Growth, cultural characteristics, and antibacterial sensitivity of Leptospira interrogans serovar hardjo.

Nutrient requirements of Leptospira interrogans serovar hardjo were investigated using a 1% bovine serum albumin (BSA) medium, supplemented separately with polysorbates (Tweens) 80, 60, 40, 20, NH4Cl, and vitamins thiamine and cyanocobalamin (vitamin B12). L. hardjo was tested in vitro against 30 antibacterial compounds incorporated into semisolid medium (0.2% agar) at 3 compound concentrations. Growth was superior in polysorbate 80 (oleic acid rich) and polysorbate 40 (palmitic rich) media. A linear growth response to vitamin B12 could be shown. Hamster isolates all required thiamine and vitamin B12 for growth. The antibacterial compounds could be classed as: 100% bacteriocidal, bacteriocidal at the 2 highest concentrations, bacteriocidal at only 1 concentration, and completely noninhibitory. The tetracyclines were strongly bacteriocidal. The comparative growth rates of hamster isolates were much reduced when compared to the type strain hardjoprajitno. These studies were performed acknowledging that the polysorbates were mixtures of fatty acids. Nephelometry was used as an accepted method to monitor the synthesis of leptospiral cell mass.

Infections with Encephalitozoon cuniculi and Leptospira interrogans, serovars grippotyphosa and ballum, in a kennel of foxhounds.

Leptospira interrogans serovars grippotyphosa and ballum were isolated from kidney and urine of an American Foxhound pup. The pup was from a litter of 12, all of which were unthrifty. Titers for serovar grippotyphosa in pups from the litter ranged from 200 to 6,400 and 23 of 36 adult dogs in the kennel had titers to that serovar. None of the sera was tested for antibodies to serovar ballum. Leptospires were not isolated from or observed in 2 littermates and 1 penmate, but gram-positive organisms morphologically compatible with Encephalitozoon cuniculi were detected in their brains and kidneys.

Isolation of Leptospira biflexa from commercially prepared deionized water labeled "sterile for tissue culture".

Leptospira biflexa were isolated from urine cultures of two patients with clinical and laboratory findings compatible with leptospirosis. Neither patient had detectable leptospiral agglutinins. The source of the L. biflexa was water labeled " "sterile for tissue culture" purchased from M. A. Bioproducts, formerly Microbological Associates. M. A. Bioproducts water is sterilized by filtration through a 0.22-mum-pore size membrane filter. Leptospiral contamination can occur in products sterilized by filtration. Heat sterilization of water eliminates this possibility.

Viability of Leptospira interrogans serotype grippotyphosa in swine urine and blood.

Normal swine urine, devoid of its microbial flora, diminished the viability and virulence of Leptospira interrogans serotype grippotyphosa. Bovine serum albumin diluent effectively offset the urine's deleterious effects. Membrane filtration (0.45 micrometer) rendered urine free of bacteria, but permitted passage of limited numbers of leptospires. Most of the commonly used anticoagulants did not alter viability of grippotyphosa in whole blood. However, EDTA significantly reduced the number of viable cells.

Growth, virulence, and immunogenicity of Leptospira interrogans serotype szwajizak.

Leptospira interrogans serotype szwajizak was characterized by (1) its growth in polysorbate 80-bovine albumin medium, (2) its virulence and course of infection in laboratory animals, and (3) its immunogenicity. Growth of this organism was continuous and vigorous at 29 C and 37 C in liquid medium for 10 serial subcultures. Some specific lots of agar were superior to other agars if tested for the ability to support the growth of small inoculums. Individual colonies resulted from growth of small inoculums on solid polysorbate medium. Virulence of the organisms did not appear to be altered by 10 serial subcultures in liquid medium incubated at 29 C. The estimated median lethal dose of szwajizak for hamsters by the intraperitoneal route was 2 cells. Virulence, infectivity, and pathogenicity of szwajizak were shown in the hamster and the guinea pig. Protection results indicate the heat-inactivated szwajizak bacterin was a substantially better immunizing agent than the chemically inactivated bacterin. Serotype hardjo bacterins provided hamsters some protection against death if challenge exposed with szwajizak, but afforded no protection against infection.

Immunising potency of Leptospira interrogans serotype canicola after heat inactivation at different temperatures.

The immunogenicity of Leptospira interrogans serotype canicola suspensions inactivated by various degrees of heat exposure was examined in hamsters. No differences between leptospires killed at 50 degrees C and at 98 degrees C were shown. After exposure to 121 degrees C, suspensions retained their ability to protect against lethal infections but lost their ability to prevent leptospiruria. Tests with vaccines inactivated at or below 98 degrees C showed that the doses required for complete protection varied with the interval between vaccination and challenge. Larger doses were required to prevent the development of leptospiruria than to prevent death.

Growth, survival, antigenic stability, and virulence of Leptospira interrogans serotype canicola.

Leptospira interrogans serotype canicola (strain NADL A-13) grew from inocula as small as two cells in liquid polysorbate 80 medium (P-80 medium, in P-60, P-40 and P-20 media, and in P-80 medium from which polysorbate, NH4C1 or thiamine had been omitted. It grew well initially in vitamin B12-deleted P-80 medium, but only with inocula as large as 26 x 10(4) cells per ml. P-80 medium lacking both polysorbate and NH4Cl supported light growth from small inocula, but the omission of thiamine and vitamin B12 in addition seriously affected the properties of the medium. Where readily detectable growth did not develop in liquid nutrient-deleted medium, viable ortanisms could often be demonstrated indirectly by subculture to semisolid medium, and their occurrence was influenced by the presence of albumin, thiamine, and vitamin B12. Growth on semisolid media was comparable with that in liquid media of similar composition. The absence of polysorbate 80, thiamine, or vitamin B12 prevented the appearance of Dinger's zones of growth from small inocula. Antigenic composition as measured by microscopic agglutination tests with homologous and heterologous antisera was not appreciably affected by repeated subculturing in various complete and incomplete media. Homogenates of infected-hamster-kidney tissue in bovine serum-albumin diluent still contained viable organisms after 60 days' storage at 23-25 degrees C. Organisms derived from this material after 3 and 16 days' storage showed no loss of virulence. Organisms grown in artificial culture showed no loss of virulence after storage in bovine albumin diluent or phosphate buffer for 7 days at 23-25 degrees C. Cultures of the organism survived without loss of virulence for 15 months in 13 semisolid media of differing complexity. Single colonies derived from five different solid media were grown in semisolid forms of the parent media and stored at 23-25 degrees C for 10 months without loss of virulence.

Death and lysis of leptospirae when cultured in asbestos-filtered growth media.

Death and lysis of leptospirae, when cultured in asbestos-filtered bovine albumin polysorbate 80 media, was quantitated. The pathogens (virulent and avirulent) required 2 x 10(6) cells/ml to initiate growth in such media, whereas inocula of 2 to 20 cells/ml grew in control medium. Saprophytic leptospirae initiated growth from 2 cells/ml in asbestos-filtered medium as well as control medium. The adverse action of asbestos-filtered medium was not removed by storage of medium for 2 years at 25 C and was not diminished when such medium was frozen at -80 C. Washing with water, HCl and NaHCO(3)-NaCl, citric acid, and medium components did not remove the lytic activity associated with asbestos-filtered culture medium. Continuous subculture in asbestos-filtered medium was possible from large inocula; however, upon subsequent dilution and reinoculation into asbestos-filtered media, there was no evidence of acquired resistance, and all pathogens failed to grow.