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Biomedical subjects

A P Gibb

Publications and source records attributed to A P Gibb.

At least 19 recordsLinked to original sources
PubMed2006

A cluster of deep bacterial infections following eye surgery associated with construction dust.

SUMMARY: Three cases of serious eye infection (two endophthalmitis, one orbital cellulitis; two caused by Staphylococcus aureus, one caused by viridans streptococci) occurred shortly after surgery (two cataracts, one retinal detachment repair) within two weeks. There had been construction work adjacent to the theatres during this time, and fine dust was found on horizontal surfaces. Further surgery was cancelled, the construction work was completed and theatres were cleaned before recommencing with no further infections. Following a review of factors that may be involved in the pathogenesis of endophthalmitis, it is proposed that the mechanism of infection in these cases may have been due to the presence of foreign material enhancing the pathogenicity of the small numbers of organisms often found in intra-ocular fluids during surgery. This hypothesis could be tested in experimental models of endophthalmitis.

Cellulitis↗
PubMed2006

How much time is needed for hand hygiene in intensive care? A prospective trained observer study of rates of contact between healthcare workers and intensive care patients.

There are few data measuring rates of contact by healthcare workers (HCWs) with intensive care unit (ICU) patients (direct contacts) and their immediate environment (indirect contacts), or estimates of the time needed for 100% hand hygiene compliance. We measured this using a prospective trained observer study in a 12-bedded UK adult general ICU admitting > 600 mixed medical/surgical patients annually. HCWs were observed in ICU bed spaces for 1-h periods by a single researcher using a pre-determined plan, such that all 12 beds were observed for similar times and throughout the day. Mean daily rates of direct and indirect contact between HCWs and ICU patients were calculated. Observed post-contact hand hygiene compliance was also measured. Numbers of contacts/day that were or were not followed by hand hygiene, and estimates of the time needed daily for 100% compliance were calculated. On average, each patient was contacted directly 159 [95% confidence intervals (CI) 144-178] times and contacted indirectly 191 (95% CI 174-210) times/day. Observed post-contact hand hygiene rates were 43% for direct contacts and 12% for indirect contacts. Staff contacting more than one patient during routine care, who carry the highest risk of transmitting infection between patients, made, on average, 22 direct and 107 indirect contacts without adequate hand hygiene/patient/day. One hundred percent hand hygiene compliance by all healthcare workers would require about 230 min/patient/day (100 min for direct and 130 min for indirect contacts).

Cross Infection↗
PubMed2005

Antibiotic prescription practice in an intensive care unit using twice-weekly collection of screening specimens: a prospective audit in a large UK teaching hospital.

Controversy exists regarding the optimal method of managing intensive care unit (ICU)-acquired infection. Antibiotic prescriptions in 177 sequential admissions to our ICU, which collected twice-weekly screening samples, were audited. Seventy-seven percent of patients received at least one antibiotic prescription, and 45% of patients received at least one prescription for suspected or proven sepsis. Of the 353 antibiotic prescriptions audited, 86 were prophylactic and 61 were first prescribed prior to ICU admission. One hundred and eighty-three were prescribed for sepsis; of these, 108 (59%) were empirical prescriptions and only 21% of these were subsequently changed. For the 75 prescriptions for specific organisms, 28% targeted organisms isolated at least four days previously. Clinicians in our ICU reviewed the data and reached consensus that screening was associated with decision making that did not represent current evidence-based practice, because empirical prescriptions were rarely changed or stopped on the basis of new samples, and those prescribed for confirmed infection frequently targeted organisms isolated before the septic episode. After our audit, we stopped regular collection of screening samples and used more targeted and invasive sampling, in response to clinical suspicion, to guide therapy and maintain data concerning local microbial epidemiology.

Anti-Bacterial Agents↗
PubMed2000

Cefpodoxime screening of Escherichia coli and Klebsiella spp. by Vitek for detection of organisms producing extended-spectrum beta-lactamases.

We used a Vitek custom card to detect cefpodoxime MIC of--2 mg/L as a screen for extended-spectrum beta-lactamase (ESBL) production in E. coli and Klebsiella spp. Of 2873 organisms tested, 60 were screen positive, but only 3 were confirmed to be ESBL producers. Cefpodoxime is believed to be a sensitive screen for ESBL production, but a more specific test is desirable.

Ceftizoxime↗
PubMed1998

Comparative study of BacT/Alert FAN bottles and standard BacT/Alert bottles.

A total of 5,230 paired blood cultures were studied. One sample was divided between aerobic and anaerobic BacT/Alert standard bottles, and the other divided between aerobic and anaerobic BacT/Alert FAN bottles. There were 44 occasions where Staphylococcus aureus was recovered only from the FAN bottles, compared to six where only the standard bottles were positive (p < 0.001), and 21 occasions where Escherichia coli was isolated only from FAN bottles, compared to eight occasions where only the standard bottles were positive for this organism (p < 0.05). In 21 of 28 cases reviewed where S. aureus was isolated from FAN bottles only the patient had been receiving anti-staphylococcal antibiotics. However, only 2 of 30 cases where Gram-negative bacilli were isolated from FAN bottles had documented recent appropriate antibiotic therapy. Patients in whom FAN bottles are more likely to recover organisms cannot be selected on the basis of documented antibiotic treatment.

Anti-Bacterial Agents↗
PubMed1998

Inhibition of PCR by agar from bacteriological transport media.

We observed inhibition of PCR in throat swabs submitted in routine bacteriological transport media. Experimental studies showed that agar, which was extracted with DNA by DNAzol (Gibco BRL, Gaithersburg, Md.), was the inhibitory agent. No inhibitory effect was observed with a transport medium which did not contain agar.

Agar↗
PubMed1997

Reduction in blood culture contamination rate by feedback to phlebotomists.

OBJECTIVE: To determine whether monitoring and feedback of blood culture contamination rates to phlebotomists would reduce the overall contamination rate. DESIGN: Before and after interventional study. SETTING: Blood cultures collected by venipuncture by phlebotomists at Foothills Hospital, Calgary, a tertiary care teaching hospital. INTERVENTION: Feedback of contamination rates calculated from a laboratory definition of blood culture contamination. The definition was based on isolation of typical skin organisms from a single blood sample when two samples were obtained. MAIN OUTCOME MEASURE: Reduction in the laboratory-defined contamination rate in the second year. RESULTS: Of 8462 cultures collected by phlebotomists in the prefeedback year, 224 (2.6%) were contaminated, compared to 131 (1.4%) of 9282 cultures in the postfeedback year. There was a rise in the total number of positive cultures regarded as significant but a fall in the number of coagulase-negative staphylococci that were regarded as significant by our definition. The rate of contamination in blood cultures collected by nonphlebotomists did not change. CONCLUSIONS: The contamination rate decreased after feedback. Our definition of contamination was imperfect and could be improved, but it was valuable in achieving a real reduction in blood culture contamination.

Bacteria↗
PubMed1996

Paracoccidioidomycosis: case report and review.

A previously well 59-year-old man presented with paracoccidioidomycosis, more than 15 years after leaving South America. He failed to respond to conventional therapies, first with oral itraconazole and then with amphotericin B plus sulfadiazine, and eventually died of recurrent arterial emboli possibly due to paracoccidioidomycotic aortitis. This patient's presentation demonstrates the difficulties that may be encountered in diagnosing and managing this disease. Paracoccidioidomycosis should be suspected in patients with an appropriate travel history who experience weight loss and have pulmonary, mucosal, and cutaneous lesions. This article comprehensively reviews the literature, with emphasis on epidemiology, clinical presentation, diagnosis, and therapy with imidazole antifungal medications.

Amphotericin B↗
PubMed1996

Failure to kill Yersinia enterocolitica by plasma diluted to the concentration found in red cell units.

The possibility that the use of additive solutions for red cell storage might impair the ability of plasma to kill Yersinia enterocolitica was investigated by studying killing of Y enterocolitica by neat and diluted plasma. The ability of neat citrated plasma to kill complement sensitive organisms was lost at around 26%, the dilution typically found in red cell units. These results should be considered in the light of evidence that killing in plasma is important in the protection of donated blood against growth of Y enterocolitica, and the observation that the increase in frequency of transfusion reactions caused by Y enterocolitica coincided with the widespread introduction of additive solutions. Taken together, these points support the suggestion that the introduction of additive solutions may have precipitated the problem of growth of Y enterocolitica in stored blood.

Blood Bactericidal Activity↗
PubMed1995

Rate of growth of Pseudomonas fluorescens in donated blood.

AIMS: To examine how delayed refrigeration of blood affects the growth of Pseudomonas fluorescens, one of the two most important causes of sepsis resulting from transfusion of contaminated blood. METHODS: Two donations of whole blood were each divided into three aliquots and inoculated with 5-10 cfu/ml of a P fluorescens strain from a case of transfusion associated sepsis. From each donation, one aliquot was placed at 4 degrees C, one was held at 20 degrees C for six hours prior to refrigeration and the third was held at 20 degrees C for 24 hours prior to refrigeration. Samples were aseptically withdrawn over 17 days and bacterial counts were determined using a pour plate technique. RESULTS: The rate of growth of P fluorescens in blood at 20 degrees C was increased compared with blood at 4 degrees C. At 24 hours the aliquots held at 20 degrees C for six and 24 hours had, respectively, 174 and 29,000 cfu/ml compared with 15 cfu/ml in aliquots held at 4 degrees C. There was no evidence of increased killing of P fluorescens at the higher temperature. CONCLUSIONS: These results suggest that blood for transfusion should be refrigerated as soon as possible after collection.

Blood↗
PubMed1994

Modeling the growth of Yersinia enterocolitica in donated blood.

BACKGROUND: Sepsis and death subsequent to the transfusion of blood containing Yersinia enterocolitica is an increasing problem. The organisms probably originate from bacteremia in the donor and can subsequently multiply at low temperature. STUDY DESIGN AND METHODS: Reported here are experiments with a strain of Y. enterocolitica associated with a case of transfusion-associated bacteremia. RESULTS: It was found that the rapid early killing of Y. enterocolitica injected into donated blood does not require viable phagocytes and can be explained by complement-mediated killing. Complement resistance in Y. enterocolitica is known to be plasmid-coded. It is expressed at 37 degrees C, but not at 20 degrees C, and is favored by calcium-deficient culture media. Y. enterocolitica organisms induced to express complement resistance were still killed in donated blood, though the initial rate was slower. Such organisms multiplied in plasma at 37 degrees C, but were killed after 6 hours of incubation at 20 degrees C, presumably because complement resistance genes are switched off at this temperature. CONCLUSION: This experiment is thought to reflect the natural history of Y. enterocolitica contamination of blood, in which complement-resistant organisms in the donor blood encounter lower temperatures after donation. These observations suggest that the practice of plasma depletion may have contributed to the increased incidence of mortality due to Y. enterocolitica contamination of donated blood.

Blood↗
PubMed1993

Serological investigation into the association between Streptococcus bovis and colonic cancer.

AIMS: To determine if there was an increase in antibody titre to Streptococcus bovis in patients with colonic cancer, and if this might be a useful marker of the presence for colonic cancer. METHODS: Serum samples from 16 patients and 16 age matched controls were tested by immunoblot and enzyme linked immunosorbent assay (ELISA) against antigen preparations from two strains of S bovis and one strain of Enterococcus faecalis. RESULTS: No distinction between cancer patients and controls could be made using immunoblots. ELISA did show an increase in antibodies to S bovis, but there was a greater increase in antibodies to E faecalis. The increase in antibody titres was greatest with antigens which had been treated with periodate, and was therefore thought not to be caused by antibody to the shared group D carbohydrate antigen. CONCLUSION: It may be possible to construct a test for the detection of colonic cancer based on the detection of antibody to S bovis or E faecalis, though considerable further development of this concept is required.

Antibodies, Bacterial↗
PubMed1992

Frequencies of lipopolysaccharide core types among clinical isolates of Escherichia coli defined with monoclonal antibodies.

Mouse monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) core types R1, R2, and R3 of Escherichia coli and a cross-reactive MAb that binds to the LPS core of almost all E. coli were used in ELISA to determine the frequency of cores resembling R1, R2, and R3 in strains of E. coli isolated from clinical samples (blood and urine specimens) and from the feces of asymptomatic individuals. Of the 180 wild-type isolates, 123 were assigned to R1 core type, 14 to R2, and 18 to R3. Twenty-five wild-type E. coli isolates could not be assigned to a particular core type and may have either an R4 or K12 core or a previously unrecognized core type. R1 core type was associated with O types 1, 4, 6, 8, and 18 and with K1 or K5 capsules. R3 was associated with O15. O75 isolates could be of either R1 or R2 core type.

Antibodies, Monoclonal↗
PubMed1992

Urinary IgG antibody against mixed heat-killed coliform antigen and lipopolysaccharide core antigen.

AIMS: To determine whether antibody to lipopolysaccharide-core (LPS-core) antigen is an important component of the antibody, detected by mixed heat-killed coliform antigen, in urine from patients with suspected urinary tract infection. METHODS: LPS-core antigen and mixed heat-killed coliform antigen were used in an enzyme linked immunosorbent assay (ELISA) to measure IgG antibody in midstream urine samples. Seventy two samples from students attending their general practitioner with symptoms suggestive of urinary tract infection, six samples from which a Gram positive organism was isolated, and 16 asymptomatic controls were tested. Plates coated with LPS-core antigen were also used to absorb out the antibody detected by the mixed heat-killed coliform antigen. RESULTS: Antibody to either antigen was associated with a positive culture, but neither was a useful predictor of a positive culture. There was a significant correlation between the results of the two assays (r = 0.7633; p less than 0.001), and absorption with LPS-core antigen did reduce the level of antibody to the mixed heat-killed coliform antigen. Antibody to both preparations was found in patients with Gram positive urinary tract infection. CONCLUSION: Antibody to LPS-core antigen forms a substantial part of the antibody detected by mixed heat-killed coliform ELISA. The antibodies detected by these assays are probably the result of non-specific leakage of antibody into the urine, rather than a specific immune response.

Antibodies, Bacterial↗