Plague and other human infections caused by Yersinia species.

With an estimated 100 million victims, pandemically and epidemically occurring plague has been looked upon as a classical scourge of mankind during the last two millenia. Without treatment at least 50% of the affected individuals die from infection with Yersinia pestis, a bacterium belonging to the family of Enterobacteriaceae. The disease takes a fulminant course. After an incubation period of 2-6 days, bubonic plague primarily attacks one group of lymph nodes. The onset of pulmonic plague, transmitted by droplet infection, takes place within several hours and causes bronchopneumonia. Early recognition facilitates a promising antibiotic therapy with tetracycline, streptomycin or chloramphenicol. Human beings acquire the bacteria through bites of fleas from domestic rats in densely populated cities of countries with low hygienic standards, or sporadically in the open country from infected wild rodents. Laboratory procedure includes microscopy supplemented by immunofluorescence and cultivation of the bacterium from clinical material. Direct serology and PCR result in a fast detection of specific antigens or nucleotide sequences. Determination of serum antibodies is principally used for epidemiological investigation. Today, physicians in the civilized western world lack experience for the recognition of plague, and analytical techniques for diagnosis are only available in some specialized laboratories. Yersiniosis becomes primarily manifest as gastroenteritis caused by Yersinia enterocolitica or as pseudoappendicitis caused by Yersinia pseudotuberculosis and requires antibiotics only in severe septic cases. Different extraintestinal symptoms may be observed in dependence on the patient's HLA type and gender. The ubiquitous germ is mainly transmitted by the fecal-oral route via infected domestic or farm animals and contaminated food. The relevant virulence factors are encoded on a 70 kB plasmid common to all Yersinia species and strains that are human pathogens. The most important tools for laboratory diagnosis are culture from suitable body fluids and serological detection of specific antibodies. The infection rate among healthy individuals in Europe in terms of percentage of elevated IgA or IgG titers has been quoted to be 3-40% in different investigations but does not significantly correlate to direct bacteriological detection.

Hospital infestation by the cluster fly, Pollenia rudis sensu stricto Fabricius 1794 (Diptera: Calliphoridae), and its possible role in transmission of bacterial pathogens in Germany.

The potential of the cluster fly, Pollenia rudis sensu stricto, to transmit bacterial pathogens was investigated during a mass infestation that took place in a German hospital. Cluster flies were individually examined for mesophilic bacteria carried on the exoskeleton. Bacterial growth could only be detected by using the enrichment culture technique to increase sensitivity, but not by direct intoculation of fly samples to agar plates. All 50 cluster fly samples that were tested carried opportunistic aerobic mesophilic Bacillus spp., whereas 41 fly samples were positive for Erwinia spp., 16 samples for Erwinia amylovara, 24 samples for Stenotrophomonas maltophilia, and 4 samples for Flavobacterium odoratum. Staphylococcus lugdunensis and Pseudomonas aeruginosa were found in 5 samples. No bacteriologically sterile cluster fly samples were obtained. The whole bacterial pattern found on P. rudis s. s. is known for its potential to cause opportunistic and/or nosocomial infections in humans. The results obtained led to the assumption that mass infestations of cluster flies occurring in sensitive areas, especially in hospitals, may cause a low, but not neglectable health threat due to mechanical transmission of bacterial pathogens.

Serodiagnosis of Helicobacter pylori infections by detection of immunoglobulin G antibodies using an immunoblot technique and enzyme immunoassay.

A transferable solid phase enzyme immunoassay (TSP-EIA) and an immunoblot technique were evaluated for the detection of IgG antibodies against Helicobacter pylori. Using the biopsy urease test as reference method, the sensitivity and specificity of the EIA were 96% and 100%, respectively. Immunoblot analysis was carried out by testing sera from patients with a positive urease test who suffered from type B gastritis, gastric and duodenal ulcers, and a negative control group. The immunoblotted Helicobacter pylori proteins showed reproducible immunoreactive bands at molecular weights of 130, 93, 75 and 67 kDa. The molecular weight protein fractions of Helicobacter pylori of 180 kDa and higher were found to be of minor immunological significance. Proteins of less than 60 kDa exhibited wide serum-specific variations in reactivity after immunostaining. No correlation between specific immunoblot patterns and clinical signs induced by Helicobacter pylori infection was observed.

Evaluation of an immunofluorescence assay for specific detection of immunoglobulin G antibodies directed against Helicobacter pylori, and antigenic cross-reactivity between H. pylori and Campylobacter jejuni.

An immunofluorescence assay (IFA) for the detection of immunoglobulin G antibodies directed against Helicobacter pylori was evaluated by comparing 20 serum specimens from patients with a positive urease test on biopsy material and 20 serum specimens from patients with a negative test and with defined clinical symptoms. The resulting anti-H. pylori titers were classified as follows: negative, less than or equal to 64; borderline, 128; and positive, greater than or equal to 256. By using these criteria, the IFA was subsequently tested, using 100 serum specimens from patients with gastric complaints. Overall, the titers were 71% positive, 10% borderline, and 19% negative. Depending on the patients' biopsy urease test results, the sensitivity and specificity of the assay were calculated to be 96%. Furthermore, these sera were classified into three subgroups on the basis of clinical manifestations: gastritis with 74% positive and 10% borderline titers, duodenal ulcer with 84% positive and 4% borderline titers, and gastric ulcer with 52% positive and 16% borderline titers. A serologic follow-up study was carried out with three patients with gastric ulcers who had been treated with colloidal bismuth subcitrate for 4 weeks and erythromycin for the final 2 weeks. The results indicate that a significant decrease in titer could be expected within 9 to 12 months after successful therapy, as determined by repeated negative CLO tests. Absorption experiments demonstrated that possible cross-reactivity between H. pylori and C. jejuni did not influence serodiagnosis.