Antimicrobial Drug Resistance in Peru

To the Editor: In Latin American countries, rates of antimicrobial drug resistance among bacterial pathogens are high. Data on these rates in Peru are incomplete (1), and no institution in Peru has participated in multinational surveillance studies (2– 4). To document the antimicrobial drug resistance profi le of key pathogens, we organized a surveillance network of clinical laboratories from 9 hospitals (public, general, tertiary care, and quaternary care) in Lima, the capital of Peru. Over a 12-month period (April 2008–March 2009), we consecutively collected positive bacterial blood culture isolates (other than coagulase-negative staphylococci) from each of the 9 hospitals. Only the fi rst isolate per patient was included. Patients' age and hospital ward were recorded. Identifi cation and susceptibility testing were performed at the Institute of Tropical Medicine Alexander von Humboldt (Lima, Peru). Staphylococcus aureus was identifi ed by conventional methods, and susceptibility testing was conducted by oxacillin salt agar screening and disk diffusion (5). For gram-negative bacilli, including extended-spectrum β-lactamases (ESBL), identifi cation and susceptibility testing were performed by conventional techniques and by MicroScan NC50 panels (Dade-Behring, West Sacramento, CA, USA) (5). American Type Culture Collection strains were used as controls. During the study period, we collected 1,681 unique isolates. We report the fi rst 934 isolates tested from the more common species collected (375 Staphylococcus aureus, 321 Klebsiella pneumoniae, 125 Escherichia coli, and 113 Pseudomonas aeruginosa). Overall, S. aureus was the most frequently recovered species, accounting for 22.0% of organisms. Of 375 S. aureus isolates tested, 244 (65.0%) were methicillin resistant (MRSA) and 131 were methicillin susceptible. MRSA frequency was highest among isolates from intensive care units (ICUs) (61 [68.5%] of 89 isolates), but it was also high among isolates from emergency wards (55 [57.3%] of 96 isolates); this difference did not reach statistical signifi cance. Among the 244 MRSA isolates, 170 (69.6%) were also co-resistant to the combination of ciprofl oxacin, gentamicin, and clindamycin; rates of co-resistance did not differ signifi cantly among MRSA isolates from patients in the emergency ward (32/55, 58.2%) and those from patients in ICUs and hospital wards (133/184, 72.3%, p = 0.67). Among the 131 methicillin-susceptible isolates, resistance rates were as follows: ciprofl oxacin (5.3%), gentamicin (10.7%), clindamycin (14.5%), and erythromycin (14.5%). All S. aureus isolates were susceptible to linezolid, teicoplanin, and vancomycin; clindamycin-inducible resistance was found in 10 (38.5%) of 26 isolates resistant to erythromycin and apparently susceptible to clindamycin. K. …