Selective and differential medium for recovery of Pseudomonas cepacia from the respiratory tracts of patients with cystic fibrosis

Abstract

A selective and differential medium, OFPBL (oxidation-fermentation base supplemented with agar, lactose, and two antimicrobial agents), for the isolation of Pseudomonas cepacia from respiratory specimens of patients with cystic fibrosis was developed and tested. Among 725 specimens submitted from seven centers over a 4to 6-month period, 58 (8%) yielded P. cepacia on OFPBL; only 19 of these were recovered on MacConkey or sheep blood agar (P < 0.001). No isolate was recovered on MacConkey or sheep blood agar alone. Ranges of recovery rates among centers were 0 to 15% on OFPBL and 0 to 10% on MacConkey or sheep blood agar. Ninety percent of P. cepacia isolates were detected on OFPBL in c3 days. Other nonfermenters and yeasts isolated on OFPBL were distinguished from P. cepacia by failure to acidify the medium. The new medium was clearly superior to MacConkey and sheep blood agars for the isolation of P. cepacia from the respiratory secretions of patients with cystic fibrosis. Patients with cystic fibrosis (CF) are predisposed to colonization and acute and chronic pulmonary infections caused by microorganisms such as Staphyloccoccus auri-eus, Haeinophilus influence, Psezidom7ionas aeruginosa, and Pseudoinonas cepac-ia (2, 6, 7, 12). It has been hypothesized that lytic enzymes of these microbes or of inflammatory cell origin contribute to progressive destruction of lung tissue (1, 2, 6, 9) and, hence, the limited life expectancy associated with CF. Recognition of the colonizing or infecting agents of the respiratory tract in individuals with CF may permit specific antimicrobial therapy to be used. However, culture media which permit the isolation of these important bacterial pathogens from complex mixtures of other oropharyngeal flora must be used. Various selective media for S. auireus, H. influenzae, and P. aeruginosa have been described and shown to facilitate detection of these species in sputum (8, 13). Until recently, the recognition of P. cepacia in cultures of respiratory specimens has been complicated by the lack of a similarly useful selective culture method for this organism. Gilligan et al. (5) reported a selective medium for isolation of P. cepacia from patients, and Wu and Thompson (14) developed a medium intended for isolation of P. cepacia from environmental samples. We report the development and evaluation of an additional selective and differential medium and the experience with its use in a multicenter study to examine comparative recovery rates of P. cepacia from the respiratory tracts of individuals with CF.

Accuracy of four commercial systems for identification of Burkholderia cepacia and other gram-negative nonfermenting bacilli recovered from patients with cystic fibrosis

“…The following tests and media were prepared in house: triple sugar iron (TSI); citrate; urea; lysine decarboxylase; ornithine decarboxylase; arginine dihydrolase; oxidation-fermentation (OF) sugars (glucose, xylose, lactose, mannitol, sucrose, maltose, fructose, galactose, mannose) with bromthymol blue as a pH indicator; o-nitrophenyl-␤-D-galactoside (ONPG); nitrate reduction and gas; gelatin; esculin; egg yolk agar for lecithinase activity; litmus milk; cetrimide; flo; tech; growth at 42ЊC; hemolysis; motility; and growth on MacConkey, PC, and OFPBL agars. PC and OFPBL agars are selective media used in the isolation of B. cepacia from clinical specimens (9,24). Medium components and reagents were purchased from the following manufacturers: Difco, Detroit, Mich.; Becton-Dickinson MicroSystems, Cockeysville, Md.…”

Population transcript accumulation of Pseudomonas aeruginosa exotoxin A and elastase in sputa from patients with cystic fibrosis

“…Sputolysin-treated sputum samples were serially diluted in saline solutions. Samples (100 ,ul) of either i0-' or [40]) agar plates. The samples were enumerated at 24 and 48 h after inoculation.…”

Infection control recommendations for patients with cystic fibrosis: Microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

“…OFPBL (oxidative-fermentative basal medium with polymyxin B, bacitracin, and lactose) agar, developed by Welch et al, uses oxidative fermentative basal media as an indicator with lactose as the nutrient sugar and bacitracin and polymyxin as selective agents. 108 Using OFPBL, 58 (8%) of 725 specimens yielded B. cepacia complex while only 19 (2.6%) were positive using MacConkey and sheep blood agar.…”