Metallo-β-lactamase-producing clinical isolates of <i> Acinetobacter</i> species and <i> Pseudomonas aeruginosa</i> from intensive care unit patients of a tertiary care hospital

Abstract

Prompt detection of metallo-β-lactamase (MBL) producing isolates is necessary to prevent their dissemination. Frequency of MBLs producing strains among multidrug resistant (MDR) Acinetobacter species and Pseudomonas aeruginosa was evaluated in critical care patients using imipenem-EDTA disk method. One hundred MDR Acinetobacter spp. and 42 Pseudomonas aeruginosa were checked for MBL production, from January to June 2001. MBL was produced by 96.6 % of imipenem-resistant Acinetobacter isolates, whereas 100% imipenem-resistant Pseudomonas aeroginosa isolates were MBL producers. Carbapenem resistance in MDR Acinetobacter spp. and Pseudomonas aeruginosa isolates in this study was due to MBLs. This calls for strict infection control measures to prevent further dissemination. Key words: Acinetobacter spp, metallo-β-lactamase, Pseudomonas aeruginosaCarbapenem group of antibiotics play a vital role in the management of hospital-acquired gram negative infections, because of their broad spectrum activity and stability to hydrolysis by most of the β-lactamases, including extended spectrum β-lactamases (ESBLs). Nosocomial outbreaks of carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter spp. due to metallo-β-lactamases (MBLs) production have been reported from different regions. [1][2][3] The emergence of these MBLs in gram negative bacilli is becoming a therapeutic challenge as these enzymes possess high hydrolytic activity that leads to degradation of higher generation cephalosporins. Moreover, the treatment alternatives are unavailable, or expensive/toxic with poor outcome.[4] Plasmid mediated MBL genes spread rapidly to other species of gram negative bacilli; [5] therefore rapid detection of metallo-ß-lactamases production is necessary to modify therapy and to initiate effective infection control to prevent their dissemination. To date there has been one report from Pakistan suggesting presence of MBL producing isolate.[6] There is however need for a systematic study to assess the extent of this form of resistance amongst our isolates. The purpose of this study was to evaluate the metallo-ß-lactamase (MBL) production among multidrug resistant (MDR) Acinetobacter spp. and Pseudomonas aeruginosa, isolated from clinical specimens of intensive care unit patients. Materials and MethodsThis study was conducted in the clinical microbiology laboratory of The Aga Khan University Hospital, Karachi, Pakistan. One hundred MDR clinical isolates of Acinetobacter species and 42 Pseudomonas aeruginosa were studied for MBL production. These organisms were isolated from respiratory secretions, wound swabs, urine and blood culture specimens of intensive care unit patients, admitted from January to April 2001. A multidrug resistant isolate was deÞ ned as resistance to two or more drugs or drug classes of therapeutic relevance. [7] All the isolates of Pseudomonas aeruginosa were characterised to species level using standard procedures. Similarly, Acinetobacter isolates were characterised to the genus level using these proced...

Epidemiological Pattern of Non-Fermenting Metallo Beta Lactamase Producing Bacterial Pathogens Isolated From Clinical Specimens in a Tertiary Care Hospital in Kakinada

“…Shali Preet Sidhu et al [10] reported that 6.97% of the Pseudomonas aeruginosa showed resistance to the carbapenems, and it is coinciding with the present study. Irfan et al [4] reported (100%) of the carbapenem resistant isolates of Pseudomonas aeruginosa were MBL producers, which are also coinciding with the study. All the pathogenic cultures which were isolated in the current investigation showed 100% sensitivity to Polymyxin-B.…”

“…So this enzyme is responsible for multidrug resistance, and they possess high hydrolytic activity that leads to degradation of higher generation cephalosporins. Plasmid mediated MBL genes spread rapidly to other species of gram negative bacilli, therefore rapid detection of metallo-beta-lactamase production is necessary to modify therapy and to initiate effective infection control to prevent their dissemination [4]. So identification of metallo-beta-lactamase producing non-fermenters was also included in this study.…”

Acinetobacter species meningitis in children: a case series from Karachi, Pakistan

“…Polymyxin discs of 300 units were used for susceptibility testing [1,12,13]. The disc diffusion technique was reported to be an unreliable method for evaluating the susceptibility of bacteria to polymyxins because these antibiotics diffuse poorly in agar.…”

Study of Acinetobacter Species with Special Reference to Species Differentiation and Metallo-Beta Lactamase Production in a Rural Tertiary Care Hospital

“…Out of that rate of MBL producing strain by disc potentiation test was 77.8% and that of by E strip technique was 74.07%. Irfan et al, have reported 97% of the MBL producing Acinetobacter species by Disc potentiation technique (Irfan et al, 2008). In one of the Indian study on the Acinetobacter baumanii species stated that 70.9% of these isolates produced metallo beta lactamase by Disc potentiation technique, while another study reported from Kerala, India, states that 21% of the Acinetobacter baumannii isolates were found to be metallo-β-lacatmase producers (Uma et al, 2009;Anil et al, 2011).…”