Alper Ergin

Evaluation of 120 Mycobacterial Strains Isolated from Clinical Specimens to the Species Level by Polymerase Chain Reaction-Restriction Enzyme Analysis

In this study, a total of 120 mycobacterial strains isolated from clinical specimens in Hacettepe University Hospital Clinical Pathology Laboratories were evaluated by polymerase chain reaction-restriction enzyme analysis (PRA), which analyses the common mycobacterial heat shock protein gene (hsp65). 95 of 120 strains (79.1%) were identified as Mycobacterium tuberculosis and 25 (20.8%) were identified as non-tuberculous mycobacteria (NTM). M. gordonae I and IV were the most common NTM species (3.3% each) followed by M. chelonae (2.5%). Other NTM species isolated were M. gordonae III, M. avium, M. peregrinum (1.6%), M. fortuitum, M. flavescens, M. malmoense and M. mucogenicum (0.8%). Four isolates had PRA patterns that did not match any patterns previously described. The patients who had NTM had underlying diseases; the most frequent clinical diagnosis among these was chronic obstructive pulmonary disease (COPD) and chronic renal failure. AIDS and pulmonary carcinoma were the other underlying diseases detected.In this study, a total of 120 mycobacterial strains isolated from clinical specimens in Hacettepe University Hospital Clinical Pathology Laboratories were evaluated by polymerase chain reaction-restriction enzyme analysis (PRA), which analyses the common mycobacterial heat shock protein gene (hsp65). 95 of 120 strains (79.1%) were identified as Mycobacterium tuberculosis and 25 (20.8%) were identified as non-tuberculous mycobacteria (NTM). M. gordonae I and IV were the most common NTM species (3.3% each) followed by M. chelonae (2.5%). Other NTM species isolated were M. gordonae III, M. avium, M. peregrinum (1.6%), M. fortuitum, M. flavescens, M. malmoense and M. mucogenicum (0.8%). Four isolates had PRA patterns that did not match any patterns previously described. The patients who had NTM had underlying diseases; the most frequent clinical diagnosis among these was chronic obstructive pulmonary disease (COPD) and chronic renal failure. AIDS and pulmonary carcinoma were the other underlying diseases detected.

In vitro susceptibility, tolerance and MLS resistance phenotypes of Group C and Group G streptococci isolated in Turkey between 1995 and 2002.

A total of 105 clinical strains of Group C and Group G streptococci were examined for their susceptibility to penicillin, cefotaxime, erythromycin, meropenem and vancomycin using a broth microdilution method. Minimum bactericidal concentrations of the antimicrobial agents and phenotypes of strains resistant to erythromycin were also evaluated. No resistance to penicillin, cefotaxime, meropenem and vancomycin was found in years 1995-2002, but there was 6.7% resistance to erythromycin. No tolerance was seen for penicillin and vancomycin, but there were strains tolerant to cefotaxime, erythromycin and meropenem. The resistance phenotypes of erythromycin-resistant isolates were determined by the double disc test with erythromycin and clindamycin which showed inducible MLS (57.1%) and M phenotype (42.8%) resistance. This in vitro finding shows that classical antimicrobial agents used for the treatment of GCS and GGS have good activity against clinically significant isolates, but the presence of macrolide resistance and tolerant isolates suggests that careful surveillance of the streptococcal isolates should be carried out.

Evaluation of restriction endonuclease analysis of BRO beta-lactamases in clinical and carrier isolates of moraxella catarrhalis

A rapid increase in the prevalance of beta-lactamase producing M. catarrhalis isolates has highlighted its pathogenic potential. In this study, we aimed to detect the BRO beta-lactamases of our clinical (n=32) and carrier (n=32) strains of Moraxella catarrhalis and compare the relationship of the enzyme type in assesment of MIC results of the antibiotics tested. BRO beta-lactamases were differentiated by restriction endonuclease analysis. Antibiotic susceptibility was performed by the agar dilution method recommended by NCCLS (M7A5). The clinical isolates produced 96.9%, whereas the carrier strains produced 90.6% beta-lactamase positivity by the restriction enzyme analysis. BRO-1 was isolated as 90.6% (n=29) while the BRO-2 and non-beta-lactamase producers (NBLP) were isolated as 6.3% (n=2) and 3.1% (n=1) respectively among clinical isolates. The rate of BRO-1 in the carrier strains was 75.0% (n=24), BRO-2 was 15.6% (n=5) and NBLP was 9.4% (n=3). The beta-lactamase production with nitrocefin test was 96.9% (31/32) in clinical isolates and 90.6% (29/32) in carrier strains. M. catarrhalis needs a continous monitoring of antibiotic susceptibility; in this era restriction endonuclease analysis could be useful to screen BRO beta-lactamase genes.

Molecular characterization of oxacillinases and genotyping of invasive Acinetobacter baumannii isolates using repetitive extragenic palindromic sequence-based polymerase chain reaction in Ankara between 2004 and 2010.

Abstract Background: Multidrug-resistant Acinetobacter baumannii (MDRAB) is an increasing problem worldwide. We aimed to determine the antibiotic susceptibility, diversity of oxacillinases, and molecular types of MDRAB. Methods: A total of 100 non-duplicate A. baumannii blood culture isolates were evaluated. Antimicrobial susceptibilities of the isolates were determined according to the standard Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Colistin, doripenem, and tigecycline susceptibilities were analyzed by E-test. The presence of blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, and blaOXA-58-like genes was investigated by multiplex polymerase chain reaction (PCR). Typing of A. baumannii isolates was performed using repetitive extragenic palindromic sequence-based PCR (rep-PCR; DiversiLab). Results: Most isolates were susceptible to colistin (98% susceptible) and tigecycline (94% susceptible), whereas fewer isolates were susceptible to imipenem, meropenem, and doripenem (17%, 17%, and 18% susceptible, respectively). Carbapenem resistance was associated with the presence of blaOXA-23-like (31% of isolates) and blaOXA-58-like (23% of isolates) genes. The occurrence of isolates carrying blaOXA-58-like genes increased between y 2004 and 2009, but decreased in 2010. In contrast, isolates with blaOXA-23-like genes increased during the 2008–2010 period. Out of 100 isolates, 62 were categorized into 13 major rep-PCR patterns, with the highest prevalence in pattern 1 (10 isolates), followed by patterns 2 and 3 (9 isolates each). Conclusions: Carbapenem-resistant invasive A. baumannii isolates carrying the blaOXA-23-like gene became more prevalent and replaced isolates carrying the blaOXA-58-like carbapenemase gene through the 7 y. Rep-PCR genotyping of these strains confirmed that ongoing MDRAB resulted from a long-term persistence and mixture of several clusters.