Streptobacillus moniliformis (Sm), the causative agent of rat-bite fever and Haverhill fever in man, is also a pathogen in certain laboratory and domestic animals. With the introduction of modern maintenance systems, this microorganism seemed to be eradicated from laboratory animal units, but recent reports of Streptobacillus moniliformis (Sm) in colonies of laboratory rodents give evidence that this 'forgotten' bacterium can still be found even behind hygienic barrier systems. Although various national and international recommendations on microbiological screening include Sm, attempts to screen might fail because of insufficient knowledge about this remarkable bacterium. This article highlights these problems. As there is no recent review of Streptobacillus moniliformis, present knowledge of this zoonotic agent is summarized to include: description of the bacterium, its taxonomic position, host spectrum and clinical importance for animals and man, cultivation, diagnosis, antibiotic therapy, risk to laboratory personnel (occupational hazard) and geographical distribution.

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Of 209 healthy infants examined, 44 (21.1%) carried Escherichia coli Kl in their feces. Of these 44 isolates, 36 (81.8%) were attributed to 10 different known clonal groups of E. coli Kl and 4 isolates represented unknown types. The influence of mannose-resistant (MR) adhesins, aerobactin production, and resistance to serum on colonization and invasiveness of E. coli KJ in orally infected inbred LEW baby rats was investigated.Strains expressing MR adhesins had significantly higher colonization and invasion rates than non-MR strains did. Mixed-infection experiments of LEW rats revealed interactions between different types of E. coli Kl strains affecting colonization and invasion rates. P-fimbriated strains appeared to have a selective advantage for colonization. The bacteremic potentials of different E. coli Kl strains could not be associated with their resistance to sera from LEW rats free of members of the family Enterobacteriaceae. No differences in virulence between fecal E. coli Kl isolates and clinical isolates from diseased humans were found. An influence of the major histocompatibility complex on host susceptibility to invasive E. coli Kl was indicated by comparing the parental LEW rat strain with different congenic LEW strains (RTI).

Polyhedral inclusion bodies were observed in cells of a Nitrosomonas species. They were present in growing cells as well as in resting cells. In thin sections their size was about 130 nm in growing cells and about 185 nm in diameter in resting cells. The bodies were commonly located in the nucleoplasm. They appeared to be bounded by a nonunit membrane and had a granular substructure. In thin sections about 70% of the exponentially grown cells and about 20% of the resting cells of the investigated strain showed 1-7 respectively 1-3 inclusion bodies.

Thirty-nine guinea pigs were examined for Bordetella bronchiseptica infection by culture and serology, using the enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence (IIF) test. Each serological method detected evidence of B. bronchiseptica infection in more guinea pigs than did culture. IIF using an antigen prepared from a mouse isolate of B. bronchiseptica detected fewer infected guinea pigs than when performed with antigens prepared from B. bronchiseptica isolates from a rat, a dog and a guinea pig. ELISA and IIF detected a comparable incidence of infection. Cross-reactivity was investigated further by carrying out ELISAs using 5 antigens prepared from B. bronchiseptica isolates from different species and antiserum to these antigens raised in non-infected guinea pigs.