Enhanced chlorine resistance of tap water-adapted Legionella pneumophila as compared with agar medium-passaged strains

Previous studies have shown that bacteria maintained in a low-nutrient "natural" environment such as swimming pool water are much more resistant to disinfection by various chemical agents than strains maintained on rich media. In the present study a comparison was made of the chlorine (Cl2) susceptibility of hot-water tank isolates of Legionella pneumophila maintained in tap water and strains passaged on either nonselective buffered charcoal-yeast extract or selective differential glycine-vancomycin-polymyxin agar medium. Our earlier work has shown that environmental and clinical isolates of L. pneumophila maintained on agar medium are much more resistant to Cl2 than coliforms are. Under the present experimental conditions (21 degrees C, pH 7.6 to 8.0, and 0.25 mg of free residual Cl2 per liter, we found the tap water-maintained L. pneumophila strains to be even more resistant than the agar-passaged isolates. Under these conditions, 99% kill of tap water-maintained strains of L. pneumophila was usually achieved within 60 to 90 min compared with 10 min for agar-passaged strains. Samples from plumbing fixtures in a hospital yielded legionellae which were "super"-chlorine resistant when assayed under natural conditions. After one agar passage their resistance dropped to levels of comparable strains which had not been previously exposed to additional chlorination. These studies more closely approximate natural conditions than our previous work and show that tap water-maintained L. pneumophila is even more resistant to Cl2 than its already resistant agar medium-passaged counterpart.

[1]  G F Mallison,et al.  An outbreak of Legionnaires' disease associated with a contaminated air-conditioning cooling tower. , 1980, The New England journal of medicine.

[2]  J. C. Hoff,et al.  Growth of Legionella pneumophila in continuous culture , 1985, Applied and environmental microbiology.

[3]  J. Dowling,et al.  Hot water systems as sources of Legionella pneumophila in hospital and nonhospital plumbing fixtures , 1982, Applied and environmental microbiology.

[4]  J. D. Berg,et al.  Effect of Antecedent Growth Conditions on Sensitivity of Escherichia coli to Chlorine Dioxide , 1983, Applied and environmental microbiology.

[5]  J. Brown.  Bergey's Manual of Determinative Bacteriology (5th ed.) , 1939 .

[6]  B. Olson,et al.  Chlorine resistance patterns of bacteria from two drinking water distribution systems , 1982, Applied and environmental microbiology.

[7]  R. Weaver,et al.  Detection of Legionnaires disease bacteria by direct immunofluorescent staining , 1978, Journal of clinical microbiology.

[8]  N J Petersen,et al.  Factors affecting comparative resistance of naturally occurring and subcultured Pseudomonas aeruginosa to disinfectants. , 1972, Applied microbiology.

[9]  R. Wadowsky,et al.  Satellite growth of Legionella pneumophila with an environmental isolate of Flavobacterium breve , 1983, Applied and environmental microbiology.

[10]  G. Bohach,et al.  Characterization of surfaces involved in adherence of Legionella pneumophila to Fischerella species , 1983, Infection and immunity.

[11]  B. Iglewski,et al.  Isolation and characterization of the Legionella pneumophila outer membrane , 1984, Journal of bacteriology.

[12]  S. T. Cowan.  Bergey's Manual of Determinative Bacteriology , 1948, Nature.

[13]  R. J. Gibson,et al.  Pittsburgh pneumonia agent: direct isolation from human lung tissue. , 1980, The Journal of infectious diseases.

[14]  M. Favero,et al.  Growth characteristics of atypical mycobacteria in water and their comparative resistance to disinfectants , 1978, Applied and environmental microbiology.

[15]  M. Favero,et al.  Factors influencing the occurrence of high numbers of iodine-resistant bacteria in iodinated swimming pools. , 1966, Applied microbiology.

[16]  N. Grossowicz,et al.  Effect of Growth Conditions on Chlorine Sensitivity of Escherichia coli , 1959, Applied microbiology.

[17]  C. Fliermans,et al.  Isolation of Legionella pneumophila from nonepidemic-related aquatic habitats , 1979, Applied and environmental microbiology.

[18]  J. Feeley,et al.  A major focus of Legionnaires' disease in Bloomington, Indiana. , 1979, Annals of internal medicine.

[19]  A. W. Fynsk,et al.  Treatment of cooling systems containing high levels of Legionella pneumophila , 1982 .

[20]  R M Wadowsky,et al.  Susceptibility of Legionella pneumophila to chlorine in tap water , 1983, Applied and environmental microbiology.

[21]  T. Chai.  Characteristics of Escherichia coli grown in bay water as compared with rich medium , 1983, Applied and environmental microbiology.

[22]  R M Wadowsky,et al.  Multiplication of Legionella pneumophila in unsterilized tap water , 1982, Applied and environmental microbiology.

[23]  R. Wadowsky,et al.  Glycine-containing selective medium for isolation of Legionellaceae from environmental specimens , 1981, Applied and environmental microbiology.

[24]  H. Goldfine.  Comparative aspects of bacterial lipids. , 1972, Advances in microbial physiology.