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Biomedical subjects

A P Johnson

Publications and source records attributed to A P Johnson.

At least 19 recordsLinked to original sources
PubMed1996

Prevalence of antibiotic resistance and serotypes in pneumococci in England and Wales: results of observational surveys in 1990 and 1995.

OBJECTIVE: To assess the prevalence of antibiotic resistance and serotype distribution among pneumococci in England and Wales in 1990 and 1995. DESIGN: Observational surveys in March 1990 and March 1995. During two weeks in each survey period all pneumococci isolated in public health laboratories in England and Wales were collected and assessed for sensitivity to antibiotics and the distribution of serogroups or serotypes. SETTING: The network of public health laboratories throughout England and Wales. SUBJECTS: 1127 individual patient isolates of Streptococcus pneumoniae obtained during the two surveys. MAIN OUTCOME MEASURES: Sensitivity or resistance to a range of antibiotics; serogroup or serotype. RESULTS: The prevalence of intermediate or full resistance to penicillin increased from 1.5% in 1990 to 3.9% in 1995 and resistance to erythromycin increased from 2.8% to 8.6%. About 92% of isolates belonged to serogroups or serotypes included in the currently available pneumococcal vaccine. CONCLUSION: Resistance to penicillin and erythromycin has increased among pneumococci in England and Wales. Continued surveillance to assess further increases in the prevalence of pneumococcal resistance to antibiotics is essential.

Anti-Bacterial Agents↗
PubMed1996

Quinolone resistance in Oligella urethralis-associated chronic ambulatory peritoneal dialysis peritonitis.

Oligella urethralis is an organism which is normally isolated as a commensal from the genitourinary tract. We describe the first two reported cases of CAPD-associated peritonitis caused by this organism. Both isolates were found to be resistant to ciprofloxacin, while relatively sensitive to a wide range of antimicrobial drugs. These findings indicate that this organism may be an opportunistic pathogen for CAPD patients, and that extensive ciprofloxacin usage provides a selection pressure for emergence of resistance.

Adult↗
PubMed1996

Detection of the mec-A gene and phenotypic detection of resistance in Staphylococcus aureus isolates with borderline or low-level methicillinresistance.

Eighty-three isolates of Staphylococcus aureus for which MICs of methicillin of 4-16 mg/L had previously been recorded were tested for the presence of the mecA gene with a DNA probe and a PCR assay. There was complete agreement between the results obtained by these methods; 39 isolates were mecA-positive and 44 were mecA-negative. Using the presence of mecA as the defining standard, several phenotypic methods for determining resistance to methicillin were evaluated and a high-inoculum, agar-incorporation breakpoint test was found to offer the best combination of high sensitivity and high specificity. However twenty-seven of the 44 mecA-negative strains were methicillin-resistant according to agar dilution MICs (MIC > 4 mg/L on at least one of the four media used) but none had MICs exceeding 32 mg/L. One of the mecA-positive strains had a methicillin MIC of only 8 mg/L and did not appear to be heteroresistant. The clinical significance of these two groups of 'atypical' isolates may need further investigation. This study highlights the problems of detecting reliably S. aureus with low level methicillin resistance by phenotype methods and the usefulness of direct detection of the mecA gene.

Bacterial Proteins↗
PubMed1995

Urinary isolates of apramycin-resistant Escherichia coli and Klebsiella pneumoniae from Dublin.

Twenty-two gentamicin-resistant urinary isolates of Escherichia coli and five gentamicin-resistant urinary isolates of Klebsiella pneumoniae from a Dublin hospital were examined for resistance to the veterinary aminoglycoside antibiotic apramycin. Five isolates of E. coli and one isolate of K. pneumoniae were found to be resistant. The apramycin-resistant isolates, which were also resistant to the veterinary anthelmintic agent hygromycin B, hybridized with a DNA probe for the gene encoding the enzyme 3-N-aminoglycoside acetyltransferase type IV (AAC(3)IV). Resistance to apramycin and hygromycin B was co-transferable in four of the five isolates of E. coli and the isolate of K. pneumoniae. In one isolate of E. coli apramycin resistance was not transferable. On the basis of their restriction enzyme digestion profiles and the antimicrobial resistance traits encoded, the transferable plasmids encoding resistance to apramycin and hygromycin B comprised three distinct types. Genetic linkage between the gene encoding AAC(3)IV and genes encoding resistance to ampicillin and either tetracycline or trimethoprim, means that the relatively widespread use of these antimicrobial agents provides a selective pressure for the persistence of resistance to apramycin and gentamicin even in the absence of bacterial exposure to aminoglycosides.

Conjugation, Genetic↗
PubMed1995

Symptomatic Rathke's cleft cyst with hypophysitis.

We report a case of symptomatic Rathke's cleft cyst (RCC) with associated chronic hypophysitis. Symptomatic RCCs are rare and an associated inflammatory reaction is even rarer. The clinical and pathological findings are discussed in the light of previous published reports, together with the problems involved in making a preoperative diagnosis in such cases.

Adenoma↗
PubMed1995

Should ENT out-patients be seen in hospital or General Practitioners' surgeries?

This was a prospective trial involving 1000 consecutive patients attending an ENT out-patient department to assess the degree of investigation and procedures undertaken in routine practice. Results demonstrate that the majority of patients (both new and old) require a procedure which would necessitate either additional staff or equipment if the consultation occurred in a General Practitioner's (GP's) surgery. The results argue against out-patient clinics taking place in a GP's surgery.

Delivery of Health Care↗
PubMed1995

Current perspectives on glycopeptide resistance.

In the last 5 years, clinical isolates of gram-positive bacteria with intrinsic or acquired resistance to glycopeptide antibiotics have been encountered increasingly. In many of these isolates, resistance arises from an alteration of the antibiotic target site, with the terminal D-alanyl-D-alanine moiety of peptidoglycan precursors being replaced by groups that do not bind glycopeptides. Although the criteria for defining resistance have been revised frequently, the reliable detection of low-level glycopeptide resistance remains problematic and is influenced by the method chosen. Glycopeptide-resistant enterococci have emerged as a particular problem in hospitals, where in addition to sporadic cases, clusters of infections with evidence of interpatient spread have occurred. Studies using molecular typing methods have implicated colonization of patients, staff carriage, and environmental contamination in the dissemination of these bacteria. Choice of antimicrobial therapy for infections caused by glycopeptide-resistant bacteria may be complicated by resistance to other antibiotics. Severe therapeutic difficulties are being encountered among patients infected with enterococci, with some infections being untreatable with currently available antibiotics.

Anti-Bacterial Agents↗
PubMed1995

Haemophilus aphrophilus discitis and vertebral osteomyelitis.

An unusual case of discitis and vertebral osteomyelitis due to Haemophilus aphrophilus is described. Infections due to this organism have usually responded to treatment with beta-lactam antibiotics. However, our isolate was resistant to third-generation cephalosporins which has not been reported previously in the world literature. The patient made a good clinical response to ciprofloxacin treatment.

Abscess↗
PubMed1995

Theory M: A restructuring process.

Through the Nursing Incentive Reimbursement Award (NIRA) Program initiated by the New Jersey Department of Health, a medical center tested, over a two-year time frame, the impact of a staff-developed "Theory M" nursing model. Three nursing units served as control groups and one as the experimental group that incorporated the following features: restructuring of a nursing unit through the redefinition of roles; modifying nurse staffing patterns to change existing ratio of RNs to NAs; incorporating matrix management principles; developing, implementing and evaluating training and educational programs; and renovating a nursing unit.

Health Care Reform↗
PubMed1994

Vertebro-carotid anastomosis as a cause of uncontrollable epistaxis.

Uncontrolled epistaxis may require a long hospital stay, multiple blood transfusions and multiple arterial ligations. This case report highlights vertebro-carotid anastomosis as a rare cause of uncontrolled epistaxis. The importance of angiography in the identification of rare arterial anastomoses is stressed.

Adult↗
PubMed1994

The pathogenicity of enterococci.

In order to produce infection, enterococci must be able to colonize host tissues, resist the host's non-specific and immune defence mechanisms and produce pathological changes. With regard to colonization of host tissues, adherence assays have shown that enterococci can attach to intestinal and urinary tract epithelial cells and heart cells by means of adhesins expressed on the bacterial surface. The expression of these adhesins by enterococci has further been shown to be affected by bacterial growth conditions. In addition, the adherence of Enterococcus faecalis to renal tubular cells in vitro is enhanced if the organisms produce aggregation substance, a proteinaceous surface material that aggregates donor and recipient bacteria to facilitate plasmid transfer. Bacterial growth conditions also affect the interaction of enterococci with polymorphonuclear leucocytes (PMNLs), with serum-grown organisms showing less association with PMNLs than organisms grown in broth. Efficient killing of enterococci by PMNLs in vitro requires the presence of serum complement proteins and is enhanced by anti-enterococcal antibodies. Enterococci produce a number of factors that may be associated with pathological changes in the host. Both sex pheromones and plasmid-encoded pheromone inhibitors produced by E. faecalis are chemotactic for PMNLs in vitro, and may mediate, at least in part, the inflammatory response often associated with enterococcal infection. E. faecalis may also produce a plasmid-encoded haemolysin, which is associated with increased severity of infection. In addition, enterococci are capable of inducing platelet aggregation and tissue factor-dependent fibrin production, which may be relevant to the pathogenesis of enterococcal endocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Gentamicin resistance in clinical isolates of Escherichia coli encoded by genes of veterinary origin.

Seven (27%) of 26 gentamicin-resistant human clinical isolates of Escherichia coli were resistant to the veterinary aminoglycoside antibiotic apramycin. A gentamicin-resistant Klebsiella pneumoniae isolate from a patient infected with gentamicin/apramycin-resistant E. coli was also resistant to apramycin. DNA hybridisation studies showed that all gentamicin/apramycin-resistant isolates contained a gene encoding the enzyme 3-N-aminoglycoside acetyltransferase type IV (AAC[3]IV) that mediates resistance to gentamicin and apramycin in bacteria isolated from animals. Seven of the eight gentamicin/apramycin-resistant isolates were also resistant to the veterinary antihelminthic agent hygromycin B, a phenomenon observed previously in gentamicin/apramycin-resistant Enterobacteriaceae isolated from animals. Resistance to gentamicin/apramycin and hygromycin B was co-transferable in six of the isolates. Restriction enzyme analysis of plasmids in apramycin-resistant transconjugants derived from E. coli and K. pneumoniae isolates from the same patient were virtually identical, suggesting that inter-generic transfer of plasmids encoding apramycin resistance had occurred in vivo. These findings support the view that resistance to gentamicin and apramycin in clinical isolates of E. coli results from the spread of resistant organisms from animals to man, with subsequent inter-strain or inter-species spread, or both, of resistance genes on transferable plasmids.

Acetyltransferases↗
PubMed1994

Speech restoration following total laryngo-pharyngectomy with free jejunal repair.

Nine patients who have undergone total laryngo-pharyngectomy with free jejunal reconstruction between 1984 and 1993, have had Blom-Singer valves inserted. All patients had little or no voice prior to valve insertion, compared with a good but gravelly voice after valve insertion. Tracheo-oesophageal puncture and valve insertion provides a safe and reliable means of restoring voice after laryngo-pharyngectomy with free jejunal repair.

Esophagus↗