Biomedical subjects

F R Cockerill

Publications and source records attributed to F R Cockerill.

At least 73 records · Page 4Linked to original sources

PubMed1996

Prospective evaluation of the utility of molecular techniques for diagnosing nosocomial transmission of multidrug-resistant tuberculosis.

OBJECTIVE: To compare molecular techniques with conventional diagnostic methods for evaluating nosocomial transmission of multidrug-resistant tuberculosis (MDR-TB). DESIGN: We conducted a 12-week postexposure inception cohort study of health-care personnel who had been exposed to a patient with MDR-TB. MATERIAL AND METHODS: In addition to baseline and follow-up tuberculin skin tests and chest roentgenography, weekly pulmonary specimens were evaluated by (1) auramine-rhodamine fluorescent staining, (2) culture for mycobacteria, and (3) polymerase chain reaction (PCR) to amplify IS6110, a nucleic acid insertion sequence unique to the Mycobactrium tuberculosis complex. RESULTS: The index patient's isolate of M. tuberculosis showed a mutation in codon 531 of the RNA polymerase beta subunit (rpoB) gene of M. tuberculosis, which is associated with rifampin resistance and considered a marker for this MDR-TB strain. All pulmonary and gastric specimens from study participants had negative auramine stains and cultures for mycobacteria, One person, however, had separate specimens with repeatedly positive PCR results for IS6110 sequences, but the specimens contained a wild-type M. tuberculosis rpoB codon 531 dissimilar from the index patient's strain. CONCLUSION: Although both molecular and conventional testing showed that no exposed person was infected with the MDR-TB strain, molecular test results were available sooner and seemed more sensitive for detecting M. tuberculosis in one exposed person, presumably in a preinfection or "colonized" stage. Molecular methods provided information that helped distinguish this person's M. tuberculosis strain from the index patient's MDR-TB strain. Additional prospective studies should assess the value of these molecular techniques in similar clinical settings.

Antitubercular Agents↗

PubMed1995

Rapid identification of a point mutation of the Mycobacterium tuberculosis catalase-peroxidase (katG) gene associated with isoniazid resistance.

The complete catalase-peroxidase (katG) gene DNA sequence was determined for 15 strains of Mycobacterium tuberculosis with a wide range of susceptibility to isoniazid. Five of 9 strains with isoniazid MICs > or = 1.0 microgram/mL had one or more missense mutations and all 5 strains had a common G-->T transversion in codon 463, causing the replacement of arginine with leucine and the loss of an NciI or MspI restriction site. None of 6 strains with an isoniazid MIC < 1.0 microgram/mL had mutations affecting codon 463. Restriction analysis of 43 strains with isoniazid MICs > or = 1.0 microgram/mL showed that 19 (44.2%) had lost the NciI-MspI restriction site at the locus of codon 463 while only 1 of 32 strains with isoniazid MICs < or = 1.0 microgram/L had this restriction polymorphism. These results indicate that the mutation arginine-->leucine in codon 463 of the catalase-peroxidase gene occurs in a significant fraction (44.2%) of M. tuberculosis strains with isoniazid MICs > or = 1.0 microgram/mL.

Bacterial Proteins↗

PubMed1995

Evaluation of an immunoassay for direct detection of Escherichia coli O157 in stool specimens.

An enzyme-linked immunosorbent assay (ELISA) produced by LMD Laboratories, Inc., Carlsbad, Calif., was compared with culture for the detection of Escherichia coli O157. Nine of 185 stool specimens evaluated had positive results by the LMD E. coli O157 ELISA and grew E. coli O157 on culture; 174 had negative by LMD E. coli O157 ELISA results and did not grow E. coli O157 on culture. Of 174 specimens negative by LMD E. coli O157 ELISA, 117 specimens grew other enteric pathogens: Campylobacter spp. (46 isolates), Salmonella spp. (43 isolates), Yersinia spp. (20 isolates), and Shigella spp. (8 isolates). There were two indeterminant results by the LMD E. coli O157 ELISA. One stool specimen did not grow other enteric pathogens on culture, and one grew a Campylobacter sp. on culture. Both had negative LMD E. coli O157 ELISA results upon repeat testing. The LMD E. coli O157 ELISA is an accurate, easy-to-read screening method for the detection of E. coli O157 in fecal specimens.

Antibodies, Bacterial↗

PubMed1995

Clinical comparison of the isolator and BacT/Alert aerobic blood culture systems.

The performance characteristics of the Isolator (Wampole Laboratories, Cranbury, N.J.) and the BacT/Alert (Organon Teknika Corporation, Durham, N.C.) aerobic blood culture systems were compared for 6,009 blood culture sets obtained from patients with suspected bloodstream infections. The BacT/Alert aerobic bottle [BTA(O2)] was continuously agitated while it was incubated in 5% CO2 at 36 degrees C; culture plates prepared from the Isolator tube [I(O2)] were incubated in 5% CO2 at 37 degrees C. From 394 blood cultures, 416 clinically significant isolates of bacteria and yeasts were recovered. The overall yields for BTA(O2) and I(O2) were not significantly different (319 versus 336; P = 0.20). I(O2) recovered significantly more staphylococcus (P < 0.05) and yeast isolates (P < 0.01). BTA(O2) recovered significantly more aerobic and facultatively anaerobic gram-negative bacilli (P < 0.05). In blood culture sets which produced growth of the same organisms in both the BTA(O2) and I(O2) systems, the BTA(O2) system detected growth sooner, but more rapid identification was possible with the I(O2) system by virtue of earlier isolation of colonies on solid media.

Bacteremia↗

PubMed1995

Comparison of in-house and commercially prepared haemophilus test media for disk diffusion testing of ampicillin against Haemophilus species.

The performance characteristics of two lots of Haemophilus Test Medium (HTM) prepared in-house at Mayo Clinic, one lot obtained from BBL (Cockeysville, Md.) and one lot obtained from Remel (Lenexa, Kans.), for disk diffusion susceptibility testing of ampicillin against 81 Haemophilus strains were assessed. Insufficient growth occurred in 2.5 to 13.6% of strains, depending on the HTM used, and was most frequent for beta-lactamase-negative, ampicillin-resistant strains when they were tested with one lot of HTM prepared in-house. Results for all 14 beta-lactamase-positive Haemophilus strains were in complete agreement for all lots of HTM when either 1990 or 1993 National Committee for Clinical Laboratory Standards (NCCLS) interpretive guidelines were followed. However, these beta-lactamase-positive Haemophilus strains could be as precisely, but more rapidly, identified by the cefinase disk method. Results for 56 beta-lactamase-negative, ampicillin-susceptible strains and 11 beta-lactamase-negative, ampicillin-resistant strains varied significantly among all HTM lots tested and as to whether 1990 or 1993 NCCLS interpretive guidelines were followed. We conclude that in our hands disk diffusion testing with HTM prepared in-house or obtained from two commercial sources and following either 1990 or 1993 NCCLS guidelines is an unacceptable method for determining the susceptibilities of Haemophilus strains to ampicillin.

Ampicillin↗

PubMed1994

Lactobacillemia in liver transplant patients.

Lactobacillemia is rare and, to our knowledge, previously undescribed in liver transplant patients. We reviewed the clinical records of all patients who had undergone orthotopic liver transplantation between January 1985 and August 1992 for whom a blood culture after transplantation yielded Lactobacillus species. A case-control study for determination of risk factors for lactobacillemia in this patient population was also performed. Eight cases of lactobacillus bacteremia were identified. All patients received nonabsorbable oral antibiotics for selective bowel decontamination. In addition, six of eight case patients received intravenous vancomycin prior to the development of lactobacillemia. The biliary anastomosis in each case patient was a Roux-en-Y choledochojejunostomy. Analysis of the case-control study revealed that the presence of a Roux-en-Y choledochojejunostomy at the time of lactobacillemia is a statistically significant risk factor (odds ratio [OR] = infinity, 95% confidence interval [CI] = 1.8-infinity, P < or = .05) but that prior administration of intravenous vancomycin is not a statistically significant risk factor (OR = 2.6, 95% CI = 0.38-30.0, P value not significant) for lactobacillemia. The use of selective bowel decontamination and of intravenous vancomycin in liver transplant patients may select for Lactobacillus species. Furthermore, a Roux-en-Y choledochojejunostomy may allow colonization of the intrahepatic biliary tract with enteric flora.

Adult↗

PubMed1994

A comparison of 16S ribosomal DNA sequences from five isolates of Helicobacter pylori.

Other workers have found that clinical isolates of Helicobacter pylori exhibit very extensive DNA sequence polymorphisms when they are examined by ribotyping or some other genomic sequence characterization technique. In fact, it is rare to find similar clones, much less identical ones, among isolates. We found that the levels of divergence between the 16S ribosomal DNA sequences of individual organisms and the consensus sequence of the five isolates which we examined ranged from 0.2 to 0.5%. In contrast, other workers have shown that levels of divergence between the 16S ribosomal DNA sequence of H. pylori and the 16S ribosomal DNA sequences of four other Helicobacter species range from 2.7 to 8.0%. Our results show that the H. pylori 16S ribosomal DNA is not very polymorphic and support the conclusion that H. pylori is a unique species.

Base Sequence↗

PubMed1994

Evaluation of two rapid antigen assays, BioStar Strep A OIA and Pacific Biotech CARDS O.S., and culture for detection of group A streptococci in throat swabs.

Two rapid methods, BioStar Strep A OIA (OIA; BioStar, Inc., Boulder, Colo.), an optical immunoassay, and CARDS O.S. (O.S.; Pacific Biotech, Inc., San Diego, Calif.), a color immunochromographic assay, and two culture methods, one with 5% sheep blood agar (SBA) and one with Todd-Hewitt broth (TH; Remel, Lenexa, Kans.), were evaluated for use in the detection of Streptococcus pyogenes from pharnygeal swabs. Seven hundred forty-six double swabs (Culturette II) were processed, with OIA and SBA culture performed on one swab and O.S. and SBA culture performed on the other swab. The pledget from the Culturette II was incubated overnight in TH and was subcultured onto SBA for an additional 48 h in ambient air. All beta-hemolytic streptococci from culture were tested by a direct fluorescent-antibody test (Difco Laboratories, Detroit, Mich.). Specimens with discordant fluorescent-antibody test and rapid test results were also tested by using the Streptex latex agglutination reagent (Murex Diagnostics Limited, Dartford, England). The results obtained by all testing methods were compared with a combined test result ("gold standard"), which was defined as any positive culture detected by the SBA or TH culture methods and confirmed by Streptex latex agglutination or, in the case of negative results by both culture methods, a concomitant positive result by OIA and O.S. antigen testing. Sensitivity and specificity results for each of the methods were as follows, respectively: OIA, 81.0 and 97.5%; O.S., 74.4 and 99.0%; SBA culture, 92.3 and 98.3%; and TH culture, 86.4 and 100%. Both OIA and O.S. are suitable screening methods for detecting S. pyogenes directly from throat swabs but are of insufficient sensitivity to eliminate the need for backup cultures for specimens with negative OIA and O.S. results.

Antigens, Bacterial↗

PubMed1994

Comparison of Gen-Probe Group A streptococcus Direct Test with culture for diagnosing streptococcal pharyngitis.

The Group A Streptococcus Direct Test (GP-ST test; Gen-Probe, Inc., San Diego, Calif.) was compared with culture for the detection of Streptococcus pyogenes from throat swabs of 767 patients with pharyngitis. Swabs were tested by the GP-ST test after inoculating a 5% sheep blood agar (SBA) plate. SBA plates were incubated at 35 degrees C in room air for 72 h. SBA plates with no evidence of beta-hemolytic colonies after 18 to 24 h of incubation were subcultured by taking a swipe across the primary inoculum from the SBA plate to an agar selective for Streptococcus spp. In a low-prevalence (11.9%) population and in comparison with the number of positive cultures detected by the 72-h single-culture method (SBA plate method), the GP-ST test had a sensitivity of 88.6%, a specificity of 97.8%, a positive predictive value of 83.9%, and a negative predictive value of 98.5%. In comparison with the growth of any colonies of S. pyogenes on the 72-h SBA plates plus a subculture onto selective blood agar, the sensitivities and specificities were as follows: 72-h SBA plate method, 96.7 and 100%, respectively; GP-ST test, 85.7 and 97.8%, respectively. The GP-ST test is an easy-to-perform, reliable test for batch screening of throat swabs for S. pyogenes.

Bacteriological Techniques↗

PubMed1994

Comparison of agar dilution, broth dilution, and disk diffusion testing of ampicillin against Haemophilus species by using in-house and commercially prepared media.

An evaluation to determine the optimal method for the in vitro susceptibility testing of Haemophilus strains to ampicillin was undertaken. In our hands, in-house-prepared Haemophilus Test Medium used by either the broth macrodilution or agar dilution method produced the most consistent results, especially for beta-lactamase-negative, ampicillin-resistant H. influenzae strains.

Agar↗

PubMed1993

Bacteremia due to Enterococcus avium.

Enterococcus avium, formerly "group Q streptococcus," has rarely been reported as a pathogen in humans. To determine the clinical significance of this organism, we reviewed the records of all patients whose blood cultures were positive for E. avium who were seen at our institution from 1986 through 1991 and identified nine cases of bacteremia due to E. avium. All isolates were believed to be clinically significant. Five of nine cases developed in patients with significant gastrointestinal illnesses. The remaining clinical scenarios included intravenous catheter sepsis and factitious disorders. E. avium bacteremias were polymicrobial in seven cases; in six cases, the coisolates were gastrointestinal organisms. These observations suggest that E. avium bacteremia most often originated from a gastrointestinal tract source. We conclude that, though rare, E. avium can be pathogenic in humans and that E. avium bacteremia is associated with gastrointestinal abnormalities.

Adult↗

PubMed1993

Indications for selective decontamination of the digestive tract.

Controversy exists as to the utility of selective decontamination of the digestive tract (SDD) as a method of infection prevention in critically ill patients. A number of prospective randomly controlled studies and 2 meta-analyses have shown a statistically significant protective effective of SDD against nosocomial infection. Most other SDD trials have shown reductions in nosocomial infections, but these reductions have not been statistically significant. Nearly all SDD studies have shown a less clear mortality benefit, and in no trial has cost-effectiveness been critically evaluated. Side effects of SDD have been limited. Despite nearly a decade of use at some institutions, reports of antimicrobic resistance evolving with SDD and causing disease are infrequent. At this time, SDD cannot be recommended for all intensive care patients in all clinical settings. SDD may be an effective infection prevention method in intensive care units in which there is a high rate of nosocomial pneumonia and/or other infections and in the postoperative period of orthotopic liver transplantation. SDD may also be useful to eliminate resistant gram-negative bacilli colonizing patients who are at high risk for infection sequelae. When SDD is used, periodic surveillance for the emergence of resistant microorganisms is imperative.

Anti-Bacterial Agents↗

PubMed1992

Prevention of infection in critically ill patients by selective decontamination of the digestive tract.

OBJECTIVE: To determine whether selective decontamination of the digestive tract using oral and nonabsorbable antimicrobial agents and parenteral cefotaxime prevents infection in critically ill patients. DESIGN: Randomized, controlled trial without blinding. SETTING: Surgical trauma and medical intensive care units in a tertiary referral hospital. PATIENTS: One hundred fifty patients admitted to surgical trauma and medical intensive care units during a 3-year interval, whose condition suggested a prolonged stay (greater than 3 days). INTERVENTION: Patients were randomly allocated to an experimental group (n = 75) that received cefotaxime, 1 g intravenously every 8 hours for the first 3 days only, and oral, nonabsorbable antibiotics (gentamicin, polymyxin, and nystatin by oral paste and oral liquid) for the entire stay in the intensive care unit. Control patients (n = 75) received usual care. MEASUREMENTS: The number of infections, total hospital days, and deaths, as well as the number of days in intensive care unit, were recorded. RESULTS: Control patients experienced more infections (36 compared with 12, P = 0.04), including bacteremias (14 compared with 4, P = 0.05) and pulmonary infections (14 compared with 4, P = 0.03). Although total hospital days, days in intensive care, and the overall death rate all were lower in the treatment group, these differences were not statistically significant. Clinically important complications of selective decontamination of the digestive tract were not encountered. CONCLUSIONS: Selective decontamination of the digestive tract decreases subsequent infection rates, especially by gram-negative bacilli, in selected patients during long-term stays in the intensive care unit.

Administration, Oral↗

PubMed1992

Listeria monocytogenes infection in prosthetic joints.

Listeria monocytogenes is increasingly recognised as a cause of prosthetic joint infection. These infections tend to be more insidious and indolent in contrast to similar infections with Staphylococcus aureus. They can occur in patients who are immunocompromised due to malignancy or other illness or in nonimmunocompromised elderly patients. Listeria infections should not be treated with cephalosporins and prolonged antimicrobial treatment is generally advised for prosthetic joint infections. We noted a high affinity of L. monocytogenes for foreign bodies. Three of twenty-seven cases 11%) of listeriosis under the period of investigation were associated with foreign bodies (hip prosthesis, knee prosthesis and arterial graft).

Aged↗

PubMed1991

Trimethoprim-sulfamethoxazole.

The antimicrobial combination of trimethoprim and sulfamethoxazole is active in vitro against various gram-positive and gram-negative bacteria. Clinically, it is useful for prophylaxis and treatment of selected infections of the genitourinary, respiratory, and gastrointestinal tracts. Trimethoprim-sulfamethoxazole by itself or in combination with other antimicrobial agents is indicated for most Nocardia asteroides infections and is the antimicrobial agent of choice for Pneumocystis carinii pneumonia. The drug is relatively nontoxic in patients who do not have the acquired immunodeficiency syndrome (AIDS) and is available in both oral and intravenous forms. The native compounds and the metabolites of trimethoprim and sulfamethoxazole are excreted primarily in the urine. When the creatinine clearance is less than 30 ml/min, the dosage of trimethoprim-sulfamethoxazole should be adjusted.

Drug Resistance, Microbial↗

PubMed1991

Tetracyclines, chloramphenicol, erythromycin, clindamycin, and metronidazole.

The tetracyclines are effective in the treatment of Chlamydia, Mycoplasma pneumoniae, and rickettsial infections and also can be used for gonococcal infections in patients unable to tolerate penicillin. These drugs may cause gastrointestinal irritation, diarrhea, phototoxic dermatitis, and vestibular damage, and fatal reactions due to hepatotoxicity have occurred in pregnant women. Chloramphenicol has a broad spectrum of bacteriostatic activity, but its association with suppression of the bone marrow and aplastic anemia has relegated it to a historical role. Erythromycin is the drug of choice for the treatment of infections caused by M. pneumoniae, Legionella species, group A beta-hemolytic streptococci, and Streptococcus pneumoniae. The frequency of serious adverse effects associated with the use of erythromycin is low; dose-related epigastric distress may occur. Clindamycin is bactericidal to most nonenterococcal gram-positive aerobic bacteria and many anaerobic microorganisms. Although historically it was a frequent cause of antibiotic-associated diarrhea and colitis, clindamycin is considered an excellent alternative to beta-lactam antibiotics for treatment of many staphylococcal infections, and it has therapeutic utility in anaerobic infections and in several protozoan infections in immunosuppressed patients. Metronidazole is efficacious for treating nonpulmonary anaerobic infections, various parasitic infections (trichomoniasis, amebiasis, and giardiasis), nonspecific vaginitis, and Clostridium difficile-mediated colitis. With use of metronidazole, mild side effects such as epigastric discomfort, diarrhea, reversible neutropenia, and allergic-type cutaneous reactions may occur.

Chloramphenicol↗

PubMed1988

Serologic testing for human immunodeficiency virus antibodies.

Familiarity with available serologic tests for antibodies to human immunodeficiency virus (HIV) has become increasingly important in a wide variety of clinical settings. Enzyme-linked immunosorbent assay (ELISA) commercial kits are most often used as Enzyme-linked immunosorbent assay (ELISA) commercial kits are most often used as screening tests, and Western blot techniques are used for confirmation of positive results. ELISA specificity and sensitivity exceed 98%; the predictive value of a positive test varies from 2% for a weakly positive test in a low-prevalence population to 99% for a strongly positive test in a high-risk group. Confirmatory Western blot testing identifies antibodies with affinity for specific HIV antigens. Indeterminate Western blot antibody patterns necessitate subsequent testing or alternative methods for interpretation. A "window" period of up to 3 or more months follows acute HIV infection before seropositivity occurs.

Antibodies, Viral↗

PubMed1988

Fungal infections of the immunocompromised host: clinical and laboratory aspects.

Fungal infections of the immunocompromised host are being seen with greater frequency than ever before. In addition, a growing list of unusual and unexpected etiologic agents presents a unique and difficult challenge to the clinician and microbiologist. The clinical manifestations of opportunistic fungal infections are often not characteristic and, in many instances, may prevent a rapid diagnosis from being made. Clinical microbiology laboratories should consider any organism as a potential etiologic agent. This requires that all fungi recovered from immunocompromised patients be thoroughly identified and reported so that their clinical significance may be assessed. This review presents a brief discussion of the clinical and laboratory aspects of some fungal infections seen in this important group of patients.

Humans↗