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. © 2008 Journal of Microbiology, Immunology and Infection

Frequency of azole resistance in clinical and environmental strains of Aspergillus fumigatus in Turkey: a multicentre study

Objectives Aspergillus fumigatus causes several diseases in humans and azole resistance in A. fumigatus strains is an important issue. The aim of this multicentre epidemiological study was to investigate the prevalence of azole resistance in clinical and environmental A. fumigatus isolates in Turkey. Methods Twenty-one centres participated in this study from 1 May 2018 to 1 October 2019. One participant from each centre was asked to collect environmental and clinical A. fumigatus isolates. Azole resistance was screened for using EUCAST agar screening methodology (EUCAST E.DEF 10.1) and was confirmed by the EUCAST E.DEF 9.3 reference microdilution method. Isolates with a phenotypic resistance pattern were sequenced for the cyp51A gene and microsatellite genotyping was used to determine the genetic relationships between the resistant strains. Results In total, resistance was found in 1.3% of the strains that were isolated from environmental samples and 3.3% of the strains that were isolated from clinical samples. Mutations in the cyp51A gene were detected in 9 (47.4%) of the 19 azole-resistant isolates, all of which were found to be TR34/L98H mutations. Microsatellite genotyping clearly differentiated the strains with the TR34/L98H mutation in the cyp51A gene from the strains with no mutation in this gene. Conclusions The rate of observed azole resistance of A. fumigatus isolates was low in this study, but the fact that more than half of the examined strains had the wild-type cyp51A gene supports the idea that other mechanisms of resistance are gradually increasing.This work was partly supported by Bursa Uludag University Scientific Research Projects Commission (QUAP[T]-2015-5) and Ener Private Health Service Company.Bursa Uludag University Scientific Research Projects Commission [QUAP[T]-2015-5]; Ener Private Health Service Compan

Frequency of azole resistance in clinical and environmental strains of Aspergillus fumigatus in Turkey: a multicentre study

Objectives Aspergillus fumigatus causes several diseases in humans and azole resistance in A. fumigatus strains is an important issue. The aim of this multicentre epidemiological study was to investigate the prevalence of azole resistance in clinical and environmental A. fumigatus isolates in Turkey. Methods Twenty-one centres participated in this study from 1 May 2018 to 1 October 2019. One participant from each centre was asked to collect environmental and clinical A. fumigatus isolates. Azole resistance was screened for using EUCAST agar screening methodology (EUCAST E.DEF 10.1) and was confirmed by the EUCAST E.DEF 9.3 reference microdilution method. Isolates with a phenotypic resistance pattern were sequenced for the cyp51A gene and microsatellite genotyping was used to determine the genetic relationships between the resistant strains. Results In total, resistance was found in 1.3% of the strains that were isolated from environmental samples and 3.3% of the strains that were isolated from clinical samples. Mutations in the cyp51A gene were detected in 9 (47.4%) of the 19 azole-resistant isolates, all of which were found to be TR34/L98H mutations. Microsatellite genotyping clearly differentiated the strains with the TR34/L98H mutation in the cyp51A gene from the strains with no mutation in this gene. Conclusions The rate of observed azole resistance of A. fumigatus isolates was low in this study, but the fact that more than half of the examined strains had the wild-type cyp51A gene supports the idea that other mechanisms of resistance are gradually increasing