Pasteur Institute of Iran

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.