Antimicrobial susceptibility pattern of carbapenemase-producing Gram-negative nosocomial bacteria at Al Zahra hospital, Isfahan, Iran.

BACKGROUND AND OBJECTIVES

Bacterial antibiotic resistance is one of the most important threats for public health around the world. Carbapenemase-producing Gram-negative bacteria have resistance to most antibiotics including carbapenems complicating the treatment of infections. The aim of this study was to determine the antimicrobial susceptibility pattern of carbapenemase-producing nosocomial Gram-negative pathogens at a referral teaching hospital to reveal the best options for treatment of related infections.

MATERIALS AND METHODS

Gram-negative bacteria, isolated from hospitalized patients with nosocomial infections, underwent meropenem susceptibility test by disk diffusion method. Meropenem-resistant strains were evaluated for the presence of carbapenemase using Modified Hodge test (MHT). Finally, the antibiotic susceptibility test was performed to determine the sensitivity of each carbapenemase-positive strain against various antimicrobial agents according to the guidelines of Clinical and Laboratory Standards Institute (CLSI).

RESULTS

Over the study period, 155 carbapenemase-positive isolates were detected. Pneumonia was the most frequent related nosocomial infection (67.1%) followed by UTI (23.2%). (53.5%) and (40%) were the most frequently isolated pathogens. The pathogens had high rate of resistance to all antibiotics. Colistin had the most effect against all pathogens. Also, had a co-trimoxazole sensitivity rate equal to colistin (30.6%).

CONCLUSION

Carbapenemase-positive Gram-negative bacteria causing nosocomial infections are common in our hospital and have high rate of resistance to most antibiotics. Improvement in the pattern of antibiotic use and infection control measures are necessary to overcome this resistance.