Yasar Nakipoglu

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.

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

BackgroundThe 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.MethodsHeterogeneous 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.ResultsEight (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 106 – 107 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 wokers hands. Hetero-VISA strain was not detected.ConclusionHeterogeneous 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.

Heterotrophic Bacteria and Filamentous Fungi Isolated from a Hospital Water Distribution System

In recent years, hospital infections caused by opportunist micro-organisms in immunosupressed patients groups have become increasingly important. These micro-organisms grow easily in water distribution systems even to the extent of producing bio-film. In the present study the aim was to determine microbial populations in water samples collected from the distribution system of a big hospital. Water samples were collected from one hundred different points around the water distribution system in different sections of the hospital. To analyse the water a membrane filter method was used. In eighty-four samples heterotrophic bacteria were isolated. The most frequent bacteria determined were Bacillusspp. (77%), Bacillus cereus (11%), Pseudomonasspp. (5%) and Staphylococcus spp. (4%). In fifteen samples more than one species of bacteria were isolated. In fifty-one samples, sixteen species of fungi were isolated, the most frequent being Penicilliumspp. (24%), Aspergillusspp. (8%) and Acremoniumspp. (5%). In thirteen samples more than one type of fungi was determined. In only six samples was no growth of fungi or bacteria observed. Over all the one hundred samples the counts of heterotrophic bacteria were not significantly correlated with the filamentous fungi counts (rs 012, p 0.05). Differences in the level of isolation or the concentration of bacteria and fungi between water from three old buildings and water from four new buildings were not significant (p 0.05).

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.