Jon H. Standridge

Development of a Plating Medium for Selection of Helicobacter pylori from Water Samples

ABSTRACT The goal of this study was to develop a simple plating medium to allow large-scale screening of water samples for the presence of Helicobacter pylori. Five conventional plating media (brain heart infusion, brucella agar, Columbia blood agar base, campylobacter agar kit Skirrow, and HPSPA medium), each containing a commercial antibiotic supplement, were initially evaluated. Eight strains selected as common waterborne organisms (Acinetobacter, Aeromonas, Bacillus, Escherichia coli, Enterobacter, Enterococcus, Helicobacter pylori, and Pseudomonas strains) were individually plated onto each of these media. Three organisms (Acinetobacter, E. coli, and H. pylori) were able to grow on all five media. This growth was unacceptable since Helicobacter grows very slowly and competing organisms must be inhibited for up to 7 days. Therefore, a more selective medium (HP agar) containing a novel mixture of growth supplements plus amphotericin B and polymyxin B was developed. This medium also included a phenol red color indicator for urease production. Aliquots of nonsterile well water that contained native flora (Flavobacterium, Serratia, Citrobacter, Pasteurella, Ochrobactrum, Rahnella, and unidentified molds) and were further adulterated with the eight strains listed above (106 CFU of each strain per 100 ml) were spiked with H. pylori and were plated. In spite of the heavy mixed microbial load, only H. pylori colonies grew during 7 days of incubation at 37°C. The color indicator system allowed presumptive identification of H. pylori colonies sooner (12 to 20 h) than the conventional media tested allowed. The HP formulation developed in this study provides a medium with superior selectivity for H. pylori from mixed microbial populations in water and reduces the time required to complete the assay.

Effect of Filtration Conditions on removal of emerging waterborne pathogens

This study evaluated removal of live emerging waterborne pathogens by pilot‐scale conventional treatment with alum coagulation, flocculation, sedimentation, and filtration. The microbes tested were Cryptosporidium parvum oocysts, Encephalitozoon intestinalis spores, enteropathogenic Escherichia coli O157:H7, Aeromonas hydrophila, and bacteriophage MS2. The study showed the effects of filter run time, alternative loading rates, alternative filter media, and pH on pathogen removal. Results indicated that turbidity breakthrough was accompanied by breakthrough of all pathogens tested in this study. Results also suggest that the breakthrough of A. hydrophila and E. coli O157:H7 occurred more rapidly than that of turbidity. In general, filtration rate or alternative filter media configurations had no apparent effect on pathogen removal.

A Note on Algal Toxins in Wisconsin Waters Experiencing Blue-green Algal Blooms

ABSTRACT Certain blue-green algae commonly found in lakes can produce potent toxins during blooms. In Wisconsin there were several incidents over the years when wildlife and domestic deaths were attributed to algal toxins; however, little information existed on how widespread these toxins were in Wisconsins many lakes and ponds. Thus, a study was undertaken to determine the incidence of measurable toxins in Wisconsin waters. Samples were collected from 86 lakes and ponds, the algae identified by genus, and the toxicity tested using a mouse bioassay. In 25 lakes toxins were present during bloom conditions. Lakes with toxins were found in both the southern and northern portions of the state. The results indicated toxic blooms were not uncommon in Wisconsin, and that algal toxins may be a more critical lake management issue than generally realized.

Bacteriological analysis of indoor and outdoor water parks in Wisconsin.

Water parks are a rapidly growing element of the United States tourist industry. To reduce incidence of abrasion and impact injuries in such parks, designers are searching for padding materials that can withstand the harsh oxidative environments of chlorinated water. Although padded features help reduce physical injuries, they may also compromise the microbiological safety of water attractions. This study describes bacteriological testing performed on 31 different pad materials, play features and pools from 10 Wisconsin water parks. Materials and surrounding pool waters were sampled and tested quantitatively for total coliforms, Escherichia coli, E. coli 0157:H7, enterococci, staphylococci, heterotrophic bacteria, and Pseudomonas aeruginosa, using standard methods. Each location was sampled during three visits, and results were averaged. Pool waters were within acceptable levels of target organisms and disinfectant residuals, but target organisms were found on water features, even those submerged in chlorinated water. Bacteria were detected more frequently in pools using pad materials compared with pools without. These findings provide data that will help the public health community understand the relations between designs, materials and maintenance of water features. Additionally, the information will help state regulators and owner/operators develop guidelines to improve public health and safety at water parks.