes isolates, 36 strains were found, one of which included two genetically identical isolates (PFGE method). In all examined strains, the following genes were found: hlyA, plcB, plcA, inlA, inlB, prfA, iap, and actA. The presence of virulence genes, mpl, and fbpA was confirmed in 32 (88.9%) strains. It was reported that 30 (83.3%) of the strains belonged to serogroup 1/2a-3a. It was also found that the rate of coaggregation with S. enteritidis bacilli was 16.5–36.3%. Among the investigated L. monocytogenes strains, 25 (69.4%) were sensitive to all antibiotics used. Resistance to penicillin was reported most often among strains (n = 6, 16.7%). The assessment of L. monocytogenes virulence level is an important aspect for the protection of public health. It was reported that strains isolated from fish contain genes coding for virulence factors and some of them are antibiotic-resistant. In our study, it was found that strains with a high degree of genetic similarity also showed a high degree of similarity at the level of protein profiles.

Listeria monocytogenes is a Gram-positive bacterium, commonly found in food, water or sewage. This microorganism is capable of forming biofilm on different surfaces such as steel, glass, polypropylene etc. Recently an increase in cases of listeriosis has been noted, making L. monocytogenes the important health threat. Therefore, there is a need for rapid and sensitive detection of this pathogen. This study aimed to compare the number of L. monocytogenes cells recovered from the biofilm (prepared on steel and polypropylene) using the detection and amplification of the hlyA gene (droplet digital PCR, ddPCR) and the classical culture method. The research material consisted of 96 L. monocytogenes strains. A total of 58 isolates were obtained from clinical samples and 38 isolates derived from the municipal sewage treatment plant. Additionally, the reference strain ATCC®19111™ (WDCM00020) was used. The Pearson correlation coefficient for the results obtained by the classical culture-based method and ddPCR was 0.864 and 0.725, for biofilms produced on AISI 304 stainless steel surface and the polypropylene surface, respectively. Correlations were statistically significant (p ≤ 0.001), indicating that the ddPCR technique is an effective tool for the assessment of bacteria number in the biofilm.

Since bacterial biofilm may contribute to the secondary contamination of food during the manufacturing/processing stage there is a need for new methods allowing its effective eradication. Application of food additives such as vitamin C already used in food industry as antioxidant food industry antioxidants may be a promising solution. The aim of this research was evaluation of the impact of vitamin C (ascorbic acid), in a range of concentrations 2.50 &micro, g mL&minus, 1&ndash, 25.0 mg mL&minus, 1, on biofilms of Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes strains isolated from food. The efficacy of ascorbic acid was assessed based on the reduction of optical density (&lambda, = 595 nm). The greatest elimination of the biofilm was achieved at the concentration of vitamin C of 25.0 mg mL&minus, 1. The effect of the vitamin C on biofilm, however, was strain dependent. The concentration of 25.0 mg mL-1 reduced 93.4%, 74.9%, and 40.5% of E. coli, L. monocytogenes, and S. aureus number, respectively. For E. coli and S. aureus lower concentrations were ineffective. In turn, for L. monocytogenes the biofilm inhibition was observed even at the concentration of 0.25 mg mL&minus, 1. The addition of vitamin C may be helpful in the elimination of bacterial biofilms. Nonetheless, some concentrations can induce growth of the pathogens, posing risk for the consumers&rsquo, health.

Mucormycosis is a rare fungal infection in immunocompetent patients, whereas in immunocompromised, it may be systemic and disseminated infection associated with high mortality. Mucormycosis is one of the most rapidly progressing and fulminant forms of fungal infections; Mucor circinelloides is rarely isolated species, also from immunocompromised patients. The reported case of mucormycosis after a traffic accident indicates that it may be the result of a contamination of wound by M. circinelloides coming from the environment. The fungal strain was identified by phenotypic methods and confirmed by molecular methods. Etest method was used for susceptibility testing of the fungal strain. No mycotoxins were detected in the analyzed sample. The infection was successfully treated with amphotericin B, but amputation of the lower limb was necessary.

Objectives To analyse VIM/IMP-type MBL-producing Enterobacteriaceae isolates identified in Poland during 2006-12. Methods Isolates were typed by PFGE, followed by MLST. blaVIM/IMP genes were amplified and sequenced within class 1 integrons. Their plasmidic versus chromosomal location was assessed by nuclease S1 and I-CeuI plus hybridization experiments. Plasmids were characterized by transfer assays and PCR-based replicon typing. Results One hundred and nineteen VIM/IMP-positive Enterobacteriaceae cases were reported in Poland from the first case in 2006 until 2012. The patients were in 54 hospitals and were infected or colonized by 121 organisms, including Enterobacter cloacae complex (n = 64), Klebsiella oxytoca (n = 23), Serratia marcescens (n = 20) and Klebsiella pneumoniae (n = 11). The isolates represented numerous pulsotypes and mainly original STs, and carried eight integrons with blaVIM-1-like genes (blaVIM-1/-4/-28/-37/-40; n = 101), three with blaVIM-2 variants (blaVIM-2/-20; n = 17) and one with blaIMP-19 (n = 3). Six integrons were new, and five and two formed prevalent families of In238-like (n = 96) and In1008-like (n = 16) elements, respectively. In238 (aacA4-blaVIM-4rpt) and In1008 (blaVIM-2-aacA4) had been originally observed in Polish Pseudomonas aeruginosa, suggestive of their transfer to enterobacteria, followed by spread and diversification. Four organisms have disseminated inter-regionally, i.e. Enterobacter hormaechei ST90 with plasmidic In238/In238a integrons (n = 36), K. oxytoca ST145 with a chromosomal In237-like element (n = 18) and two subclones of E. hormaechei ST89 with In1008- or In238-type variants (n = 8 and n = 7, respectively). Conclusions The epidemiology of VIM/IMP-producing Enterobacteriaceae in Poland has revealed a remarkable number of specific or novel characteristics of the organisms, with some possible links to other mid-southern European countries.

Alcoholic propolis extracts may be used to eliminate microbes in mucous membranes and skin inflammations and in wound infections. The aim of this study was an assessment of the ethanol extract of propolis (EEP) activity against biofilm formation by P. mirabilis. Six clinical strains of P. mirabilis isolated from patients with chronic wound infection, and one reference strain of P. mirabilis ATCC 29906 were used. Biofilm was formed in 96-well plate. In order to evaluate the effect of EEP at a concentration range of 1.56–100 mg/mL on the forming and mature biofilm, P. mirabilis cells were released by sonication. In this study the effectiveness of 25–100 mg/mL of EEP on the forming P. mirabilis biofilm and concentrations of 25–50 mg/mL of EEP on formed biofilm has been demonstrated. Our results suggest the possibility of using the EEP in treatment of chronic wound infection caused by P. mirabilis.

Introduction: Listeria monocytogenes strains are widespread in the natural environment and are the etiological factor of listeriosis. Food is the main source of L. monocytogenes. Secondary contamination of food products which results from the formation of biofilm by L. monocytogenes on the surfaces of the processing devices makes an essential problem. Material and methods: We evaluated the ability of biofilm formation in media supplemented with sheep blood (in a volume of 5.0, 10.0, 20.0 and 50.0%) for the reference strain L. monocytogenes ATCC 7644 and strains isolated from the human blood and carrots on the polypropylene surface. Results: The strain isolated from blood most efficiently formed a biofilm with increasing blood sheep’s addition (nutrient broth — 4.87 × 105 CFU × cm-2, blood supplement 50.0% (v/v) — 3.4 × 107 CFU × cm-2).The number of L. monocytogenes recovered from the biofilm for the reference strain and the strain from carrot increased to 20.0% by volume of the blood addition (3.07 × 105 CFU × cm-2 and 4.03 × 105 CFU × cm-2 respectively — nutrient broth; 1.1 × 107 CFU × cm-2 and 9.23 × 106 CFU × cm-2 — blood supplement 20.0% (v/v)). Decrease in the number of cells recovered from the biofilm for the reference strain and the one isolated from carrot has been demonstrated at 50.0% addition of blood into nutrient medium (8.8 × 106 CFU × cm-2 and 7.87 × 106 CFU × cm-2 respectively). Conclusion: The addition of sheep blood to the medium at concentrations up to 20.0% increases the number of cells recovered from the biofilm for all studied L. monocytogenes strains whereas medium with 50.0% blood stimulates the biofilm formation only by the strain isolated from blood.

Background: Raoultella is a Gram-negative bacteria, which commonly occur in the natural environment such as water, soil and on plants. In recent years, Raoultella spp. gained more interest. There is also an increasing number of publications describing mainly clinical cases involving these bacteria. Identification of Raoultella spp. is difficult due to a phylogenetic relationship with Klebsiella spp. Purpose: Available biochemical tests do not always allow for their identification to species. Thus, the aim of this study was to evaluate selected methods of identification of Raoultella spp. and their differentiation from genus Klebsiella. Materials and Methods: In this evaluation three methods were used such as manual test ID32E (bioMérieux), automatic test VITEK2 Compact (bioMérieux) and matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) method (Bruker). Results: Good identification of the species was obtained for 81.4% of the strains in the ID32E test, 93.3% in VITEK2 Compact test, and 97.4% in MALDI-TOF MS method, respectively. Conclusion: It was established that MALDI-TOF MS method is reliable in identifying genus Raoultella.

Vaginal and/or rectal Escherichia coli colonization of pregnant women is sometimes associated with neonatal infections. Despite the relevance of these strains, they have been rarely described before. Thus, the aim of this study was to compare vaginal (VEC) and rectal E. coli (REC) isolates in respect of antimicrobial susceptibility and the frequency of virulence-associated genes (VAGs). The antimicrobial susceptibility of 50 VEC and 50 REC isolates was performed by using the disc diffusion method, and VAGs were detected by PCR. There were no significant differences in the antimicrobial resistance between VEC and REC. Both VEC and REC isolates were mostly resistant to ticarcillin (36 and 30%) and ampicillin (36 and 22%). None of the tested isolates was positive for ESBL. Gene's fimH, fimA, sfa/foc, iutA, ibeA, hlyF, and neuC were detected, respectively, in 98, 92, 32, 28, 12, 8, and 2% of VEC and in 94, 72, 12, 34, 8, 10, and 8% of REC isolates. The co-occurrence of fimA/H and sfa/foc genes was significantly more prevalent among VEC isolates, in comparison to REC isolates. The study indicated that VEC and REC isolates are quite similar in terms of antimicrobial non-susceptibility and VAGs.

Aims The aim of the study was to evaluate the microbicidal effectiveness of radiant catalytic ionization (RCI) against Listeria monocytogenes strains in the form of planktonic cells and biofilm on food products and food contact surfaces as a method of food preservation. Methods and results The study material comprised six strains of L. monocytogenes, isolated from food. Samples of different types of food available by retail (raw carrot, frozen salmon filets, soft cheese) and the fragments of surfaces (stainless steel AISI 304, rubber, milled rock tiles, polypropylene) were used in the experiment. The obtained results showed the effectiveness of RCI in the inactivation of both forms of the tested L. monocytogenes strains on all the surfaces. The effectiveness of RCI for biofilm forms was lower as compared with planktonic forms. The PRR value ranged from 18·19 to 99·97% for planktonic form and from 3·92 to 70·10% for biofilm. Conclusions The RCI phenomenon induces the inactivation of L. monocytogenes on surfaces of food and materials used in the processing industry to a varying degree, depending on the manner of surface contamination, the properties of the contaminated materials as well as on the origin of the strain and the properties of surrounding dispersive environment in which the micro-organisms were suspended. Significance and impact of the study Searching of new actions aimed at the reduction of the microbial contamination of food and food contact surfaces are extremely important. RCI method has been already described as an effective technique of microbial and abiotic pollution removal from air. However, our studies provide new, additional data related to evaluation the RCI efficacy against microbes on different surfaces, both in planktonic and biofilm form.

Proteus spp. is an etiological factor of urinary tract and bloodstream infections. The aim of this study was the retrospective analysis of susceptibility of Proteus spp. strains isolated from bloodstream infections (BSIs) as well as similarity evaluation of the strains isolated from different clinical samples. Proteus spp. strains were isolated in 2009-2017 from hospital patients. Identification was based on the colony's morphology and biochemical or MALDI-TOF MS analyzes. The antibiotic susceptibility test was done using the diffusion method. Biofilm formation was evaluated with microplate method using TTC. Bacteremia caused by Proteus spp. was found in 97 patients, mainly secondary to urinary tract infection. Most of the strains were susceptible to piperacillin with tazobactam (95.9%) and amikacin (86.7%). Elderly patients have a higher risk of mortality after BSIs caused by Proteus spp. A detailed analysis was made for randomly chosen 26 strains isolated from 11 patients with Proteus mirabilis bacteremia. Using PFGE, we found that 10 (90.9%) isolates, collected from different clinical specimens of the same patient, were genetically identical. Proteus spp. is an etiological factor of urinary tract and bloodstream infections. The aim of this study was the retrospective analysis of susceptibility of Proteus spp. strains isolated from bloodstream infections (BSIs) as well as similarity evaluation of the strains isolated from different clinical samples. Proteus spp. strains were isolated in 2009–2017 from hospital patients. Identification was based on the colony’s morphology and biochemical or MALDI-TOF MS analyzes. The antibiotic susceptibility test was done using the diffusion method. Biofilm formation was evaluated with microplate method using TTC. Bacteremia caused by Proteus spp. was found in 97 patients, mainly secondary to urinary tract infection. Most of the strains were susceptible to piperacillin with tazobactam (95.9%) and amikacin (86.7%). Elderly patients have a higher risk of mortality after BSIs caused by Proteus spp. A detailed analysis was made for randomly chosen 26 strains isolated from 11 patients with Proteus mirabilis bacteremia. Using PFGE, we found that 10 (90.9%) isolates, collected from different clinical specimens of the same patient, were genetically identical.

Candida spp. is able to form a biofilm, which is considered resistant to the majority of antifungals used in medicine. The aim of this study was to evaluate the in vitro activity of micafungin against Candida spp. biofilms at different stages of their maturation (2, 6, and 24 h). We assessed the inhibitory effect of micafungin against 78 clinical isolates of Candida spp., growing as planktonic or sessile cells, by widely recommended broth microdilution method. The in vitro effect on sessile cells viability was evaluated by colorimetric reduction assay. All examined strains were susceptible or intermediate to micafungin when growing as planktonic cells. At the early stages of biofilm maturation, from 11 (39.3%) to 20 (100%), tested strains, depending on the species, exhibited sessile minimal inhibitory concentrations (SMICs) of micafungin at ≤ 2 mg/L. For 24-h-old Candida spp. biofilms, from 3 (10.7%) to 20 (100%) of the tested strains displayed SMICs of micafungin at ≤ 2 mg/L. Our findings confirm that micafungin exhibits high potential anti-Candida-biofilm activity. However, this effect does not comprise all Candida species and strains. All strains were susceptible or intermediate to micafungin when growing as planktonic cells, but for biofilms, micafungin displays species- and strain-specific activity. Paradoxical growth of C. albicans and C. parapsilosis was observed. Antifungal susceptibility testing of Candida spp. biofilms would be the best solution, but to date, no reference method is available. The strongest antibiofilm activity of micafungin is observed at early stages of biofilm formation. Possibly, micafungin could be considered as an effective agent for prevention of biofilm-associated candidiasis, especially catheter-related candidaemia.

In recent years, colistin has been the drug of choice for treatment of nosocomial infections, especially in bloodstream infections, lower respiratory tract infections, or urinary tract infections. In this study, 65 multidrug-resistant Klebsiella pneumoniae isolated from different clinical samples were included. Minimum inhibitory concentration (MIC) of colistin was detected by broth microdilution method in three different ways. For selected K. pneumoniae strains, eazyplex SuperBug mcr-1 test was performed. This test detects mcr-1 gene, which encodes a colistin-resistance determinant. Most of the analyzed K. pneumoniae strains were resistant to colistin in all applied methods. The exception was two strains, where MIC of colistin was 2 mg/L in SensiTest Colistin and MIC-Strip Colistin tests. In MIC COL test, MIC for these strains was 4 mg/L. All analyzed strains produced extended-spectrum beta-lactamases and 11 (16.9%) metallo-beta-lactamases. Eleven (16.9%) K. pneumoniae strains were resistant to all antibiotics, whereas 17 (26.1%) were susceptible to only one drug. Colistin MIC values varied from 2 to >64 mg/L in MIC-Strip Colistin test; from 2 to >16 mg/L in SensiTest Colistin and from 4 to >16 mg/L in MIC COL test. None of the analyzed K. pneumoniae strains carried mcr-1 gene. Data of this work suggest that resistance to colistin emerged among multidrug-resistant K. pneumoniae strains. The tests allowed for reliable estimation of susceptibility to colistin and could be used in microbiological diagnostics.

Between 2014 and 2017, 6,662 Enterobacterales and 1,953 P. aeruginosa isolates were collected by 19 centers in four central European countries and Israel. A further 2,585 Enterobacterales and 707 P. aeruginosa isolates were collected in 2018 by 28 centers in seven European countries and Israel as part of the Antimicrobial Testing Leadership and Surveillance (ATLAS) study. A central laboratory performed antimicrobial susceptibility testing using broth microdilution panels according to Clinical Laboratory Standards Institute (CLSI) guidelines. Susceptibility rates among Enterobacterales were highest to ceftazidime-avibactam (≥98.5%), colistin (≥97.3%), and meropenem (≥95.8%). Ceftazidime-resistant and multidrug-resistant (MDR) Enterobacterales subsets were highly susceptible to ceftazidime-avibactam (≥94.9%) and colistin (≥94.7%). Susceptibility rates to colistin among all P. aeruginosa were ≥97.4% and were ≥96.3% among ceftazidime-resistant and MDR subsets. Susceptibility rates to ceftazidime-avibactam were 91.9% (2014-2017), 86.3% (2018) and, in common with comparator agents, were lower among ceftazidime-resistant (≥51.7%) and MDR isolates (≥57.1%).

Bactericidal properties of honey depend on botanical and geographical origin, where thermal treatment can have a significant affect. The aim of this study was to investigate the effect of temperature on minimum bactericidal concentration (MBC), vitamin C content, total polyphenols content and antioxidant capacity of ferric reducing antioxidant potential (FRAP) of several nectar honey varieties from northern Poland (lime, rapeseed, multifloral and buckwheat). The honeys were subjected to thermal treatment at 22 °C, 42 °C, 62 °C, 82 °C and 100 °C for two exposure times. The results showed a significant reduction of antimicrobial properties (MBC ⩾ 50%) at 82 °C and 62 °C after 15 and 120 min exposure time for most samples. Short time exposure reduced vitamin C content ( ⩽ 50 %) but increased total polyphenols content ( ⩾ 27%) and FRAP value ( ⩾ 106%).

Introduction. Infection induced by Streptococcus pneumoniae concerns mainly children, the elderly, and people suffering from chronic diseases. The number of deaths caused by pneumococcus infections is rising worryingly. The ability to create biofilm is the main virulence factor for S. pneumoniae . The aim of this study was to evaluate the ability to form biofilm (using two different dyes) of the bacterial strains isolated from nasal and BAL, and evaluate the relationship between antibiotic sensitivity and production of biofilm. Materials and methods. For the study of S. pneumoniae biofilm formation in 96-well microtitre plates, crystal violet (CV) and tetrazolium dyes — 2,3,5-triphenyl-tetrazolium chloride (TTC) were used. Results. All isolates were able to form some degree of biofilm. The results obtained by the two methods were not significantly correlated when comparing the biofilm mass. The strains produced biofilm mass intensive when the dye was CV — 29 (96.6%) strains of S. pneumoniae strong biofilm production. When the dye was TTC, it was observed that 14 (46.6%) strains of S. pneumoniae formed strong biofilm. Conclusions. There was no significant relationship between the ability of S. pneumoniae to form biofilms and the source of isolates.

Introduction: The aim of the study was to evaluate genetic relatedness and antimicrobial susceptibility of extended-spectrum beta-lactamase-producing E. coli strains isolated from patients hospitalized in the University Hospital in Bydgoszcz (Poland).Material and methods: The study included 33 extended-spectrum beta-lactamase-producing E. coli strains isolated from 31 patients. The chromosomal DNA was extracted from the strains and separated by pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was performed by the agar dilution method and carried out according to the European Committee on Antimicrobial Susceptibility Testing recommendations.Results: According to the pulsed-field gel electrophoresis results, 32 distinct pulsotypes were revealed. Based on Molecular Analyst Fingerprinting software analysis, the studied isolates were divided into four subgroups: 6 (18.2%) isolates showing similarity greater than 90% (group A); 19 (57.6%) showing 80-90% similarity (group B); 7 (21.2%) showing 70-79% similarity (group C); and one isolate with less than 70% similarity (group D). Among E. coli isolates showing similarity greater than 90%, four antimicrobial patterns were noted. Among the isolates showing 80-90% similarity, 18 antimicrobial patterns were observed. E. coli isolates showing 70-79% similarity presented 6 antimicrobial patterns.Conclusions: Our results show a high degree of genetic diversity of extended-spectrum beta-lactamase-producing E. coli isolates. However, based on a similarity of ≥80%, almost 75% of E. coli isolates were clonally related. Although it is difficult to identify definitive transmission events based on the recovery of indistinguishable pulsed-field gel electrophoresis types alone, we speculate that extended-spectrum beta-lactamase-producing E. coli strains may have disseminated throughout the hospital.

Introduction. Equipment for sterilization used in medical laboratories must be absolutely effective in eliminating microorganisms and their spores. It often directly influences human health, even life. The aim of the study was to compare the effectiveness of sterilization using the steam sterilizer ASV E, microwave sterilizer EnbioJet ML1, microwave sterilizer for baby bottles and breast pumps AVENT and microwave oven. Materials and methods. Evaluation of the effectiveness of sterilization with the use of selected devices based on pressure-thermal and microwave-thermal methods was conducted, on the basis of elimination of G. stearothermophilus PCM 2104 and C. sporogenes IW 1306 spores. Results. After using the steam sterilizer, 100% inactivation of spores of both species was noted. In the case of EnbioJet ML1 sterilizer, in the test containing 106 CFU × cm–3 G. stearothermophilus spores, 1.63 × 101 CFU × cm–3 survived. The baby bottles sterilizer proved less effective. While the microwave, in the case of tests with the highest spore content, provided their inactivation only at the level of more than 70.0%. The steam sterilizer and EnbioJet ML1 sterilizer were the most effective, whereas the latter ensured a very short time of high temperature effect, which has a favorable impact on the properties of sterilized products, for example compounds decomposing in high temperature. Conclusion. Results of own, as well as other authors’ studies allow to confirm the large potential in the scope of using microwave radiation for the sterilization and disinfection of materials of various sensitivity to temperature.

Introduction Mastitis may result in physical, chemical and microbiological changes in milk and pathological lesions in the glandular tissue. Milk derived from cows with mastitis may become a cause of infections in humansw and animals. Objectives The aim of this study was to assess the effectiveness of selected dipping agents in the inactivation of several bacteria that may cause mastitis in cattle. Material and methods Three strains of each of the following species: Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus and Listeria monocytogenes , isolated from milk, were used in the study. Identification of isolates was carried out using the automatic system VITEK2 Compact. Evaluation of the genetic similarity between the tested strains was made using the RAPD technique. Drug susceptibility of strains was evaluated with the disc diffusion method. Assessment of the effectiveness of iodine, stabilized iodine, povidone iodine and chlorhexidine was performed using fragments of skin from cow teats. Results All the tested strains were genetically different. Most of them were susceptible to the studied antibiotics. Only two strains of L. monocytogenes were resistant to all the studied antibiotics. The percentage rate of reduction in the number of bacteria after using of dipping agents was very high (>90%). The most susceptible to the dipping preparations used were L. monocytogenes (99.6 – 99.9%). Stabilized iodine was the most effective dipping agent for all tested bacteria, causing a reduction rate in the number of bacteria from 99.80% ( E. coli ) – 99.99% ( S. aureus , L. monocytogenes ). Conclusions The results obtained may contribute to a reduction in udder infections in cows, especially mastitis, and improve the quality of the milk.

An increased frequency of multidrug-resistant non-fermenting rods isolation has resulted in the excessive use of colistin – often the last chance antimicrobial. However, determination of colistin susceptibility is difficult, mainly because of its structure and limited diffusion properties. This study was performed to compare colistin susceptibility testing among Pseudomonas aeruginosa (n = 49) and Acinetobacter baumannii (n = 49) strains. Four methods were applied: colistin gradient strips (Liofilchem, Italy), semi-automated method Phoenix BD (Becton Dickinson, USA) and two broth microdilution methods: SensiTest Colistin (Liofilchem, Italy) and MICRONAUT MIC-Strip (MERLIN Diagnostika GmbH, Germany). Data were analyzed by comparison of MIC values and strains susceptibility interpretation criteria (resistant and sensitive, respectively). The same interpretation results were obtained for 46 (93.9%) P. aeruginosa and 37 (75.5%) A. baumannii isolates in all of the applied methods. Using broth microdilution methods, the same interpretation was obtained for 48 (98.0%) P. aeruginosa and 42 (85.7%) A. baumannii isolates. The results obtained by colistin gradient strips usually confirm the results of broth microdilution tests for P. aeruginosa isolates, the automated method is in turn less labor-intensive. However, MIC values, obtained with their use, are less precise because of the antibiotic dilutions limited to only several concentrations. The results underline the importance of choosing of the appropriate type of method, also among those recommended and commercially available.