Detecting imipenem resistance in Acinetobacter baumannii by automated systems (BD Phoenix, Microscan WalkAway, Vitek 2); high error rates with Microscan WalkAway.

BACKGROUND: Increasing reports of carbapenem resistant Acinetobacter baumannii infections are of serious concern. Reliable susceptibility testing results remains a critical issue for the clinical outcome. Automated systems are increasingly used for species identification and susceptibility testing. This study was organized to evaluate the accuracies of three widely used automated susceptibility testing methods for testing the imipenem susceptibilities of A. baumannii isolates, by comparing to the validated test methods. METHODS: Selected 112 clinical isolates of A. baumanii collected between January 2003 and May 2006 were tested to confirm imipenem susceptibility results. Strains were tested against imipenem by the reference broth microdilution (BMD), disk diffusion (DD), Etest, BD Phoenix, MicroScan WalkAway and Vitek 2 automated systems. Data were analysed by comparing the results from each test method to those produced by the reference BMD test. RESULTS: MicroScan performed true identification of all A. baumannii strains while Vitek 2 unidentified one strain, Phoenix unidentified two strains and misidentified two strains. Eighty seven of the strains (78%) were resistant to imipenem by BMD. Etest, Vitek 2 and BD Phoenix produced acceptable error rates when tested against imipenem. Etest showed the best performance with only two minor errors (1.8%). Vitek 2 produced eight minor errors(7.2%). BD Phoenix produced three major errors (2.8%). DD produced two very major errors (1.8%) (slightly higher (0.3%) than the acceptable limit) and three major errors (2.7%). MicroScan showed the worst performance in susceptibility testing with unacceptable error rates; 28 very major (25%) and 50 minor errors (44.6%). CONCLUSION: Reporting errors for A. baumannii against imipenem do exist in susceptibility testing systems. We suggest clinical laboratories using MicroScan system for routine use should consider using a second, independent antimicrobial susceptibility testing method to validate imipenem susceptibility. Etest, whereever available, may be used as an easy method to confirm imipenem susceptibility.

[First isolation and detection of multiple clones of vancomycin-resistant enterococci in the pediatric unit of Van Yuzuncu Yil University Turkey]. / Van Yüzüncü Yil Universitesi Pediatri Servisinde vankomisine dirençli enterokoklarin ilk izolasyonu ve çogul klonlarin tespiti.

Upon isolation of the first vancomycin resistant enterococcus (VRE) from the urine sample of a nine months old patient in pediatric unit of Van Yuzuncu Yil University Hospital (located in eastern part of Turkey), we aimed to search for the presence of VRE isolates in the unit, to determine the resistance genotypes and to evaluate the clonal relationships among isolates. A total of 28 rectal swabs and 28 skin swabs from the patients, 12 skin swabs from the staff giving care to the patients, 15 skin swabs from the mothers of the patients and 96 environmental samples from the pediatric unit were screened. Antibiotic susceptibilities were tested and the resistance genotypes were determined. Molecular typing of the isolates was performed using pulsed-field gel electrophoresis (PFGE). Apart from the first case, 13 more VRE isolates, one being a clinical isolate from the urine of a patient and 12 isolates from the screening samples (8 rectal swabs, one skin swab and three swabs from patients' beds) were obtained. All of the isolates were identified as Enterococcus faecium with similar antibiotic susceptibility patterns. VanA gene was present in all of the isolates. PFGE demonstrated two major clones and five clones closely related with the major ones. This was the first VRE isolation and colonization reported in our region. The isolates belonged to more than one clone. Currently, VRE did not seem to be a significant pathogen in Turkey, however, there may be an underestimation of the problem and continuous surveillance studies should be undertaken in every region.

Demographic and microbial characteristics and drug resistance of childhood tuberculosis in Istanbul: analysis of 1,541 cases.

INTRODUCTION: Although tuberculosis (TB) is frequently seen in Turkey, there are limited studies on childhood TB. We aimed to describe clinical and laboratory findings, including drug resistance, of children with TB in Istanbul, Turkey. METHODOLOGY: The study included all children aged 0-14 years who were registered in public dispensaries between 2006 and 2010. RESULTS: The study included 1,541 cases. Forty-four percent (n = 763) of the patients were male with a mean age of 8.86 ± 4.19 years. Fifty-five percent of the patients had pulmonary TB, 39% had extrapulmonary TB, and 6% had both pulmonary and extrapulmonary TB. The most common extrapulmonary involvement sites were the pleura (n = 193), lymph nodes (n = 247), and central nervous system (n = 41). Forty-one percent of the patients were evaluated microbiologically and 35% of them were positive. For the total study group, 14% of them were positive. A drug susceptibility test was performed on 108 patients. Drug resistance to at least one drug was detected in 16% (n = 17), to isoniazid in 15% (n = 16), streptomycin in 12% (n = 12), rifampicin in 9% (n = 10), ethambutol in 7% (n = 8), and multi-drug resistance in 8% (n = 9) of patients. CONCLUSIONS: This is the largest analysis on demographic features and drug resistance of childhood TB in Turkey. In Turkey, the rate of microbiological diagnosis is low, similar to rates worldwide. More microbiological studies and drug resistance tests should be done and annual changes should be followed with multi-center studies.

Characterisation of carbapenem-resistant Acinetobacter baumannii outbreak strains producing OXA-58 in Turkey.

The aim of this study was to characterise the molecular epidemiology and mechanisms of carbapenem resistance of nosocomial Acinetobacter baumannii isolates in a new university hospital in Turkey. A total of 145 carbapenem-resistant A. baumannii (CRAB) isolates were collected during the period 2003-2006. All isolates were typed by amplified fragment length polymorphism (AFLP) analysis. AFLP analysis showed three predominant clusters consisting of 72, 20 and 12 clinical strains as well as some smaller clusters and 23 unique strains. The three main clonal AFLP types corresponded to three major antibiotic susceptibility patterns. One environmental isolate was found related to the major outbreak clone. The reference type strains of European clones I, II and III were also typed by AFLP and analysed for clonal similarity. Polymerase chain reaction (PCR) analysis of different carbapenem resistance genes showed that strains from each of the three main clusters as well as 79% of the remaining strains harboured the bla(OXA-58) gene. No genes encoding the metallo-beta-lactamases GIM-1, SIM-1, SPM-1, IMP-like and VIM-like or the oxacillinases OXA-24-like and OXA-23-like were detected. In conclusion, multiple clones of CRAB strains producing OXA-58-type oxacillinase were responsible for a sustained CRAB outbreak occurring in a hospital in Turkey. These isolates were not associated with A. baumannii strains of the major European clones I, II or III.

Identification of Candida species isolated from patients in intensive care unit and in vitro susceptibility to fluconazole for a 3-year period.

Species level identification of Candida and antifungal susceptibility testing is not generally performed in routine laboratory practice. There is limited information about the distribution of Candida species and antifungal susceptibility in Turkey. In this study, we aimed at identifying Candida isolates to species level from various samples obtained from patients treated in an intensive care unit between 2002 and 2005 and to evaluate fluconazole susceptibilities of the isolates. A total of 320 Candida isolates obtained from 270 patients were identified by conventional methods and using API (Candida and/or 20C AUX) system. Antifungal susceptibility testing was performed by broth microdilution method. Candida albicans was isolated with the highest frequency (65.6%) followed by C. parapsilosis (11.3%), C. glabrata (8.8%) and C. tropicalis (7.8%). Of all the isolates, 92.9% revealed susceptibility to fluconazole. Susceptibility to fluconazole was highest for C. albicans followed by C. parapsilosis and C. glabrata. The MIC(90) values for C. albicans, C. parapsilosis, C. glabrata and C. tropicalis were 1, 2, 8 and 4 mug ml(-1) respectively. Fluconazole remains effective against both C. albicans and the majority of non-albicans Candida species. In this study, we determine the distribution of Candida species and evaluate the susceptibilities of the isolates, particularly for the azoles.