Investigation of multidrug-resistant Salmonella serotype typhimurium DT104 infections linked to raw-milk cheese in Washington State.

CONTEXT: Multidrug-resistant Salmonella Typhimurium DT104 has recently emerged as a cause of human and animal illness in Europe and North America. In early 1997, health officials in Yakima County, Washington, noted a 5-fold increase in salmonellosis among the county's Hispanic population. OBJECTIVES: To characterize bacterial strains and identify risk factors for infection with Salmonella Typhimurium in Yakima County. DESIGN: Laboratory, case-control, and environmental investigations. SETTING AND PARTICIPANTS: Patients with culture-confirmed Salmonella Typhimurium infection living in Yakima County and age- and neighborhood-matched control subjects. MAIN OUTCOME MEASURES: Food vehicle implication based on case-control study and outbreak control. RESULTS: Between January 1 and May 5, 1997, 54 culture-confirmed cases of Salmonella Typhimurium were reported. The median age of patients was 4 years and 91% were Hispanic. Patients reported diarrhea (100%), abdominal cramps (93%), fever (93%), bloody stools (72%), and vomiting (53%); 5 patients (9%) were hospitalized. Twenty-two patients and 61 control subjects were enrolled in the case-control study. Seventeen case patients (77%) reported eating unpasteurized Mexican-style soft cheese in the 7 days before onset of illness compared with 17 control subjects (28%) (matched odds ratio, 32.3; 95% confidence interval, 3.0-874.6). All case-patient isolates were phage definitive type 104 (DT104) (n = 10) or DT104b (n = 12), and 20 (91%) were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. The cheese produced and eaten by 2 unrelated patients was made with raw milk traced to the same local farm. Milk samples from nearby dairies yielded Salmonella Typhimurium DT104. The incidence of Salmonella Typhimurium infections in Yakima County returned to pre-1992 levels following interventions based on these findings. CONCLUSIONS: Multidrug-resistant Salmonella Typhimurium DT104 emerged as a cause of salmonellosis in Yakima County, and Mexican-style soft cheese made with unpasteurized milk is an important vehicle for Salmonella Typhimurium DT104 transmission. We postulate that recent increases in human salmonellosis reflect the emergence of Salmonella Typhimurium DT104 among dairy cows in the region. Continued efforts are needed to discourage consumption of raw milk products, promote healthier alternatives, and study the ecology of multidrug-resistant Salmonella Typhimurium.

The occurrence and replication of Escherichia coli in cattle feeds.

Sixty-three of 209 (30.1%) samples of cattle feed that were collected from multiple commercial sources and from farms were found to contain Escherichia coli. However, none of the feed samples examined were culture-positive for E. coli O157. Replication of fecal E. coli, including E. coli O157, was demonstrated in a variety of feeds at temperatures that were similar to those found on farms in summer months. Fresh mixed rations containing corn silage were sampled from 16 dairies. Rations from 12 of these dairies were found to contain E. coli, and the rations from 5 dairies had concentrations of E. coli that were greater than 1000 cfu/g. The ability of experimental mixed rations to support the replication of E. coli was correlated with the concentration of organic acids in the corn silage that was used in the ration. Widespread contamination of cattle feeds with E. coli and the ability of E. coli to replicate in feeds suggest that feeds are a potentially important factor in the ecology of organisms that can be transmitted from feces to mouth, such as E. coli O157.

Evaluation of udder health and mastitis in llamas.

OBJECTIVE: To investigate intramammary infections in llamas, identify the pathogens responsible, and determine whether effects of intramammary infection could be detected by use of mastitis indicator tests commonly used for cows. DESIGN: Observational study. ANIMALS: 100 llamas on 10 farms. PROCEDURE: Milk samples were evaluated by bacterial culturing and by determination of somatic cell count (SCC), using direct microscopic and automated counting methods, California Mastitis Test score, pH, and N-acetyl-beta-d-glucosaminidase activity. Correlation coefficients were determined among the various mastitis indicator tests, and test results were determined for milk from infected and uninfected glands. RESULTS: Evidence of intramammary infection was evident in 76 of 369 (21%) milk samples, with 54 of 94 (57%) llamas having at least 1 infected gland. Staphylococcus sp other than Staphylococcus aureus were the predominant pathogens. None of the llamas had clinical signs of mastitis, and significant differences were not detected in SCC, California Mastitis Test score, pH, or N-acetyl-beta-d-glucosaminidase activity between infected and uninfected samples. California Mastitis Test scores were negative or trace for 307 of 313 (98%) samples, and SCC were low. In contrast, pH and N-acetyl-beta-d-glucosaminidase activity of milk from uninfected glands were higher than values reported for milk from uninfected cows, and neither variable was significantly correlated with the number of somatic cells in samples of llama milk. CLINICAL IMPLICATIONS: Although intramammary infections develop in llamas, inflammation (mastitis) appears to be rare. Values for mastitis indicator tests used for cows cannot be directly extrapolated to llamas. Subclinical mastitis is apparently not an important problem in llamas in the United States.

Composition of milk from llamas in the United States.

Neonatal llamas must receive supplemental milk when the dam has inadequate milk yield or fails to accept the cria. Data on llama milk composition are limited, and selection of suitable milk supplements has been difficult. Milk from 83 llamas on eight farms in four states (Illinois, Kentucky, Michigan, and Colorado) was collected, and milk composition was analyzed. Llamas had no history or signs of mastitis, and major mastitis pathogens were not isolated from the milk. Total solids were determined gravimetrically. A colorimetric method, a dye-binding assay, and the modified Mojonnier method were used to quantify lactose, protein, and fat, respectively. Concentrations of seven macrominerals and 17 trace elements were obtained by inductively coupled plasma atomic emission spectroscopy, and Cl was quantified by anion chromatography. Llama milk was higher in sugar (6.5%) and lower in fat (2.7%) and energy content (70.0 kcal/100 g) than milks of domestic ruminants. Llama milk also contained more Ca and less Na, K, and Cl. In general, milk composition was not affected by stage of lactation, lactation number, or body condition score of the llama, but several milk constituents varied among farms.

Hydrallantois in a caprine doe.

Hydrallantois was diagnosed in a 5-year-old Toggenburg doe. Clinical signs included bilateral abdominal distention, anorexia, and recumbency. Ultrasonographically, excessive fluid and live fetuses were detected in the uterus. At the time of cesarean section, the fluid (approx 12 L) was determined to be in the allantoic cavities; concentrations of electrolytes in the fluid were similar to concentrations in allantoic fluid from cows with hydrallantois. Two viable fetuses and 1 nonviable fetus were delivered. The doe retained its placentas for 60 hours, but made a good recovery. Hydrallantois should be considered in the differential diagnosis of abdominal distention in caprine does in late gestation.