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Abstract 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. Highlights • cMLS-B MRSA were selected under the pressure of clindamycin from previous iMLS-B. • Spontaneous mutations caused an increase in the incidence of cMLS-B variants. • A 14-fold increase in the occurrence of cMLS-B was noted between 1991 and 2014. • Limiting clindamycin use may lead to restoration of the inducible phenotype. [ABSTRACT FROM AUTHOR]

Abstract 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 mec A/ aacA-aphD/aadD/aph(3″)-IIIa were detected using PCR. SCC mec 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 aad D, 15/29 or aph(3″)-IIIa, 10/29); the aac A- aph D 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 SCC mec 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 aac A- aph D gene was sufficient to express the resistance phenotype to GEN/TOB/AK/NET. Resistant isolates were closely related to each other. Highlights • 66.7% of tested HA-MRSA were resistant to at least 1 aminoglycoside antibiotic. • Almost 70% of AR-MRSA were resistant to 3 or 4 of the tested drugs. • The aac A- aph D is sufficient to express a high resistance to GEN, TOB, AK, and NET. • 75% of AR-MRSA belonged to the CC8 group, mainly the Brazilian and Finland-UK clones. • Nearly 42% of resistant variants included SCC mec type III cassettes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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%). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 IS 16 considered as one of the markers of hospital-associated strains. All 79 VRE strains of E faecium possessed IS 16 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 IS 16 and multiple resistance determinants prove that strains colonizing or infecting solid organ recipients were typical nosocomial pathogens. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract 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 bla NDM 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 bla NDM-1 gene was confirmed using the polymerase chain reaction technique. Results and Conclusions There were 77 bla NDM-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 <1–20 months. Most isolates were susceptible only to colistin, gentamicin, amikacin, tigecycline, and/or sulfamethoxazole/trimethoprim. Gastrointestinal-tract-colonizing K pneumoniae are the main reservoir of the bla NDM-1 gene. Following the introduction of on-admission mandatory screening for carbapenem-resistant strains, the rates of NDM-producing K pneumoniae isolation increased (7.5-fold), while the rates of isolation from patients with symptomatic infections considerably decreased (2.8-fold). Highlights • NDM-producing K pneumoniae cause serious therapeutic and epidemiological problems. • KP-NDM in the gastrointestinal tract constitute the main reservoir of bla NDM gene. • Mandatory on-admission screening tests for NDM-positive CRE are highly advisable. • Early detection of asymptomatic NDM-carriage reduces the incidence of infections. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]