Comparison of nosocomial infections due to Staphylococcus aureus and enterococci in a general hospital.

Hospital acquired infections caused by enterococci are increasing in incidence. This increase has been attributed, in part, to widespread use of cephalosporin antibiotics which lack activity against enterococci. To test this hypothesis, we compared patients having nosocomial enterococcal pulmonary and wound infections with those patients having nosocomial staphylococcal infections for antecedant cephalosporin use. In a six month period, we found 14 instances of nosocomial enterococcal wound and respiratory infections; 13 were superinfections (occurring during or up to one week after administration of antimicrobials). Seven had coexisting pathogens noted. In the same six month period, 30 instances of Staphylococcus aureus nosocomial respiratory tract and wound infections were found and only 13 were superinfections (p less than 0.002 compared with enterococcal superinfections). Nine had coexisting pathogens noted. The mean age, gender distribution and underlying illnesses in the Staphylococcus aureus and enterococcal superinfection groups were comparable. Of the 14 instances of enterococcal nosocomial infections, 11 were associated with administration of a cephalosporin compared with seven of 30 for staphylococcal infections (p less than 0.002). Nosocomial enterococcal infections are commonly associated with antimicrobial therapy and the use of cephalosporins may selectively predispose patients to increased risk of enterococcal superinfections.