title: Use of surrogate antimicrobial agents to predict susceptibility to ertapenem.
abstract: Broth or agar dilution susceptibility test results for Enterobacteriaceae (11,775 strains), anaerobes (2888 strains), staphylococci (2206 strains), Haemophilus spp. (840 strains), group A streptococci (280 strains), group B streptococci (269 strains), Streptococcus pneumoniae (709 strains), and 160 other streptococci were analyzed to identify surrogate antimicrobial agents to predict susceptibility to ertapenem. Ertapenem MIC interpretive categories approved by the United States FDA were compared to those of imipenem, oxacillin (staphylococci), or penicillin (streptococci). Ertapenem resistance was rare (1.2%) among 8187 consecutively collected clinical isolates of Enterobacteriaceae, including a large proportion of isolates from intensive care units. Absolute categorical agreement between ertapenem and imipenem, and very major (false susceptible) and major errors (false resistant) using imipenem to predict ertapenem results were 97.2%, 0.9%, and 0.4%, respectively, for Enterobacteriaceae (10,992 strains tested against both drugs) and 99.0%, 0.2%, and 0% for anaerobes. All Haemophilus spp., groups A and B streptococci, penicillin-susceptible and -intermediate S. pneumoniae, and other penicillin-susceptible streptococci were susceptible to ertapenem. All oxacillin-susceptible Staphylococcus aureus were ertapenem susceptible, except 1 that was intermediate. Surrogate antimicrobial agents that can be used to reliably predict ertapenem susceptibility by MIC tests are imipenem for Enterobacteriaceae and anaerobes, oxacillin for staphylococci, and penicillin for streptococci.
authors.affiliation: Merck Research Laboratories, West Point, PA 19486-0004, USA.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Friedland
authors.forename: Robin
authors.initials: R
authors.lastname: Isaacs
authors.forename: Lori A
authors.initials: LA
authors.lastname: Mixson
authors.forename: Mary
authors.initials: M
authors.lastname: Motyl
authors.forename: Gail L
authors.initials: GL
authors.lastname: Woods
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D000077727:Ertapenem; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D007769:Lactams; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013845:Thienamycins / Q000494:pharmacology; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D007769:Lactams; D010406:Penicillins; D013845:Thienamycins; D047090:beta-Lactams; D015378:Imipenem; D000077727:Ertapenem; D010068:Oxacillin