Comparative antimicrobial susceptibility of aerobic and facultative bacteria from community-acquired bacteremia to ertapenem in Taiwan.
BACKGROUND
Ertapenem is a once-a-day carbapenem and has excellent activity against many gram-positive and gram-negative aerobic, facultative, and anaerobic bacteria. The susceptibility of isolates of community-acquired bacteremia to ertapenem has not been reported yet. The present study assesses the in vitro activity of ertapenem against aerobic and facultative bacterial pathogens isolated from patients with community-acquired bacteremia by determining and comparing the MICs of cefepime, cefoxitin, ceftazidime, ceftriaxone, ertapenem, piperacillin, piperacillin-tazobactam, ciprofloxacin, amikacin and gentamicin. The prevalence of extended broad spectrum beta-lactamases (ESBL) producing strains of community-acquired bacteremia and their susceptibility to these antibiotics are investigated.


METHODS
Aerobic and facultative bacteria isolated from blood obtained from hospitalized patients with community-acquired bacteremia within 48 hours of admission between August 1, 2004 and September 30, 2004 in Chang Gung Memorial Hospital at Keelung, Taiwan, were identified using standard procedures. Antimicrobial susceptibility was evaluated by Etest according to the standard guidelines provided by the manufacturer and document M100-S16 Performance Standards of the Clinical Laboratory of Standard Institute. Antimicrobial agents including cefepime, cefoxitin, ceftazidime, ceftriaxone, ertapenem, piperacillin, piperacillin-tazobactam, ciprofloxacin, amikacin and gentamicin were used against the bacterial isolates to test their MICs as determined by Etest. For Staphylococcus aureus isolates, MICs of oxacillin were also tested by Etest to differentiate oxacillin-sensitive and oxacillin-resistant S. aureus.


RESULTS
Ertapenem was highly active in vitro against many aerobic and facultative bacterial pathogens commonly recovered from patients with community-acquired bacteremia (128/159, 80.5 %). Ertapenem had more potent activity than ceftriaxone, piperacillin-tazobactam, or ciprofloxacin against oxacillin-susceptible S. aureus (17/17, 100%)and was more active than any of these agents against enterobacteriaceae (82/82, 100%).


CONCLUSIONS
Based on the microbiology pattern of community-acquired bacteremia, initial empiric treatment that requires coverage of a broad spectrum of both gram-negative and gram-positive aerobic bacteria, such as ertapenem, may be justified in moderately severe cases of community-acquired bacteremia in non-immunocompromised hosts.
Lee
Sai-Cheong
SC
Division of Infectious Diseases, Chang Gung Memorial Hospital, Keelung, Taiwan, Republic of China. Lee.sch@msa.hinet.net
Huang
Shie-Shian
SS
Lee
Chao-Wei
CW
Fung
Chang-Phone
CP
Lee
Ning
N
Shieh
Wen-Bin
WB
Siu
L K
LK
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology*; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000472:pathogenicity; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000382:microbiology*; D000077727:Ertapenem; D005260:Female; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000472:pathogenicity; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000472:pathogenicity; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D013624:Taiwan; D047090:beta-Lactams / Q000494:pharmacology* / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D000077727:Ertapenem