Hospital-onset Gram-negative Surveillance Program annual report, 2011

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• The Australian Group on Antimicrobial Resistance (AGAR) conducts periodic prevalence studies to track antimicrobial resistance (AMR) in Gram-negative enteric pathogens.
• The 2011 survey specifically focused on hospital-onset infections, analyzing isolates from specimens presumed to be disease-causing.

Observation:

• In 2011, 1,827 Escherichia coli, 537 Klebsiella spp., and 269 Enterobacter spp. isolates were tested using the Vitek 2 automated method.
• Results were interpreted using Clinical and Laboratory Standards Institute (CLSI) breakpoints effective January 2012.
• Non-susceptibility rates were observed for ceftriaxone (9.6% E. coli, 9.5%-12.1% Klebsiella spp.), ciprofloxacin (10.6% E. coli, 0.0%-8.3% Klebsiella spp., 0.0%-5.0% Enterobacter spp.), and gentamicin (8.6% E. coli, 2.9%-10.9% Klebsiella spp., 0.0%-15.6% Enterobacter spp.).

Findings:

• Significant non-susceptibility rates were identified for third-generation cephalosporins and fluoroquinolones among E. coli, Klebsiella spp., and Enterobacter spp.
• Eight strains (5 Klebsiella spp., 3 Enterobacter spp.) were found to possess a carbapenemase, specifically IMP-4.
• These findings highlight evolving resistance patterns in key hospital-acquired pathogens.

Implications:

• The prevalence of resistance necessitates ongoing surveillance and potential adjustments in empirical antibiotic treatment guidelines.
• The emergence of carbapenemase-producing Enterobacteriaceae (CPE) like IMP-4 poses a significant threat to effective infection control and treatment options.
• These data underscore the critical need for antimicrobial stewardship programs to mitigate the spread of resistance.