No abstract

An outbreak of Salmonella typhimurium definitive type (DT) 193 affecting 206 persons occurred in July and August 1989 in a small town in northern England. A descriptive study suggested that cold meats including pork from a butcher's shop in the town were vehicles of infection. An analytical study of a cohort attending a function in the town showed a significant association between illness and consumption of cold roast pork supplied by the butcher's shop (P = 0.00000004). S. typhimurium DT 193 with the same antibiotic resistance pattern (to ampicillin, streptomycin, sulphonamides and tetracyclines) as the outbreak strain, and possessing a single plasmid of 80 MDa was isolated from samples of meat bought from the shop and implicated in illness, and from samples of pig faeces taken from the farm supplying the shop. It was concluded that inadequate processing of infected pork meat at the shop may have contributed to this outbreak but that cross contamination also played an important part in transmission. Control measures included a temporary closure of the shop and subsequent implementation of a detailed protocol for meat processing and monitoring of all procedures at the shop.

During a two-year period of observationBacteroidesspecies were isolated from specimens of pus and vaginal swabs from 115 patients in this hospital. Thirty-five representative strains proved on examination to beBacteroides fragilis.Minimal inhibitory and minimal bactericidal concentrations of six antibiotics for these strains were determined. All strains were resistant to streptomycin, neomycin, and polymyxin, slightly sensitive to penicillin and ampicillin, and fully sensitive to tetracycline, chloramphenicol, erythromycin, and lincomycin. The minimum bactericidal concentrations of chloramphenicol, erythromycin, and lincomycin were two to four times the minimal inhibitory concentrations. Tetracycline failed to exert any consistent bactericidal effect.The treatment of patients with infections caused byB. fragilisis discussed in the light of the findingsin vitro.

SYNOPSISThe effect of 10% carbon dioxide on the sensitivity to four antibiotics of 10

A low-speed centrifugation technique for the preparation of grids after minimal purification of fecal extracts is described for examination of viruses by direct electron microscopy using negative staining. Results showed that adenovirus, astrovirus, rotavirus, and "small round" viruses were frequently shed into the gastrointestinal tract in clumps of variable size. Differential centrifugation study showed that a substantial proportion of the virus in the sample was lost in the initial pellet at the first step of clarification; this finding casts doubt on the validity of immune electron microscopy for direct typing of strains of these viruses from stools. In addition, particle counts based on conventional specimen processing are likely to grossly underestimate the true value.