Biomedical subjects

F Cockerill

Publications and source records attributed to F Cockerill.

7 recordsLinked to original sources

PubMed2001

Comparison of the BACTEC MYCO/F Lytic bottle to the isolator tube, BACTEC Plus Aerobic F/bottle, and BACTEC Anaerobic Lytic/10 bottle and comparison of the BACTEC Plus Aerobic F/bottle to the Isolator tube for recovery of bacteria, mycobacteria, and fungi from blood.

The BACTEC MYCO/F Lytic blood culture bottle (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) is designed to optimize the recovery of fungi and mycobacteria; however, this bottle also supports the growth of most aerobic bacteria. We compared the MYCO/F Lytic bottle with two other BACTEC bottles and the Isolator system for the recovery of bacteria as well as fungi and mycobacteria from blood. A total of 6,108 blood culture sets were inoculated with blood obtained from adult patients. Twenty-five to 28 ml of blood collected by a phlebotomy team for each blood culture set was randomly distributed into each of four blood culture receptacles: the Isolator tube (Wampole Laboratories, Cranbury, N.J.) and three BACTEC bottles: the MYCO/F Lytic bottle, the BACTEC Plus Aerobic/F bottle, and the BACTEC Anaerobic Lytic/10 bottle. The sediment from the Isolator tube was inoculated onto chocolate agar (CA), brain heart infusion agar (BHI), and Sabouraud dextrose agar (SDA) and into a BACTEC 13A bottle. Incubation durations were as follows: MYCO/F Lytic bottle, 42 days; Plus Aerobic/F bottle, 5 days; Anaerobic Lytic/10 bottle, 5 days; sediment from Isolator tube on CA, 3 days; sediment from Isolator tube on BHI, 30 days; sediment from Isolator tube on SDA, 30 days; and sediment from Isolator tube in a BACTEC 13A bottle, 42 days. Two isolates of Histoplasma capsulatum were recovered from the Isolator tube only. Three isolates of Mycobacterium tuberculosis complex were recovered: two isolates from the MYCO/F Lytic bottle only and one isolate from the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle) only. Two isolates of Cryptococcus neoformans were recovered: one from the MYCO/F Lytic bottle only and the other from the MYCO/F Lytic bottle and the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle). For potential pathogens overall, there was a statistical difference in recovery that favored the Isolator system over the MYCO/F Lytic bottle (P = 0.0015), including statistically significant differences for Staphylococcus aureus (P = 0.0001) and Streptococcus pneumoniae (P = 0.0313). However, there was no statistically significant difference between the two blood culture systems when detection of bloodstream infection was considered. The time to detection for all potential pathogens combined was less for the MYCO/F Lytic bottle than for the Isolator system (P = 0.0004). Overall, the potential pathogen recovery was greater for the BACTEC Plus Aerobic/F bottle than for either the Isolator system (P = 0.0003) or the MYCO/F Lytic bottle (P = 0.0001). However, the BACTEC Plus Aerobic/F bottle did not recover M. tuberculosis, H. capsulatum, or C. neoformans isolates. The combination of the Isolator system and MYCO/F Lytic bottle may be useful as a selective blood culture method to optimize the recovery of fungi and mycobacteria from blood. Compared with the manual Isolator system, the MYCO/F Lytic system has the advantage of less preanalytic processing and continuous automated monitoring of bottles for growth by the BACTEC 9240 instrument.

Adult↗

PubMed2000

Antibiotic bacterial resistance in ambulatory patients.

BACKGROUND: This study evaluates trends in antibiotic resistance in patients who were treated in an ambulatory setting. METHODS: The authors compiled the data from all lower respiratory track(sputum) cultures collected from ambulatory patients who visited the Olmsted Medical Center and Mayo Clinic between 1985 and 1998. Cultured organisms were identified, and Minimal Inhibitory Concentration (MIC) values were presented and categorized as susceptible, intermediate, or resistant based on the National Committee for Clinical Laboratory Standards (NCCLS) guidelines for MIC and antibiotic susceptibility. RESULTS: 4,297 potentially pathogenic organisms were obtained from sputum cultures for 1,921 patients. The most discernible changes in antibiotic resistance appeared to be in cultures positive for Pseudomonas aeruginosa. A trend toward increasing resistance of isolates of Streptococcus pneumoniae to beta-lactam drugs was observed in a portion of the population. An emerging intermediate susceptibility among isolates of Klebsiella pneumoniae and Pseudoumonas species was noted. CONCLUSIONS: Trends in antimicrobial resistance of respiratory pathogens from ambulatory patients are less clear than those from hospitalized patients, but must be monitored because of the high percentage of ambulatory patients who receive empirical therapies. Trends in intermediate susceptibility patterns may help reveal emerging antimicrobial resistance.

Ambulatory Care↗

PubMed1999

Comparison of susceptibility testing methods with mecA gene analysis for determining oxacillin (methicillin) resistance in clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus spp.

Ninety-nine clinical staphylococcal isolates (58 coagulase-negative Staphylococcus spp. [CoNS] and 41 Staphylococcus aureus isolates) were evaluated for susceptibility to oxacillin. The following susceptibility testing methods, media, and incubation conditions were studied: agar dilution by using Mueller-Hinton (MH) medium (Difco) supplemented with either 0, 2, or 4% NaCl and incubation at 30 or 35 degrees C in ambient air for 24 or 48 h; disk diffusion by using commercially prepared MH medium (Difco) and MH II agar (BBL) and incubation at 35 degrees C in ambient air for 24 or 48 h; and agar screen (spot or swab inoculation) by using commercially prepared agar (Remel) or MH agar (Difco) prepared in-house, each containing 4% NaCl and 6 microg of oxacillin/ml (0.6-microg/ml oxacillin was also studied with MH agar prepared in-house for the agar swab method and CoNS isolates) and incubation at 35 degrees C in ambient air for 24 or 48 h for swab inoculation and at 30 or 35 degrees C in ambient air for 24 or 48 h for spot inoculation. The results for these methods were compared to the results for mecA gene detection by a PCR method. Given the ability to support growth and the results for susceptibility testing (the breakpoint for susceptible isolates was </=2 microg/ml), the best methods for CoNS isolates were (i) agar dilution by using MH medium supplemented with 4% NaCl and incubation at 35 degrees C for 48 h (no growth failures were noted, and sensitivity was 97.6%) and (ii) agar screen (swab inoculation) by using MH medium prepared in-house supplemented with 4% NaCl and containing 0.6 microg oxacillin/ml and incubation at 35 degrees C for 48 h (one isolate that did not carry the mecA gene did not grow, and the sensitivity was 100%). All but one (agar dilution without added NaCl and incubation at 30 degrees C for 48 h) of the methods tested revealed all oxacillin-resistant S. aureus isolates, and no growth failures occurred with any method. If the breakpoint for susceptibility was lowered to </=1 microg/ml for agar dilution methods, more CoNS isolates with oxacillin resistance related to the mecA gene were detected when 0 or 2% NaCl agar supplementation was used. Only one CoNS isolate with mecA gene-associated resistance was not detected by using agar dilution and MH medium supplemented with 4% NaCl with incubation for 48 h. When the breakpoint for susceptibility was decreased 10-fold (from 6.0 to 0.6 microg of oxacillin per ml) for the agar swab screen method, fully 100% of the CoNS isolates that carried the mecA gene were identified.

Bacterial Proteins↗

PubMed1997

Comparison of agar dilution, broth dilution, disk diffusion, and the E-test for susceptibility testing of penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae.

An evaluation to determine the optimal methods for the in vitro susceptibility testing of 41 clinical isolates and the ATCC 49619 strain of Streptococcus pneumoniae to penicillin was undertaken. No very major or major interpretive errors were observed with the following test methods and media: agar dilution using either Mueller-Hinton medium with lysed horse blood or Haemophilus test medium; broth dilution using cation-adjusted Mueller-Hinton medium with lysed horse blood, Haemophilus test medium, or Todd-Hewitt medium; and the epsilo-meter test (E-test) using agar containing Mueller-Hinton medium and 5% sheep blood. The disk diffusion method using agar containing Mueller-Hinton medium and 5% sheep blood agar was an effective screening method, requiring confirmation by a dilution susceptibility test method.

Bacteriological Techniques↗

PubMed1996

Polysaccharide side chains are not required for attaching and effacing adhesion of Escherichia coli O157:H7.

Escherichia coli of the serotype O157:H7 is an enterohemorrhagic human pathogen which demonstrates attaching and effacing adhesion to colonocytes in vivo and to epithelial cells grown in tissue culture. Transposon TnphoA mutants of E. coli O157:H7 strain CL-8 were produced. Two of 300 alkaline phosphatase positive mutants, designated JB6 and JB27, did not express O157 side chains as assessed by agglutination with specific polyclonal O157 antiserum, silver staining of lipopolysaccharide extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western immunoblots with polyclonal O157-specific antiserum. Both O157-negative mutants and the parent strain demonstrated localized adherence to HEp-2 cells when examined by Giemsa staining and bright-field microscopy. Furthermore, both O157-negative mutants showed enhanced adherence to HEp-2 cells compared with the parent strain when assessed by quantification of adherent bacterial CFUs. The parent strain, CL-8, and both of the mutants produced fluorescent foci when adherent bacteria and HEp-2 cells were stained with fluorescein isothiocyanate-labelled phalloidin. Transmission electron microscopy confirmed attaching and effacing adherence of strain CL-8 and the OO7-negative mutants to HEp-2 cells. These findings indicate that mutants deficient in O157 polysaccharide repeats exhibit adherence to tissue culture cells in vitro and that O157 polysaccharide repeats are not required to produce the attaching and effacing lesion.

Agglutination Tests↗

PubMed1993

Multiple determinants of verotoxin-producing Escherichia coli O157:H7 attachment-effacement.

Verotoxin-producing Escherichia coli strains of the serotype O157:H7 belong to a class of gastrointestinal pathogens that adhere to epithelial cells in a characteristic pattern known as attaching and effacing. Recent insight into the nature of E. coli O157:H7 adhesion was provided by the cloning and sequencing of the chromosomal eaeA (for E. coli attaching and effacing) gene homolog (G. Beebakhee, M. Louie, J. De Azavedo, and J. Brunton, FEMS Microbiol. Lett. 91:63-68, 1992, and J. Yu and J. B. Kaper, Mol. Microbiol. 6:411-417, 1992) and isolation of a 60-MDa plasmid referred to as pO157 (I. Toth, M. L. Cohen, H. S. Rumschlag, L. W. Riley, E. H. White, J. H. Carr, W. W. Bond, and I. K. Wachsmuth, Infect. Immun. 58:1223-1231, 1990, and S. Tzipori, H. Karch, K. I. Wachsmuth, R. M. Robins-Browne, A. D. O'Brien, H. Lior, M. L. Cohen, J. Smithers, and M. M. Levine, Infect. Immun. 55:3117-3125, 1987) and an approximately 94-kDa outer membrane protein (94-kDa OMP; P. Sherman, F. Cockerill III, R. Soni, and J. Brunton, Infect. Immun. 59:890-899, 1991). In this study, we examined the gene products of both eaeA and pO157 in relation to the 94-kDa OMP and as candidate effectors for O157:H7 attachment-effacement. Peptide sequencing and immunoassay demonstrated that the C. coli O157:H7 eaeA gene product is distinct from the 94-kDa OMP. Using ultrastructural analyses, we found that both parent and pO157 plasmid-cured O157:H7 strains demonstrated attaching and effacing adhesion to host epithelial cells and reacted equally well to rabbit antiserum raised against the 94-kDa OMP. By both transmission electron microscopy and light microscopy, E. coli HB101 transformed separately with the cloned eaeA gene and the pO157 plasmid did not form attaching and effacing lesions on cultured epithelial cells in vitro and rabbit intestinal tissues in vivo. Since additional determinants may mediate the attaching and effacing phenotype, we examined transposon TnphoA mutants constructed from E. coli O157:H7 strain CL8. Two TnphoA mutants were found deficient in bacterial factors that are necessary for O157:H7 attachment-effacement and likely distinct from the eaeA gene product.

Adhesins, Bacterial↗

PubMed1991

Outer membranes are competitive inhibitors of Escherichia coli O157:H7 adherence to epithelial cells.

Escherichia coli of serotype O157:H7 are Vero cytotoxin-producing enteric pathogens that have been associated recently with sporadic cases and outbreaks of hemorrhagic colitis and with the hemolytic-uremic syndrome. Adherence of many enteropathogenic bacteria to mucosal surfaces is a critical step in the pathogenesis of diarrheal disease. We showed previously that adherence of E. coli O157:H7 strain CL-56 to epithelial cells in vitro is inhibited by outer membranes. In this study we examined whether outer membranes from a series of E. coli O157:H7 strains mediated competitive inhibition of bacterial binding to epithelial cells grown in tissue culture. We also determined which constituents of the outer membrane mediated inhibition of CL-56 adherence. Binding of six O157:H7 strains to HEp-2 cells was determined by quantitating the number of adherent bacteria in the presence and absence of outer membranes which were extracted from each strain with N-lauroyl sarcosinate (1.7%, wt/vol). After separation of outer membranes by gel electrophoresis, four bands (94, 40, 36, and 30 kDa) were collected by electroelution. Immune sera were raised in rabbits to each of the four eluted bands. Outer membrane extracts from each of the six O157:H7 strains inhibited binding of homologous organisms to the HEp-2 cells. At dilutions which did not cause bacterial agglutination, antiserum raised against the 94-kDa outer membrane protein showed maximal inhibition of bacterial adherence (17.0 +/- 7.3% adherence of control levels). Growth of bacteria in iron-depleted broth did not affect their binding to HEp-2 cells, suggesting that iron-regulated outer membranes were not involved. Fluid accumulation in ileal ligated loops of rabbits in response to E. coli O157:H7 challenge was diminished following both parenteral immunization with outer membranes extracted from the homologous strain and coincubation of organisms with immune serum which contained antibodies to outer membrane extracts. These data indicate that outer membranes are competitive inhibitors of E. coli O157:H7 adherence. Specific constituents of the outer membrane may function as bacterial attachment factors (i.e., adhesins) for E. coli O157:H7 adherence to epithelial cell surfaces.

Actins↗