Genotype and antibiotic susceptibility patterns of drug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii isolates in Taiwan. Microb
ABSTRACT Rapid and accurate identification of the drug susceptibility profile of clinical strains is very important for controlling bacterial infections and determining the antibiotic therapy. The objective of this study was to investigate the spectrum of the correlation between phenotypic and genetic characters of the drug-resistant clinical isolates. A total of 133 clinical isolates, including 76 Acinetobacter baumannii and 57 Pseudomonas aeruginosa, were examined for their antibiotic susceptibility by the method of disc diffusion. Among them, most of the isolates were multiresistant, and 80% of the strains showed phenotypic resistance to beta-lactam antibiotics. Using PCR analysis, among the several types of beta-lactamases, TEM was the most prevalent, and OXA was the second most prevalent. The integron harbored was identified by conserved segment PCR, and 50% of the test isolates carried integrons with various gene cassette sizes inserted. The results obtained from this study reveal that the majority of these isolates displayed multiple drug resistance phenotypes that were associated with their mutational gene profiles.
- SourceAvailable from: Abbas Farahani
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- "The isolates were identified for a phenotypic MBL screening with the E-test MBL (bio-Mérieux, Marcy L'Etoile, France) as per the manufacturer's instructions (14). Indistinguishable MBL producing isolates were detected and confirmed by Cica-Beta-Test Strip (Kanto Chemical, Tokyo) as per the manufacturer's instructions. "
ABSTRACT: Acinetobacter baumannii is an aerobic non-motile Gram-negative bacterial pathogen that is resistant to most antibiotics. Carbapenems are the most common antibiotics for the treatment of infections caused by this pathogen. Mechanisms of antibiotic-resistance in A. baumannii are mainly mediated by efflux pumps-lactamases. The aim of this study was to determine antibiotic susceptibility, the possibility of existence of OXAs genes and fingerprinting by Pulsed-Field Gel Electrophoresis (PFGE) among clinical isolates of Acinetobacter collected from Kermanshah hospitals. One hundred and four isolates were collected from patients attending Imam Reza, Taleghani and Imam Khomeini hospitals of Kermanshah (Iran). Isolates were identified by biochemical tests and API 20NE kit. The susceptibility to different antibiotics was assessed with Kirby-Bauer disk diffusion method. PCR was performed for detection of bla OXA-23, bla OXA-24, bla OXA-51 and bla OXA-58 beta-lactamase genes. Clonal relatedness was estimated by PFGE (with the restriction enzyme Apa I) and DNA patterns were analyzed by Gel compare II 6.5 software. All isolates showed high-level of resistance to imipenem, meropenem as well as to other antimicrobial agents, while no resistance to polymyxin B, colistin, tigecylcine and minocycline was observed. The bla OXA-23like and bla OXA-24 like were found among 77.9% and 19.2% of the isolates, respectively. All isolates were positive for bla OXA-51, but none produced any amplicon for bla OXA-58. PFGE genotype analysis suggested the existence of eight clones among the 104 strains [A (n = 35), B (n = 29), C (n = 19), D (n = 10), E (n = 4), F (n = 3), G (n = 3), H (n = 1)]. Clone A was the dominant clone in hospital settings particularly infection wards so that the isolates in this group, compared to the other clones, showed higher levels of resistance to antibiotics. The bla OXA-51-like and bla OXA-23like were the predominant mechanisms of resistance to imipenem in A. baumannii. A high prevalence of clone A, B and C in different parts of the healthcare system showed that hospitalized patients should be safeguarded to prevent the spread of these clones. Early recognition of the presence of carbapenem-resistant A. baumannii clones is useful for preventing their spread within the hospital environment.09/2013; 5(3):195-202.
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- "In brief, disks containing 750 µg of EDTA plus 10 µg of imipenem were placed on the inoculated plates containing Muller Hinton agar. An increase of≥17 mm in zone diameter in the presence of 750 µg of EDTA compared to imipenem alone indicated the presence of an MBL (9). "
ABSTRACT: Carbapenems are therapeutic choice against infections caused by gram-negative bacilli including strains of Acinetobacter baumannii. Resistance to these antibiotics is mediated by efflux pumps, porins, PBPs and ß-lactamases. The aim of this study was to determine the possibility of existence of MBLs, OXAs and GES-1 betalactamase genes among clinical isolates of Acinetobacter collected from Tehran hospitals. Two hundred and three Acinetobacter isolates were collected from patient at Tehran hospitals. The isolates were identified using biochemical tests. The susceptibility to different antibiotics was evaluated by disk diffusion method and MICs of imipenem were determined using Micro broth dilution method (CLSI). PCR was performed for detection of bla(VIM-2), bla(SPM-1), bla(IMP-2), bla(GES-1), bla(OXA-51), bla(OXA-23) betalactamase genes. Clonal relatedness was estimated by PFGE with the restriction enzyme SmaI. Of 100 isolates of imipenem resistant Acinetobacter spp. collected from Tehran hospitals in 2009 and 2010, 6 isolates produced metallo-beta-lactamases and 94 isolates produced OXA-type carbapenemase. The bla(SPM-1), bla(GES-1), bla(OXA-51), bla(OXA-23) genes were detected by PCR among 6, 2, 94 and 84 isolates of A. baumannii, respectively. The MICs of isolates to imipenem were 8-128 µg/mL. PFGE analysis of 29 bla(OXA-51) and bla(OXA-23)-positive A. baumannii isolates gave 6 different patterns. This is the first report of SPM-1 and GES-1 beta-lactamase producing A. baumannii. Production of the OXA-23, OXA-51, GES-1 and SPM-1 enzyme presents an emerging threat of carbapenem resistance among A. baumannii in Iran.Iranian Journal of Microbiology 06/2011; 3(2):68-74.
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ABSTRACT: With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannii (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannii (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children.