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Biomedical subjects

J G Wells

Publications and source records attributed to J G Wells.

At least 73 records · Page 4Linked to original sources
PubMed1988

Escherichia coli O157:H7, an emerging gastrointestinal pathogen. Results of a one-year, prospective, population-based study.

To examine the incidence of Escherichia coli O157:H7 enteric infections in the United States and to evaluate the vehicles of transmission for sporadic cases, we conducted a one-year, population-based study at a large health maintenance organization (HMO) in the Puget Sound area of Washington State. All stool specimens submitted for culture to the HMO laboratory were screened for E coli O157:H7; the organism was identified in 25 (0.4%) of 6485 stool specimens. All patients with E coli O157:H7 identified had diarrhea; 24 patients (96%) had bloody diarrhea. Exposure histories demonstrated that rare ground beef was consumed more often by patients (21%) than by age-matched control subjects (4%) in the week before onset of illness. Raw milk also was consumed by two patients but by none of the control subjects. Incidence rates for laboratory-confirmed enteric infections in the HMO population were as follows: Campylobacter, 50/100,000 person-years; Salmonella, 21/100,000 person-years; E coli O157:H7, 8/100,000 person-years; and Shigella, 7/100,000 person-years. The organism is a more common pathogen in the United States than is generally recognized, and the diagnosis should be considered for patients with suspected enteric infection.

Adolescent↗
PubMed1988

Toward a population genetic analysis of Salmonella: genetic diversity and relationships among strains of serotypes S. choleraesuis, S. derby, S. dublin, S. enteritidis, S. heidelberg, S. infantis, S. newport, and S. typhimurium.

Variation in the chromosomal genomes of 1527 isolates of eight common serotypes (O and H antigen profiles) of Salmonella was assessed by analysis of electrophoretically demonstrable allelic polymorphism at 23 metabolic enzyme loci. Seventy-one distinctive electrophoretic types, representing multilocus genotypes, were identified. A basically clonal population structure was indicated by the presence of strong linkage disequilibrium among enzyme loci, the association of each serotype with a relatively small number of multilocus enzyme genotypes, and the global distribution of certain genotypes. For each of six of the serotypes, 83-96% of isolates were members of a single clone. The occurrence of each of four serotypes (S. derby, S. enteritidis, S. infantis, and S. newport) in isolates of clones belonging to several evolutionary lineages, some of which are distantly related, suggests that the horizontal transfer and recombination of chromosomal genes mediating expression of cell-surface antigens has been a significant process in the evolution of the salmonellae. Two divergent clone clusters of S. derby differ in the relative frequency with which they cause disease in birds versus mammals, and two major lineages of S. newport differ in the frequency with which their clones are associated with disease in humans versus animals.

Alleles↗
PubMed1987

Changes in antimicrobial resistance of Salmonella isolated from humans in the United States.

Changes were examined that occurred in the antimicrobial susceptibility between 1979-1980 and 1984-1985 of Salmonella organisms isolated from humans who resided in a random sample of counties in the United States. Resistance to one or more antimicrobials rose significantly from 16% (82 of 511 isolates) in 1979-1980 to 24% (117 of 485 isolates) in 1984-1985. In addition, statistically significant increases occurred in the proportion of organisms resistant to only one antimicrobial (from 4% to 9%), the rate of resistance of Salmonella typhimurium (from 14% to 26%), and the rate of resistance to tetracycline. For one commonly occurring serotype, Salmonella heidelberg, the proportion of resistant strains fell significantly from 67% in 1979-1980 to 35% in 1984-1985. When epidemiologic characteristics of patients were examined, previous use of antimicrobials for treatment of other illnesses was a significant risk factor for acquiring clinically important infections with antimicrobial-resistant Salmonella. Changes detected in the antimicrobial resistance of Salmonella during this time will ultimately affect the efficacy of antimicrobial therapy in treating human disease.

Drug Resistance, Microbial↗
PubMed1987

Staphylococcal food poisoning on a cruise ship.

Two waves of vomiting and/or diarrhoea affected approximately 215 of the 715 passengers on a Caribbean cruise ship. The outbreak was independently associated with eating cream-filled pastries at two separate meals. Staphylococcus aureus phage type 85/+ was isolated from cases and pastry cooks, but not from controls. This is the first well-documented outbreak of staphylococcal food poisoning on a cruise ship.

Disease Outbreaks↗
PubMed1987

Unusual verotoxin-producing Escherichia coli associated with hemorrhagic colitis.

All strains of Escherichia coli isolated from cases of hemorrhagic colitis and sent to the Centers for Disease Control, Atlanta, Ga., over a 3-year period were assayed for toxicity in Vero cell cultures. Strains that produced moderate or high levels of verotoxin were characterized by serotype, biotype, antimicrobial resistance, plasmid profile, and adherence to HeLa cells. Over 200 isolates were typical O157:H7 strains. Six isolates were atypical O157:H7 strains; two were resistant to antimicrobial agents; one was indole negative, two were citrate positive, and one was urea positive. Six isolates were nonmotile O157 strains. All of these isolates were similar to typical O157:H7 strains by plasmid profile and negative or slow sorbitol fermentation. Eleven other verotoxigenic isolates did not possess the O157 antigen, had a variety of plasmid profiles, and were sorbitol positive. Two of the eleven were enteropathogenic serotypes (O111:NM and O26:H11), yet none were adherent to HeLa cells. We conclude that verotoxigenic E. coli associated with hemorrhagic colitis includes atypical O157 strains and other serotypes. Hence, investigators should use current screening methods with caution.

Bacterial Adhesion↗
PubMed1987

Non-01 Vibrio cholerae infections in Cancun, Mexico.

To determine the role of Vibrio cholerae as a cause of diarrheal illness in Cancun, Mexico, an investigation was conducted in July and August 1983. Although toxigenic V. cholerae 01 were not found, non-01 V. cholerae were isolated from 22 (16%) of 134 stools from persons with diarrheal illness and none of 22 stools from well persons; 58 (92%) of 63 sewage samples; 12 (86%) of 14 untreated well water samples; a home storage tank for treated water; and 5 (21%) of 24 samples of raw seafood. None of the V. cholerae isolates from patients were toxigenic. The illness occurred mainly in small children, and were characterized principally by diarrhea and abdominal pain. No patient was seriously ill, and all recovered without sequelae. Seven different serotypes of non-01 V. cholerae were isolated from the stool specimens, and Smith serotype 12 accounted for 10 (46%) of the 22 isolates. A matched-pair case-control study found that cases were more likely than controls to have eaten home prepared gelatin (P = 0.03, OR = 5/0) and seafood (P = 0.06, OR = 4/0).

Adolescent↗
PubMed1986

An outbreak of a newly recognized chronic diarrhea syndrome associated with raw milk consumption.

A previously undescribed chronic diarrhea syndrome affected 122 residents of Brainerd, Minn, between December 1983 and July 1984. The illness lasted at least one year for 75% of case-patients and was characterized by acute onset, marked urgency, a lack of systemic symptoms, and a failure of response to antimicrobial agents. Clinical and laboratory data indicate that the diarrhea was caused by a secretory mechanism. Consumption of raw milk from a single dairy was associated with illness (odds ratio, 28.3; 95% confidence interval, 9.0 to 89.0). A median incubation period of 15 days was determined for seven case-patients. Possible secondary transmission was noted in one family. Extensive laboratory examination did not identify an etiologic agent. Outbreaks or sporadic cases of a similar illness have occurred in at least seven states; the outbreaks were less extensively investigated and findings were not published, but raw milk consumption was common in the affected persons. This illness appears to represent a previously unrecognized but important clinical entity and public health problem. The etiology and effective therapy for this illness must be determined by further studies of sporadic cases and outbreaks.

Aged↗
PubMed1986

Hemolytic uremic syndrome and diarrhea associated with Escherichia coli O157:H7 in a day care center.

Three cases of hemolytic uremic syndrome with bloody diarrhea occurred during an outbreak of diarrheal illness in children aged 4 months to 9 years who attended a day care center. Thirty-six (34%) of 107 had diarrhea (three or more loose or watery stools in 24 hours) lasting greater than or equal to 3 days. Thirty-one (48%) of 64 children younger than 4 years of age but only (12%) of 43 in the older classes became ill (relative risk 4.0, P less than 0.001). Eleven (31%) of the 36 children with diarrhea had blood in their stools. Sequential movement of illness from class to class was consistent with person-to-person spread. Ten (18%) of 56 family members of ill children but only one of 45 family members of well children younger than 4 years of age developed a diarrheal illness (P less than 0.05). Escherichia coli O157:H7 was detected in two of eight stool specimens from children who had bloody diarrhea (one with hemolytic uremic syndrome), two of seven with nonbloody diarrhea, and none of nine who remained well. All three stool specimens obtained at less than or equal to 6 days compared with one of nine obtained at greater than 6 days after onset yielded this organism (P less than 0.02). E. coli O157:H7 can cause hemolytic uremic syndrome and both nonbloody and bloody diarrhea, and can spread within families and through modes other than foodborne transmission.

Child↗
PubMed1986

Escherichia coli O157:H7 diarrhea in a nursing home: clinical, epidemiological, and pathological findings.

In September 1984, an outbreak of Escherichia coli O157:H7 infection occurred in a nursing home. It was the first recognized outbreak of this organism in the United States since 1982, when two outbreaks led to its recognition as a pathogen. Thirty-four of 101 residents developed a diarrheal illness; 14 were hospitalized with a severe illness characterized by crampy abdominal pain, marked abdominal distention, and grossly bloody diarrhea, and four died. The spectrum of illness associated with the infection was broad and included the following: asymptomatic infection, nonbloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and death. Clinical, radiographic, and postmortem pathological findings suggested involvement of the cecum and right colon. No evidence of response to antimicrobial agents could be documented, and antidiarrheal agents may have aggravated the disease. This investigation implicated hamburger as the vehicle transmission. Seventeen of 19 residents with hemorrhagic colitis, but only 28 of 67 healthy residents, had eaten hamburger on 13 September (P less than .001, Fisher's two-tailed exact test; relative risk [RR] = 7.7). Infection with E. coli O157:H7 can cause a wide range of manifestations. In the elderly these can be particularly severe and may resemble ischemic colitis.

Adult↗
PubMed1985

Turtle-associated salmonellosis in Puerto Rico. Hazards of the global turtle trade.

After the Puerto Rico Department of Health received a report of salmonellosis in an infant who had contact with a pet turtle, we conducted a case-control study in two urban areas in Puerto Rico to measure the extent of pet turtle-associated salmonellosis there. Ten (17%) of 60 infants with salmonellosis but none of their matched controls had a history of exposure to a pet turtle in the two weeks before onset of illness. Two other case patients were also exposed to a pet turtle--an 8-year-old child and an adult with acquired immunodeficiency syndrome and Salmonella bacteremia. A variety of Salmonella serogroups were represented in the turtle-associated cases. All turtle lots collected from pet shops in Puerto Rico were culture-positive for Salmonella; 89% yielded Salmonella pomona. Contamination of the turtles probably occurred at the farm before distribution, since S pomona was also isolated from turtles exported from the same farm to Guam and to Yugoslavia. The estimated 3 to 4 million turtles exported annually from the United States are an important potential route for global dissemination of human salmonellosis.

Adult↗
PubMed1985

Acoustic emission and mechanical properties of trabecular bone.

The mechanical properties of trabecular bone and a simple plug prosthetic system have been determined over a range of displacement from 0.1 to 5 mm/min. Acoustic emission, a technique which is capable of detecting dynamic processes within a material, was used to monitor the compression tests on the prosthetic system. It was found that the stiffness and strength of trabecular bone and the prosthetic system increased with increasing strain rate of testing. The acoustic emission results demonstrated that the improvement in mechanical behaviour at the fast strain rates was accompanied by a decrease in the extent of the failure of the trabeculae. The technique of activation analysis has been applied to the results in order to identify the rate controlling fracture mechanism. Finally, the strength of the prosthetic system was correlated with the shear and compressive strengths of trabecular bone.

Acoustics↗
PubMed1985

A multistate outbreak of gastrointestinal illness caused by enterotoxigenic Escherichia coli in imported semisoft cheese.

In September 1983, three clusters of gastrointestinal illness with similar symptoms affected 45 persons in Washington, D.C., after office parties. The illness lasted a mean of 4.4 days and was characterized by watery diarrhea (91%), abdominal cramps (80%), headache (38%), nausea (38%), and subjective fever (20%). Illness was strongly associated with having eaten imported French Brie cheese one to six days before onset of illness (P less than .0001 by Fisher's two-tailed exact test). After publicity about these outbreaks, additional cheese-associated cases were identified over an eight-week period in Illinois, Wisconsin, Georgia, and Colorado. Stool specimens from ill persons in four states yielded Escherichia coli serotype O27:H20. These organisms produced heat-stable enterotoxin and had similar plasmid profiles. When commercially distributed foods are contaminated, enterotoxigenic E. coli can cause widespread disease even in a developed country, and the disease can easily escape correct diagnosis.

Adolescent↗
PubMed1985

Person-to-person transmission in an outbreak of enteroinvasive Escherichia coli.

In the summer of 1981, an outbreak of diarrhea occurred in students and staff at a school for mentally retarded adults and children in Columbia, Missouri. Forty-one (48%) of 86 students and 38 (28%) of 137 staff members in the two dormitories with the lowest functioning students were ill. Enteroinvasive Escherichia coli 0124:H30 was isolated from 20 persons including six staff members, 13 students, and the ill mother of one of the students. Contact with students was associated with illness. Thirty-eight (33%) of the 115 student-care staff members and none of the 22 nonstudent-care staff members who worked in the two dormitories were ill (p = 0.004, chi-square). In the dormitory with the most dependent students, illness in student-care staff was associated with the number of contacts with ill students and with having taken a student home during the outbreak. Control measures to interrupt transmission included separation of symptomatic or culture-positive students from those who were well, and emphasizing handwashing. The authors present these findings as the first report of person-to-person transmission in an outbreak of enteroinvasive E. coli.

Adolescent↗
PubMed1985

Comparison of gauze swabs and membrane filters for isolation of Campylobacter spp. from surface water.

The epidemiology of Campylobacter jejuni indicates that waterborne transmission is important; the organism has been isolated from seawater, fresh water, and estuarine sites. Membrane filtration, with and without use of an enrichment broth, has been the most common method for isolating C. jejuni from water. We evaluated two methods for isolating C. jejuni from water: membrane filtration and gauze filtration. The membrane filters evaluated included 0.22- and 0.45-micron-pore Millipore filters (Millipore Corp., Bedford, Mass.), 0.2- and 0.4-micron-pore Nuclepore filters (Nucleopore Corp., Pleasanton, Calif.), and a 0.45-micron-pore Zetapor filters (AMF Cuno, Meridian, Conn.). The gauze filters included both Moore and Spira swabs. Of the membrane filters evaluated, the 0.45-micron-pore Millipore and Zetapor filters were the most sensitive for recovery of C. jejuni from seeded waters. The 0.45-micron-pore Millipore filter placed in Oosterom broth was better for recovery of C. jejuni from seeded stationary surface waters than either the Spira or Moore swab. However, the 0.45-micron-pore Millipore filter placed on a plate or in enrichment broth was equivalent to the Spira gauze swab when used to examine water from Atlanta area streams. C. jejuni organisms were isolated from 9 of 24 surface water samples representing 5 of 12 streams.

Campylobacter fetus↗
PubMed1984

Animal-to-man transmission of antimicrobial-resistant Salmonella: investigations of U.S. outbreaks, 1971-1983.

The importance and origin of antimicrobial-resistant Salmonella infections were examined in 52 outbreaks investigated by the Centers for Disease Control between 1971 and 1983. The case fatality rate was higher for patients infected with antimicrobial-resistant Salmonella (4.2 percent) than for those with antimicrobial-sensitive infections (0.2 percent). In the 38 outbreaks with identified sources, food animals were the source of 11 (69 percent) of 16 resistant and 6 (46 percent) of 13 sensitive outbreak strains.

Animals↗
PubMed1984

Outbreak of invasive Escherichia coli gastroenteritis on a cruise ship.

An invasive strain of Escherichia coli (ONT:NM) was isolated from stool specimens from 7 of 10 ill passengers who developed diarrhea during a 5-day ocean cruise. The ill passengers had shared no common exposures off the ship before or during the cruise. Three of the persons whose stools were cultured were part of a tour group of 219 persons, and a food consumption and health history questionnaire was completed by 190 members (87%) of this tour group. Forty-seven (25%) had had diarrhea during the cruise; other symptoms among those with diarrhea included nausea (72%), abdominal cramps (68%), headache (68%), chills (60%), dizziness (53%), myalgias (43%), subjective fever (36%), and vomiting (26%). The median duration of symptoms was 3 days. Eating at cold buffets on ship and eating potato salad, a buffet food item, were significantly associated with illness. No evidence of secondary spread of illness in household contacts of the ill person was found.

Adolescent↗