Vol. 9, Issue 3, Part B (2023)

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-β-lactamases (MBLs) are carbapenemases which require zinc in the active site and are predominantly produced by Pseudomonas 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. The present study aimed to investigate the prevalence and resistance patterns of MBL-producing Pseudomonas 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 Pseudomonas aeruginosa were done in order to formulate a policy of empirical therapy and to take preventive measures in hospital settings.

Of the 160 Pseudomonas aeruginosa isolates, 12 were Imipenem resistant; of which nine were MBL producers. Most isolates were collected in the age group of 21-30 years, followed by that of 31–40 years and 1-10 years. 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. The study found a relatively high prevalence of Pseudomonas MBL producers (9/60) with 100% Polymyxin susceptibility. Hence, our preliminary results were against a high use of Polymyxins in clinical settings. Additionally, however this 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.