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.

Pulsed-field fingerprinting of vaginal group B streptococcus in pregnancy.

OBJECTIVE: There is more to be learned about the epidemiology of group B beta-hemolytic streptococci infections in pregnancy. In this study, we investigated the discriminating capabilities of pulsed-field gel electrophoresis of group B streptococci strains from pregnant patients and mother/infant pairs of patients compared with serotyping. METHODS: Forty-two vaginal strains of group B streptococci cultured from pregnant patients in the third trimester and strains from 20 mother/infant pairs with documented newborn group B streptococci infection were studied. Isolates were serotyped by the Lancefield capillary precipitin method and molecularly characterized by counterclamped homogeneous electrical field pulsed-field gel electrophoresis with rarely cutting restriction enzymes. RESULTS: Nine of the 13 serotypes of group B streptococci identified thus far in the scientific literature (Ia, Ia/c, Ib, Ib/c, II, IIc, III, V, and NT/c) were represented among the 62 isolates. Among the 42 maternal isolates, eight serotypes were represented, and among the 20 mother/infant isolates, six serotypes were represented. Serotypes of mother/infant isolates matched in nine of the ten pairs. Restriction endonuclease profiles, or digests, from the 42 maternal isolates resulted in 25 unique profiles that were arranged into five major groups based on the overall relatedness. Each group was comprised of one predominant serotype. The 20 mother/infant paired isolates displayed nine unique restriction endonuclease profiles and nine of the ten paired isolates showed indistinguishable restriction endonuclease profiles between mother and infant. CONCLUSION: Deoxyribonucleic acid profiling using pulsed-field gel electrophoresis is more discriminating of group B streptococci strains than serotyping because of the different yet closely related patterns within each restriction endonuclease profile group that are linked to one specific serotype. Pulsed-field gel electrophoresis can refine our epidemiologic studies of group B streptococci transmission and acquisition.

Influence of Beef Tallow and Muscle on the Antilisterial Activity of Pediocin AcH and Liposome-Encapsulated Pediocin AcH.

The activity of free and liposome-encapsulated pediocin AcH was monitored in slurries (25% in dH2O) of beef tallow and beef muscle. Significant loss of pediocin AcH activity was observed within 1.5 min [24-60% recovery of original arbitrary units (AU)] following the addition of 30,000 AU of pediocin per ml slurry. Pediocin activity continued to decrease up to 35 min (14-40% recovery of original AU), but thereafter, pediocin activity did not decrease appreciably. More activity was recovered from tallow-than muscle-based slurries and from heated (100°C, 3 min) slurries compared to unheated slurries. Also, the addition of pediocin AcH to slurries (10,000 AU increments) identified saturation levels of ca. 80,000-90,000 AU for tallow compared to ca. 100,000 AU for muscle. Lastly, the encapsulation of pediocin AcH within phosphatidylcholine liposomes resulted in a 27.5% (heated muscle) and 28.9% (heated tallow) increase in the recovery of pediocin activity compared to otherwise similar slurries containing free pediocin.

Use of Pediococcus acidilactici to Control Listeria monocytogenes in Temperature-Abused Vacuum-Packaged Wieners.

Pediococcus acidilactici JBL1095 (pediocin AcH producer) and P. acidilactici LB42 (bacteriocin nonproducer) were evaluated for the production of antilisterial compounds in packages of all-beef wieners. Commercially processed, freshly manufactured, unpackaged wieners were surface inoculated (ca. 105 CFU/g) as follows: (i) untreated control; (ii) a three-strain (Scott A, V7, 101M) mixture of Listeria monocytogenes ; (iii) strain JBL1095; (iv) L. monocytogenes and strain JBL1095; and (v) L. monocytogenes and strain LB42. Wieners were vacuum packaged and cell numbers, pH, and bacteriocin activity within packages were determined following storage at refrigeration (4°C) or abuse (25°C) temperatures for 72 and 8 d, respectively. L. monocytogenes and pediococci survived in packages held at 4°C, but pediococci did not produce acid or pediocin during refrigerated storage. At 25°C, total numbers of L. monocytogenes (treatment ii) increased 3.2 log10 CFU/g and the pH of the fluid (exudate) within packages increased from 5.5 to 5.6. In contrast, L. monocytogenes survived but did not grow in packages inoculated with strain LB42 (treatment v), and was inhibited (average reduction of 2.7 log10 CFU/g) in packages inoculated with strain JBL1095 (treatment iv) during storage at 25°C for 8 d. The pH of exudate in packages inoculated with strains JBL1095 (treatment iv) or LB42 (treatment v) showed a similar decline (ca. 5.5 to 4.6). The onset of bacteriocin production coincided with early-logarithmic growth of JBL1095 (treatment iv) and continued into the late logarithmic phase. These data suggest that bacteriocinogenic pediococci can be used to control L. monocytogenes in temperature-abused, cook/chili meats.

Evaluation of Sodium Diacetate and ALTA™ 2341 on Viability of Listeria monocytogenes in Turkey Slurries.

The antilisterial activity of sodium diacetate and a commercial shelf-life extender (ALTA™ 2341) were monitored at 25°C in slurries prepared with turkey breast meat. In slurries prepared without either ingredient, populations of Listeria monocytogenes increased about 5-log10 units in 7 d. The addition of 0.3% diacetate extended the generation time (7 h) compared to the control (no food additives; 1.7 h), whereas 0.5% inhibited the pathogen somewhat (0.4-log10 unit decrease in 7 d compared to the control). Slurries containing ALTA (0.25, 0.5, or 0.75%) and 0.3% diacetate extended the lag phase of L. monocytogenes to a greater extent than slurries with 0.3% diacetate alone. In contrast, 0.5% diacetate in combination with all three levels of ALTA tested was listericidal (ca. 2-log10 unit decrease after 7 d compared to the control). These data confirm the efficacy of diacetate for inhibiting L. monocytogenes in turkey meat and indicate that multiple barriers such as diacetate with ALTA may further lessen the likelihood of food-related listeriosis.