Systematic review of respiratory case definitions in metalworking fluid outbreaks.

BACKGROUND: Since the mid-1990s, outbreaks of asthma and extrinsic allergic alveolitis (EAA) have been identified in workers exposed to metalworking fluids (MWFs). The cause of these outbreaks remains to be determined. AIMS: To identify and review all previously published occupational lung disease case definitions and diagnostic criteria that have been utilized during MWF outbreak investigations. METHODS: Respiratory outbreaks due to MWFs were identified by a systematic literature search for articles published between 1990 and October 2011. Investigations reporting the usage of disease case definitions or diagnostic criteria for respiratory disease were reviewed and summarized. RESULTS: The literature search identified 35 papers relating to 27 outbreaks of respiratory disease in MWF-exposed workers. Fourteen case definitions for MWF-related respiratory disease were identified: seven for EAA, five for occupational asthma and one each for humidifier fever and industrial bronchitis. A single paper was identified where any comparison of different disease case definitions (for EAA) had been performed. CONCLUSIONS: A range of case definitions and diagnostic criteria for MWF respiratory disease have been utilized in outbreak investigations, but the majority have been produced for individual outbreak investigations without previous validation. It may be difficult to compare the findings of future workplace studies without a more standardized approach to case identification and diagnosis.

Wild rabbits (Oryctolagus cuniculus) as potential carriers of verocytotoxin-producing Escherichia coli.

In summer 2001, visitors to a wildlife park in Norfolk, uk, became infected with verocytotoxin-producing Escherichia coli (vtec) O157, which was associated with wild rabbit faeces. The rabbits lived in an adjacent field together with E coli O157-positive cattle. A pilot study was therefore performed to investigate the factors affecting the association between E coli O157-positive cattle and wild rabbits. Samples of faeces were taken from 16 herds of cattle that lived close to populations of wild rabbits. Analysis by culture and pcr showed that seven of the herds were positive for E coli O157. Faeces were collected from individual rabbits at six of these farms during late winter, when there were few rabbits, and during high summer, when there were many. None of the 32 samples collected on two farms in late winter was positive for E coli O157, but eight of 97 samples collected in summer were positive on four of the six farms. pcr analysis for vtec, including non-O157, showed that 20 of the 97 samples were positive.

Purification of ovine neutrophils and eosinophils: Anaplasma phagocytophilum affects neutrophil density.

Studies on the functions of ovine granulocytes require pure and functionally active populations of neutrophils and eosinophils. This report describes an improved technique for the separation of neutrophils and eosinophils from the peripheral blood of sheep infected with Anaplasma phagocytophilum and from normal sheep. After centrifugation and discarding the buffy coat layer, which contains the bulk of mononuclear cells, neutrophils with a high degree of purity (94.87 [+/-1.7]%, n=9) and good yield (69 [+/-9]%, n=9) were obtained by density gradient centrifugation on Percoll with a density of 1.09 g/ml (65%). However, this density was not suitable for neutrophils obtained from sheep during the peak period of A. phagocytophilum bacteraemia. Improved purity of infected neutrophils was obtained when the leucocytes were separated on Percoll with a density of 1.08 g/ml (55%). Relatively good purity of eosinophils was obtained when leucocytes from normal sheep were separated on Percoll with a density of 1.10 g/ml (70%). Ovine eosinophils formed a distinct band just below the band of mononuclear cells when a continuous Percoll gradient with a density of 1.10 g/ml was used. The purity of the eosinophils obtained was 87.7 (+/-12.5)% (n=6; range 64.1-97.6%), with a mean recovery rate of 61.9 (+/-20.3)%.

Cultivation of an ovine strain of Ehrlichia phagocytophila in tick cell cultures.

Ehrlichia phagocytophila (previously known as Cytoecetes phagocytophila) which causes tick-borne fever (TBF) in sheep and pasture fever in cattle in the UK and mainland Europe is transmitted by the temperate hard tick Ixodes ricinus. The disease in sheep is characterized by fever, leucopenia and immunosuppression. Studies on the pathogenesis and other aspects of the disease have been hampered because the organism has not been cultivated in continuous or primary cell culture systems. This paper describes the first successful cultivation of a European isolate of E. phagocytophila in two continuous cell lines, IDE8 and ISE6, derived from the temperate hard tick Ixodes scapularis. Once adapted to tick cell cultures the organism was serially sub-cultured in new cells by transferring small portions of infected cell suspension every 2 to 3 weeks. The identity of the organism was confirmed by polymerase chain reaction (PCR), with primers specific to the granulocytic ehrlichiae. Sequence analysis of the PCR products amplified from infected tick cells were shown to be identical with those amplified from the blood of sheep infected with the same strain of E. phagocytophila. A susceptible sheep inoculated with a third passage of the tick cell-adapted E. phagocytophila reacted with fever and rickettsiaemia 5 days later, thus satisfying Koch's postulates.

Intraphagocytic growth induces an antibiotic-resistant phenotype of Legionella pneumophila.

The antimicrobial susceptibilities of Legionella pneumophila isolates grown either in U937 human monocytic cells or in Acanthamoeba polyphaga were studied after release from the host cells without further subculture. Time-survival studies showed that exposure of L. pneumophila cells, gown exclusively in vitro, to 5 micrograms of rifampin per ml resulted in at least 99% killing after 6 h and no detectable survivors at 24 h. Similar rates of killing were observed for in vitro-grown cells tested by exposure to ciprofloxacin. Conversely, time-survival studies revealed that macrophage-grown and amoeba-grown cells were ca. 1,000-fold more resistant to the activities of both drugs. Macrophage-grown cells treated with 5 micrograms of rifampin per ml showed 70 and 62% survival after 6 and 24 h, respectively. Intracellularly grown legionellae were also highly resistant to erythromycin (8 microgram/ml). After 24 h of exposure to the drug, there was 70 and 60% survival for amoeba-grown and macrophage-grown legionellae, respectively, whereas in vitro-grown cells showed a 2-log10 reduction in viable count. when intracellularly grown L. pneumophila cells were subcultured in broth for 48 h, they reverted to the phenotype characteristic of in vitro growth. Morphologically, the cells were larger than their intracellularly grown counterparts and resistance characteristics were lost. The susceptibilities of the subcultured cells to all three drugs were similar to those of Legionella cells grown exclusively in vitro. In view of these findings, the successful treatment of Legionnaires disease may be related as much to the resistance phenotype induced by intramacrophage growth as to the ability of the antibiotic to enter phagocytic cells.