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Imipenem resistance in nonfermenters causing nosocomial urinary tract infections
N Taneja1, S Maharwal, M Sharma
1Department of Medical Microbiology, PGIMER, Chandigarh-160012, India.
Abstract:
Nonfermenting gram-negative bacilli (nonfermenters) have emerged as important nosocomial pathogens causing opportunistic infections in immunocompromised hosts. These organisms show high level of resistance to b-lactam agents, fluoroquinolones and aminoglycosides. Imipenem is a carbapenem antibiotic, which can be very useful for treatment of infections caused by nonfermenters. Eighty-five nonfermenters causing nosocomial UTI were tested for MIC to imipenem by agar dilution method. Resistance to other antimicrobial agents was compared between imipenem sensitive (S) and resistance (R) groups. Overall 36.4% of nonfermenters were resistant to imipenem. Forty two percent of P. aeruginosa and 18.5% of Acinetobacter baumanii were imipenem resistant. Other nonfermenters showed variable resistance, resistance in Alcaligenes spp. being very high. More than 70% of the nonfermenters were resistant to ceftazidime, gentamicin and ciprofloxacin. Piperacillin and amikacin had the best in vitro susceptibility. No significant difference was found in the antibiotic susceptibility profile among imipenem sensitive (S) or resistant (R) strains.
Insights
Nonfermenting gram-negative bacilli are opportunistic pathogens resistant to common antibiotics. Imipenem resistance was observed in 36.4% of these nosocomial pathogens, impacting treatment options.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Nonfermenting gram-negative bacilli (nonfermenters) are significant nosocomial pathogens.
- These bacteria frequently cause opportunistic infections in immunocompromised individuals.
- Nonfermenters exhibit high resistance to common antibiotic classes like beta-lactams, fluoroquinolones, and aminoglycosides.
Purpose of the Study:
- To evaluate the in vitro susceptibility of nosocomial nonfermenters to imipenem.
- To compare antimicrobial resistance patterns between imipenem-susceptible and imipenem-resistant nonfermenter strains.
Main Methods:
- Eighty-five nonfermenter isolates from nosocomial urinary tract infections were analyzed.
- Minimum Inhibitory Concentration (MIC) of imipenem was determined using the agar dilution method.
- Antibiotic susceptibility profiles were compared between imipenem-sensitive and resistant groups.
Main Results:
- Overall, 36.4% of nonfermenters demonstrated resistance to imipenem.
- Imipenem resistance rates were 42% for Pseudomonas aeruginosa and 18.5% for Acinetobacter baumanii.
- High resistance (>70%) was noted for ceftazidime, gentamicin, and ciprofloxacin, while piperacillin and amikacin showed better susceptibility.
- No significant differences in antibiotic susceptibility were observed between imipenem-sensitive and imipenem-resistant strains.
Conclusions:
- A substantial proportion of nosocomial nonfermenters are resistant to imipenem, a key carbapenem antibiotic.
- Understanding resistance patterns is crucial for effective management of infections caused by these challenging pathogens.
- Piperacillin and amikacin appear to be more reliable options based on in vitro susceptibility, though further clinical correlation is needed.