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Biomedical subjects

P M Hawkey

Publications and source records attributed to P M Hawkey.

At least 19 recordsLinked to original sources
PubMed1995

Replacement of NCTC 4175, the current type strain of Proteus vulgaris, with ATCC 29905. Request for an opinion.

The current type strain of Proteus vulgaris, NCTC 4175 (= ATCC 13315), differs substantially from typical strains of this species both biochemically and chemotaxonomically. DNA relatedness studies revealed that strains previously classified as P. vulgaris belong to six genomospecies. One of these genomospecies contains strains that are negative in indole, salicin, and esculin reactions (biogroup 1) and has been named Proteus penneri. A second genomospecies, which is most frequently isolated from human urine, contains typical P. vulgaris strains that are positive in indole, salicin, and esculin reactions (biogroup 2). The members of the remaining four genomospecies are indole positive and negative in salicin and esculin reactions (biogroup 3). Of 36 biogroup 3 strains studied, only strain NCTC 4175T (T = type strain) and one other strain, CDC 1732-80, belong to genomospecies 3. To retain NCTC 4175 as the type strain of P. vulgaris would restrict this species to these two strains, whose origins are unknown. This would mean that hundreds of strains for which the description of P. vulgaris was written and which have been representatives of this species for the past 50 years would have to be renamed as members of a new species. To prevent this confusion, we request that biogroup 2 reference strain ATCC 29905 (= CDC PR1) replace NCTC 4175 as the type strain of P. vulgaris.

DNA, Bacterial↗
PubMed1995

Campylobacter jejuni in the stomach.

Campylobacter jejuni is the commonest cause of acute bacterial enteritis in the UK. However, in this case a 74-year-old lady underwent gastroscopy for an upper gastrointestinal haemorrhage and was noted to have a gastric ulcer. Gastric biopsy revealed spiral gram-negative bacteria and culture yielded a moderate growth of C. jejuni. Identification was confirmed by growth characteristics, biochemical tests and PCR amplification of the species-specific flagellin gene--fla A. To prevent misidentification, it is important that laboratories routinely culturing gastric biopsies for Helicobacter pylori should perform a rapid urease test and not rely solely on microscopic morphology.

Aged↗
PubMed1994

Description of Leeds Acinetobacter Medium, a new selective and differential medium for isolation of clinically important Acinetobacter spp., and comparison with Herellea agar and Holton's agar.

Acinetobacter spp. are responsible for an increasing number of opportunistic, nosocomial infections. They have been isolated from diverse inanimate objects in the hospital environment and are resistant to most of the commonly used antibiotics. Existing media for the isolation of Acinetobacter spp. are either nonselective, allowing the growth of unwanted bacteria, or too inhibitory, inhibiting the growth of many Acinetobacter strains. For the rapid isolation and effective control of Acinetobacter infection, a new selective and differential medium, Leeds Acinetobacter Medium (LAM), has been developed to isolate Acinetobacter spp. from clinical and environmental sources. The concentration of antibiotics and other ingredients in this medium have been determined according to the results of MIC and viable counts performed for these ingredients. LAM was compared with other selective and differential media for the isolation of Acinetobacter spp. from a local hospital environment and proved to be better in terms of recovery and selectivity.

Acinetobacter↗
PubMed1993

Staphylococcal pneumonia in ventilated patients: a twelve-month review of cases in an intensive care unit.

We reviewed staphylococcal lower respiratory tract infections in our intensive care unit over a 12-month period. Staphylococcus aureus was isolated from tracheal aspirates more commonly in patients with intracranial trauma (P < 0.001), between one and six days (mean = 3) after admission to the intensive care unit. Bacteriophage typing of all S. aureus lower respiratory tract isolates from the 17 patients with head injury did not provide evidence for a common external source of infection or patient-to-patient transmission.

Bacteriophage Typing↗
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↗
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↗