[Investigation of CTX-M type beta-lactamases in Klebsiella pneumoniae clinical isolates by phenotypic and molecular methods]. / Klebsiella pneumoniae klinik izolatlarinda CTX-M tipi beta-laktamazlarin fenotipik ve moleküler yöntemlerle arastirilmasi.

Rapid spread of CTX-M type extended-spectrum beta-lactamases (ESBL) between the members of Enterobacteriaceae receives attention increasingly all throughout the world. The aim of this study was to investigate the presence of CTX-M type ESBL in Klebsiella pneumoniae clinical strains by phenotypic and molecular methods. A total of 217 non-repetitive K. pneumoniae strains isolated from clinical specimens (152 urine, 20 sputum, 17 wound swabs, 13 blood, 9 tracheal aspirate, 3 CSF and 3 conjunctival swab samples) of inpatients (n = 128) and outpatients (n = 89) admitted to Pamukkale University Medical Faculty Hospital, between January 2006-January 2007, were included to the study. In vitro antimicrobial susceptibilities were determined by disk diffusion technique in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines, and CT (cefotaxime)/CTL (cefotaxime-clavulanate) containing Etest strips (AB Biodisk, Sweden) were applied for phenotypic detection of cefotaximase production. PCR was performed for the detection of CTX-M genes and the subgroups, while the clonal relatedness of the CTX-M positive isolates was investigated by random amplified polymorphic DNA (RAPD) analysis. While imipenem resistance was not detected in any of the isolates, highest rates of resistance were detected for ampicillin (94%) and cephalothin (64.5%) in 217 K. pneumoniae strains. Using the E-test 39.6% (86/217) of the isolates were found positive, and CTX-M positivity was significantly higher in the strains isolated from inpatients (87.4%) than outpatients (12.6%) (p < 0.001). CTX-M gene was identified in 22.1% (19/86) of the E-test positive isolates. All of the CTX-M positive isolates were identified as CTX-M group-1. The highest resistance rates of CTX-M-1 strains were detected for amoxycillin-clavulanate (94.7%) and netilmicin (89.5%), while the lowest rates were detected for ciprofloxacin (26.3%), trimethoprim/sulphamethoxazole (26.3%) and amikacin (42.1%). RAPD identified 11 different banding patterns among the 19 CTX-M-1 positive isolates, the most frequent clusters being Kp3 (n = 3), Kp4 (n = 3) and Kp5 (n = 3). Five of the 8 isolates from pediatric intensive care unit and 4 of the 5 isolates from other pediatric wards exhibited the same band pattern indicating a possible clonal dissemination. Continuous surveillance of beta-lactamases and the identification of their types in gram-negative enteric bacteria has important clinical impact, since it can often provide valuable information for effective infection control measures and for the choice of appropriate antimicrobial therapy.

Evaluation of biofilm production, gelatinase activity, and mannose-resistant hemagglutination in Acinetobacter baumannii strains.

BACKGROUND AND PURPOSE: Acinetobacter baumannii is an important nosocomial pathogen, but its pathogenic characteristics are not well defined. The purpose of this study was to evaluate biofilm production, mannose-resistant hemagglutination, and gelatinase production in A. baumannii strains isolated from various clinical specimens. METHODS: Eighty six strains of A. baumannii isolated from 86 hospital inpatients were studied for biofilm formation, gelatinase activity, and mannose-resistant hemagglutination. The isolates were identified using conventional techniques and/or the API 2ONE system. Comparisons of biofilm production, gelatinase activity, and mannose-resistant hemagglutination were made by chi-squared analysis. RESULTS: Twenty two and 61 of the isolates agglutinated human group O and AB erythrocytes in the presence of mannose, respectively. Gelatinase activity was detected in 12 isolates (14%), while 64 isolates formed biofilms. CONCLUSIONS: Several parameters may play important roles in causing infection in colonized patients. Identifying the factors that influence virulence may help to separate the colonizing strains into those with high or low potential virulence.

[Does pre-incubation period affect detection of Pseudomonas aeruginosa and Acinetobacter baumannii species with automatized BACTEC 9120 blood culture system?]. / Pre-inkübasyon süresi Pseudomonas aeruginosa ve Acinetobacter baumannii türlerinin otomatize BACTEC 9120 kan kültür sisteminde saptanmasini etkiliyor mu?

In this study, the effect of the pre-incubation period on detection of non-fermentative species in blood culture system was investigated. Different concentrations of Pseudomonas aeruginosa and Acinetobacter strains were inoculated into BACTEC-9120 plus+Aerobic/F bottles and incubated for 0, 4, 8, 16 hours at 36 dgerees C and then were loaded to the system. Both P. aeruginosa and A.baumannii strains yielded positive signals within 24 hours after loading. In all preincubation periods, as the concentration of P. aeruginosa strains decreased, the detection time was increased. The higher the concentration of A.baumannii strains, is the longer the signalling time as the pre-incubation period is increased, whereas the lower the concentration of A. baumannii strains, is the shorter the signalling time as the preincubation period is increased. Our study indicated that the BACTEC-9120 blood culture system determined non-fermentative bacteria after a pre-incubation time of 16 hours.