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Biomedical subjects

J M Boyce

Publications and source records attributed to J M Boyce.

At least 73 records · Page 4Linked to original sources

Evaluation of the Cathra inoculating device for susceptibility testing of methicillin-susceptible and methicillin-resistant Staphylococcus aureus strains.

We compared the antimicrobial susceptibility results obtained with the Cathra replicator and reference methods when Staphylococcus aureus strains were tested by using agar dilution techniques. The Cathra replicator and the 0.001-ml calibrated loop gave results that fell within +/- 1 log2 dilution for greater than or equal to 95% of isolates when methicillin and cefamandole were tested.

Cefamandole

Reliability of the MS-2 system in detecting methicillin-resistant Staphylococcus aureus.

The MS-2 system (Abbott Diagnostics, Division of Abbott Laboratories, Dallas, Tex.) is an automated system capable of rapid antimicrobial susceptibility testing. However, the short incubation periods used by the device may adversely affect its ability to detect slowly growing resistant organisms. Shortly after the introduction of the MS-2 system into the University of Mississippi Medical Center clinical microbiology laboratory, we noted discrepancies between the MS-2 and the disk diffusion susceptibility reports when methicillin-resistant Staphylococcus aureus isolates were tested. Subsequently, we determined the susceptibilities of 75 such isolates by the MS-2 and Kirby-Bauer disk diffusion methods and measured the minimum inhibitory concentrations of methicillin, oxacillin, and cephalothin for 33 of the 75 isolates by standardized agar dilution techniques. There was only 47% overall agreement between the MS-2 and disk diffusion methods when methicillin was tested and 15% agreement when cephalothin was the test drug. There was 93% or more overall agreement between the two methods when other antimicrobial agents were tested. The minimum inhibitory concentration of methicillin was greater than or equal to 16 micrograms/ml for all 33 isolates evaluated by the agar dilution method. A comparison of the MS-2 and agar dilution results revealed an overall agreement of 49% when the susceptibilities to methicillin were determined. The MS-2 system reported that multiple methicillin-resistant S. aureus isolates obtained from a single patient were either resistant, intermediate, or sensitive to methicillin. Inconsistent results were also obtained when a single isolate was tested simultaneously in 10 cuvette cartridges. We conclude that the MS-2 system does not reliably detect methicillin and cephalothin resistance among S. aureus.

Cephalothin

Patterns of Shigella infection in families in rural Bangladesh.

To assess the mode of transmission of Shigella infection in rural Bangladesh, questionnaire and culture surveys were conducted in baris (neighborhoods) where persons with diarrhea associated with Shigella infection and index controls with non-Shigella diarrhea lived. Nineteen percent of persons in Shigella baris and 7% of persons in control baris were infected during the survey periods (P less than 0.001). The prevalence of Shigella infection was highest for children 1-9 years of age and for females than 39 years and was not related to socioeconomic status, family size or household crowding. Use of surface water for drinking was not a risk factor for Shigella infection; in fact, use of river water was more frequent in control baris. Both household and bari contacts of Shigella index cases frequently excreted different serotypes from that excreted by the person with the index case. In Shigella baris, families with infection were significantly more likely than uninfected families to have a history of an overnight stay away from home by a family member during the previous week. These observations suggest there were multiple introductions of Shigella into some families and that the epidemiology of Shigella infection for families in rural Bangladesh differs from that observed for families living in more industrialized countries.

Adolescent

Epidemiology of eltor cholera in rural Bangladesh: importance of surface water in transmission.

In order to define the role of water used for drinking, cooking, bathing, and washing in the transmission of Vibrio cholerae biotype eltor infections in an area with endemic cholera, surveillance was initiated in neighbourhoods with a culture-confirmed cholera index case and others with index cases with non-cholera diarrhoea as controls. In neighbourhoods with cholera infection, 44% of surface water sources were positive for V. cholerae, whereas only 2% of surface sources were positive in control neighbourhoods. Canals, rivers, and tanks were most frequently positive. There was an increased risk of infection for families using water from culture-positive sources for drinking, cooking, bathing, or washing and for those using water sources used by index families for drinking, cooking or bathing. Analysis of the results for individuals showed that in this case there was an increased risk of infection associated with using water from culture-positive sources for cooking, bathing, or washing, but not with using water from culture-positive sources for drinking. Individuals who used the same water source as an index family for bathing were more likely to be infected than those using different sources. For families drinking from a culture-negative source, there was an association between infection and bathing in a positive source. For families using a different bathing source from the index family there was an association between infection and drinking from the same source as the index family, and for families using a different drinking source from the index family there was an association between infection and bathing in the same source as the index family. These data suggest that use of surface water is important in the transmission of V. cholerae and that, in addition to providing safe drinking water, education regarding the risk of transmission of infection by water from potentially contaminated sources used for other purposes, especially bathing, may also be necessary to control transmission in areas where eltor cholera is endemic.

Adolescent

Cunninghamella bertholletiae wound infection of probable nosocomial origin.

After closed reduction and casting of a tibial fracture in a 69-year-old diabetic man, a gangrenous lesion developed under the cast. Cultures of debrided tissue revealed multiple bacteria, including Bacillus sp, plus two fungi, Fusarium sp and a zygomycete identified as Cunninghamella bertholletiae. Large nonseptate hyphae in thrombosed blood vessels suggested that C bertholletiae played a major role in the development of the infection. Recovery of organisms from our patient's wound and from the cast padding suggests that the wound infection was acquired from nonsterile dressings.

Bandages

Airborne spread of brucellosis.

review of epidemic and endemic brucellosis at six abattoirs demonstrates a correlation between case distribution and flow of air from the kill department (stage II) to other areas within an abattoir. Air from the kill department disseminated to nearby departments led to abnormally high brucellosis attack rates for persons who worked in these areas at two abattoirs. Complete physical separation or maintaining negative air pressure in the kill department was associated with reduced risk for workers in other areas at four abattoirs. Cases in persons who had exposure to kill department air but no contact with animal tissues provide strong evidence for airborne transmission of infection. Brucellosis is also contracted through skin contact with infectious animal tissues, but this route of transmission appears less important than formerly believed.

Abattoirs

Endemic human plague in New Mexico: risk factors associated with infection.

A retrospective case-control study was conducted to identify risk factors, other than contact with infected animal tissues, for infection caused by Yersinia pestis in non-Indian residents of areas with endemic sylvatic plague in New Mexico. The study group consisted of 16 persons who had bacteriologically confirmed cases of plague in the period 1975-1976 and 45 controls who were matched by age, sex, and location of residence. Participants were questioned about outdoor activities, environmental conditions in and around the home, procedures of pet care, exposure to animals and insects, and medical history. The availability of harborage and food sources for wild rodents as a result of human activity in the immediate home environment was associated with risk of infection. Failure to take steps to control fleas on dogs and cats also appeared to be a possible risk factor. No other significant differences were found between patients and controls. Plague in New Mexico appears to result primarily from entry of the reservoir host into the habitat of the human rather than from entry of the human into the sylvatic habitat of the reservoir host.

Animals

Production of heat-stable, methanol-soluble enterotoxin by Yersinia enterocolitica.

Seven isolates of Yersinia enterocolitica serotype 0:8, recovered during an outbreak of gastrointestinal illness, were examined for enterotoxin production. All seven strains were enterotoxigenic in the suckling mouse model, and three of five isolates tested produced keratoconjunctivitis in the guinea pig eye model (Sereny test). Enterotoxin was detected in broth supernatant fluid after 12 h of incubation at 25 degrees C. The toxin was not inactivated by exposure to 121 degrees C for 30 min or by storage at 4 or -40 degrees C for at least 5 months. The enterotoxin was also acid stable and methanol soluble. Methanol extraction did not affect its heat stability or enterotoxic activity in suckling mice. These physical characteristics plus limited ultrafiltration studies suggest that the enterotoxin is a low-molecular-weight substance. Y. enterocolitica enterotoxin resembles Escherichia coli heat-stable enterotoxin in heat and pH stability, methanol solubility, and enterotoxic activity in suckling mice. However, its role in the pathogenesis of human diarrhea has not been established.

Bacterial Toxins

Vibrio parahaemolyticus enterocolitis in Bangladesh: report of an outbreak.

In March 1974 eight men in Chandpur, Bangladesh, experienced an illness characterized by severe abdominal cramps, nausea, vomiting and bloody diarrhea with onset 20 min to 9 h (median 2.5 h) after eating one of two fish dishes at a restaurant. Rectal cultures from all eight grew Kanagawa-positive strains of Vibrio parahaemolyticus (serotype O3K5) that were negative in the Sereny test for invasiveness and the Y-1 adrenal cell and infant mouse assays for enterotoxin production. The short incubation, severity of abdominal cramps and grossly bloody stools distinguish this illness from that usually associated with V. parahaemolyticus infection in the United States.

Adolescent

An epizootiologic study of anthrax in Falls County, Texas.

In June and July, 1974, an anthrax epizootic in Falls County, Texas, resulted in the death of 236 animals (228 cattle, 5 horses, 2 mules, and 1 pig) on 48 premises. Death rates were highest for horses (18.2%) and bulls (16.8%). The epizootic was apparently precipitated by drought, and infection appeared to be the result of ingesting intrinsically contaminated soil and grass. Human illness was not associated with the epizootic.

Animals

Wound infection by an indigenous Pseudomonas pseudomallei-like organism isolated from the soil: case report and epidemiologic study.

A 27-year-old farmer in the Oklahoma panhandle was pinned under his overturned tractor for 2 hr and received superficial and deep lacerations. He contracted an infection of a pelvic wound with an organism that had cultural and biochemical characteristics identical to those of Pseudomonas pseudomallei. Identical organisms were recovered from soil taken from the site of the accident. The organism isolated from the wound proved to be less virulent in guinea pigs than usual laboratory strains of P. pseudomallei; fatty acid analysis showed a distinctly different pattern from that of laboratory strains of P. pseudomallei. The infecting organism may be a variant of P. pseudomallei or a new species of Pseudomonas.

Adult

Epidemiologic and clinical features of an outbreak of bubonic plague in New Mexico.

An outbreak of seven cases of bubonic plague in New Mexico was investigated. Clinical features were studied and correlated with field studies in an attmept to determine the source of infection in patients with indefinite histories of exposure. Most patients presented with fever, malaise, and an acute painful lymphadenitis (bubo). One death occurred in a patient with bubonic-septicemic plague complicated by meningitis due to Yersinia pestis. All patients lived in rural or semirural areas, and most had been in the general vicinity of their usual residence during the six days prior to onset of symptoms. The outbreak was associated with probable epizootics in rodents in two different areas of the state. One case was traced to direct hand contact with plague-infected rabbits. One patient developed insect bites after sleeping in the same bed with a flea-infested cat. Three of the other five patients had insect bites, presumably flea bites, but none of the five recalled contact with rodents or rabbits. Four of the five, however, had been in contact with dogs or cats that were later shown to have titers of antibody to Y. pestis. These findings provide further support for the hypothesis that contact with domestic dogs and cats may result in direct or indirect transmission of Y. pestis to humans.

Adult

Nosocomial staphylococcal cervical lymphadenitis in infants: report of an outbreak.

Staphylococcus aureus infections developed in 16 of 721 infants born at a general hospital during a six-month period (October 1972 to March 1973). Twelve of the 16 affected infants had cervical adenitis, which usually became manifest two to four months after they were discharged from the hospital. Although most infants with adenitis underwent incision and drainage procedures, physicians noted few constitutional symptoms. Staphylococcal phage types from infants with adenitis were identical to phage types commonly recovered from colonized newborns and nursery personnel at the hospital. Despite the long period between hospital discharge and onset of clinical symptoms, cases of cervical adenitis were probably nosocomial in origin.

Cross Infection