Multilocus-sequence typing reveals clonality of Staphylococcus aureus in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is exacerbated by Staphylococcus aureus, which is capable of displacing not only the physiological microbiota, but also other strains of its own species. Analyses of the molecular characteristics and relationships of S. aureus strains present in different microniches are lacking.

OBJECTIVES

To determine, using multilocus sequence typing (MLST), the relationship of S. aureus isolates from the lesional and nonlesional skin and anterior nares of patients with AD, and to review the characteristics of the dominant clones.

METHODS

Sixty-three individuals with active AD were enrolled. Ten patients with moderate-to-severe AD (SCoring of Atopic Dermatitis score ≥ 25) colonized by S. aureus in all analysed locations were included in the MLST analysis.

RESULTS

The most prevalent sequence types were 7 (10/30 strains; 33.3%), 15 and 97 (both 5/30 strains; 16.7%) all of which were associated with the expression of adhesins and toxins promoting chronic microbial dysbiosis, skin barrier damage and inflammation. Six patients (60%) were carriers of clonal S. aureus strains at all analysed locations, three (30%) carriers in lesional and nonlesional skin, and one (10%) was a carrier in nonlesional skin and the anterior nares.

CONCLUSIONS

The results imply that the identified S. aureus lineages are better adapted to dominate the microbiota in AD. Decontaminating the identified reservoirs of S. aureus (i.e. anterior nares and nonlesional skin) could reduce the severity of AD.

The Impact of Harsh Stratospheric Conditions on Survival and Antibiotic Resistance Profile of Non-Spore Forming Multidrug Resistant Human Pathogenic Bacteria Causing Hospital-Associated Infections

Bacteria are constantly being lifted to the stratosphere due to air movements caused by weather phenomena, volcanic eruptions, or human activity. In the upper parts of the atmosphere, they are exposed to extremely harsh and mutagenic conditions such as UV and space radiation or ozone. Most bacteria cannot withstand that stress, but for a fraction of them, it can act as a trigger for selective pressure and rapid evolution. We assessed the impact of stratospheric conditions on the survival and antibiotic resistance profile of common non-spore-forming human pathogenic bacteria, both sensitive and extremely dangerous multidrug-resistant variants, with plasmid-mediated mechanisms of resistance. Pseudomonas aeruginosa did not survive the exposure. In the case of strains that were recovered alive, the survival was extremely low: From 0.00001% of Klebsiella pneumoniae carrying the ndm-1 gene and methicillin-resistant Staphylococcus aureus mecA-positive with reduced susceptibility to vancomycin (MRSA/VISA), to a maximum of 0.001% of K. pneumoniae sensitive to all common antibiotics and S. aureus sensitive to vancomycin (MRSA/VSSA). We noticed a tendency towards increased antibiotic susceptibility after the stratospheric flight. Antimicrobial resistance is a current real, global, and increasing problem, and our results can inform current understandings of antibiotic resistance mechanisms and development in bacteria.

Enterotoxin Gene Cluster and selX Are Associated with Atopic Dermatitis Severity-A Cross-Sectional Molecular Study of Staphylococcus aureus Superantigens

Staphylococcus aureus superantigens (SAgs) have been reported to aggravate atopic dermatitis. However, comprehensive analyses of these molecules in multiple microniches are lacking. The present study involved 50 adult patients with active atopic dermatitis. S. aureus was isolated from the lesional skin, nonlesional skin, and anterior nares. Multiplex-PCR was performed to identify genes encoding (1) selX (core genome); (2) seg, selI, selM, selN, selO, selU (enterotoxin gene cluster, EGC); and (3) sea, seb, sec, sed, see, tstH (classic SAgs encoded on other mobile genetic elements). The results were correlated to clinical parameters of the study group. selx and EGC were the most prevalent in all microniches. The number of SAg-encoding genes correlated between the anterior nares and nonlesional skin, and between the nonlesional and lesional skin. On lesional skin, the total number of SAg genes correlated with disease severity (total and objective SCORAD, intensity, erythema, edema/papulation, lichenification and dryness). Linear regression revealed that AD severity was predicted only by selx and EGC. This study revealed that selX and EGC are associated with atopic dermatitis severity. Anterior nares and nonlesional skin could be reservoirs of SAg-positive S. aureus. Restoring the physiological microbiome could reduce the SAg burden and alleviate syndromes of atopic dermatitis.

Genomic Insights of First ermB-Positive ST338-SCCmecVT/CC59 Taiwan Clone of Community-Associated Methicillin-Resistant Staphylococcus aureus in Poland

We report the first Polish representative of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), lukS/F-PV-positive, encoding the ermB gene, as a genetic determinant of constitutive resistance to macrolides, lincosamides, and streptogramin B antibiotics, cMLS-B. This is the first detection of the CA-MRSA strain responsible for nosocomial infection in the Warsaw Clinical Hospital. Resistance to β-lactams associates with a composite genetic element, SCCmec cassette type V_T (5C2&5). We assigned the strain to sequence type ST338 (single-locus variant of ST59), clonal complex CC59, spa-type t437, and agr-type I. Genomic-based comparison was designated SO574/12 as an international Taiwan clone, which has been so far described mainly in the Asia-Pacific region. The ermB gene locates on the chromosome within the 14,690 bp mobile element structure, i.e., the MES_PM1-like structure, which also encodes aminoglycoside- and streptothricin-resistance genes. The MES_PM1-like structure is a composite transposon containing Tn551, flanked by direct repeats of IS1216V insertion sequences, which probably originates from Enterococcus. The ermB is preceded by the 273 bp regulatory region that contains the regulatory 84 bp ermBL ORF, encoding the 27 amino acid leader peptides. The latest research suggests that a new leader peptide, ermBL2, also exists in the ermB regulatory region. Therefore, the detailed function of ermBL2 requires further investigations.

The Propensity to Form Biofilm in vitro by Staphylococcus aureus Strains Isolated from the Anterior Nares of Patients with Atopic Dermatitis: Clinical Associations

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.

Prevalence of methicillin resistant and mupirocin-resistant Staphylococcus aureus strains among medical students of Medical University in Warsaw

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.

The presence of antibiotic resistance genes and bft genes as well as antibiotic susceptibility testing of Bacteroides fragilis strains isolated from inpatients of the Infant Jesus Teaching Hospital, Warsaw during 2007-2012

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.

Production of extracellular polysaccharide and biofilm under different oxygen conditions by clinical isolates of Staphylococcus aureus non-susceptible to glycopeptides

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.

Resistance to Aminoglycosides of Methicillin-Resistant Strains of Staphylococcus aureus, Originating in the Surgical and Transplantation Wards of the Warsaw Clinical Center-A Retrospective Analysis

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.

Significance of Screening Tests and the Incidence of New Delhi Metallo-beta-lactamase-Producing Gram-negative Bacilli in the Surgery and Transplantation Wards of a Warsaw Medical Center During the Period From April 2014 to May 2017

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 <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 blaNDM-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).

Characteristics of glycopeptide-resistant Staphylococcus aureus strains isolated from inpatients of three teaching hospitals in Warsaw, Poland

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.

Effect of Selective Antibiotic Pressure on the MLS-B Phenotype in Methicillin-Resistant Staphylococcus aureus Strains Originating From Patients From Transplantation Wards: 24 Years of Observations

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.

In vitro effect of clindamycin against Bacteroides and Parabacteroides isolates in Poland

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 ≥256mg/L. Resistance to clindamycin in Bacteroides and Parabacteroides species is correlated mainly with the presence of the ermF gene.

Comparison of Staphylococcal Flora in Denture Plaque and the Surface of the Pharyngeal Mucous Membrane in Kidney Transplant Recipients

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.

Molecular and phenotypic characteristics of methicillin-resistant Staphylococcus aureus strains isolated from hospitalized patients in transplantation wards

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%).

Evaluation of the prevalence of insertion element IS16 in vancomycin-resistant enterococci strains of Enterococcus faecium isolated from transplantology patients from a Warsaw Hospital between 2010 and 2012

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.

[Comparison of phenotypic methods for the detection of beta-lactamases MBL in strains from the Enterobacteriaceae family and non-fermentative bacilli isolated from clinical specimens]

INTRODUCTION

Bacterial resistance is growing because of treatment a broad spectrum antibio- tics. Gram-negative pathogens which producing carbapenemase are a one of major problem in many hospitals. Rapid detection those strains provide an early inhibition of infection and control the expansion of microorganisms. The aim of work was to characterize the frequency of appearance MBLs in specific groups of Gram-negative bacilli which are resistant or intermediate to at least one of carbapenems.

METHODS

Bacterial isolates were collected from Baby Jesus Clinical Hospital from 2003 to 2009. Pathogens were isolated from urine, blood, fluids, swab of the wound, pharyngeal swab. They were identified by the ID 32 E (bioMérieux, France) and Vitek2. Antimicrobial resistance was marked by the ATB G-5 and ATB UR (bioMérieux, France). Detection of metalo-beta-lactamases was tested by disk diffusion test recommended by the EUCAST. The DDS test using imipenem, ceftazidime, ethylenediaminetetraacetic acid (EDTA) and 2-mercaptopropionic acid (2-MPA). Positive test was reading as enlargement of inhibition zone about imipenem- or ceftazidime-impregnated disk.

RESULTS

Of the 88 isolates, 32 come fromEnterobacteriaceae and 56 from non-fermentative bacilli. All strains were tested of production of MBL by disk diffusion test. This method used two inhibitors: ethylenediaminetetraacetic acid and 2-mercaptopropionic acid. As a result of EDTA there was 45 MBL positive strains. In apply 2-MPA there was 55 MBL positive strains. Both the EDTA and 2-MPA disk test showing the highest percentage of positive result in Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and Pseudomonas putida.

CONCLUSIONS

Resistance to carbapenems in the non-fermentative bacilli occurs more often than in the Enterobacteriaceae. Method with 2-mercaptopropionic acid was more effective to detect metallo-beta-lactamases than EDTA. Concerns especially bacilli from Enterobacteriaceae.

The dominant sequence types of vancomycin-resistant Enterococcus faecium among transplantation ward patients

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.

A threat of the Klebsiella pneumoniae carbapenemase-producing strains among transplant recipients

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.

[Occurrence of aminoglycoside transpherase genes in methicillin-resistant strains of Staphylococcus aureus]

Fifty MRSA strains originated from clinical specimens were examined by the PCR method, for the presence of three genes: aacA-aphD, aadD oraz aph(3")-IIIa. The obtained results were correlated with the susceptibility of the strains to gentamicin, tobramicin, kanamicin, neomicin, amikacin and netilmicin. The susceptibility results were interpreted according with CLSI and EUCAST guidelines. aacA-aphD gene was found in 34 strains, aadD in 27 strains and aph(3")-IIIa was present in 22 strains. In 19 strains (38%) was present one of the investigated genes, in 29 (58%) strains two genes and in two strains (4%) all three genes were found. The most frequent variant was combination of aacA-aphD and aadD genes.