The Anaerobic Culture of Clinical Specimens: A 14-Month Study

Abstract

THE isolation rate of anaerobic bacteria from clinical specimens increased manyfold in our laboratory when the techniques for anaerobic bacteriology were revised. We present here an account of our findings with these methods applied as a routine to clinical specimens, and make recommendations concerning the techniques of incubation, media and the use of certain identification tests. The isolation of anaerobic species from different anatomical sites is described, and special attention is given to the yield of organisms from empyema fluid, the peritoneal cavity, surface lesions and blood. MATERIALS AND METHODSWith the general exception of urines, faeces, respiratory specimens and cerebrospinal fluid (CSF), specimens of exudates received between 1 Dec. 1974 and 31 Jan. 1976 were cultured for anaerobic bacteria as described below. Transport of specimens. Samples of pus were transported to the laboratory in sterileMcCartney bottles. Swabs of purulent material were sometimes transported deep in a tube of Cary and Blair transport medium (Cary and Blair, 1964), but many swabs were received in the ordinary dry state.Macroscopic examination. Specimens were examined for colour, odour, consistency and the presence of sulphur granules. Liquid pus samples were examined for brick-red fluorescence under an ultraviolet light (Blak-Ray UVL 21, Ultraviolet Products Inc., San Gabriel, California) at a distance of 6-9 in. (15-23 cm) for presumptive evidence of the presence of Bacteriodes melaninogenicus.Microscopic examination. Samples of pus were examined by gram stain to ascertain the number and proportion of morphological forms present.Culture of clinical material. Our complete range of media used for culture in this study were as follows :1. Blood agar: Columbia Agar Base (London Analytical and Bacteriological Media) with 5 % defibrinated horse-blood; this was obtained as poured plates from London Analytical and Bacteriological Media Ltd, Salford, Lancs. (LAB M). 2. Supplemented brucella agar: Brucella Agar (Difco Laboratories Ltd, West Molesey, Surrey) with 5 % defibrinated horse blood and menadione 0.5 pg per ml (Sigma Chemical Co. Ltd, Kingston-upon-Thames, Surrey). 3. Supplemented selective brucella agar: supplemented brucella agar rendered selective by adding kanamycin 75 pg per ml (Kantrex solution, Bristol Laboratories, Langley, Bucks).

Isolation and Characterisation of Bacteria From Abscesses in the Subcutis of Cats

“…multocida nor any other organism isolated appeared to play a dominant role in the production of the subcutaneous abscesses that we examined. The many recent studies in which modern anaerobic-culture techniques were used have revealed the diversity of human infections that are caused by anaerobes or mixtures of anaerobes (Finegold, 1974;Gorbach, 1974;Wren et al, 1977). In such human infections, gram-negative anaerobic bacilli were the most common isolates and B. fragilis was the species most commonly encountered.…”

Rational use of antibiotic therapy after appendicectomy.

“…13 Isolates were identified conventionally13 14 and antibiotic sensitivities obtained by the comparative method using discs.…”

The Culture of Clinical Specimens for Anaerobic Bacteria: A Comparison Of Three Regimens

“…In all, 50% of the isolates were anaerobic gramnegative bacilli and a further 33.6% of the strains were anaerobic cocci. DISCUSSION Earlier work in this laboratory revealed that significantly greater numbers of anaerobic bacteria can be recovered from clinical specimens cultured on primary anaerobic plates if the plates are incubated for 48 h rather than 24 h before being examined for the first time (Wren et al, 1977).…”