Therapeutic implications in the treatment of aural Pseudomonas infections based on in vitro susceptibility patterns.
OBJECTIVE
To examine the in vitro susceptibility patterns of aural isolates of Pseudomonas aeruginosa and to identify changes over a 4-year period.


METHODS
Retrospective case series.


METHODS
The outpatient department at Children's Hospital of Pittsburgh (Pa), a tertiary referral center.


METHODS
Ambulatory children younger than 18 years from whose ears P aeruginosa was isolated.


METHODS
The in vitro susceptibility of aural isolates of P aeruginosa to ampicillin, cefotaxime, chloramphenicol, sulfisoxazole, ticarcillin, mezlocillin, gentamicin, tobramycin, cefazolin, tetracycline, piperacillin, nitrofurantoin, cephalexin hydrochloride, ceftriaxone, cefuroxime axetil, and sulfamethoxazole-trimethoprim.


CONCLUSIONS
No changes were found in the trends of the susceptibility patterns over the 4-year study period, with the exception of the semisynthetic penicillins, ticarcillin and mezlocillin. These two agents were found to be relatively ineffective against the strains of P aeruginosa isolated in 1989 (59% and 18% susceptibility, respectively). This finding is in contrast to their effectiveness over the remainder of the study period (96% and 90% susceptibility, respectively), which was excellent. These observations likely reflect a change in the breakpoints for the minimal inhibitory concentrations between these periods. The intravenous agent with the best susceptibility profile was piperacillin (96%). Of the aminoglycosides tested, 94% of the isolates were sensitive to tobramycin, as opposed to only 79% for gentamicin. This finding may have significance when one is empirically selecting ototopical therapy, since both tobramycin and gentamicin are available as topical preparations. Of the oral agents, the combination of sulfamethoxazole-trimethoprim was most effective (46%).
Dohar
J E
JE
Department of Otolaryngology, University of Pittsburgh School of Medicine, Pa, USA.
Kenna
M A
MA
Wadowsky
R M
RM
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004425:Ear Cartilage / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D010032:Otitis Externa / Q000188:drug therapy* / Q000382:microbiology; D011552:Pseudomonas Infections / Q000188:drug therapy*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D012189:Retrospective Studies
D000900:Anti-Bacterial Agents