Comparison of phenol- and heat-killed antigens in the indirect immunofluorescence test for serodiagnosis of Legionella pneumophila group 1 infections

Immune Response Profile against Persistent Endodontic Pathogens Candida albicans and Enterococcus faecalis In Vitro

INTRODUCTION

Persistent microorganisms such as Candida albicans and Enterococcus faecalis might be directly related to endodontic treatment failure. The host response to these microorganisms impairs the reestablishment of intraradicular and periradicular health.

METHODS

The present investigation evaluated the expression of inflammatory mediators produced by RAW 264.7 cells in the presence of heat-killed antigens (HK) C. albicans and E. faecalis. Cultures of RAW cells were stimulated with both antigens in the presence or absence of recombinant interferon (rIFN)-γ. Parameters of cell viability, production of nitric oxide (NO), as well as the synthesis of interleukin (IL)-1α, IL-6, IL-10, IL-12, monocyte chemotactic protein-1, and tumor necrosis factor (TNF)-α were analyzed.

RESULTS

Results demonstrated that cell viability was especially reduced in antigens and rIFN-γ-stimulated groups. Groups stimulated with HK C. albicans upregulated IL-10 production. Otherwise, the addition of rIFN-γ to HK C. albicans upregulated TNF-α and NO production. Groups stimulated with HK E. faecalis upregulated TNF-α production. HK E. faecalis and rIFN-γ upregulated TNF-α and NO synthesis. The production of other cytokines remained unchanged by all stimuli.

CONCLUSIONS

Knowledge regarding the host mechanism of response to microorganisms that perpetuate endodontic infection and the periradicular lesions can contribute to optimization of endodontic therapy. The mentioned inflammatory mediators and virulence factors involved in endodontic failure might guide lesion progression and also be targets in the development of disinfectant and immunomodulatory agents.

One-year surveillance of legionellosis in burned patients and Legionella environmental monitoring

Burned patients have a theoretically high risk of Legionella infection because burns produce a compromised immune system. Cutaneous surfaces are without protective barriers, and bathing tank water is frequently used for washing and caring. A one-year surveillance study was performed on 65 burned patients by antibody determination and by culture of bronchial aspirates. Environmental culturing for Legionella was done in the patients' care areas every four months during the same period. Low titers ranging from 8 to 32 were found in 30 (46.1%) subjects against 18 antigens including several Legionella species. No increase in antibody titers was shown in 193 patients' sera. Cultures of respiratory samples were negative. L. pneumophila serogroups 4, 5, 6 and 8 and L. rubrilucens were isolated from 55.5% of water samples. Despite no evidence of Legionella infection among patients included in this study, the authors believe it to be advisable to improve control measures in hospital water supplies, used by burned patients, to minimise the risk of legionellosis.

Prevalence of Legionella pneumophila serogroup 1 antibodies in blood donors

The prevalence of anti-Legionella pneumophila serogroup 1 antibodies in 777 blood donors of the Turin area was determined by the indirect immunofluorescence assay (IFA) and by the microagglutination test (MA). Low titers (IFA of 1/16 and MA of 1/8) were found in 0.3% of the subjects. A statistically significant difference was not observed by sex and by age for IFA titers, but was noted by sex for MA titers of > or = 1/4 (p < 0.05). The upper limit of normal titer was < 1/8 by IFA and < 1/4 by MA at 15% cutoff level and 1/8 by IFA and 1/4 by MA at 1% cutoff level. In conclusion, the prevalence of antibodies in the Turin area was very low; IFA titers of > or = 1/64 and MA titers of > 1/16 can be considered as presumptive of infection in a single serum specimen of a patient with pneumonia; no change in the epidemiology of the disease was observed in the recent years.

Proximity of the home to a cooling tower and risk of non-outbreak Legionnaires' disease

OBJECTIVE

To study the source of non-outbreak legionnaires' disease, particularly the role of cooling towers, by comparing the locations of patients' homes in relation to the location of cooling towers.

DESIGN

Retrospective, descriptive study of a case series of patients with legionnaires' disease ill between 1978 and 1986 and, for comparison, a case series of patients with lung cancer. A prospectively developed register and interview based survey provided data on the location of cooling towers.

SETTING

The city of Glasgow.

PATIENTS

134 patients aged 14-84 with legionnaires' disease during 1978-86 and 10,159 patients with lung cancer during the same period.

MAIN OUTCOME MEASURES

The locations of patients' homes and cooling towers as defined by postcodes, which provided map grid references accurate to 10 m; numbers of expected and observed cases of legionnaires' disease in census enumeration districts; and distance of enumeration districts from the nearest cooling tower as defined by five distance categories.

RESULTS

Most cooling towers were in or near the city centre or close to the River Clyde, as were the places of residence of patients with community acquired, non-travel, non-outbreak legionnaires' disease (n = 107). There was an inverse association between the distance of residence from any cooling tower and the risk of infection, the population living within 0.5 km of any tower having a relative risk of infection over three times that of people living more than 1 km away. There was no such association with respect to travel related legionnaires' disease, and for lung cancer the association was weak (relative risk less than or equal to 1.2 in any distance group).

CONCLUSION

In Glasgow cooling towers have been a source of infection in two outbreaks of legionnaires' disease and, apparently, a source of non-outbreak infection also. Better maintenance of cooling towers should help prevent non-outbreak cases. This method of inquiry should be applied elsewhere to study the source of this and other environmentally acquired disease.

A family cluster of Legionella pneumophila infections

Three members of one single family of 4, the father, a son and a daughter, showed seroconversion against Legionella pneumophila serogroup 1 (Lp SG1). The son had a severe pneumonia, whereas the father and the daughter did not develop any other illness than mild and transient fever. A fourth member, the mother, remained seronegative. Lp SG1 was detected by a direct immunofluorescence test in water samples from the shower at home, in tap water in the family's butcher shop, and in condensation water from the ventilator of refrigerator cells in the shop. Two different sources of infection appear to have occurred: showering at home and an aerosol of contaminated condensation water. Reports of more than one case of legionella infection within a family seem to be extremely rare and have not been found in the literature.

Laboratory diagnosis of infections caused by legionellae

Legionnaires' disease can be diagnosed by detection of antibody to the organism or by direct detection of the bacterium and/or its products using immunological means, culture or a DNA probe. Culture isolation, still the most specific and sensitive test, can be done with sputum samples if proper selective techniques are used. Antibody detection is more suited for epidemiological purposes than individual cases. It has been overused to the exclusion of more specific and rapid methods, such as culture and other means of bacterial detection. Immunofluorescent microscopy remains an important tool in diagnosis, although urinary antigen detection and DNA probes are promising alternative tests. For optimal sensitivity, culture must be performed, regardless of which test is used.