Pasteur Institute of Iran

Introduction: Pseudomonas aeruginosa is one of the leading causes of nosocomial infections, and antibiotic resistance of this pathogen is an important concern in treating such infections. The current work was conducted to investigate the prevalence of bla-IMP, and bla-VIM metallo-beta-lactamase (MBL) among clinical and environmental P. aeruginosa isolates obtained from ICUs of different hospitals in Rasht, Iran. Methods: A total number of 35 P. aeruginosa strains including 20 clinical and 15 environmental strains were isolated from ICUs. The isolated bacteria were screened for MBL production using Combined Disc Synergy Testing (CDST) assay. The frequency of bla-IMP and bla-VIM among MBL producing P. aeruginosa (MBL-PA) was investigated using Polymerase Chain Reaction (PCR). Also, the antibiotic susceptibility of all isolates was determined. Results: According to the results, 51% of isolates were regarded as MBL-PA while bla-IMP or bla-VIM genes were detected in 37% of isolates. The environmental isolates showed higher resistance to the majority of antibiotics compared to the clinical isolates, and MBL genes were more prevalent among environmental isolates. Conclusion: Higher resistance of environmental P. aeruginosa strains in ICUs shows a need to pursue newer approaches, including novel cleaning methods and surveillance programs, to reduce nosocomial infections.

Introduction: Non-fermentative Gram-negative bacilli (NFGNB) are occasionally involved in infectious diseases pathology, but have shown resistance to multiple antibiotics and the capability to gain new resistance factors in the hospital environment. The present study was aimed to investigate the antibiotic susceptibility pattern of rare NFGNB isolated from different clinical samples and the prevalence of Metallo-beta-lactamase (MBL) producing non-fermenters among the carbapenem-resistant isolates. Methods: A total of 250 clinical samples from the patients suffering from various infections were analyzed by using different standard microbiological techniques like microscopy, culture methods, biochemical reactions and antibiotic susceptibility using Kirby-Bauer method. MBL detection was performed by imipenem-EDTA combined disc test and imipenem-EDTA double disc synergy test (DDST). Results: The non-fermenters bacteria rate isolated from different clinical samples was 4.8%. The highest rate of non-fermentative isolates was observed in patients with hospital-acquired infections (91.6%). The various species of NFGNB included Pseudomonas putida (33.3%), Pseudomonas stutzeri (25%), Burkholderia cepacia (16.6%), Achromobacter xylosoxidans (16.6%) and Ochrobactrum anthropic (8.33%). The isolates showed high resistance to carbapenems, and the incidence of MBL producing non-fermenters among the carbapenem-resistant organisms was found to be 100%. Conclusion: NFGNB are now emerging as organisms of nosocomial infections. The use of broad spectrum antibiotics should be avoided, and quick detection and efficient infection control measures are essential to prevent further spread of MBLs to other Gram-negative bacilli. Detection of MBL production and rationale antibiotic usage are the most important factors which control the gradually increasing NFGNB related infections.