ORIGINAL ARTICLES   

Gazzetta Medica Italiana Archivio per le Scienze Mediche 1998 February;157(1):9-14

Copyright © 1998 EDIZIONI MINERVA MEDICA

language: Italian

Anaerobic infections of the appendix. A bacteriological study

Ronchetto F. ¹, Pistono P. G. ², Cestonaro G. ², Musso V. ¹

¹ Azienda USL 9 - Ivrea, Ospedali Riuniti del Canavese, Ospedale «Mario Nubola» - Castellamonte (Torino), Divisione di Medicina 3; ² Azienda USL 9 - Ivrea, Ospedali Riuniti del Canavese, Ospedale «Mario Nubola» - Castellamonte (Torino), Laboratorio Analisi Chimico-Cliniche e Microbiologiche

Background. The microbial flora in the infections of the appendix most often consists of a mixture of aerobic and anaerobic bacteria. In recent years, the literature reports a high incidence of resistance to established anti-anaerobe antibiotics in anaerobes. In this study the entity of partecipation of anaerobic bacteria to infections of the appendix and the susceptibility of B. fragilis to antibiotics is considered.
Methods. The results of the cultures of every sample of appendicular pus collected during surgery for perforated and gangrenous appendicitis over a period of six years have been examined.
Results. Eighty-five (64.3%) of 132 samples of appendicular exudate from 129 patients aged between 2 and 83 years showed bacterial growth. The unimicrobial samples were 10 (11.8%), those polymicrobial were 75 (88.2%). The microorganisms isolated were 259: 159 (61.4%) aerobes, 100 (38.6%) anaerobes. The aerobic bacteria most frequently found were: Escherichia coli (64 strains) and Streptococcus intermedius (22 strains). Among anaerobes the most commons were B. fragilis (47 strains) and B. thetaiotaomicron (11 strains). Bacte-roides fragilis group counted 86 strains. Six per cent of strains of B. fragilis tested was susceptible to amoxicillin, 94% to amoxicillin-clavulanic acid, 33% to piperacillin, 46% to ticarcillin, 86% to cefoxitin, 89% to clindamycin , 94% to metronidazole and chloramphenicol, 100% to imipenem.
Conclusions. This study demonstrates that the resistance of B. fragilis to certain beta-lactam antibiotics could be overcome adding a beta-lactamase inhibitor. Cefoxitin possesses a good in vitro activity against the anaerobes most often involved in these infections but metronidazole, clindamycin and imipenem are more active.