Pseudoepidemic of Legionella pneumophila serogroup 6 associated with contaminated bronchoscopes.

An investigation of a pseudoepidemic of Legionella pneumophila serogroup 6 contaminating bronchoalveolar lavage specimens traced the source to contaminated tap water used to rinse disinfected bronchoscopes. The problem recurred despite plumbing changes and the installation of filters in the endoscopy unit water system because of inadequate maintenance of the filters.

Herpes simplex virus encephalitis in pediatrics: diagnosis by detection of antibodies and DNA in cerebrospinal fluid.

Between 1983 and 1991, 16 cases of herpes simplex encephalitis were diagnosed at the Royal Children's Hospital, Melbourne by virus isolation from the brain or cerebrospinal fluid (CSF) (2 cases), by detection of herpes simplex virus-specific IgM, IgA or IgG by enzyme immunoassay (12 cases) or by polymerase chain reaction (PCR) and herpes simplex virus-specific antibodies (2 cases). Specific antibody was detected in 4 of 13 CSF samples taken on Days 1 to 4 after onset of neurologic symptoms compared with 15 of 17 samples taken after the fourth day of illness. PCR was retrospectively applied to 20 stored CSF samples from 11 patients; 5 of 8 samples taken less than 4 days after onset of symptoms were positive compared with 2 of 12 taken after Day 4. In contrast all 5 fresh unfrozen CSF samples taken from Days 2 to 21 were positive by PCR. These results indicate that PCR is more sensitive for early diagnosis of herpes simplex encephalitis than detection of specific antibody in CSF which is most useful after the fourth day of illness.

Perfil profissional dos alunos dos cursos de especializaçäo em Medicina do Trabalho / Professional profile of specialization course students in Occupational Medicine

Os autores levantaram o perfil profissional dos médicos que freqüentaram, nos últimos sete anos, os Cursos de Especializaçäo em Medicina do Trabalho oferecidos pela Faculdade de Medicina da USP. No seu bojo, além de um histórico de como os cursos se desenrolaram e as modificaçöes havidas para o reconhecimanto da especialidade de "Médicos do Trabalho", constam, principalmente, em oito quadros, os resultados da pesquisa que vem ratificar, até mesmo, a quantidade de emprego que um médico é obrigado a exercer para obter um salário razoável para sua sobrevivência

[Professional profile of students in specialization courses on Occupational Medicine]. / Perfil profissional dos alunos dos cursos de especialização em Medicina do Trabalho.

The authors tied to find out a physician's professional profile who attended specialization courses in Occupational Medicine offered by the University of São Paulo Medical School. There are eight charts that show how the courses developed and the necessary changes made for their recognition in this specialty. The results also show how many jobs a physician needs to obtain a reasonable salary for his survival.

Pathogenesis of Providencia alcalifaciens-induced diarrhea.

Providencia alcalifaciens is a member of the family Enterobacteriaceae. There are reports that P. alcalifaciens can cause diarrhea, but the mechanism(s) by which it causes diarrhea is known. We studied P. alcalifaciens isolated from a child and two adults with diarrhea for enteropathogenicity. The three isolates did not exhibit any characteristic adherence to cultured HEp-2 cell monolayers, and they did not produce enterotoxins, cytotoxins, or keratoconjunctivitis in the Sereny test. Two isolates invaded cultured HEp-2 cell monolayers, producing localized bacterial clusters and actin condensation. The pattern of actin condensation was different from that produced by enteropathogenic Escherichia coli but similar to that produced by Shigella flexneri. Invasion and actin condensation were poor for the third isolate. Histology of adult rabbit small intestinal loops inoculated with all three isolates revealed bacterial attachment to, penetration of, and microulcer formation on the surface epithelium and hyperemia, edema, and polymorphonuclear cell infiltration of lamina propria. All the isolates produced diarrhea in rabbits with removable intestinal ties, and some of these rabbits developed hindlimb paralysis. Intestinal histology of the rabbits with removable intestinal ties which developed diarrhea showed changes similar to that in adult rabbits on which ileal loop assays had been performed. Transmission electron microscopy of intestinal tissues also confirmed tissue penetration by the isolates. Nerve tissue histology of two rabbits that developed hindlimb paralysis showed focal mononuclear cell infiltration around peripheral nerve sheaths. It is concluded that some strains of P. alcalifaciens are enteropathogenic and that they cause diarrhea by invading the intestinal mucosal epithelium. However, the relevance to human disease of the hindlimb paralysis observed in this animal model is not clear.

Studies with enteroaggregative Escherichia coli in the gnotobiotic piglet gastroenteritis model.

Two strains of enteroaggregative Escherichia coli of human origin fed to gnotobiotic piglets caused diarrhea or death in the majority of them. Histological examination revealed moderate hyperemia of the distal small intestine and cecum, swelling of small intestinal villi, and layers of aggregated bacteria stacked together in a mucus gel-like matrix overlying intact epithelium. These findings confirm that enteroaggregative E. coli strains produce distinctive intestinal lesions different from those caused by other major categories of diarrheagenic E. coli.

Localized adherence and attaching-effacing properties of nonenteropathogenic serotypes of Escherichia coli.

Traditional enteropathogenic Escherichia coli serotypes demonstrate a plasmid-mediated localized adherence in cultured HeLa or HEp-2 cells and induce an attaching-effacing intestinal lesion, both of which are considered pathognomonic and causes of diarrhea. This study describes three E. coli strains from infantile diarrhea which share these properties but belong to serotypes (O2:H2, O2:H25 and O15:H2) not considered enteropathogenic.

Hafnia alvei, a probable cause of diarrhea in humans.

Hafnia alvei, a member of the family Enterobacteriaceae, was the only species of bacteria cultured from the stool of a 9-month-old child who was admitted with a 3-day history of watery diarrhea. The isolated strain of H. alvei failed to produce heat-labile or heat-stable enterotoxins or Shiga-like toxin I or II and did not invade HeLa cells, nor did it cause keratoconjunctivitis (determined by the Sereny test) in a guinea pig's eye. The strain, however, induced diarrhea in 8 of 12 adult rabbits with removable intestinal ties (removable intestinal tie-adult rabbit diarrhea [RITARD] assay) and in 1 of 2 orally fed animals. No diarrhea could be induced with Escherichia coli K-12 in eight RITARD assay rabbits and three orally fed rabbits, respectively. Microscopic examination of affected animals revealed moderate inflammatory cellular infiltration of the intestinal mucosa, in which bacterial attachment to the surface epithelium and loss of the microvillus border were evident in the ileum and colon. Electron microscopy demonstrated cellular modifications of the apical surface, with cupping or pedestal formation and increased terminal web density at sites of bacterial "attachment-effacement," a well-known characteristic and mechanism of diarrhea of enteropathogenic E. coli. Identical lesions were also induced by H. alvei in rabbit ileal loops, which ruled out naturally occurring rabbit enteropathogenic E. coli strains, which are known to produce similar lesions. It is concluded that at least some strains of H. alvei have the potential to cause diarrhea and that attachment-effacement is a virulence characteristic shared by bacteria other than E. coli.

Nature and distribution of mucosal lesions associated with enteropathogenic and enterohemorrhagic Escherichia coli in piglets and the role of plasmid-mediated factors.

Bacterial attachment-effacement (att-eff) is emerging as an important virulence characteristic common to both enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC). The contribution of the plasmid-encoded EPEC adherence factor to the production of mucosal lesions and diarrhea was investigated in gnotobiotic piglets. Bacterial att-aff in the intestinal mucosa of piglets infected with plasmid-cured EPEC strain E2348/69 (O127) was indistinguishable from that in piglets infected with the parent strain, but the distribution of lesions was different; it occurred in the small intestines of 6 of 7 piglets infected with the parent strain compared with only 2 of 11 (P = 0.006) infected with the plasmid-cured strain. Plasmid-encoded factors in EPEC and EHEC strains did not appear to contribute to bacterial competition with normal gut microflora. Of 13 strains belonging to five EPEC serogroups, O55, O142, O26, O119, and O111, 3 fulfilled the criteria for EHEC (2 O26 and 1 O111). There were three distinct patterns of bacterial association with the intestinal mucosa of infected piglets. (i) EHEC strains caused bacterial att-eff associated with extensive destruction of surface and glandular epithelia in the large intestines with little or no inflammatory response. (ii) Some EPEC strains caused severe diarrhea which correlated with the extent of bacterial att-eff in the proximal small intestine, disruption of the epithelial cell membrane, and inflammation. It is suggested that, with respect to virulent strains, this degree of involvement determines the clinical outcome. Mildly pathogenic strains (O127 and O119), in which bacterial att-eff was restricted to the distal halves of the small and large intestines, caused little or no diarrhea. In such strains, nonimmune host factors (smaller, poorly feeding, and lethargic piglets) tended to play a determining role with regard to the degree of involvement of the small intestine and hence the clinical outcome. (iii) One strain (O55) caused illness and mucosal damage which could not be accounted for by the sparse bacterial att-eff observed in the gut. Instead, bacteria penetrated into and proliferated in the lamina propria, undermining the villous tips in the small intestine. Bacterial att-eff was the most important virulence factor in most of the strains examined, but plasmid-mediated factors facilitated bacterial adhesion in the small intestine, which may explain the reduced pathogenicity of the plasmid-cured variant of strain E2348/69 for human volunteers.