Membrane filter method for the isolation and enumeration of Pseudomonas aeruginosa from swimming pools

Microbial flora of in-use, display eye shadow testers and bacterial challenges of unused eye shadows

We surveyed 15 different brands of eye shadow on display for customer use in different retail stores for microbial contamination. This was the first reported microbial surveillance of in-use eye shadow display testers in retail establishments. Cultures were obtained at each retail store. Sterile dacron swabs were rolled and rubbed over the entire used surface of each shadow, and each inoculum was streaked onto the surfaces of blood agar plates. Of the 1,345 individual samples obtained, 67% were contaminated with one or more species of microorganisms representing the genera Staphylococcus, Micrococcus, Corynebacterium, Acinetobacter, Bacillus, and Moraxella. We also purchased two different brands of water-miscible eye shadows in replicate unit containers. Each brand was challenged separately with a few hundred to several thousand colony-forming units of Staphylococcus aureus, Pseudomonas aeruginosa, or Acinetobacter calcoaceticus. Both brands permitted growth of P. aeruginosa but not growth of S. aureus. A. calcoaceticus was inhibited after inoculation into one brand. With the other brand, the inoculum of Acinetobacter multiplied in one of the two different lots tested. This experimental challenge procedure can serve as a useful model system for studying the behavior of microbes in eye shadows and similar matrices.

An outbreak of otitis externa in competitive swimmers due to Pseudomonas aeruginosa

Pseudomonas aeruginosa was isolated from the ears of 18 of the 25 members of a team of competitive swimmers who complained of painful discharging ears. This group of swimmers trained twice daily in the pool, in the early morning and late afternoon. In contrast swabbing of the ears of a similar group of 54 competitive swimmers who used the pool only in the afternoon revealed only one swimmer with P. aeruginosa. Investigation of the swimming pool revealed that chlorination was often inadequate when the first group of swimmers were training in the early morning. Strains of P. aeruginosa were isolated from various sites around the pool and from the bag of a vacuum used to clean the pool. Pyocin typing, serotyping and phage typing were performed on all isolates. The dominant strain recovered from the swimmers' ears was found to be almost identical to that from the vacuum bag and belonged to serotype 0--11 which has been particularly associated with outbreaks of P. aeruginosa infection in whirlpools in the United States. These results support the hypothesis that there is a direct correlation between the development of otitis externa and swimming in water contaminated with P. aeruginosa.

Factors influencing detection and enumeration of Pseudomonas aeruginosa by most-probable-number and membrane filtration techniques

Most-probable-number (MPN) and membrane filtration (mF) techniques were evaluated with respect to selectivity, sensitivity, and efficiency in recovering Pseudomonas aeruginosa strains in hospital fluids and extramural water environments. Known numbers of cells of a naturally occurring strain of P. aeruginosa maintained in distilled water or cells subcultured on Standard Methods agar were added to test samples containing various types and levels of background microbial contamiants. Environmental samples containing unknown numbers of P. aeruginosa strains also were tested. Asparagine and acetamide broths were employed as presumptive media in MPN tests, and mPA and Pseudosel agars were used in mF assays. Statistical analyses of data showed the superiority and comparability of the asparagine-MPN and mPA-mF systems. Greater precision and accuracy were consistently obtained in either assay technique by the use of naturally occurring cells as test organisms. The type of filter and nature of diluents employed, as well as pH of assay media, were found to greatly influence both recovery and developemnt of characteristic colonial morphology in the mPA-mF system.

Evaluation of a most-probable-number technique for the enumeration of Pseudomonas aeruginosa

A most-probable-number (MPN) technique was evaluated for detecting and enumerating Pseudomonas aeruginosa in water and wastewater. Both the presumptive and confirmatory media, as described in the 13th edition of Standard Methods for the Examination of Water and Wastewater, as well as modifications of these media were included in evaluations. Various samples of water were tested, namely chlorinated tap water, creek water, and influent to a wastewater treatment plant. Modified media repeatedly gave higher estimated MPNs of P. aeruginosa than media listed in Standard Methods. P. aeruginosa was detected and recovered from all creek water and wastewater samples, but not from tap water samples tested. This organism was determined to be present in as large numbers as the fecal coliforms and in even greater quantities than the fecal streptococci in all samples, whenever MPN estimations were determined from those positive tubes containing the modified confirmatory medium.

Preliminary studies of fluorescent pseudomonads capable of growth at 41 C in swimming pool waters

During the summer of 1973 cultures of Pseudomonas aeruginosa and other fluorescent pseudomonads capable of growth at 41 C were obtained from swimming pool waters at a training center for the mentally retarded. Isolates were subjected to selected physiological tests, pyocine typing, and immunotyping. High counts of P. aeruginosa or other fluorescent pseudomonads consisted mainly of single predominant types. Both P. aeruginosa strains and unidentified fluorescent Pseudomonas strains predominated in pool waters at different times.