Background: It has previously been reported that patients infected with Burkholderia cenocepacia (genomovar III) before lung transplantation have a poorer outcome than those with other B cepacia complex infections. Methods: An extensive study was conducted to determine the prevalence and clonality of B cepacia complex genomovars isolated from patients referred for transplant assessment between 1989 to the present and, where appropriate, whether strain type was related to transplant outcome. Results: Isolates from 29 patients were identified as B cepacia complex organisms by molecular analysis. Thirteen patients (45%) were infected with the highly transmissible ET-12 strain of B cenocepacia recA lineage III-A, while all remaining patients were infected with genetically unique B cenocepacia, B multivorans, and B vietnamiensis strains. All previously reported deaths following transplantation were associated with ET-12 infection. Conclusions: The ET-12 strain is the predominant cause of B cenocepacia infections in patients with cystic fibrosis referred to our pulmonary transplant centre and is associated with poor transplant outcomes using standard treatment regimens.

Aims:  To evaluate three previously unreported substrates for the detection of β‐glucosidase activity in clinically relevant bacteria and to compare their performance with a range of known substrates in an agar medium. Methods and Results:  The performance of 11 chromogenic β‐glucosidase substrates was compared using 109 Enterobacteriaceae strains, 40 enterococci and 20 strains of Listeria spp. Three previously unreported β‐glucosides were tested including derivatives of alizarin, 3′,4′‐dihydroxyflavone and 3‐hydroxyflavone. These were compared with esculin and β‐glucoside derivatives of 3,4‐cyclohexenoesculetin, 8‐hydroxyquinoline and five indoxylics. All substrates yielded coloured precipitates upon hydrolysis in agar. Alizarin‐β‐d‐glucoside was the most sensitive substrate tested and detected β‐glucosidase activity in 72% of Enterobacteriaceae strains and all enterococci and Listeria spp. The two flavone derivatives showed poor sensitivity with Gram‐negative bacteria but excellent sensitivity with enterococci and Listeria spp. Conclusions:  Alizarin‐β‐d‐glucoside is a highly sensitive substrate for detection of bacterial β‐glucosidase and compares favourably with existing substrates. β‐glucosides of 3′,4′‐dihydroxyflavone and 3‐hydroxyflavone are effective substrates for the detection of β‐glucosidase in enterococci and Listeria spp. Significance and Impact of the Study:  The data presented allow for informed decisions to be made regarding the optimal choice of β‐glucosidase substrate for detection of pathogenic and/or indicator bacteria.

Aims:  Enzyme substrates based on 4‐methylumbelliferone are widely used for the detection of Escherichia coli and enterococci in water, by detection of β‐glucuronidase and β‐glucosidase activity respectively. This study aimed to synthesize and evaluate novel umbelliferone‐based substrates with improved sensitivity for these two enzymes. Methods and Results:  A novel β‐glucuronide derivative based on 6‐chloro‐4‐methylumbelliferone (CMUG) was synthesized and compared with 4‐methylumbelliferyl‐β‐d‐glucuronide (MUG) using 42 strains of E. coli in a modified membrane lauryl sulfate broth. Over 7 h of incubation, the fluorescence generated from the hydrolysis of CMUG by E. coli was over twice that from MUG, and all of the 38 glucuronidase‐positive strains generated a higher fluorescence with CMUG compared with MUG. Neither substrate caused inhibition of bacterial growth in any of the tested strains. Four β‐glucosidase substrates were also synthesized and evaluated in comparison with 4‐methylumbelliferyl‐β‐d‐glucoside (MU‐GLU) using 42 strains of enterococci in glucose azide broth. The four substrates comprised β‐glucoside derivatives of umbelliferone‐3‐carboxylic acid and its methyl, ethyl and benzyl esters. Glucosides of the methyl, ethyl and benzyl esters of umbelliferone‐3‐carboxylic acid, were found to be superior to MU‐GLU for the detection of enterococci, especially after 18 h of incubation, while umbelliferone‐3‐carboxylic acid‐β‐d‐glucoside was inferior. However, the variability in detectable β‐glucosidase activity among the different strains of enterococci in short‐term assays using the three carboxylate esters (7 h incubation) may compromise their use for rapid detection and enumeration of these faecal indicator bacteria. Conclusions:  The β‐glucuronidase substrate CMUG appears to be a more promising detection system than the various β‐glucosidase substrates tested. Significance and Impact of the Study:  The novel substrate CMUG showed enhanced sensitivity for the detection of β‐glucuronidase‐producing bacteria such as E. coli, with a clear potential for application in rapid assays for the detection of this indicator organism in natural water and other environmental samples.

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Chemotactic N‐formyl oligopeptides are produced by bacteria at sites of bacterial colonization in the digestive tract, but are susceptible to degradation by intestinal mucosal and luminal carboxypeptidases. Since production of such peptides by oral bacteria may promote neutrophil leukocyte accumulation in periodontal inflammatory disease, the activity and source of chemotactic peptide‐degrading enzymes in human saliva was investigated. An N‐formyl‐methionyl‐leucyl‐phenylalanyl carboxypeptidase was identified in whole mixed, but not pure parotid or submandibular saliva. The enzyme activity was attributable to a bacterial rather than a host source.