Antibiotic Usage Measured by Absence of Microbial Growth on Gram Stain and/or Culture

Antibiotic Usage Measured by Absence of Microbial Growth on Gram Stain and/or Culture Page E21 T. Rucker*, J. Mastroianni, T. Schneider Close Close preview | Purchase PDF (56 K) | Related articles | Related reference work articles AbstractAbstract Abstract BACKGROUND: The nasopharynx is colonized with a variety of mixed normal flora. The lower respiratory tract is normally sterile. Expectorated sputum samples collected, transported, and stored per lab standards, yielding >25 polymorphonuclear leukocytes (PMNs) and <10 epithelial cells per 100X field should result in a positive gram stain and/or culture result of either normal nasopharyngeal flora or bacterial growth. We report a trend in a 170-bed facility over a 60-day timeframe in sputum samples having few to no organisms seen on the smear and few colonies to no growth in cultures. METHODS: All sputum specimens were evaluated for adequacy by a CAP grading system. Group 4 with >25 WBC and 10–25 epi; Group 5 with >25 WBC and <10 epi; and Group 6 with <10 WBC and <10 epi were suggestive of lower respiratory microbial flora, considered “adequate,” and included in this review. A culture was considered “good” if it was collected appropriately, transported to the lab within 30 minutes, and plated out or preserved by refrigeration. A culture was considered “poor” if any of the above conditions were not met. Microbiology staffing during this timeframe was stable, with no change in management, supplies, technique, or procedure. Consideration was given to bacterial pathogens such as Mycoplasma and Chlamydia which are not readily detected, viral infection which might decrease bacterial burden, and use of rifampin which may obviate culture results. All antibiotics used prior to lab submission of the sputum specimen were accounted for by # days of use. RESULTS: Of the 23 specimens evaluated as “adequate,” 8 had a positive gram stain and/or culture result and were considered “good” cultures. The remaining 15 specimens had few to no organisms seen on the gram stain and few to no colonies grow on culture and were considered “poor” cultures. A total of 40 antibiotic days were calculated for the “good” specimens (mean = 5 days) and 202 days (mean = 13.6 days) for the “poor” specimens. Three patients with “good” specimens were antibiotic-free. All others received 1-10 antibiotics. CONCLUSIONS: There were more antibiotic days with the “poor” specimens. The sample size was too small for statistical significance. CDC has focused on the alteration in antimicrobial sensitivity and resistance patterns in hospital settings as a guide for judging antibiotic use (Emerging Pathogens Initiative). Consultation with Microbiology for “adequacy” of submitted specimens might also offer epidemiological staff insight to antibiotic usage.