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Biomedical subjects

J Naidoo

Publications and source records attributed to J Naidoo.

15 recordsLinked to original sources
PubMed1992

Characterization of orthopoxviruses isolated from feline infections in Britain.

The biological properties and genomes of orthopoxviruses isolated from cats in Britain were compared with strains of cowpox virus isolated from cows and their handlers. All the isolates tested produced haemorrhagic pocks and A-type inclusions on the CAM, but did not produce pocks above 40 degrees C. Thus the feline isolates behaved as typical strains of cowpox virus. Differences were found in the heat resistance of the virions and in the character of the A-type inclusion which did not correlate with the host from which the viruses were isolated. Analysis of the genomes with a variety of restriction endonucleases showed very close relationship between all the isolates and also failed to separate feline isolates from cowpox virus. However again minor differences, which may prove to be of epidemiological value were detected. We conclude that the orthopoxvirus currently isolated from domestic cats in Britain is cowpox virus and that there is no evidence that a feline variant or subspecies circulates in Britain.

Animals↗
PubMed1992

Cross-infection of gentamicin-methicillin-resistant Staphylococcus aureus in a male surgical ward at Rajavithi General Hospital.

Between January and December 1987, gentamicin-methicillin-resistant strains of Staphylococcus aureus (GMRSA) were isolated from 7 patients in a male surgical ward at Rajavithi General Hospital. Six patients developed significant infection which included sepsis (2), pneumonia (1), infection in the eye, ear and wound (1), wound infection (2), and one patient had GMRSA isolated from his sputum. The strains were untypable with standard phage type and were resistant to methicillin, gentamicin, amikacin, kanamycin, streptomycin, tetracycline, erythromycin and chloramphenicol, but susceptible o vancomycin and cotrimoxazole. GMRSA were also isolated from bed-rail and the used rubber gloves left in the affected room. The GMRSA strains contained 5 plasmids of molecular weight of 18, 11, 2, 1.8 and 1.7 Md. The 2Md plasmid coded for chloramphenicol resistance and the 1.8 Md plasmid for erythromycin resistance.

Cross Infection↗
PubMed1989

A community outbreak of group A beta haemolytic streptococci with transferable resistance to erythromycin.

Erythromycin resistance amongst group A streptococci (GAS) in Great Britain is a relatively rare occurrence and outbreaks have been sporadically reported. Over an 8-month period in 1986 ten associated cases occurred in the town of Bridgewater in Somerset. Isolates were group A, type M4 and resistant to erythromycin (MIC 8 mg/l) but sensitive to lincomycin and clindamycin. Erythromycin resistance was transferable from all isolates to a group A recipient strain. No plasmid DNA could be detected in the original isolates or transconjugants.

Adult↗
PubMed1989

High-level vancomycin-resistant enterococci causing hospital infections.

Nosocomial infection or colonization due to enterococci with high-level resistance to vancomycin (minimal inhibitory concentrations [MICs] between 64 and greater than 2000 mg/L) has occurred in 41 patients with renal disease. These vancomycin-resistant enterococci were cultured from many sources including blood. All but one strain contained one or more plasmids ranging in molecular weight from 1.0 to 40 Megadaltons (MDa). Vancomycin resistance was transferable by conjugation to a susceptible recipient strain of Enterococcus faecalis but this was not always associated with plasmid DNA. The emergence of transferable high-level vancomycin resistance in enterococci causing significant clinical infections is of particular importance since vancomycin is widely regarded as a reserve drug for the management of infections with multi-resistant Gram-positive organisms.

Acute Kidney Injury↗
PubMed1988

Evaluation of electrophoretic methods for typing methicillin-resistant Staphylococcus aureus.

Three electrophoretic methods of typing methicillin-resistant Staphylococcus aureus (MRSA) strains--plasmid profiles (PP), whole-cell protein profiles (WCPP) and immunoblotting profiles (IP)--were evaluated and compared with phage typing. The results obtained with isolates from 12 outbreaks were compared both within the outbreaks, to determine the consistency of results, and between outbreaks. There was generally good agreement between the typing methods but in only six outbreaks did all four methods indicate the same relationship between isolates. WCPP comprised more than 50 bands; when differences occurred, they were seen in only a few bands. In contrast, IP comprised only one or two major bands and the differences were much easier to interpret. The PPs of many of the isolates were similar; many isolates contained a plasmid of mol. wt (18-25) x 10(6). In several outbreaks both WCPP and IP showed minor differences between isolates that were not apparent with phage typing. When comparisons were made between the 12 index strains and an isolate representing the London epidemic MRSA strain, phage typing and WCPP were the most discriminatory methods; both gave nine distinct patterns, whereas there were eight IPs and only six PPs amongst the 13 strains. It was concluded that both WCPP and IP could provide valuable epidemiological data on MRSA and that IP was the easiest of the three methods to interpret.

Bacterial Proteins↗
PubMed1987

Unusual occurrence of an epidemic of type Ib/c group B streptococcal sepsis in a neonatal intensive care unit.

An epidemic of late-onset sepsis due to type Ib/c group B Streptococcus (Ib/c-GBS) occurred in a neonatal intensive care unit (NICU). During a seven-week period, five very low birth weight infants (index cases [ICs]) more than four weeks of age became bacteremic. Bacteriologic surveillance of neonates revealed persistent colonization in three ICs and identified three asymptomatic carriers (ACs). All ICs and one AC acquired Ib/c-GBS nosocomially, whereas the other two ACs were colonized at birth. Among nursery personnel, 39% carried GBS, but only two harbored Ib/c-GBS. Although phage typing of Ib/c-GBS isolates identified two patterns of susceptibility, we believe a single strain was involved in the epidemic, because the patterns overlapped and most isolates carried the same lysogenic phage. Analysis of events suggested infant-to-infant spread via the hands of personnel, but acquisition from the colonized staff was also possible. The control measures instituted prevented further spread of Ib/c-GBS in the NICU.

Anti-Bacterial Agents↗
PubMed1986

Strategies for typing and properties of epidemic methicillin-resistant Staphylococcus aureus.

Isolates of 17 strains of epidemic methicillin-resistant Staphylococcus aureus from outbreaks in ten hospitals in the UK were investigated with a variety of techniques both to explore their properties and to type them in order to confirm or refute known or suspected epidemiology. The techniques consisted of a biotyping system, peptidoglycan analysis, testing of antibiotic sensitivity to 21 agents, various phage-typing methods including heat shock, plasmid pattern analysis, and heat cure derivation of plasmid-less isogenic strains. All strains resembled those originally isolated in Australia, being in the possession of a large number of chromosomal resistance factors, pigmentation, ability to produce lipase and large molecular weight plasmids (c.15 Md to c.23 Md) which conferred resistance to gentamicin, propamidine, ethidium bromide, cetrimide and chlorhexidine. Some strains also had a c.3 Md plasmid conferring chloramphenicol resistance and others a c.1 Md cryptic plasmid. A large percentage of the population was resistant to 25 mg/l methicillin at 37 degrees C, an unusual feature. All the strategies, with the exception of peptidoglycan analysis, contributed to typing of the strains.

Bacteriophage Typing↗
PubMed1985

Some effects of plasmids coding for antibiotic resistance on the virulence of Staphylococcus aureus.

The relative virulence of pairs of staphylococci differing in resistance plasmid content has been studied using the neonatal mouse weight gain test. Both clinical and laboratory strains were used which had undergone genetic manipulation, either curing for loss of plasmids or transduction for gain of plasmids. A difference in virulence was detected between two variants of S. aureus NCTC 8325 possessing different plasmids coding for penicillinase. However in most cases any form of genetic manipulation seemed to reduce the virulence of the staphylococcus. In the case of NCTC 9789 (PS 80) which was originally an epidemic strain, curing of a plasmid coding for cadmium resistance resulted in reduced virulence but original virulence could not be restored by transduction of the plasmid into the cured derivative.

Animals↗
PubMed1978

Acquisition of antibiotic resistance by Staphylococcus aureus in skin patients.

Acquisition of resistance to neomycin, gentamicin, fusidic acid, or clindamycin has been observed in three strains of Staphylococcus aureus and data from three patients infected with these strains are presented in detail. Clindamycin resistance followed the expected pattern by appearing in a strain of Staph. aureus with dissociated resistance to erythromycin after treatment with erythromycin and clindamycin. Low-level resistance to fusidic acid appeared in two strains in the apparent absence of exposure to that antibiotic. Labile neomycin resistance was encountered in a previously sensitive strain after topical neomycin therapy. Gentamicin resistance appeared in all three strains after topical therapy. In all three strains, a labile resistance (presumably plasmid-mediated) occurred with minimum inhibitory concentrations (MICs) of 64-128 microgram/ml but in one strain a stable resistance with MIC over 3000 microgram/ml appeared.

Anti-Bacterial Agents↗