Investigation of the prevalence of carbapenem resistance genes in faecal carriage of carbapenem resistant Klebsiella spp. isolates by multiplex real-time PCR method.

INTRODUCTION: Increased carbapenem resistance in Klebsiella spp. strains causes high morbidity and mortality. The genes encoded for carbapenemaseare transferrable between different bacterial species. In the present study, we aimed to investigate carbapenem resistance genes in Klebsiella spp. strains. METHODOLOGY: Fifty Klebsiella spp. strains were isolated from rectal swabs of patients hospitalized in the neonatal intensive care unit (NICU). All strains were identified with API20E. The minimum inhibitory concentrations (MICs) of carbapenems were determined by the broth dilution method. The major five carbapenem genes (OXA-48, NDM, VIM, KPC, and IMP) were detected by the multiplex real-time PCR method. RESULTS: It was found that 49 (98%) of the strains were resistant to ertapenem (MIC ≥ 2µg/mL) and imipenem(MIC ≥ 4 µg/mL), and 47 (94%) of the strains were resistant to doripenem (MIC ≥ 4 µg/mL)and meropenem(MIC ≥ 4 µg/mL).NDM was detected in 42%, OXA-48 in 16%, and VIM in one (2%) isolate, and NDM + OXA-48 co-existed in 36% of the isolates. The KPC and IMP genes were not detected. CONCLUSIONS: NDM and NDM co-existing with OXA-48 were prevalent in the NICU of Istanbul Medical Faculty Hospital. Paying attention to the hand hygiene of healthcare workers, screening of rectal swabs of hospitalized patients for the presence of carbapenem resistance strains, and isolation of infected patients can effectively control the spread of carbapenem-resistant strains.

[Evaluation of In vitro Efficacy of Meropenem/Colistin and Meropenem/Fosfomycin Combinations on Multidrug Resistant Gram-Negative Bacilli]. / Çok Ilaca Dirençli Gram-Negatif Basillerde Meropenem/Kolistin ve Meropenem/Fosfomisin Kombinasyonlarinin In vitro Etkinliginin Degerlendirilmesi.

The rate of extensively drug-resistant and pan-resistant gram-negative rods isolated as infectious agents is increasing around the world and in Türkiye. One of the important options in the treatment of these infections is the combined use of antibiotics. Therefore, the aim of this study was to investigate the in vitro effect of meropenem/colistin and meropenem/fosfomycin combinations on carbapenem-resistant gram-negative bacilli isolated as infectious agents. Escherichia coli (n= 6), Klebsiella pneumoniae (n= 10), Pseudomonas aeruginosa (n= 5), and Acinetobacter baumannii (n= 6) isolates were recovered from blood and tracheal aspirate samples of patients hospitalized in our hospital's intensive care unit were included in the study. In the first stage of the combination study, minimal inhibitory concentrations (MIC) were investigated by broth microdilution for meropenem and colistin, and agar dilution methods for fosfomycin. In the second stage of the study, synergy, partial synergy, indifference, and antagonistic effects were investigated with the checkerboard method for the meropenem/colistin combination and the agar dilution method for the meropenem/fosfomycin combination. The checkerboard results were interpreted as follows: fractional inhibitory concentration index (FICI) values ≤ 0.5 synergy, < 0.5-≤ 1 partial synergy, > 1-≤ 4 indifference and FIC values of > 4 antagonism. MIC values obtained in the study were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Of the 27 isolates studied with the broth microdilution method, 63% were found to be colistin-resistant and 37% susceptible. The MIC values of fosfomycin against Enterobacterales group bacteria were found to be in the range of 2-2048 mg/L. Two of the six E.coli isolates and nine of the 10 K.pneumoniae isolates were found to be resistant to fosfomycin (IV). The MIC values of ≥ 128 mg/L were found in all 11 non-fermentative gram-negative rods with intrinsic resistance to fosfomycin. In the combination of meropenem/ colistin, synergy and partial synergy were observed in 11 (40.7%) of 27 isolates, an indifference effect was observed in 13 (48.2%), and antagonistic effects were observed in three (11.1%) of the isolates. The synergy and partial synergy effects of this combination were 37.5% for Enterobacterales group bacteria, 50% for E.coli, and 30% for K.pneumoniae. Regarding the 11 non-fermentative gram-negative rods included in the study, 83.3% synergy and partial synergy was found in A.baumannii for the meropenem/colistin combination, while no synergy and partial synergistic effect was found in P.aeruginosa. Meropenem/fosfomycin synergy and partial synergy effects were 83.3% (5/6) for E.coli, 100% (8/8) for K.pneumoniae, 100% (6/6) for A.baumannii, and 25% (1/4) for P.aeruginosa. In all of the isolates studied, meropenem/fosfomycin combination was found to be more effective than the meropenem/colistin combination. It would be meaningful to support these data obtained in vitro with clinical efficacy results to be obtained as a result of the application of antibiotics in vivo, taking into account the pharmacokinetic and pharmacodynamic properties of the antibiotics used in this study.

Investigation of in vitro efficacy of meropenem/polymyxin B and meropenem/fosfomycin combinations against carbapenem resistant Klebsiella pneumoniae strains.

The incidence of infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) is increasing worldwide, and very limited number of effective antibiotics are available for therapy. In our study, the in vitro efficacy of meropenem/polymyxin B and meropenem/fosfomycin combinations against CRKP strains was investigated. The efficiency of meropenem/polymyxin B and meropenem/fosfomycin combinations was tested by checkerboard microdilution and checkerboard agar dilution methods, respectively, against 21 CRKP strains containing major carbapenem resistant genes (7 blaKPC, 7 blaOXA-48 gene, and 7 blaOXA-48+ blaNDM), and seven additional CRKP strains without carbapenemase genes.Among the 28 CRKP strains, the meropenem/polymyxin B combination was synergistic in ten (35.7%), partially synergistic in 12 (42.8%), and indifferent in six (21.4%) isolates. The meropenem/fosfomycin combination was found to be synergistic in three isolates (10.7%), partially synergistic in 20 (71.4%), and indifferent in five (17.8%). In 21 strains containing carbapenem resistance genes, meropenem/polymyxin B and meropenem/fosfomycin combinations exhibited synergistic/partial synergistic effects in 15 (71.4%) and 16 (76.2%) strains, respectively, compared to 100% synergistic/partial synergistic efficiency in both combinations in seven strains free of carbapenemase genes. No antagonistic effect was detected in either combination.Regardless of presence or absence of carbapenem resistance genes, meropenem/polymyxin B and meropenem/fosfomycin combinations both demonstrated high synergistic and partial synergistic activity against 78.4% and 82.1% of CRKP strains, respectively. Also, they have no antagonistic effects and can be used successfully to prevent therapeutic failure with monotherapy, according to our in vitro studies.

Carbapenem and Colistin Resistance, Integrons and Plasmid Replicon Types in Multi-Drug Resistant Klebsiella Strains Isolated in Turkey.

BACKGROUND: Multidrug-resistant (MDR) Klebsiella is a globally important nosocomial pathogen. In the present study, 101 multidrug-resistant Klebsiella strains isolated from various clinical specimens obtained from two different Medical Faculties' hospitals were involved. We aimed to find out the prevalence of carbapenemase, mobile colistin resistance genes, and integrons in MDR Klebsiella strains. METHODS: The antibiotic susceptibilities of strains were determined by Kirby Bauer disc-diffusion method and resistance to colistin was confirmed by detection of minimum inhibitory concentrations. The prevalence of carba-penemase genes (blaOXA-48, blaNDM, blaIMP, blaVIM, blaKPC), mobile colistin-resistance genes (mcr-1 and mcr-2), and integrons (class I, II and III) were examined in Klebsiella strains by polymerase chain reaction. RESULTS: All strains were resistant to ß-lactam antibiotics, carbapenems, and quinolones. On the other hand, only nine (8.9%) strains were resistant to colistin. The most common carbapenemase genes were blaNDM (64.3%) and blaOXA-48 (53.5%). Besides, 28 (27.7%) strains were found to harbor both blaNDM and blaOXA-48. These 28 strains be-longed to the IncA/C (18.7%), IncL/M (7.7%), and IncFIIs (1.1%) plasmid replicon types. No strain was positive for blaIMP, mcr-1, and mcr-2. Class I and Class II integrons were shown to be harbored in 83.2% and 63.3% of strains, respectively. In total, 63 (63.6%) of strains harbored both classes I and II integrons. Class III integron was not detected. There was a statistically significant relationship between the presence of integrons and antibiotic resistance for cefotaxime (p = 0.024), ciprofloxacin (p < 0.001) trimethoprim/sulfamethoxazole (p < 0.001) and levofloxacin (p = 0.002). To our knowledge, this study represents the first report of a human isolate for the co-presence of blaNDM, blaOXA-48 and both Class I and Class II integrons, from Turkey. CONCLUSIONS: Our findings also highlight the dissemination of integrons and carbapenemases and the importance of surveillance on emerging antibiotic resistance.

Investigation of Staphylococcus lugdunensis and Selected Coagulase Negative Staphylococci Isolated from Blood Culture bottles and Determination of their Sensitivities to Antibiotics.

Objectives: Coagulase-negative staphylococci (CNS) are commensal skin microbiota but may also cause septicemia, endocarditis, and systemic infections. Staphylococcus lugdunensis, is a member of CNS, but their antibiotic susceptibility test should be evaluated as Staphylococcus aureus not as CNS. We aimed to investigate S.lugdunensis and selected CNS strains by simple biochemical method and determination of their susceptibilities to antibiotics. Methods: A total of 251 CNS isolates were collected from blood culture bottles sent to Istanbul Faculty of Medicine Department of Medical Microbiology, between 2018 and 2019. PYR (pyrrolidonyl arylamidase) and ODC (ornithine decarboxylase) tests were performed on total of CNS isolates and API Staph was used for identification of the isolates giving positive result in both or either of these two tests. Disk diffusion method was used for the determination of antibiotic susceptibility of the isolates. S. aureus ATCC 25923 and S S.lugdunensis ATCC® 49576 strains were used as quality control strains in disc diffusion method, and biochemical tests, respectively. Results: Twenty three out of 251 CNS isolates were positive in each or both of PYR and ODC tests. We detected the first S.lugdunensis isolate from eye vitreous fluid of patient developed a postoperative endophthalmitis in Turkey. This isolate gave dual positive with ODC, PYR, and API Staph. Other 22 CNS isolates were from blood cultures and distributed as follows; 14 Staphylococcus haemolyticus and three Staphylococcus chromogenes isolates were PYR positive and ODC negative and five Staphylococcus epidermidis isolates were ODC positive and PYR negative. All isolates except S.lugdunensis were resistant to penicillin (95.7%) and 20 (87.0%) isolates were found to be methicillin resistant. Conclusions: ODC and PYR are cost effective tests and easily applicable for accurate identification of S.lugdunensis, and eliminating of opportinistic pathogens such as S. epidermidis, S. haemolyticus, and S. chromogenes from other CNS species in postoperative endophthalmitis and pateints with malignancies. Linezolid was very effective (100%) on four selected CNS species.

Investigation of Chlorhexidine Tolerance and its Association with Antibiotic Resistance in Clinical Gram-Negative Bacilli Isolates.

BACKGROUND: Chlorhexidine (CHX) is one of the most frequently used antiseptic agents in challenging multidrug-resistant (MDR) isolates. There is an increasing number of reports on reduced susceptibility (tolerance) to CHX in MDR isolates. We aimed to investigate CHX tolerance in Gram-negative bacilli (GNB) and its possible association with antibiotic resistance. METHODS: A total of 84 enteric GNB (ENT) and 40 non-fermentative GNB (NFGNB) isolates were collected from different clinical specimens. Disk diffusion method was performed to differentiate between MDR and non-MDR isolates and tolerance to CHX was determined by a modified agar dilution method. In GNB isolates, CHX tolerance was defined as a minimum inhibitory concentration (MIC) ≥ 4 mg/L. RESULTS: We detected that 26.2% (22/84) of ENT and 50.0% (20/40) of NFGNB were MDR and the rest were non-MDR isolates. The CHX tolerance rate was detected as 50.0% (10/20) in MDR-NFGNB and 15.0% (3/20) in non-MDR-NFGNB, and this difference was statistically significant (p < 0.05). Conversely, the tolerance rate was observed as 4.5% (1/22) in MDR-ENT and 1.6% (1/62) in non-ENT, and this difference was not statistically significant (p ˃ 0.05). CONCLUSIONS: NFGNB isolates had a higher tendency to CHX tolerance than ENT, and antibiotic resistance facili-tates the selection of CHX tolerance in NFGNB but not in ENT isolates.

Investigation of Fibronectin Binding Protein (FBP) and Panton Valentine Leukocidin (PVL) Viulance Factors in Clinical Methicillin Sensitive and Resistant Staphylococcus Aureus Strains.

BACKGROUND: We aimed to investigate the frequency of fibronectin binding protein (FBP), which is part of the first step of adhesion, and Panton-Valentine leukocidin (PVL) toxin, which contributes to the destruction of host leukocytes and tissue necrosis, in clinical S. aureus strains. METHODS: One hundred S. aureus strains were included in the study and distributed as follows; 33 from skinwound swabs and catheter tips (SWCT), 33 from body fluid and secretion specimens (BSFS) such as tracheal aspirate, sputum, and pleural effusion fluid, 18 from tissue biopsy specimens (TBS), 10 specimens from blood, and related specimens (BRS) such as bone marrow, and cerebral spinal fluid, and six specimens from mucosal membrane of pharynx, nose, and vagina (MMS). Methicillin resistance was tested by disk diffusion method. mecA (methicillin resistance coded gene), pvl and fnbA genes were investigated by using a PCR method. RESULTS: Thirty-seven strains (37.0%) were identified as methicillin resistant S. aureus (MRSA) and 63 (63.0%) as methicillin susceptible S. aureus (MSSA) strains. fnbA was more frequent in S. aureus isolates of MMSs (100.0%); followed by BRSs (80.0%), SWCTs (78.8%), TBS (72.3%), and BSFs (66.7%), whereas pvl gene was more frequent in isolates of BRS (60.0%), followed by TBSs (50.0%), SWCTs (33.4%), BSFs (30.3%), and MMSs (16.7%). fnbA existed in 85.7% of MSSA and 56.8% of MRSA in contrast to pvl, which was more frequent in MRSA (70.3%) than those of MSSA strains (17.4%). These differences were statistically significant (p < 0.05). CONCLUSIONS: Our different clinical specimens contained a high rate of fnbA (75.0%) and low-moderate frequency of pvl (37.0%). fnbA was most frequent in S. aureus of MMSs, followed by BRSs, and SWCTs, whereas pvl was ex-isted in high proportion in S. aureus of BRSs, followed by TBSs, and SWCTs. Presence of PVL in a high proportion in MRSA strains of superfical specimens such SWCT (24.4%) and deeper serious specimens such as BRS (16.3%) compared to MSSA strains from the same specimens, 3.2% and 0%, respectively, have shown that MRSA infections still threatens patients' lives and control of their spread is urgently needed.

Frequency of antiseptic resistance genes in clinical staphycocci and enterococci isolates in Turkey.

BACKGROUND: Disinfectants and antiseptics are biocides widely used in hospitals to prevent spread of pathogens. It has been reported that antiseptic resistance genes, qac's, caused tolerance to a variety of biocidal agents, such as benzalkonium chloride (BAC) and chlorhexidine digluconate (CHDG) in Staphylococcus spp. isolates. We aimed to search the frequency of antiseptic resistance genes in clinical Staphylococcus spp. and Enterococcus spp. isolates to investigate the possible association with antiseptic tolerance and antibiotic resistance. METHODS: Antiseptic resistance genes (qacA/B, smr, qacG, qacH, and qacJ) isolated from Gram-positive cocci (69 Staphylococcus spp. and 69 Enterococcus spp.) were analyzed by PCR method. The minimum inhibitory concentrations (MICs) of BAC and CHDG were determined by agar dilution method, whereas antibiotic susceptibility was analyzed by disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) criteria. RESULTS: The frequency of antiseptic resistance genes was found to be high (49/69; 71.0%) in our clinical staphylococci isolates but absent (0/69; 0%) in enterococci isolates. The frequency of qacA/B and smr genes was higher (25/40; 62.5% and 7/40; 17.5%, respectively) in coagulase negative staphylococci (CNS) when compared to Staphylococcus aureus strains (3/29; 10.3%, and 4/29; 13.8%, respectively). In contrast, the frequency of qacG and qacJ genes was higher (11/29; 37.9% and 8/29; 27.5%, respectively) in S. aureus than those of CNS (5/40; 12.5%, 10/40; 25.0%) strains. qacH was not identified in none of the strains. We found an association between presence of antiseptic resistance genes and increased MIC values of BAC (>4 µg/mL) in staphylococci and it was found to be statistically statistically significant (p < 0.01). We also showed that MICs of BAC and CHDG of vancomycin-resistant enterococci (VRE) isolates were significantly higher than those of vancomycin-susceptible enterococci (VSE) isolates (p < 0.01). CONCLUSIONS: For our knowledge, our study is the first to investigate antiseptic resistance genes in enterococci and also qacG, qacH, and qacJ genes in staphylococci isolates in Turkey. Further studies are needed to revise the biocide policy and to support infection control programs to avoid the development of new resistance mechanisms.

An Investigation of the Frequency of Upper Respiratory Tract Infection Pathogens and their Antibiotic Patterns in Tonsils and Adenoids of Adenotonsillectomy Patients.

BACKGROUND: We aimed to investigate the potentially pathogenic bacteria of upper respiratory tract infections (URTIs) and their susceptibilities to different antibiotics. METHODS: Two-hundred adenoid and tonsil specimens from 100 patients who had undergone adenotonsillectomy were obtained and analyzed bacteriologically. Identification of the pathogens was made by conventional or commercial identification systems and antibiotic susceptibility tests were carried out by disk diffusion method. RESULTS: A total of 274 pathogens were recovered from 81% specimens of 73% of the patients. Haemophilus influenzae (31.8%) was the most prevalent pathogen, followed by Staphylococcus aureus (17.2%), Group A beta hemolytic Streptococci, GABHS (12.0%), Moraxella catarrhalis (7.7%), Streptococcus pneumoniae (7.3%), and nine other bacterial species (24.0%). Penicillins (penicillin, ampicillin) had 100% activity against GABHS followed by 96.5% in H. influenzae, 45% in S. pneumoniae, and 0% in S. aureus strains. The efficacy of beta-lactamase inhibitor antibiotics (ampicillin/sulbactam, amoxycillin/clavulanic acid) were similar to those of penicillins but had superior activity (89.4%) against S. aureus strains. Cefotaxime had high activity (100%) against GABHS and H. influenzae followed by S. aureus (89.4%). Cotrimoxazole was also active in S. aureus (97.8%) and H. influenzae (83.9%) but revealed intermediate activity (45%) in S. penumoniae and was not efficient (0%) in GABHS. Macrolids (erythromycin, clindamycin) were very efficient (100%) in GABHS followed by S. aureus (95.7%) and had intermediate activity (50%) in S. pneumoniae. Levofloxacin, telithromycin, and vancomycin had 100% activity against S. pneumoniae strains. CONCLUSIONS: Our finding have shown that H. influenzae was the most prevalent pathogen followed by S. aureus, GABHS, M. catarrhalis, and S. pneumoniae and that there was no unique antibiotic to combat all prevalent pathogens, but penicillins could be the choice in GABHS and H. influenzae; beta-lactamase inhibitors and cefotaxime for GABHS, H. influenzae, and S. aureus; macrolids in GABHS and S. aureus; cotrimoxazole in H. influenzae and S. aureus; and levofloxacin and telithromycin in the treatment of S. penumoniae related URTIs.

[The prevalence of antiseptic resistance genes (qacA/B and smr) and antibiotic resistance in clinical Staphylococcus aureus strains]. / Klinik Staphylococcus aureus Suslarinda Antiseptik Direnç Genlerinin (qacA/B ve smr) ve Antibiyotik Maddelere Direnç Prevalansinin Arastirilmasi

Staphylococcus aureus is an organism of major medical importance, leading to skin and soft tissue infections, bacteremia, and endocarditis. S.aureus isolates are becoming increasingly resistant to numerous antimicrobial agents including antiseptics and disinfectants. Quaternary ammonium compounds are disinfectants that play an important role in the control of nosocomial infections. Presence of genes conferring resistance to quaternary ammonium compounds is widely distributed among clinical staphylococci isolated from certain areas of the world. In this present study, we aimed to study the prevalence of antiseptic resistance genes (qac A/B, smr) and antibiotic resistance in clinical S.aureus strains, and also to detect the possible relationship between antiseptic and antibiotic resistance. For this purpose, the presence of qac A/B and smr genes in 50 methicillin-susceptible S.aureus (MSSA) and 50 methicillin-resistant S.aureus (MRSA) clinical isolates (78 abscess, 13 blood, 3 sputum, 3 tracheal aspirate, 2 nostril swab, 1 urine) was detected by using multiplex polymerase chain reaction. The susceptibility of S.aureus strains to different antibiotics (cefoxitin, erythromycin, clindamycin, rifampin, tetracycline, ciprofloxacin, gentamicin, trimethoprim-sulfamethoxazole, vancomycin, teicoplanin) was determined by disk diffusion method according to the recommendation of Clinical Laboratory Standards Institute (CLSI). smr genes were found in 18 (36%) of 50 MRSA and qacA/B genes in 2 (4%) of 50 MSSA strains. Presence of smr gene only in MRSA strains in comparison to MSSA strains was found to be statistically significant (p< 0.001). The rates of antibiotic resistance in S.aureus strains were as follows; gentamicin 89%, tetracycline 57%, rifampin and ciprofloxacin 46%, and macrolides (erythromycin and clindamycin) 32%. No resistance was detected against trimethoprim-sulfamethoxazole, vancomycin and teicoplanin. On the other hand, presence of inducible macrolid-lincosamide-streptogramin B (iMLSB) resistance phenotype in 8 (44.5%) out of 18 smr positive strains compared to 2 (6.25%) out of 32 smr negative strains was statistically significant (p< 0.001). We concluded that smr genes were detected to be more prevalent than qacA/B genes in our clinical S.aureus isolates. smr genes were found only in MRSA strains whereas low number of qacA/B genes were found only in MSSA strains. Presence of smr genes concomitantly with iMLSB type resistance in MRSA strains was recorded to be interesting. We believe that data of this preliminary study about antiseptic and antibiotic cross resistance would be useful for the future related studies.

Prevalence of phenotypic resistance of Staphylococcus aureus isolates to macrolide, lincosamide, streptogramin B, ketolid and linezolid antibiotics in Turkey.

The incidence of drug-resistant pathogens differs greatly between countries according to differences in the usage of antibiotics. The purpose of this study was to investigate the phenotypic resistance of 321 methicillin resistance Staphylococcus aureus (MRSA) and 195 methicillin susceptible S. aureus (MSSA) in a total of 516 S. aureus strains to macrolide, lincosamide, streptogramin B (MLS B), ketolid, and linezolid. Disk diffusion method was applied to determine MLS B phenotype and susceptibility to different antibiotic agents. It was found that 54.6% of the isolates were resistant to erythromycin (ERSA), 48% to clindamycin, 55% to azithromycin, 58.7% to spiramycin, 34.7% to telithromycin, and 0.4% to quinupristin-dalfopristin, respectively. No strain resistant to linezolid was found. The prevalence of constitutive (cMLS B), inducible (IMLS B), and macrolides and type B streptogramins (M/MS B) among ERSA isolates (237 MRSA, 45 MSSA) was 69.6 %, 18.2%, and 12.2 % in MRSA and 28.9%, 40%, and 31.1% in MSSA, respectively. In conclusions, the prevalence of cMLS B was predominant in MRSA; while in MSSA strains, iMLS B and M/MS B phenotype were more higher than cMLS B phenotype resistance. The resistance to quinupristindalfopristin was very low, and linezolid was considered as the most effective antibiotic against all S.aureus strains.

Prevalence of phenotypic resistance of Staphylococcus aureus isolates to macrolide, lincosamide, streptogramin B, ketolid and linezolid antibiotics in Turkey

The incidence of drug-resistant pathogens differs greatly between countries according to differences in the usage of antibiotics. The purpose of this study was to investigate the phenotypic resistance of 321 methicillin resistance Staphylococcus aureus (MRSA) and 195 methicillin susceptible S. aureus (MSSA) in a total of 516 S. aureus strains to macrolide, lincosamide, streptogramin B (MLS B), ketolid, and linezolid. Disk diffusion method was applied to determine MLS B phenotype and susceptibility to different antibiotic agents. It was found that 54.6 percent of the isolates were resistant to erythromycin (ERSA), 48 percent to clindamycin, 55 percent to azithromycin, 58.7 percent to spiramycin, 34.7 percent to telithromycin, and 0.4 percent to quinupristin-dalfopristin, respectively. No strain resistant to linezolid was found. The prevalence of constitutive (cMLS B), inducible (IMLS B), and macrolides and type B streptogramins (M/MS B) among ERSA isolates (237 MRSA, 45 MSSA) was 69.6 percent, 18.2 percent, and 12.2 percent in MRSA and 28.9 percent, 40 percent, and 31.1 percent in MSSA, respectively. In conclusions, the prevalence of cMLS B was predominant in MRSA; while in MSSA strains, iMLS B and M/MS B phenotype were more higher than cMLS B phenotype resistance. The resistance to quinupristindalfopristin was very low, and linezolid was considered as the most effective antibiotic against all S.aureus strains.

[In vitro susceptibility of Enterococcus strains to high level aminoglycosides and heavy metals]. / Enterokok suslarinin yüksek düzeyde aminoglikozidlere ve agir metallere karsi in vitro duyarliliklarinin arastirilmasi.

The widespread use of antimicrobial agents in the hospitals and environmental contamination with heavy metals are increasingly related to resistance progression in microorganisms. The aim of this study was to investigate the resistance of enterococci to high level aminoglycosides and some heavy metals [lead (Pb+2), cadmium (Cd+2), mercury (Hg+2), arsenic (As+5)]. A total of 39 Enterococcus strains, isolated from stool and rectal swabs of hospitalized patients were included to the study. Twenty of the strains were resistant to glycopeptides (11 were resistant to vancomycin + teicoplanin and 9 were resistant to only vancomycin). Disk diffusion method was performed to determine the high level resistance to aminoglycosides (gentamicin 120 microg and streptomycin 300 microg), and agar dilution method was used to detect the sensitivities of the strains against different concentrations (0.005-20 mM) of heavy metals. Since there is no specified minimum inhibitory concentration (MIC) breakpoints for heavy metals, resistance criteria described in previous studies were used. Accordingly, enterococci which exhibited MIC > or = 1 mM for lead and cadmium, MIC > or = 0.1 mM for mercury, and MIC > or = 10 mM for arsenic were accepted as resistant. High level aminoglycoside (HLAG) resistance rates were found as 91% (10/11) for vancomycin (V) + teicoplanin (T) resistant and 42% (8/19) for glycopeptide susceptible strains. While all of the isolates were resistant to lead (100%), arsenic (2.6%) and mercury (2.6%) resistance was detected in one isolate for each metal. No cadmium resistance has been detected. In our study, enterococci have exhibited seven different resistance profiles (10 strains were resistant to V + T + HLAG + Pb; 1 was resistant to V + T + Pb; 1 was resistant to V + As + Pb; 1 was resistant to HLAG + Hg + Pb; 8 were resistant to V + Pb; 7 were resistant to HLAG + Pb; 11 were only resistant to Pb). Resistance to antibiotics (aminoglycosides and/or vancomycin and/or teicoplanin) and heavy metals (lead and arsenic and/or mercury) were detected concurrently in 28 (%71.8) of the strains. It was considered remarkable that all of the isolates were resistant to lead and there was no difference between antibiotic-resistant and-susceptible strains in terms of lead resistance. In conclusion, further investigations are needed to reveal the extreme lead resistance and the relations between antibiotic and heavy metal resistances in clinical enterococcus strains.

Comparison of polymerase chain reaction and conventional methods in detecting methicillin-resistant Staphylococcus aureus.

BACKGROUND: Accurate and rapid detection of methicillin-resistant Staphylococcus aureus is very important in a clinical laboratory setting to avoid treatment failure. Conventional methods were compared against the gold standard polymerase chain reaction (PCR) technique to determine the best combination of the routine procedures. METHODOLOGY: Methicillin resistance was investigated in 416 clinical Staphylococcus aureus isolates by PCR, oxacillin agar screening (OAS), oxacillin disk diffusion (ODD) and cefoxitin disk diffusion (CDD) methods. RESULTS: Two hundred and ten (51%) out of 416 S. aureus strains were found to be mecA-positive by PCR. Sensitivity and specificity of the ODD, CDD and OAS methods were detected as follows: 100% and 89%, 99.50% and 100%, and 99.50% and 100%, respectively. CONCLUSION: Combining the ODD and CDD methods could be a good choice for detecting methicillin resistance in S. aureus strains where mecA PCR cannot be performed.

Investigation of Staphylococcus strains with heterogeneous resistance to glycopeptides in a Turkish university hospital.

BACKGROUND: The hetero-glycopeptide intermediate staphylococci is considered to be the precursor of glycopeptide intermediate staphylococci especially vancomycin intermediate Staphylococcus aureus (VISA). For this purpose, we aimed to investigate the heterogeneous resistance to glycopeptide and their frequencies in 135 Staphylococcus strains. METHODS: Heterogeneous resistance of Staphylococcus strains was detected by inoculating the strains onto Brain Heart Infusion agar supplemented with 4 mg/L of vancomycin (BHA-V4). Agar dilution method was used for determining MICs of glycopeptides and population analysis profile was performed for detecting frequency of heterogeneous resistance for the parents of selected strains on BHA-4. RESULTS: Eight (6%) out of 135 Staphylococcus strains were exhibited heterogeneous resistance to at least one glycopeptide. One (1.2%) out of 81 S. aureus was found intermediate resistance to teicoplanin (MIC 16 mg/L). Other seven strains were Staphylococcus haemolyticus (13%) out of 54 coagulase negative staphylococci (CoNS). Six of the seven strains were detected heterogeneously reducing susceptibility to vancomycin (MICs ranged between 5-8 mg/L) and teicoplanin (MICs ranged between 32-64 mg/L), and one S. haemolyticus was found heterogeneous resistance to teicoplanin (MIC 32 mg/L). Frequencies of heterogeneous resistance were measured being one in 10(6) - 10(7) cfu/ml. MICs of vancomycin and teicoplanin for hetero-staphylococci were determined as 2-6 folds and 3-16 folds higher than their parents, respectively. These strains were isolated from six patients (7%) and two (4%) of health care workers hands. Hetero-VISA strain was not detected. CONCLUSION: Heterogeneous resistance to glycopeptide in CoNS strains was observed to be significantly more emergent than those of S. aureus strains (vancomycin P 0.001, teicoplanin, P 0.007). The increase MICs of glycopeptide resistance for subpopulations of staphylococci comparing with their parents could be an important clue for recognizing the early steps in the appearance of VISA strains. We suggested to screen clinical S. aureus and CoNS strains, systematically, for the presence of heterogeneously resistance to glycopeptide.