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Background: Atopic dermatitis is a chronic inflammatory dermatosis with complex pathogenesis. The skin microbiome in atopic dermatitis is dominated by Staphylococcus aureus which shows the ability to produce biofilm. Objectives: The aim of this work was to assess the influence of S. aureus biofilm on the course of atopic dermatitis. Methods: Disease severity was evaluated based on the SCORAD index in 56 adult patients with atopic dermatitis. Microtiter plate assay of the propensity to form biofilm was performed on S. aureus strains isolated from the anterior nares, lesional skin, and nonlesional skin. Microbiological results were correlated to the clinical parameters and total IgE concentration. Results: Biofilm-producing strains of S. aureus were identified in 76.3% (29/38) and 79.1% (34/43) of samples from the anterior nares and lesional skin, respectively (p > 0.05), and in 48.5% (16/33) of samples from nonlesional skin (p < 0.03). Patients colonized by biofilm-producing strains of S. aureus within the anterior nares showed statistically higher mean values of total and objective SCORAD and its components (extent, dryness), and of the largest extent of skin lesions during the flares in the last year when compared to patients colonized by non-biofilm-producing strains. Carriage of biofilm-producing S. aureus on lesional skin was associated with higher mean values of the extent of skin lesions during stable periods of the disease. Conclusions: The results of this study may suggest a relationship between the production of biofilm by S. aureus strains colonizing the anterior nares and the course of atopic dermatitis. Biofilm seems crucial for dispersal and persistent colonization of large areas of the skin by this pathogen. Destruction of S. aureus biofilm could positively affect the course of atopic dermatitis.

Background: The first New Delhi metallo-beta-lactamase (NDM)-producing bacteria were isolated in 2008 in the world, and in 2011 in Poland. Due to the high clonal diversity (17 types) of their blaNDM gene, encoded on (Tn125-like) mobile genetic elements, these strains usually exhibit resistance to nearly all available antibiotics, which is particularly dangerous for organ transplant recipients. Purpose: To assess of the prevalence of Gram-negative NDM-positive bacilli in surgery/transplantation wards of a teaching hospital in Warsaw and to ascertain the significance of screening tests on the rates and nature of colonization. Materials and methods: The evaluated strains were isolated from 30 patients (between April 2014 and May 2017). The species were identified with VITEK-MS, antibiotic susceptibility was determined with VITEK 2, disk-diffusion, and/or E-test methods, according to EUCAST guidelines. The presence of the blaNDM-1 gene was confirmed using the polymerase chain reaction technique. Results and conclusions: There were 77 blaNDM-1-positive Klebsiella pneumoniae strains isolated from 30 patients. Cultures from individual patients, mainly from rectal swabs (53.9%) and urine samples (39.8%), yielded 1-11 isolates. Fifteen patients were already colonized on admission, and the other 15 developed a symptomatic infection. In total, 24 (80%) patients were carriers, and their colonizations persisted for

Introduction Aminoglycoside resistance (AR) is common in health care-associated methicillin-resistant Staphylococcus aureus (HA-MRSA). AR is most often associated with the production of antibiotic modifying enzymes: bidomain AAC(6′)-Ie/APH(2″)-Ia acetyltransferase and phosphotransferase, ANT(4′)-Ia nucleotidyltransferase, and APH(3″)-IIIa phosphotransferase. Aim Determination of aminoglycoside sensitivity, presence of genes encoding enzymes, and molecular typing of HA-MRSA strains derived from patients hospitalized in surgical and transplantation wards. Materials and methods Fifty-four HA-MRSA strains, isolated from various materials from patients in the surgical and transplantation wards of Warsaw's clinical hospital, hospitalized between 1991 and 2007. The MIC values of gentamicin-GEN/tobramycin-TOB/amikacin-AK/netilmicin-NET were determined by the E-test (CLSI/EUCAST). Genes mecA/aacA-aphD/aadD/aph(3″)-IIIa were detected using PCR. SCCmec types were determined according to the Oliveira method and the sequence type (ST)/clonal complex (CC) by the MLST method. Results Of the isolates tested, 36 (66.7%) showed resistance to at least one aminoglycoside: TOB (57.4%), GEN (53.7%), AK (55.6%), NET (24.1%). The aacA-aphD gene was present in 29 MRSA-GEN-R (most often in combination with aadD, 15/29 or aph(3″)-IIIa, 10/29); the aacA-aphD gene was the only determinant of resistance in 1 isolate. The AR variants mainly belonged to the CC8 clonal complex (ST239/247/241/254/8) and most frequently contained SCCmec type III (3A) cassettes. Conclusions Resistance to at least one aminoglycoside was present in 66.7% of HA-MRSA and in more than 22% to all of them. The presence of the aacA-aphD gene was sufficient to express the resistance phenotype to GEN/TOB/AK/NET. Resistant isolates were closely related to each other.

Background Vancomycin is still one of the most commonly used drug for treatment of severe methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin-resistant S. aureus (VRSA) strains are a serious danger for public health. This study aimed to characterize healthcare-associated MRSA (HA-MRSA) strains, resistant to at least one of glycopeptide antibiotics: vancomycin (VRSA) and/or teicoplanin (TRSA), isolated at three Warsaw hospitals over a period of 17-years (1991–2007). Methods Among 600 HA-MRSA strains, isolated from patients with symptomatic infections, 47 were subjected to detailed analysis. In the study, mechanisms behind VRSA phenotypes were determined (E-tests, GRD-test, agar-dilution method and vanA/B detection). Characteristics of selected isolates on molecular level: i) by detection of resistance genes ermA/ermB/ermC, msrA/msrB, linA/linA’, aacA-aphD, aadD, aph(3”)-IIIa; ii) SCCmec-typing and iii) MLST-typing was done. Results In general population of studied strains, 11/47 (23.4%) were VRSA and 36/47 (76.6%) were resistant only to teicoplanin. All isolates exhibited van-independent mechanisms of resistance. Over 80% of isolates belonged to clonal complex CC8, with the following predominant sequence types (STs)/clones: ST247-IA/Iberian, ST241-III/Finland-UK, and ST239-III/Brazilian. Most of the isolated strains harboured ermA and aacA-aphD genes, encoding additional resistance to macrolides, lincosamides, streptogramin B, and majority of aminoglycosides. They occurred also in Polish VRSA/TRSA population over the period, which was subjected for analysis: an increase in MIC values for glycopeptides, evolution in terms of the level and extent of resistance, and genetic re-assortment in epidemic clones. Conclusions VRSA strains isolated from patients hospitalized at three Warsaw teaching hospitals in Poland, over a period of 17-years do not pose a threat as potential donors of van genes in horizontal-gene transfer processes, but are constantly evolving and represent international epidemic clones.

INTRODUCTION. Staphylococcus aureus is a microorganism, which is able to colonize the human body without any pathogenic effect, but it also can cause life-threatening infections (opportunistic pathogen). Asymptomatic colonization with both methicillin resistant (MRSA) and methicillin susceptible (MSSA) S.aureus strains state is an important predisposing factor for infections. The risk of infection for carriers of MSSA is even three-times higher than for non-colonized people, and in the case of MRSA it is even four-times higher than in MSSA carriers. Carriers can be also a source of infection for other people, especially those belonging to high-risk groups. The drug of choice used for the local eradication of S.aureus is mupirocin (Mup). In recent years, the failure of decolonization therapy has been observed. The aim of the study was to assess and compare the level of colonization of S.aureus (MRSA or MSSA) among medical students and to evaluate the sensitivity of the strains to mupirocin. For MRSA/MupRSA isolates the molecular mechanism of resistance phenotype was determined. MATERIALS AND METHODS. 955 swabs from 2014-2016 from pre-clinical students of medicine of the Medical University of Warsaw. The strains were identified using Pastorex-Staph-Plus (BioRad) and/or the VITEK-MS system (Biomerieux), according to manufacturer’s instructions. Susceptibility to methicillin and mupirocin was determined by disk diffusion and/or broth microdilution method, according to EUCAST. The presence of the mecA/mecC and mupA genes were detected with PCR technique. RESULTS. Asymptomatic colonization with S.aureus strains was found in 245/955 (25,7%) students, in particular years in the range of 21,7-29,9%. 243 isolates expressed the MSSA/MupSSA phenotype, one strain was resistant to mupirocin MSSA/MupRSA (genotype mecA/mecC-negative, mupA-positive) and one showed simultaneous resistance to methicillin and mupirocin (mecA/mupA-positive genotype). The level of MRSA and MupRSA colonization was 0,1% and 0,2%, respectively. SUMMARY AND CONCLUSIONS. The level of S.aureus colonization among surveyed students, didn’t differ from the norm for a generally healthy population, but showed an upward trend. The carriage of S.aureus, especially of multi-resistant strains among medical students at the beginning of their clinical activities, consist of a real threat to patients and other people.

Background Biofilm occurring on removable prostheses is a reservoir of bacterial flora, consisting of both physiological and pathogenic multidrug-resistant microorganisms. Patients undergoing dialysis and organ transplantation are particularly prone to bacterial infections, which can have its source in denture plaque. This study was a comparison of the composition of staphylococcal flora within the surface of the pharyngeal mucous membrane as well as denture plaque in kidney transplant recipients. Methods The study included 44 subjects with removable prostheses who reported for a kidney transplant procedure. Swab samples were collected from prostheses and the pharyngeal wall. Isolated strains were identified and investigated for drug resistance. Results A total of 72 strains of Staphylococcus were isolated from the denture plaque and 53 from the pharynx. In the pharynx, the following species prevailed: Staphylococcus epidermidis, Staphylococcus warneri , and Staphylococcus aureus. The following species prevailed in denture plaque: S epidermidis, S aureus, and Staphylococcus haemolyticus. Among the pharyngeal strains, antibiotic resistance most commonly referred to natural penicillin (77%), constitutive macrolide-lincosamide-streptogramin B resistance (28%), and tetracycline (26.4%). In case of denture plaque, the highest percentage of strains demonstrated resistance to natural penicillin (60%), fosfomycin (32%), and cefoxitin (25%). In 10 subjects (48%), Staphylococcus -induced infections occurred in the first year after transplantation, 5 of which had the same bacterial strain as cultured previously from dentures. Conclusions The denture biofilm and surface of the pharynx differ in terms of bacterial composition and bacterial drug resistance profiles. Denture plaque constitutes a considerable reservoir of staphylococcal flora, which can be a potential source of infection in organ transplant recipients.

Background Removable dentures improve function and aesthetics of masticatory organ. Their proper scheme of use and hygiene procedures have an impact on biofilm formation. Microorganisms in biofilm are often resistant to many antibiotics and may pose a potential threat to patients treated with organ transplant. The study provided for evaluation of dental prostheses hygiene standards with reference to staphylococcal microflora in kidney transplant recipients. Methods The study involved 62 patients with removable prostheses. Thirty-seven subjects of this group had renal replacement therapy. The other 25 were volunteers with normal renal function. Medical and dental history was collected. Denture hygiene was assessed and swab sampling for microbiological testing were performed on the impression surface of the denture plate. Results Denture hygiene standards and proper scheme of their use were significantly better in patients of the control group. In both groups, significantly with longer denture use, patient care to provide proper hygiene standards declines. Staphylococcal strains were found in 92% patients of the study group and 84% of the control group, 43% of which were multi-drug resistant strains. No relation was found between patients overall health conditions as well as denture use methods and composition of staphylococcal denture plaque. Conclusions Overall health conditions and denture use methods might not have an influence on staphylococcal denture plaque composition. However, the studies conducted did not answer the question of whether the above factors cause quantitative differences. Multidrug-resistant staphylococcal strains inhabiting denture surface may pose a threat to the health of kidney transplant recipients.

INTRODUCTION. Staphylococcus aureus, which is able to produce an extracellular mucopolysaccharide (MP) and biofilm (SP), is an important etiologic agent in persistent and implant-related infections. This phenotype may be expressed in different levels and character depending on various environmental and/or global intracellular regulatory mechanisms. It may also be induced by sub-inhibitory concentrations of some antibiotics, for example vancomycin. The main aim of the study was to assess the ability to produce MP and SP in different oxygen conditions by clinical isolates of S.aureus nonsusceptible to glycopeptides. MATERIALS AND METHODS. Clinical isolates of health-care associated methicillin resistant S. aureus (HA-MRSA) strains, non-susceptible to glycopeptides (GRSA, 47) and heterogeneous vancomycin intermediate S. aureus isolates (h-VISA, 8). Control group consisted of the following strains: 55 belonging to MRSA, vancomycin susceptible, VSSA and 19 as methicillin susceptible, MSSA/VSSA. The ability to produce MP was investigated according to Freeman method. SP production was tested by means of Christensen procedure. RESULTS. In aerobic conditions MRSA/GRSA and MRSA/h-VISA isolates were the strongest mucopolysaccharide (SMP) producers (12.2% and 28.6% SMP/MP), but MSSA/VSSA were the most frequent MP (100%). In anaerobic atmosphere, all isolates from all groups were MP-positive. MRSA/h-VISA were the strongest MP producers (75% SMP/MP), but MSSA/VSSA were the most susceptible to oxidative stress (the percentage of SMP among MP for MSSA/VSSA increased by 15.8 times). Each evaluated group of clinical S. aureus isolates in aerobic condition had representation in SP positive phenotype: MRSA/GRSA and MRSA/h-VISA, 63.9% and 62.5%; MRSA/VSSA and MSSA/VSSA, respectively 80% and 94.7%. For all mentioned groups of bacteria, SSP variants were present and the amount of values was higher than in similar results obtained in CRA method. The strongest slime producers (60%) were h-VISA strains. The results obtained in Christensen method for anaerobic conditions, were not conclusive due to insufficient optimization of the test parameters. SUMMARY AND CONCLUSIONS. Both methods reveal that MRSA isolates non-susceptible to glycopeptides are the strongest producers of both MP and SP. That is probably due to cell wall alterations and global regulatory system Agr disorders. The Christensen procedure allow to assess both ica- dependent and ica- independent (adhesive) mechanisms of slime production and allow to notice that, as a phenotyping “biofilm booster effect”. ica- dependent mechanism, which dominated in MSSA/VSSA strains, demonstrate phenotype with more susceptibility to oxygen stress conditions than adhesive one.

The purpose of this study was to assess drug susceptibility of clinical B. fragilis strains and to determine any correlation between drug resistance and the presence of specific genes. Antimicrobial susceptibility was assessed using E-tests. All isolates were analyzed with the PCR technique for the presence of antibiotic resistance genes (cepA, cfxA, cfiA, ermF, ermB, ermG, nim), insertion sequences elements (IS1186, IS1187, IS1188, IS942), and enterotoxin-encoding genes (bft). Susceptibility tests yielded the following rates of resistance to the evaluated antibiotics: penicillin G (100%), clindamycin (22.5%), cefoxitin (6.3%), amoxicillin/clavulanic acid (1.8%). All strain were susceptible to imipenem, and metronidazole. The following antibiotic resistance genes were detected in the evaluated isolates: cepA (in 96.4% of isolates), cfxA (in 12.6%), cfiA (in 1.8%), and ermF (in 25.2%). Genes ermB, ermG, and nim were not found. The presence of the cepA gene showed no correlation with the penicillin G MIC. However, we observed a high correlation between cefoxitin MIC values and the presence of gene cfxA as well as a nearly complete correlation between clindamycin MIC values and the presence of gene ermF. The presence of a bft gene was detected in 14.4% of the analyzed B. fragilis isolates; with the bft-1 allele found in 75%, bft-2 in 25%, and bft-3 in none of the isolates. Antibiotic susceptibility profiles of enterotoxin gene-positive isolates in our study did not differ from those of enterotoxin gene-negative isolates.

Introduction Staphylococcus aureus infection, and health care-associated-methicillin resistant S aureus (HA-MRSA) in particular, is a serious risk for patients treated with organ transplantation. The frequent combined resistance of these bacteria to macrolides, lincosamides, and streptogramin-B (MLS-B) limits the use of these drugs in therapy. Aim Evaluation of the mechanism of MLS-B resistance among HA-MRSA strains derived from patients treated in surgical-transplantation wards, over a 24-year period, and assessment of correlation of clindamycin use and resistance phenotype. Materials and methods One hundred and twelve HA-MRSA strains from patients in surgical-transplantation wards (clinical hospital, Warsaw), hospitalized in the period from 1991 to 2014. Methicillin-resistance was determined using phenotypic and genetic methods by detecting the mecA gene. Erythromycin/clindamycin resistance was determined by E-test, the iMLS-B (inductive) and cMLS-B (constitutive) phenotypes by the D-test method. The number of defined daily doses (DDD), statistically per 1000 person-days, was calculated in accordance with the WHO guidelines. Results Resistance to erythromycin/clindamycin in MRSA strains increased from 1991 to 2004–2007 from 64.7/11.8% to 100/76.9%, respectively. The frequency of the cMLS-B phenotype in the years 1991/2010–2011/2012 was 5.9%/76.9%/69.7%, respectively, and correlated with the increased use of clindamycin in the examined wards. In 2012, the percentage of MLS-B-sensitive isolates increased from 3.9 to 21.7%, while constitutive resistance decreased to 69.7%, which correlated with a decrease in the use of clindamycin. Conclusions The proportion of cMLS-B to iMLS-B phenotypes in HA-MRSA is related to the amount of clindamycin used in hospital wards. Limiting the selection pressure of antibiotics can lead to complete loss of resistance or return to the inductive mechanism of its regulation.

Background Blood infections with multidrug-resistant Gram-negative carbapenem-resistant bacilli are particularly dangerous and challenging to treat in organ transplant recipients. Resistance to carbapenems may be acquired, for example, in Enterobacteriaceae, Pseudomonas, or Acinetobacter spp. or innate, for example, in Stenotrophomonas maltophilia. The purpose of this study was to analyze blood infections caused by S maltophilia in organ transplant recipients and to compare drug susceptibility of these bacteria and the same species isolated from the blood of other inpatients. Methods A total of 26 S maltophilia strains isolated from blood samples of 26 patients (including 14 liver or kidney transplant recipients) hospitalized during 2011 to 2014 were evaluated in this study. Antibiotic susceptibility was determined via E-test and disk diffusion methods. Results Stenotrophomonas maltophilia strains isolated from blood exhibited sensitivity to trimethoprim/sulfamethoxazole (100%), levofloxacin (96.2%), ciprofloxacin (92.3%), ticarcillin/clavulanic acid (80.8%), and ceftazidime (53.9%). Conclusions Because appropriate antibiotic therapy in the case of S maltophilia differs from the standard empirical therapy administered in the case of most other Gram-negative bacilli, early identification of this pathogen is of particular significance. The use of antibiotics to which this pathogen is sensitive eliminates the infection and helps avoid graft loss.

Objectives The aims of this study were (i) to analyse strains of the genera Bacteroides and Parabacteroides isolated from clinical specimens for phenotypic resistance to clindamycin, (ii) to detect erm genes in the isolates and (iii) to determine any correlation between in vitro resistance and the presence of erm genes. Methods The Bacteroides and Parabacteroides isolates analysed were obtained from patients hospitalised at teaching hospitals in Poland. Antimicrobial susceptibility testing was performed by Etest and the results were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. All isolates were analysed by PCR for the presence of the resistance genes ermF, ermB and ermG. Results Resistance to clindamycin was detected in 31.0% (62/200) of all evaluated isolates, with the ermF and ermB genes detected in 31.0% (62/200) and 0.5% (1/200) of isolates, respectively. No isolates with ermG were detected among the evaluated strains. Pearson’s test showed an almost perfect correlation between clindamycin minimum inhibitory concentrations (MICs) and the presence of ermF in Bacteroides spp. and Parabacteroides distasonis isolates, although the ermF gene was also present in 10 clindamycin-susceptible isolates of Bacteroides spp. Conclusions This study demonstrated a substantial proportion of Bacteroides (22.5–100% depending on the species) and 50.0% of Parabacteroides strains exhibiting resistance to clindamycin. The clindamycin MIC for resistant strains in each case was ≥256 mg/L. Resistance to clindamycin in Bacteroides and Parabacteroides species is correlated mainly with the presence of the ermF gene.

Objectives Hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) frequently causes therapeutic problems and provides information about the epidemiological condition of the ward. Materials and Methods HA-MRSA isolated from patients on transplantation wards in 1991, 1994, 1996, and from 2005 to 2007 were compared using molecular methods such as restriction fragment length polymorphism–pulse field gel electrophoresis, multilocus sequence typing (MLST), multiplex polymerase chain reaction (PCR) for detection type of staphylococcal chromosomal cassette mec, and PCR for detection. Results The analysis covered HA-MRSA strains, each from a different patient. All organisms were typed using molecular methods. MLST results were compared with an international base. The examined strains belonged to five different worldwide known clonal complexes: CC8 (78%), CC5 (12%), CC1 (4%), CC30 (2%), and CC51 (4%). All could be recognized as representatives of a clonal complex CC8 clones: ST239-III (sequence type 239 and SCCmec type III named EMRSA-1, -4, -11, Brasilian, Hungarian) occurred with a frequency of 35.9%, ST254-IV (EMRSA-10, Hannover) occurred in 33.3%, ST247-I (EMRSA-5,-7, Iberian) occurred in 20.5%, ST241-III (Finland-UK) occurred in 5.15%, and ST8-IV (EMRSA-2,-6) occurred in 5.15%. Conclusion The predomination of different clones of HA-MRSA in the particular years was observed. In 1991, the EMRSA-10 (Hannover) clone predominated (53.3%). The Brasilian-Hungarian (EMRSA-1, -4, -11) clone predominated in 1994 (50%) as well as from 2005 to 2007 (41.3%), whereas in 1996 the Iberian clone was most frequent (53.9%).

Background The increasing prevalence of multi-drug–resistant methicillin-resistant Staphylococcus aureus (MRSA) is a substantial problem in hospitals worldwide, especially in wards with immunocompromised patients undergoing organ transplant. Epidemiological characteristics and antibiotic susceptibility profiles of hospital-acquired (HA) MRSA strains isolated from surgical/transplantation ward patients were studied. Methods We analyzed 26 HA-MRSA strains isolated from 22 patients hospitalized at 3 different surgical and transplantation wards at a Warsaw clinical hospital during 2010 to 2011. Eleven patients were MRSA-asymptomatic carriers. Strain relatedness was evaluated through the use of multi-locus sequence typing (MLST), multi-locus variable-number tandem repeat analysis (MLVA), and random amplified polymorphic DNA/arbitrarily primed PCR (RAPD) methods. Antibiotic susceptibility was assessed the use of routine diagnostic methods. Results The evaluated strains belonged to 4 clonal complexes (CCs) and 4 sequence types (STs): CC30/ST36 (65.4%), CC8/ST8 (15.4%), CC5/ST1827 (11.5%), and CC1/ST1 (7.7%). Six MLVA types and 6 RAPD types were isolated. A ciprofloxacin-, erythromycin-, and clindamycin-resistant CC30/ST36 clone (MLVA type 1, RAPD type 1A) was isolated in all wards. The isolated HA-MRSA strains were most often resistant to ciprofloxacin (100%), erythromycin (96.2%), clindamycin (84.6%), and gentamycin (30.8%). Conclusions A ciprofloxacin-, erythromycin-, and clindamycin-resistant HA-MRSA ST36 CC30 clone, which prevailed on transplantation wards in the years 2010 to 2011, is probably one of the international epidemic clones named UK EMRSA-16 or USA200.

The study included 79 vancomycin-resistant Enterococcus faecium (VRE) strains isolated from 33 patients after kidney (n = 19) or liver (n = 14) transplantation; these patients were hospitalized between 2010 and 2012. The strains were obtained from infected persons as well as from carriers. All examined strains were tested for the susceptibility to antimicrobials active against enterococci and for the presence of vanA and vanB genes as well as the presence of the insertion sequence IS16 considered as one of the markers of hospital-associated strains. All 79 VRE strains of E faecium possessed IS16 and the vanA (vanB-negative) determinant. All tested strains were resistant to at least three groups of drugs; therefore, they were recognized as multidrug resistant. All isolates were resistant to glycopeptides, ampicillin, and most were resistant to tetracyclines, macrolides, nitrofurans, and high concentrations of aminoglycosides. The presence of insertion element IS16 and multiple resistance determinants prove that strains colonizing or infecting solid organ recipients were typical nosocomial pathogens.

Background Recent years have seen a concerning increase in the number of carbapenem-resistant Pseudomonas aeruginosa strains. P aeruginosa is one of the most dangerous factors causing nosocomial infections, and immunosuppressed patients constitute a special risk group. The purpose of our study was to conduct a molecular analysis of 22 clinical isolates of carbapenem-resistant P aeruginosa obtained between 2008 and 2011. Materials and Methods Metallo-beta-lactamase (MBL) phenotype tests were conducted. A polymerase chain reaction technique was used to detect VIM, IMP, NDM, and GIM carbapenemase-encoding genes. The minimum inhibitory concentrations were determined for imipenem, meropenem, and doripenem. Molecular typing was conducted with the use of restriction fragment length polymorphism/pulsed-field gel electrophoresis (RFLP-PFGE). Results Of the 22 strains initially resistant to at least one carbapenem, we selected 18 that exhibited the MBL phenotype. Of those 18, we identified 15 strains expressing VIM carbapenemase-encoding genes. None of the other evaluated genes were detected. VIM-positive isolates exhibited higher levels of resistance than the other ones. The RFLP technique revealed 10 different PFGE types and 6 epidemic foci. Identical strains were isolated over the period of up to 3 years. Conclusions The reason for resistance to carbapenems in the majority (68%) of P aeruginosa strains isolated at the evaluated hospital was the presence of VIM carbapenemase. It is safe to say that the VIM carbapenemase is responsible for a higher level of resistance than unidentified mechanisms. Carbapenem-resistant strains of P aeruginosa spread clonally within individual wards and are likely to be of hospital origin.

Objectives Vancomycin-resistant enterococci (VRE) frequently cause therapeutic problems and provide information about the epidemiological condition of the ward. Materials and Methods VRE isolated from patients on transplantation wards in 2007–2008 were compared using 2 molecular methods: RFLP-PFGE (restriction fragment length polymorphism-pulse field gel electrophoresis) and MLST (multilocus sequence typing). Results The analysis covered 29 Enterococcus faecium strains resistant to glycopeptides, each from a different patient. All organisms were typed using 2 molecular methods. MLST results were compared with an international base. The 30 examined strains belonged to 8 different worldwide known sequence types. All could be recognized as representatives of a single clonal complex CC17. Conclusion Both methods of typing appeared to be useful to asses the epidemiological condition of the investigated wards.

Background Infections due to Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are associated with increased therapeutic failure and mortality. Our laboratory recognized several strains producing KPC, most of which originated from transplantation ward patients. Materials and Methods All strains of K pneumoniae resistant to at least 1 carbapenem isolated in 2010 were examined for KPC production by disc diffusion and then verified by molecular methods. Results All positive strains originated from 7 patients. Six of them were from transplantation wards. None of the KPC-producing strains was isolated from the patient's blood. Conclusions A quick, accurate diagnosis of KPC-producing strains enabled immediate isolation of carriers or infected persons. Isolation prevented spread of dangerous strains among immunocompromised patients and reduced the possibility of serious infections.