Morris E. Potter

Chloramphenicol-resistant Salmonella newport traced through hamburger to dairy farms. A major persisting source of human salmonellosis in California

Animal-to-human transmission of drug-resistant salmonella and the role of antimicrobial use in food animals in the emergence of these bacteria are controversial subjects. Investigation of a 4.9-fold increase in Salmonella newport isolations from Californians in 1985 showed that 87 percent of the isolates had an unusual antimicrobial-resistance pattern (including chloramphenicol resistance) and a single, identical plasmid. Interviews of 45 patients and 89 matched controls in Los Angeles County showed that illness was associated with penicillin or tetracycline use during the month before onset (P less than 0.001) and with eating ground beef during the week before onset (P = 0.052). The epidemic strain was isolated from hamburger products eaten by cases, abattoirs where the animals from which the meat came were slaughtered, dairies that sent cows for slaughter on days when culture-positive products were processed, and ill dairy cows. Isolation of salmonella from beef carcasses in abattoirs correlated with the proportion of dead or moribund animals received for slaughter (r = 0.60, P less than 0.05). Isolation of chloramphenicol-resistant salmonella from dairy farms was associated with the use of chloramphenicol at those dairies. We conclude that food animals are a major source of antimicrobial-resistant salmonella infections in humans and that these infections are associated with antimicrobial use on farms.

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.

Pneumonic tularemia on Martha's Vineyard.

IN the United States tularemia occurs in both sporadic and epidemic forms.1 2 3 Although ulceroglandular tularemia is readily diagnosed, pneumonic tularemia is difficult to detect in the absence of...

SCOMBROID-FISH POISONING

Despite dramatic advances in food sanitation during the 20th century, acute food-borne disease caused by infectious agents and chemical toxins remains an important public health problem. From 6 to ...

Physiological characteristics and mycotoxins of human clinical isolates of Fusarium species

Thirty-three strains of Fusarium species from clinical sources including F. solani, F. oxysporum, F. moniliforne, F. proliferatum, F. subglutinans and F. chlamydosporum were examined for their physiological characteristics and mycotoxin production. Of this collection 29 exhibited growth at 37°C and 21 were resistant to cycloheximide. Two strains of F. moniliforme and two strains of F. proliferatum produced fumonisins. No strains in this collection produced detectable amounts of trichothecenes. All 18 strains of F. solani tested produced the immunosuppressive agent cyclosporin A. The cyclosporin A-producing ability of clinical isolates of F. solani may influence their pathogenic potential.

Evidence for participation of the macrophage in Shiga-like toxin II-induced lethality in mice

Seven strains of inbred mice were compared for their susceptibility to the lethal effects of Shiga-like toxin II (SLT II). A/J mice, which are unable to produce the C5 component of complement, did not differ from C5 normal mice in susceptibility to SLT II. CBA/NJ mice (hemizygous for X-linked immunodeficiency) did not differ from the B-cell sufficient CBA/J strain. C3H/HeJ mice, defective in macrophage response to lipopolysaccharide (Lpsd), showed a consistently and significantly longer mean time to death than did the normally responsive C3H/HeN strain. C57BL/10ScN mice, which also carry the Lpsd allele, showed a similar but smaller difference in mean time to death compared with the C57BL/10SnJ strain. Production of tumor necrosis factor could be induced in vitro by SLT II treatment of C3H/HeN, but not C3H/HeJ macrophages. These results imply that antibody and complement production do not modulate SLT II lethality in mice, but that the macrophage may contribute to SLT II-induced injury.

Psittacosis. A diagnostic challenge.

In the absence of recognized pneumonitis, psittacosis is unlikely to be considered as a cause of infection in patients with febrile illnesses. To identify findings useful in the diagnosis of psittacosis, the clinical and roentgenographic characteristics of 46 cases that occurred in two outbreaks among workers in turkey processing plants were reviewed. Headache (96% of patients), chills (93% of patients), and fever (89% of patients) were the most common symptoms; a nonproductive cough occurred in 65% of patients. Rales or rhonchi were detected in only six (18%) of 33 patients examined, but 21 (72%) of 29 patients receiving a chest film had roentgenographic evidence of pneumonia. We conclude that few diagnostically useful symptoms or signs occur in patients with psittacosis but that roentgenographically confirmed pneumonitis may occur commonly in patients with little clinical evidence of pneumonitis. A history of exposure to birds, in an individual with a flu-like illness, appears to be the single best clue to the diagnosis of psittacosis.

The Investigation of Brainerd Diarrhea-Reply

In Reply.— In response to Dr Walters letter, we would like to emphasize that numerous aspects of our investigation were not described in detail because of constraints on the length of our manuscript. Therefore, we elaborated only on the specific issues that we, the manuscript reviewers, and the JAMA editors believed were most relevant from a clinical and laboratory perspective. This investigation involved extensive laboratory and veterinary support and expertise, as demonstrated in the acknowledgments section of our article. Eleven different laboratories at the Centers for Disease Control and laboratories at the Minnesota Department of Health and Department of Agriculture participated in the microbiological investigation. Our microbiological studies are continuing at this time. In addition, during the first three months of our investigation we convened a panel of 12 consultants from academic institutions nationwide, who have diverse expertise in the microbiology and clinical aspects of diarrheal diseases, to assist us