WASHINGTON — Staphylococcus aureus was the most common pathogen isolated from pediatric patients in North America in 2004, according to data from the SENTRY Antimicrobial Surveillance Program presented as a poster at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
The SENTRY program has monitored susceptibility rates and trends of pathogens worldwide since 1997. In 2004, 3,537 clinical isolates were collected from 47 medical centers as part of the program.
S. aureus also topped the list as the most common pathogen worldwide and in Europe but Escherichia coli snagged the top spot in Latin America (see table for regional rankings of the most common pathogens).
The 10 most frequently observed pathogens accounted for 84% of the organisms isolated in this study, wrote Kelley A. Fedler and her colleagues at JMI Laboratories in North Liberty, Iowa.
The researchers also noted a direct correlation between increasing patient population age and the frequency of occurrence among many pathogens, most notably S. aureus and E. coli.
S. aureus accounted for 19% of organisms in patients less than 1 year and 35% of organisms in patients aged 12–18 years. E. coli predominated in patients less than 1 year of age, at 20.6%. Klebsiella species, Enterobacter species, enterococci, and coagulase-negative staphylococci decrease in prevalence after age 1, according to the poster presented at the meeting sponsored by the American Society for Microbiology.
The researchers also looked at antimicrobial activity and resistance patterns among pediatric patients. Susceptibility tests were performed by reference broth microdilution methods of the Clinical Laboratory Standards Institute against more than 25 antimicrobial agents. Methicillin-resistant S. aureus accounted for 28% of S. aureus strains.
Both gatifloxacin and ciprofloxacin exhibited high levels of activity against the pathogens tested, “indicating the fluoroquinolone-naive nature of pediatric pathogens,” the researchers wrote.
All of the S. pneumoniae strains from North America were susceptible to gatifloxacin and levofloxacin. Two fluoroquinolone-resistant strains were identified in Europe, however. No strains of staphylococci tested had developed resistance to linezolid, quinupristin/dalfopristin, teicoplanin, or vancomycin.
Pneumococcal susceptibility was the greatest in North America. Pseudomonas aeruginosa was very susceptible to fluoroquinolones (5% resistance) in North American isolates.
However, â-lactamase-mediated resistance was highest in North America (41%) and Latin America (46%) in contrast with Europe (18%).