Valley Fever on the Rise-Searching for Microbial Antagonists to the Fungal Pathogen Coccidioides immitis.

The incidence of coccidioidomycosis, also known as Valley Fever, is increasing in the Southwestern United States and Mexico. Despite considerable efforts, a vaccine to protect humans from this disease is not forthcoming. The aim of this project was to isolate and phylogenetically compare bacterial species that could serve as biocontrol candidates to suppress the growth of Coccidioides immitis, the causative agent of coccidioidomycosis, in eroded soils or in areas close to human settlements that are being developed. Soil erosion in Coccidioides endemic areas is leading to substantial emissions of fugitive dust that can contain arthroconidia of the pathogen and thus it is becoming a health hazard. Natural microbial antagonists to C. immitis, that are adapted to arid desert soils could be used for biocontrol attempts to suppress the growth of the pathogen in situ to reduce the risk for humans and animals of contracting coccidioidomycosis. Bacteria were isolated from soil samples obtained near Bakersfield, California. Subsequently, pairwise challenge assays with bacterial pure cultures were initially performed against Uncinocarpus reesii, a non-pathogenic relative of C. immitis on media plates. Bacterial isolates that exhibited strongly antifungal properties were then re-challenged against C. immitis. Strongly anti-C. immitis bacterial isolates related to Bacillus subtilis and Streptomyces spp. were isolated, and their antifungal spectrum was investigated using a selection of environmental fungi.

A unified approach to molecular epidemiology investigations: tools and patterns in California as a case study for endemic shigellosis.

BACKGROUND: Shigellosis causes diarrheal disease in humans from both developed and developing countries, and multi-drug resistance is an emerging problem. The objective of this study is to present a unified approach that can be used to characterize endemic and outbreak patterns of shigellosis using use a suite of epidemiologic and molecular techniques. The approach is applied to a California case study example of endemic shigellosis at the population level. METHODS: Epidemiologic patterns were evaluated with respect to demographics, multi-drug resistance, antimicrobial resistance genes, plasmid profiles, and pulsed-field gel electrophoresis (PFGE) fingerprints for the 43 Shigella isolates obtained by the Monterey region health departments over the two year period from 2004-2005. RESULTS: The traditional epidemiologic as well as molecular epidemiologic findings were consistent with endemic as compared to outbreak shigellosis in this population. A steady low level of cases was observed throughout the study period and high diversity was observed among strains. In contrast to most studies in developed countries, the predominant species was Shigella flexneri (51%) followed closely by S. sonnei (49%). Over 95% of Shigella isolates were fully resistant to three or more antimicrobial drug subclasses, and 38% of isolates were resistant to five or more subclasses. More than half of Shigella strains tested carried the tetB, catA, or blaTEM genes for antimicrobial resistance to tetracycline, chloramphenicol, and ampicillin, respectively. CONCLUSION: This study shows how epidemiologic patterns at the host and bacterial population levels can be used to investigate endemic as compared to outbreak patterns of shigellosis in a community. Information gathered as part of such investigations will be instrumental in identifying emerging antimicrobial resistance, for developing treatment guidelines appropriate for that community, and to provide baseline data with which to compare outbreak strains in the future.

Selective Enterotoxin Production by a Staphylococcus aureus Strain Implicated in a Foodborne Outbreak.

More than 80 of 230 participants (>34.7%) at a literary conference became ill with acute gastroenteritis 3 to 14 h after a catered meal. Attack rate data implicated cheese tortellini as the suspect food (p=0.0087). Selective plating of partially prepared and finished tortellini produced Staphylcoccus aureus counts of 6.0 × 107 and 1.0 × 106 CFU per gram, respectively. Enterotoxin, phage typing, antibiotic sensitivity testing, and other biotyping studies were applied to S. aureus isolates from the suspect food and the single food-handler involved. All isolates reacted identically by all criteria, and each isolate produced both type A and C staphylococcal enterotoxins. Type A enterotoxin (0.90 ug/100 g) alone was detected in samples of the suspect food. The production of type C enterotoxin by the outbreak strain was delayed approximately 4 h relative to production of enterotoxin A when grown in Heart Infusion broth (pH 5.5). This study serves as an example of selective enterotoxin production by S. aureus in suspect foods which can be misleading to outbreak investigators.