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Biomedical subjects

P M Hawkey

Publications and source records attributed to P M Hawkey.

At least 91 records · Page 5Linked to original sources
PubMed1993

PCR for the detection and typing of campylobacters.

The flaA gene of Campylobacter sp. was amplified using PCR. Primers were chosen which amplified 1.3 kb of the flaA gene in Camp. jejuni and Camp. coli. 'Campylobacter upsaliensis' amplimer was approximately 1.7 kb in size and was easily distinguishable. Other species of campylobacter failed to yield amplimer. The amplimer was digested with Alu 1 which demonstrated considerable restriction fragment length polymorphism and should allow the development of a rapid novel typing scheme which does not rely on previous culture of campylobacter strains.

Bacterial Proteins↗
PubMed1993

Ecology of Haemophilus influenzae and Haemophilus parainfluenzae in sputum and saliva and effects of antibiotics on their distribution in patients with lower respiratory tract infections.

Nine patients with lower respiratory tract infections were used to study in detail the effect of ampicillin or erythromycin on the colonization patterns of Haemophilus influenzae and Haemophilus parainfluenzae in sputum and saliva. H. influenzae was isolated from purulent sputum of eight patients before the start of treatment. Ampicillin was more effective than erythromycin at clearing H. influenzae from sputum and in decreasing purulence. By careful characterization of multiple strains, the changes in biotype distribution and antibiotic susceptibility patterns were shown. Five biotypes of H. influenzae were associated with chest infection, with type II predominating. Mixed biotype infections occurred in five patients. Most saliva contained multiple biotypes of H. parainfluenzae. Neither antibiotic selected resistant haemophili in saliva or sputum. After treatment with ampicillin, the mucoid sputum was colonized with ampicillin-susceptible H. parainfluenzae biotypes previously found in saliva. We postulate that as inflammation decreases at the bronchial mucosa, the ampicillin concentration drops, allowing ampicillin-susceptible oral H. parainfluenzae isolates to seed the residual mucoid sputum.

Ampicillin↗
PubMed1993

Evaluation of the API Coryne system for identification of Listeria species.

The API Coryne system, a commercially available system for the identification of coryneform bacteria, was used to identify 103 strains of Listeria spp. from clinical and environmental sources. All isolates were identified correctly to the genus or species level, although complete characterization also required tests for beta-hemolysis and CAMP reaction.

Listeria↗
PubMed1992

Infection control in intensive care units: U.K. national survey.

A completed questionnaire was returned by 246 (85%) intensive care units participating in a national survey of infection control practice in intensive care. Thirty-three units had no provision for isolating patients in single side wards. Sixty percent of responding ICU had fewer than one washbasin per bedspace. Several units reported using ventilator filters or tubing more frequently than is currently recommended. Excessive numbers of catheter urine specimens were sent for laboratory examination by some units. A small number of units used open urinary drainage systems. A significant proportion of ICU had no formally recognized policy on the management of intravascular cannulae. Only 8% of ICU in the U.K. were using a selective decontamination regimen, and nine of these (50%) had no full time consultant microbiologist available to supervise the recommended microbiological management. The majority of ICU received a regular visit (greater than or equal to one per week) from a microbiologist. Proposals are made on the development of a specialized infection control service in order to reduce the risk of nosocomial infection in intensive care, and to improve on existing resource management.

Adult↗
PubMed1992

Gastroduodenal dysfunction as a cause of gastric bacterial overgrowth in patients undergoing mechanical ventilation of the lungs.

We have studied 15 patients undergoing mechanical ventilation of the lungs for evidence of a relationship between gastroduodenal dysfunction and gastric bacterial overgrowth. Duodenal reflux was detected by quantitative measurement of conjugated bilirubin in gastric aspirate specimens. The pH and bacterial content of these specimens were analysed. A minority of specimens with pH less than 3.5 contained measurable numbers of viable bacteria. The total bacterial count and the count of Gram negative bacteria correlated significantly with specimen pH in both cases (P less than 0.001, in both). In the 72 specimens of gastric aspirate with pH greater than 3.5, the presence of Gram negative bacteria was associated significantly with detectable bilirubin (P less than 0.001). The total bacterial count was greater also in specimens containing bilirubin (P = 0.009). These results suggest that gastroduodenal dysfunction may promote gastric bacterial overgrowth, contributing to the development of ventilator-associated pneumonia.

Adult↗
PubMed1992

Transposition of the gene encoding a TEM-12 extended-spectrum beta-lactamase.

An isolate of Klebsiella oxytoca from the blood culture of a child with leukemia was found to produce two beta-lactamases, at least one of which conferred resistance to ceftazidime. Genes encoding both enzymes were located on a single self-transmissible 100-kb plasmid, pOZ201. This plasmid was introduced into Escherichia coli UB5201 (pACYC184), and the gene encoding one beta-lactamase was transposed onto plasmid pACYC184 by exploiting a gene dosage effect. The transposable gene was found to encode a TEM-12 enzyme as determined by nucleotide sequencing. This gene was subsequently transposed onto plasmid pUB307. The transposable element encoding the TEM-12 enzyme has been designated Tn841. Both plasmids pACYC184::Tn841 and pUB307::Tn841 were shown to encode a beta-lactamase with the same isoelectric point and substrate profile as the TEM-12 beta-lactamase. Transposon Tn841, at approximately 7 kb, is larger than TnA (4.8 kb) and transposes at a lower frequency. Although it produced a resolvase which can complement the resolvase of Tn3, its transposase function was not able to complement the transposition of a TnA element which lacked transposase. The occurrence of a gene encoding an extended-spectrum beta-lactamase on a transposable element in a clinically significant bacterium is potentially a cause for concern for the spread of resistance to the extended-spectrum cephalosporins.

Base Sequence↗
PubMed1991

The future contribution of transposition to antimicrobial resistance.

Antibiotic resistance is commonplace in clinical bacterial isolates. Many of the resistance genes are transposon-borne and have the potential for rapid dispersal throughout the bacterial kingdom. Resistance genes are constantly subject to mutation and reassortment. Given appropriate selection pressure, the new resistance determinants can emerge rapidly to pose significant treatment problems. It seems likely that in the future bacterial resistance will continue to be a problem, both with respect to current antibiotics and to new ones and that transposon-borne resistance genes will continue to figure prominently.

DNA Transposable Elements↗
PubMed1991

Molecular evolution of tetracycline-resistance plasmids carrying TetM found in Neisseria gonorrhoeae from different countries.

High level tetracycline resistant strains of Neisseria gonorrhoeae (TRNG) have been shown to carry a 40.6 kb (25.2 MDa) conjugative plasmid with a Class M tetracycline resistance determinant. Restriction endonuclease analysis mapping showed that there were at least two different TRNG plasmid types which were found in geographically distinct locations. The physical maps of these two plasmids were compared to a gonococcal conjugative plasmid which did not encode tetracycline resistance. The plasmid type which is endemic in the Netherlands was found to be closely related to the gonococcal conjugative plasmid, which supports the established hypothesis that the 40.6 kb plasmid has evolved by transposition of the TetM determinant into the conjugative plasmid. The plasmid found in the United States has either evolved by substantial divergent evolution or it results from a different transposition event. In the UK there have been isolations of TRNGs carrying either of the two plasmid types reflecting a flow of people both across the Atlantic and in Europe. It is possible that further TetM-containing plasmids will be found in N. gonorrhoeae paralleling the family of TEM beta-lactamase encoding plasmids already described.

Bacterial Proteins↗
PubMed1991

Evaluation of the Rosco system for the identification of Listeria species.

The Rosco system was used to identify previously confirmed isolates of the seven currently recognised species of Listeria. These included reference cultures and recent isolates from clinical material, food products and environmental sources. The system identified all correctly. Results were obtained after 4 h if heavy inocula, as suggested by the manufacturers, were used. The method may be used to aid identification of isolates of Listeria from clinical and non-clinical specimens and would be of particular value in laboratories examining small numbers of isolates relatively infrequently. Essential tests not included in the system are beta-haemolysis on sheep-blood agar and the CAMP test.

Listeria↗
PubMed1991

Identification of Neisseria gonorrhoeae using the Neisstrip rapid enzyme detection test.

A rapid enzyme activity strip test (Neisstrip, Lab M Ltd, Bury) was compared retrospectively with Phadebact Monoclonal GC coagglutination (Pharmacia Diagnostics, Uppsala, Sweden), cystine trypticase agar sugar utilisation (CTA), and Gonochek II (J W Turner, Liverpool) enzyme methods for identification of 95 Neisseria spp and related species. These had been previously identified using standard methods and included 29 that had given aberrant results. Neisstrip identified correctly all but two, including nine incorrectly identified by Phadebact and 18 erroneously identified using CTA sugars. Results were similar to those obtained with Gonochek II. After this a prospective study was performed testing 400 oxidase positive isolates derived from clinical samples cultured on gonococcal selective medium. Two organisms, both Moraxella spp, were incorrectly identified as N gonorrhoeae by the Neisstrip. The superoxol test, when used with either the Phadebact or Neisstrip tests, maintained 100% sensitivity and specificity. The Neisstrip is a rapid, economic test that is accurate and easy to interpret. It may be used alone or in conjunction with a superoxol test or a coagglutination test, which is relatively accurate but more expensive, and found by some technical staff to be more difficult to interpret.

Aminopeptidases↗
PubMed1990

Postoperative autologous transfusion in cardiac surgery. A prospective, randomised study.

To investigate the safety and efficacy of postoperative autologous blood transfusion (AT) using the Shiley hardshell venous reservoir, a prospective, randomised, controlled study was carried out in two matched groups of twenty patients undergoing elective coronary artery bypass surgery. The mean volume of shed mediastinal blood reinfused in the first 6 h postoperatively was 371.7 +/- 63.23 ml. Use of homologous blood was reduced from 760.5 +/- 108.37 ml in the control patients to 466.25 +/- 87.44 ml in the AT patients, a reduction of 38.7% (p less than 0.05). There was no statistically significant difference in the clinical outcome, overall blood loss, use of platelets, fresh frozen plasma and colloids, haematological indices, renal and hepatic functions, or clotting mechanism, although there was a reduction in the fibrinogen level in the patients who received AT (p less than 0.05). Mediastinal blood did not clot and was defibrinogenated. It contained significant levels of haemoglobin (8.175 +/- 0.506 g/dl), platelets (96.55 +/- 10.39 per mm3 10(3)), protein (42.5 +/- 1.13 g/l), calcium (2.385 +/- 0.054 mmol/l) and was well oxygenated (PO2 = 20.46 +/- 0.81 kPa). No patients developed bacteraemia or had any AT-related infections. We conclude that postoperative autologous transfusion using the Shiley hardshell venous reservoir is a safe and efficient method for reducing postoperative homologous blood requirement after coronary artery bypass surgery.

Adult↗
PubMed1990

The 25.2 MDa tetracycline-resistance plasmid is not derived from the 24.5 MDa conjugative plasmid of Neisseria gonorrhoeae.

High-level tetracycline resistance in strains of Neisseria gonorrhoeae is due to the presence of a 25.2 MDa conjugative plasmid. This plasmid has been shown to carry the streptococcal tetM determinant, and has been thought to have evolved from the 24.5 MDa conjugative plasmid found in N. gonorrhoeae. We have derived a physical map of the 25.2 MDa plasmid pUS100 using seven restriction endonucleases. Comparison of the physical map with the previously published physical map of the conjugative plasmid pLE2451 shows there to be no obvious similarity between the two plasmids. The location of the tetM determinant has been established, by Southern hybridization, confirming the restriction endonuclease map. This has also provided evidence that the transposition functions normally associated with the tetM determinant have been lost.

Conjugation, Genetic↗
PubMed1990

Novel beta-lactamase from Capnocytophaga sp.

A novel beta-lactamase activity which confers resistance to expanded-spectrum cephalosporins and penicillins has been found in strain IC 5/21 of Capnocytophaga spp. Enzyme activity migrated at a molecular size of 38,000 daltons and at an isoelectric point of 3.6, with a minor band at 4.1. Kinetic studies suggested that it belonged to Richmond and Sykes beta-lactamase class 1c. Isoelectric focusing could be achieved only if a nonionic detergent was added to the gel, suggesting the presence of a hydrophobic enzyme akin to a membrane-bound beta-lactamase of gram-positive bacteria. The location of the gene coding for this beta-lactamase is not yet known.

Anti-Bacterial Agents↗
PubMed1990

Evaluation of the Mast ID and API 50CH systems for identification of Listeria spp.

A multipoint inoculation technique (Mast ID) for the identification and species determination of Listeria monocytogenes (sensu strictu) and six other species of the genus Listeria was evaluated. This was compared with the commercially available API 50CH system. Both methods successfully identified all 123 strains tested. The Mast ID system is inexpensive and utilizing a multipoint inoculation technique permits the screening of up to 21 isolates per 9-cm petri dish. The API 50CH system was more expensive and time consuming and is therefore suitable only for the examination of smaller numbers of strains.

Bacteriological Techniques↗
PubMed1990

Use of Ames SG10 Urine Dipstick for diagnosis of abdominal pain in the accident and emergency department.

In a prospective study of 1112 patients presenting to the Accident and Emergency Department with abdominal pain; the SG10 Ames Urine Dipsticks were shown to be a valuable screening test for the detection of infected urine. Introducing this technique would reduce by at least 37% the number of urgent requests for microscopy of midstream urines (MSUs). Dipstick testing however was not a reliable screening test for microscopic haematuria.

Abdominal Pain↗