An Analysis of Resistance Patterns of Oral Streptococci Obtained from Orofacial Infections Against Beta-lactams, Clindamycin and Vancomycin over 2014-2018.

PURPOSE: Comparison of viridans group Streptococcus (VGS) susceptibility to benzylpenicillin, ampicillin, clindamycin and vancomycin in order to determine resistance rates to assess whether guidelines for prophylactic or therapeutic antibiotic treatment include the present resistance patterns. MATERIALS AND METHODS: A retrospective analysis of antimicrobial susceptibility testing (AST) over 4 consecutive years (2014-2017) and 4 months in 2018 for 779 VGS isolates (cumulative data). Isolates originated from pus from orofacial infections cases and tissue fragments from patients undergoing maxillofacial surgeries Results: The highest resistance rate was observed to clindamycin. The highest overall resistance rate was for Streptococcus parasanguinis 43% and S. constellatus 49%; the lowest was for S. anginosus 12%. All S. anginosus isolates were susceptible to ampicillin during tested period. All isolates of analysed species were susceptible to vancomycin through studied period. CONCLUSION: Due to high resistance levels, individual antibiotic susceptibility testing for strains should become mandatory.

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.

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.

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.

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.

[Microbiologic spectrum and susceptibility of bacteria isolated from patients with intra-abdominal infection].

the analyzed peritoneal fluid and bile specimens were comparable. Multiple bacterial species were significantly more common in bile isolates than in peritoneal fluid isolates. A total of 61,7% of aerobic Gram-negative bacillus isolates obtained from peritoneal fluid and bile produced ESBL. The proportions of vancomycin-resistant enterococci (VRE) and enterococci exhibiting high-level aminoglycoside resistance (HLAR) were 32,6% and 43,5%, respectively. Ertapenem-resistant K. pneumoniae was detected in 22,2% of peritoneal fluid cultures and 71,4% of biliary cultures. Methicillin resistance was detected in 85,7% of staphylococcal isolates. The proportion of anaerobes detected in peritoneal fluids was relatively high at approximately 17% and included predominantly Gram- negative species. All Gram-negative anaerobes showed resistance to benzylpenicillin. Conclusions: Etiologies and susceptibility pattern of IAls must be monitored on a ward, hospital, regional, and world-wide scale and the findings implemented into epidemiologic surveillance programs and proposed treatment protocols.

Staphylococcus aureus nasal carriage in Ukraine: antibacterial resistance and virulence factor encoding genes.

BACKGROUND: The number of studies regarding the incidence of multidrug resistant strains and distribution of genes encoding virulence factors, which have colonized the post-Soviet states, is considerably limited. The aim of the study was (1) to assess the Staphylococcus (S.) aureus nasal carriage rate, including Methicillin Resistant S. aureus (MRSA) strains in adult Ukrainian population, (2) to determine antibiotic resistant pattern and (3) the occurrence of Panton Valentine Leukocidine (PVL)-, Fibronectin-Binding Protein A (FnBPA)- and Exfoliative Toxin (ET)-encoding genes. METHODS: Nasal samples for S. aureus culture were obtained from 245 adults. The susceptibility pattern for several classes of antibiotics was determined by disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The virulence factor encoding genes, mecA, lukS-lukF, eta, etb, etd, fnbA, were detected by Polymerase Chain Reaction (PCR). RESULTS: The S. aureus nasal carriage rate was 40%. The prevalence of nasal MRSA carriage in adults was 3.7%. LukS-lukF genes were detected in over 58% of the strains. ET-encoding genes were detected in over 39% of the strains and the most prevalent was etd. The fnbA gene was detected in over 59% of the strains. All MRSA isolates tested were positive for the mecA gene. LukS-lukF genes and the etd gene were commonly co-present in MRSA, while lukS-lukF genes and the fnbA gene were commonly co-present in Methicillin Sensitive S. aureus (MSSA) isolates. No significant difference was detected between the occurrence of lukS-lukF genes (P > 0.05) and the etd gene (P > 0.05) when comparing MRSA and MSSA. The occurrence of the fnbA gene was significantly more frequent in MSSA strains (P < 0.05). CONCLUSIONS: In Ukraine, S. aureus is a common cause of infection. The prevalence of S. aureus nasal carriage in our cohort of patients from Ukraine was 40.4%. We found that 9.1% of the strains were classified as MRSA and all MRSA isolates tested positive for the mecA gene. We also observed a high prevalence of PVL- and ET- encoding genes among S. aureus nasal carriage strains. A systematic surveillance system can help prevent transmission and spread of drug resistant toxin producing S. aureus strains.

[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]. / Porównanie metod fenotypowych wykrywania beta-laktamaz MBL u szczepów z rodziny Enterobacteriaceae oraz paleczek niefermentujacych izolowanych z próbek materialów klinicznych.

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.

Essential oils and herbal extracts as antimicrobial agents in cosmetic emulsion.

The cosmetic industry adapts to the needs of consumers seeking to limit the use of preservatives and develop of preservative-free or self-preserving cosmetics, where preservatives are replaced by raw materials of plant origin. The aim of study was a comparison of the antimicrobial activity of extracts (Matricaria chamomilla, Aloe vera, Calendula officinalis) and essential oils (Lavandulla officinallis, Melaleuca alternifolia, Cinnamomum zeylanicum) with methylparaben. Extracts (2.5 %), essential oils (2.5 %) and methylparaben (0.4 %) were tested against Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, Candida albicans ATCC 14053. Essentials oils showed higher inhibitory activity against tested microorganism strain than extracts and methylparaben. Depending on tested microorganism strain, all tested extracts and essential oils show antimicrobial activity 0.8-1.7 and 1-3.5 times stronger than methylparaben, respectively. This shows that tested extracts and essential oils could replace use of methylparaben, at the same time giving a guarantee of microbiological purity of the cosmetic under its use and storage.

[Specificity of the anaerobic bacterial infections in the surgical and orthopedic wards]. / Specyfika zakazen bakteriami beztlenowymi na oddzialach chirurgicznych i ortopedycznych.

INTRODUCTION: The aim of this study was to estimate the contribution strictly anaerobic bacteria in the etiology of infections in patients on surgery and orthopedic wards. METHODS: We examined 159 samples taken from patients hospitalized in surgical wards and 179 clinical specimens taken from orthopedic patients. Clinical strains of obligate anaerobes were identified by API 20A biochemical tests (ATB Expression, bioMerieux S.A., France). Susceptibility of the clinical strains was examined by ATB ANA (bioMerieux S.A., France) system. The MIC values were determined by the gradient diffusion method, Etest (AB BIODISK, Sweden i bioMerieux S.A., France). RESULTS: Gram-negative bacteria predominant in the samples taken from surgical patients, Most frequently we isolated rods of the genus Bacteroides (26%): B. fragilis, B. ovatus/B. thetaiotaomicron, and B. distasonis. In 44 samples (28%) we identified only anaerobic bacteria. Multibacterial isolations, with the participation of anaerobic and aerobic flora, dominated among patients in the study. Overall 238 strictly anaerobic bacteria were cultured from patients hospitalized in orthopedic wards. Gram-positive bacteria accounted for 78%. The most frequently were isolated Peptostreptococcus (56%), Propionibacterium (10%) species. In this study all Bacteroides strains were resistant to penicillin G. Some species were resistant to clindamycin, as well. Overall 40% of Bacteroides strains taken from surgical and 50% isolated from orthopedic wards showed no sensitivity to this antibiotic. A similar phenomenon was observed among bacteria of the genus Prevotella. CONCLUSIONS: In samples taken from orthopedic patients we observed the predominance of Gram-positive anaerobic bacteria. Some of them were part of the normal flora but they should not be excluded as an etiology agents of infection. The specimens taken from patients treated in surgical wards showed the presence of a mixed microflora, which included aerobic and anaerobic bacteria, primarily Gram-negative rods. Rational empirical therapy of infections with anaerobes should be mainly based on the resistance pattern in each ward and hospital. In view of the increasing in the number of resistant strains is necessary to monitor drug resistance of anaerobic bacteria.

[Occurrence of aminoglycoside transpherase genes in methicillin-resistant strains of Staphylococcus aureus]. / Wystepowanie genów transferaz aminoglikozydowych u metycylino- opornych szczepów 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.

[Genetic similarity of vancomycin resistant strains of Enterococcus faecium isolated from clinical specimens]. / Genetyczne podobienistwo opornych na wankomycyne szczepów Enterococcus faecium izolowanych z materialu klinicznego.

Twenty vancomycin resistant E. faecium strains (VRE) isolated from patients of three different hospital wards in 2005-2008 were examined. The strains originated from patients of intensive therapy, urological and internistic wards. The chosen wards differ significantly in their specificity. In all cases the presence of o vanA and lack of vanB, vanD, vanE and vanG genes and were found. Strains were compared by using RFLP-PFGE, the reference method for molecular typing of VRE. One group including fourteen strains showing similarity higher than 79.5% was distinguished. This group was divided into subgroups. The greatest similarity was found among strains from patients of intensive therapy ward. Two subgroups of strains showing similarity more than 93.3%, of four strains each were identified. The similarity between these two subgroups was 79.5%. Most strains from other two wards showed less than 79.5% similarity and they could be recognised as not related. Only one strain from internal ward and two strains from urologic ward were similar in 82.1 - 86.4% to one of subgroups of strains originated from intensive therapy.

[Enterobacter cloacae--antimicrobial susceptibility of strains isolated from hospitalized patients in 2004-2005]. / Enterobacter cloacae--wrazliwosc na antybiotyki szczepów izolowanych od chorych hospitalizowanych w latach 2004-2005.

The profiles of resistance of ESBL(-) and ESBL(+) strains of Enterobacter cloacae were analysed and compared. 466 Enterobacter cloacae strains isolated from different specimens obtained from patients of big Warsaw hospital in 2004-2005 were investigated. By using the several phenotypic methods 33.5% of strains was identified as ESBL(+). ESBL(+) strains were significantly less susceptible then ESBL(-). These two groups differed mostly in susceptibility to aminoglycosides and fluoroquinolones, e.g. 65.5% of ESBL(-) strains were susceptible to gentamicin, compared to only 25.0% ESBL(+), in case of ciprofloxacin 59.0% of ESBL(-) were susceptible whereas only 25.0% of ESBL(+) strains. The percentage of ESBL(+) grew from 26.4% in 2004 to 40.4% in 2005, whereas a tendency of growing susceptibility to aminoglycosides and fluoroquinolones was noted among all E.cloacae strains. Susceptibility to combinations of piperacillin or ticarcillin with beta-lactamase inhibitor was rather low among ESBL(+) strains.

[Assessment of the susceptibility of the gram-negative rods isolated from hospitalized patients to cefoperazone/sulbactam]. / Ocena wrazliwosci na cefoperazon/sulbaktam szczepów paleczek gram-ujemnych izolowanych od chorych hospitalizowanych.

The susceptibility to cefoperazone/sulbactam of 197 strains of Gram-negative rods demonstrating an ESBL-positive phenotype was determined. The assortment of the investigated strains was as follows (numbers of strains are given in the brackets): E. cloacae (63), S. marcescens (46), K. pneumoniae (21), P. mirabilis (17), E. coli (9), P. vulgaris (8), P. aeruginosa (20) and A. baumanni (13). 83 strains from 197 were susceptible (42.1%). The MIC values were determined and the disc-diffusion method was performed. The susceptibilities among particular species were as follows (the order of data in the brackets is: % of the susceptible strains/MIC50/MIC90): E. cloacae (54.0/16/64), S. marcescens (23.9/64/> or = 128), K. pneumoniae (38.1/32/64), P. mirabilis (41.2/32/64), E. coli (44.4/32/32), P. vulgaris (75.0/8/32), P. aeruginosa (35.0/32/64), A. baumannii (46.2/32/64). Using disc-diffusion method, for 184 strains the difference between diameter of the inhibition zone around the disc with cefoperazone and the disc with cefoperazone/sulbactam was calculated. This difference amounted 5 mm or more in the case of 76.6% of the investigated strains. The results indicate that the comparison of the inhibition zones around cefoperazone and cefoperazone/sulbactam discs may be an additional method useful for phenotypic detection of ESBL producing organisms. These results highly correlated with results obtained by using analogous test with cefpirome and cefpirome/clavulanic acid (85.6% of concordance).

[The correlation between phenotypes and genotypes of macrolides, lincosamides and streptogramins B resistance in Staphylococcus aureus]. / Korelacja genotypów i fenotypów opornoscina makrolidy, linkozamidy i streptograminy B u Staphylococcus aureus.

For 31 clinical strains of S. aureus the correlation between phenotype and genotype of resistance to macrolides, lincosamides and streptogramins B (MLSB) was established.. Phenotypes were determined on the basis of: susceptibility to erythromycin and clindamycin and the ability to an induction of the resistance (phenotypes S, susceptible; R , constitutive resistant, D, resistant after induction with erythromycin, D+, resistant after induction with erythromycin and with a presence of the small colonies inside inhibition zone between erythromycin and clindamycin discs), and on the basis of the resistance to spectinomycin (spR, resistant, spS, susceptible). Among examined S. aureus strains eight phenotypes of resistance to MLSB were recognized (the corresponding genotypes are given in brackets). Six phenotypes were typical: SspS (lack of MLS-B resistance genes), NEGspS (msrA/B, 1 strain), D+spS (ermCi, 4 strains),. DspR (ermAi, 11 strains and ermAi + msrA/B, 2 strains), RspR (ermAc, 4 strains and ermA + msrA/B,1 strain and ermA + ermC, 1 strain) and RspS (ermCc, 6 strains and ermB, 1 strain). Two rare phenotypes in two single strains were observed: SspR (ermAi, the strain with altered inducibility, inductor other than erythromycin) and DspS (ermAi, presumably mutation or lack of spc in Tn554).

[Antibmicrobial susceptibility of Serratia marcescens isolated from hospitalized patients in 2003 - 2005]. / Wrazliwosc na antybiotyki szczepów Serratia marcescens izolowanych od chorych hospitalizowanych w latach 2003 - 2005.

500 strains of Serratia marcescens isolated in 2003-2005 were examined for drug susceptibility. By using several phenotypic methods it was shown that 67.6% of these strains produced ESBLs. Strains ESBL(-) and ESBL(+) were compared, paying special attention to their susceptibility to various antibiotics. It was revealed that strains ESBL(+) were much more resistant to majority of the investigated drugs. The biggest differences were in the case of amikacin and gentamicin, sensitive about 50% of ESBL(-) and 10% of ESBL(+), ciprofloxacin, sensitive 42% of ESBL(-) and 6.3% of ESBL(+) and trimethoprim/ sulphametoxazole, sensitive 45.8% of ESBL(-) and 9.4% of ESBL(+). Strains ESBL(-) retained a high susceptibility to ceftazidime (68.9%) and cefepime (71%). All strains ESBL(-) as well as ESBL(+) were susceptible to imipenem and meropenem. 78.9% of ESBL(-) and 67.3% of investigated ESBL(+) were susceptible to piperacillin/ tazobactam.

[Estimation of activity of pharmakopeal disinfectants and antiseptics against Gram-negative and Gram-positive bacteria isolated from clinical specimens, drugs and environment]. / Wrazliwosc wybranych szczepów bakterii Gram-ujemnych i Gram-dodatnich izolowanych z materialu klinicznego, leków i srodowiska, na farmakopealne zwiazki dezynfekcyjne i antyseptyczne.

The MIC of nine different disinfectants and antiseptics were determined for the Gram-negative and Gram-positive bacteria. Strains originated from clinical specimens, drugs and environment. A sensitivity was determined against chlorhexidinum digluconate (Gram-negative: 0,625-80 mg/L, Gram-positive: 0,3-10 mg/L), benzalconium chloride (Gram-negative: 2,5-1280 mg/L, Gram-positive: 1,25-20 mg/L), salicilic acid (Gram-negative and Gram-positive: 400-1600 mg/L), benzoic acid (Gram-negative: 800-1600 mg/L, Gram-positive: 400-1 600 mg/L), boric acid (Gram-negative: 800-12 800 mg/L, Gram-positive: 1 600-6400 mg/L), chloramine B (Gram-negative: 1600-6400 mg/L, Gram-positive:800- 6400 mg/L), jodine (Gram-negative: 200-1600 mg/L, Gram-positive: 200-1600 mg/L), etacridine lactate (Gram-negative: 40 do > 20480 mg/L, Gram-positive: 40-1280 mg/L) and resorcine (Gram-negative: 1600-6400 mg/L, Gram-positive: 800-6400 mg/L). Diversified values of MIC for different strains were obtained, especially in the case of benzalconium chloride, etacridine lactate, chlorhexidinum digluconate, boric acid and iodine. Strains isolated from environment were usually more susceptible to examined compounds than clinical strains. The biggest diversification of sensitivity was observed among strains originated from drugs where besides sensitive appeared strains characterizing by very high MIC values of some substances, eg. boric acid.

[The resistance to glycopeptide antibiotics among strains of Enterococcus sp. isolated in 1998-2005 from patients of one of the university hospitals in Warsaw]. / Opornosc na glikopeptydy szczepów Enterococcus sp. izolowanychw latach 1998-2005 od chorych hospitalizowanych.

Infections due to vancomycin resistant enterococci (VRE) constitute a serious therapeutic problem in some cases. Up to date there is only poor knowledge about the frequency of isolation of VRE inthe Polish hospitals. The aim of our investigations was to compare the number and the assortment of VRE isolated during eight years (1998-2005) in the one big clinical hospital in Warsaw. All resistant strains were checked for possessing the vanA or van B ligase genes in the PCR reaction. The identification of the strains was proven by PCR with using of the ddl primers. The significant increase in the number of VRE was observed in the 2005 compared with recent years. All strains isolated in recent years possessed vanA ligase genes. Although among all enterococci E. faecalis made majority (over 70%), among VRE predominated E. faecium.