A Radhika1, Jyothi Tadi Lakshmi2, Kaliappan Ariyanachi3, Varatharajan Sakthivadivel4. 1. Department of Microbiology, Telangana Institute of Medical Sciences, Gachibowli, India. 2. Department of Microbiology, All India Institute of Medical Sciences, Bibinagar, India. 3. Department of Anatomy, All India Institute of Medical Sciences, Bibinagar, India. 4. Department of Medicine, All India Institute of Medical Sciences, Bibinagar, India.
Abstract
Introduction:Pseudomonas aeruginosa is a leading cause of nosocomial infections and is especially prevalent among patients with burn wounds, cystic fibrosis, acute leukemia, organ transplants and intravenous-drug addiction. Acquired metallo-â-lactamases (MBLs) are carbapenemases which require zinc in the active site and are predominantly produced by P. aeruginosa. They belong to Ambler's class B and Bush-Jacoby Medeiros Group 3 and hydrolyse virtually all â-lactam agents, including the carbapenems. In India, only blaVIM and NDM-1 have been reported in P. aeruginosa. Metallo beta-lactamases have recently emerged as one of the most worrisome resistance mechanisms owing to their capacity to hydrolyse all beta-lactams, including carbapenems. Aims and objectives: The present study aimed to investigate the prevalence and resistance patterns of MBL-producing P. aeruginosa in a tertiary care hospital of Ghanpur, Medchal, India, and to compare the effectiveness of two different methods of screening and detecting MBL-producing P. aeruginosa in order to formulate a policy of empirical therapy and to take preventive measures in hospital settings. Methodology: In the present study, 60 isolates of Pseudomonas aeruginosa were obtained from various clinical specimens, including pus, urine, burns, wound, sputum, pleural fluid, and CSF, which were taken from inpatients and outpatients admitted to MIMS, Ghanpur, India. The study period was from January 2017 to July 2018. The microbial isolates were studied for the detection of the prevalence of MBL production, including their antibiogram. Results: Of the 60 Pseudomonas aeruginosa isolates, 12 were Imipenem resistant, of which nine were MBL producers. Most isolates (14) were collected in the age group of 21-30 years, followed by that of 31-40 years (13) and 1-10 years (2). Of the total number of samples, 40 strains were isolated in male subjects, with a male-female ratio of 2:1. Total wound swabs accounted for 40% of the studied specimens, followed by ear swabs (20%) and sputum samples (18.3%). Wound swabs also included most Imipenem-resistant isolates (41.6%). Metallo beta-lactamase producers accounted for 75% of all carbapenem-resistant isolates, using the combined disc method and E-test. By comparison, DDST retrieved 41% of Pseudomonas MBL producers. Isolates were 100% sensitive to Polymyxin-B and showed a 44.4% sensitivity to Piperacillin/Tazobactam, followed by 22.2% for Amikacin and Tobramycin and 11.1% for Ciprofloxacin and Gentamicin. Conclusion: The study found a relatively high prevalence of Pseudomonas MBL producers (9/60) with 100% Polymyxin susceptibility. Hence, our results warn against an expected high use of Polymyxins in clinical settings. Additionally, the study supports the use of E-tests, CDST and DDST for the screening of Pseudomonas MBL producers in regions where PCR detection cannot be performed.
Introduction:Pseudomonas aeruginosa is a leading cause of nosocomial infections and is especially prevalent among patients with burn wounds, cystic fibrosis, acute leukemia, organ transplants and intravenous-drug addiction. Acquired metallo-â-lactamases (MBLs) are carbapenemases which require zinc in the active site and are predominantly produced by P. aeruginosa. They belong to Ambler's class B and Bush-Jacoby Medeiros Group 3 and hydrolyse virtually all â-lactam agents, including the carbapenems. In India, only blaVIM and NDM-1 have been reported in P. aeruginosa. Metallo beta-lactamases have recently emerged as one of the most worrisome resistance mechanisms owing to their capacity to hydrolyse all beta-lactams, including carbapenems. Aims and objectives: The present study aimed to investigate the prevalence and resistance patterns of MBL-producing P. aeruginosa in a tertiary care hospital of Ghanpur, Medchal, India, and to compare the effectiveness of two different methods of screening and detecting MBL-producing P. aeruginosa in order to formulate a policy of empirical therapy and to take preventive measures in hospital settings. Methodology: In the present study, 60 isolates of Pseudomonas aeruginosa were obtained from various clinical specimens, including pus, urine, burns, wound, sputum, pleural fluid, and CSF, which were taken from inpatients and outpatients admitted to MIMS, Ghanpur, India. The study period was from January 2017 to July 2018. The microbial isolates were studied for the detection of the prevalence of MBL production, including their antibiogram. Results: Of the 60 Pseudomonas aeruginosa isolates, 12 were Imipenem resistant, of which nine were MBL producers. Most isolates (14) were collected in the age group of 21-30 years, followed by that of 31-40 years (13) and 1-10 years (2). Of the total number of samples, 40 strains were isolated in male subjects, with a male-female ratio of 2:1. Total wound swabs accounted for 40% of the studied specimens, followed by ear swabs (20%) and sputum samples (18.3%). Wound swabs also included most Imipenem-resistant isolates (41.6%). Metallo beta-lactamase producers accounted for 75% of all carbapenem-resistant isolates, using the combined disc method and E-test. By comparison, DDST retrieved 41% of Pseudomonas MBL producers. Isolates were 100% sensitive to Polymyxin-B and showed a 44.4% sensitivity to Piperacillin/Tazobactam, followed by 22.2% for Amikacin and Tobramycin and 11.1% for Ciprofloxacin and Gentamicin. Conclusion: The study found a relatively high prevalence of Pseudomonas MBL producers (9/60) with 100% Polymyxin susceptibility. Hence, our results warn against an expected high use of Polymyxins in clinical settings. Additionally, the study supports the use of E-tests, CDST and DDST for the screening of Pseudomonas MBL producers in regions where PCR detection cannot be performed.