In vitro activity of selected cephalosporins and erythromycin against staphylococci and pneumococci isolated at 38 North American medical centers participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998

The SENTRY Antimicrobial Surveillance Program employs a worldwide network o f hospitals to monitor the predominant bacterial and fungal pathogens and a ntimicrobial susceptibility patterns associated with nosocomial and communi ty-acquired bloodstream, respiratory tract, wound, and urinary tract infect ions. The purpose of this analysis of SENTRY data is to extract information on the current North American susceptibility patterns of pneumococci and o xacillin-susceptible staphylococci from the comprehensive SENTRY program da tabase. Clinical isolates were provided by 30 centers in the United States (grouped into five regions) and eight centers in Canada. Susceptibility tes ting was performed at a central reference laboratory using broth microdilut ion methods and interpretive criteria specified by the National Committee f or Clinical Laboratory Standards. Of 34 530 North American bacterial isolat es tested during 1997 and 1998, 565 (1.6%) were oxacillin-susceptible, coag ulase-negative staphylococci (CoNS). Cefazolin, cefepime, and ceftriaxone a ll had excellent activity against these CoNS (97.3%-99.3% susceptible), and 90.4% were susceptible to ceftazidime. A total of 4404 isolates (12.8%) we re oxacillin-susceptible Staphylococcus aureus. Overall, 98.9% to 99.2% wer e susceptible to cefazolin, cefepime, and ceftriaxone; ceftazidime did not have acceptable activity against these S. aureus. Streptococcus pneumoniae accounted for 1665 (4.8%) of North American SENTRY isolates. A total of 121 2 isolates (72.8%) were fully susceptible to penicillin (MIC less than or e qual to 0.06 mu g/ml), 250 (15%) were penicillin intermediate (MIC 0.12-1 m u g/ml), and 203 (12.2%) were penicillin resistant (MIC greater than or equ al to 2 mu g/ml). The rate of penicillin susceptibility was highest in Cana da, and lowest in the South Central and South East regions of the United St ates. Cefepime, cefuroxime, ceftazidime, and erythromycin all demonstrated excellent efficacy (94%-99.8% susceptibility) against fully penicillin-susc eptible isolates of S. pneumoniae. Among pneumococci with intermediate peni cillin resistance, 88% were susceptible to cefepime, 92% to cefotaxime, and only 14% to ceftazidime. None of the antimicrobial agents in this analysis demonstrated adequate activity against fully penicillin-resistant pneumoco cci. In summary, the fourth-generation cephalosporin, cefepime, demonstrate d consistently excellent efficacy against oxacillin-susceptible staphylococ ci and most pneumococci, and remains an appropriate choice for empiric ther apy of serious infections. (C) 2000 Elsevier Science Inc. All rights reserv ed.