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Biomedical subjects

J I Roberts

Publications and source records attributed to J I Roberts.

9 recordsLinked to original sources
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

Protein A and coagulase expression in epidemic and non-epidemic Staphylococcus aureus.

Strains of Staphylococcus aureus were divided into groups on the basis of antimicrobial sensitivity and epidemiology and tested for protein A expression in a simple microtitre test, which detected the non-immunological binding of immunoglobulin to protein A on whole cells of S aureus. Isolates of the methicillin resistant strain prevalent in south east England (EMRSA) showed a low expression of protein A compared with the other strains of methicillin resistant S aureus (MRSA), other multiple resistant strains, and sensitive strains. Protein A and coagulase expression in 27 strains of MRSA from 15 countries associated with hospital outbreaks were compared with 27 strains of MRSA from 11 countries reported to be sporadic isolates. Twenty four of the 27 outbreak associated MRSA showed low expression of protein A and high expression of coagulase. Conversely, sporadic strains generally gave higher levels of protein A and a wide variety of coagulase reactions. The results suggest that many epidemic strains of MRSA may have phenotypic characteristics that distinguish them from sporadic strains.

Coagulase↗
PubMedDate not supplied

Investigation of Cryptosporidium in relation to other intestinal parasites at the Lagos University Teaching Hospital, Lagos.

Cryptosporidium spp is a coccidian protozoan which has recently been reported as a possible important aetiological agent of diarrhoea, especially in immunocompromised hosts such as patients with acquired immuno-deficiency syndrome (AIDS). In the present report, 890 stool specimens of patients including diarrhoea cases submitted for parasitologic laboratory investigation at the Lagos University Teaching Hospital from January to December 1986 were specifically screened for Cryptosporidium oocysts. There was no confirmed case of crystosporidioisis in-the 12-month study period. The reported efficient techniques for laboratory detections of Cryptosporidium were described and the literature on Cryptosporidiosis reviewed. It is hoped that the present report would create greater awareness amongst laboratory workers and clinicians in various communities and geographic locations to enable them to carry out more studies in human diseases in West Africa.

Adolescent↗
PubMedDate not supplied

U.S. Food and Drug Administration pesticide program: incidence/level monitoring of domestic and imported pears and tomatoes.

In 1992-1993, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported pears and tomatoes. For pears, 710 domestic and 949 imported samples were collected and analyzed; 79% of the domestic and 72% of the imported samples had detectable residues. Thiabendazole, a fungicide with postharvest uses, was found with greatest frequency in both groups of pears. Four domestic and 12 imported samples contained violative residues, mainly of pesticides for which there are no U.S. tolerances on pears. The statistically weighted (by shipment size) violation rates for domestic and imported pears were 1.0 and 0.9%, respectively. For tomatoes, 1219 domestic and 144 imported samples were collected and analyzed; 84% of the domestic and 91% of the imported samples had detectable residues. Methamidophos, an insecticide, had the greatest frequency of occurrence in both groups of tomatoes. Thirty-three domestic and 5 imported samples were violative, nearly all the result of acephate use, for which there is no U.S. tolerance on tomatoes. The statistically weighted violation rates for domestic and imported tomatoes were 1.9 and 7.0%, respectively. The statistically weighted violation rates calculated for domestic and imported pears and domestic tomatoes in this study were lower than those observed under FDA's regulatory monitoring in recent years. The violation rate for imported tomatoes was somewhat higher under statistical monitoring than under regulatory monitoring. The results of the statistically based study show that, as in regulatory monitoring, the levels of pesticide residues found are generally well below U.S. tolerances.

Food Contamination↗
PubMedDate not supplied

Monitoring of domestic and imported apples and rice by the U.S. Food and Drug Administration pesticide program.

In 1993-94, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported fresh apples and processed rice. For apples, 769 domestic and 1062 imported samples were collected and analyzed; 85% of the domestic and 86% of the imported samples had detectable residues. Benomyl, a widely used fungicide, was found with greatest frequency in domestic apples, while diphenylamine was found most often in imported apples. One domestic and 4 imported samples contained violative residues of pesticides for which there are no U.S. tolerances on apples. The statistically weighted (by domestic packer throughput or import shipment size) violation rates for domestic and imported apples were 0.30% (0.13 unweighted) and 0.41% (0.38 unweighted), respectively. For rice, 598 domestic and 612 imported samples were collected and analyzed; 56% of the domestic and 12% of the imported samples had detectable residues. Malathion had the greatest frequency of occurrence in both groups of rice. Eight domestic and 9 imported samples were violative, all as a result of use of pesticides for which there are no U.S. tolerances on rice. The statistically weighted violation rates for domestic and imported rice were 0.43% (1.3 unweighted) and 1.1% (1.5 unweighted), respectively. Results of the statistically based study show that, as in FDA's regulatory monitoring, the levels of most pesticide residues found in these 2 commodities are generally well below U.S. tolerances, and few violative residues are found.

Benomyl↗