Color test for the measurement of antibody to T-strain mycoplasmas

Electron microscopical study of antibody binding to Mycoplasma gallisepticum: indirect immunoferritin labelling

The ultrastructural aspects of the interaction of Mycoplasma gallisepticum with specific rabbit antibody have been studied. In particular, fixation conditions which allow the simultaneous preservation of cellular fine structure and membrane antigenicity have been established and applied in a procedure of indirect immunological labelling of the antibody-coated organisms with ferritin conjugated sheep anti-rabbit IgG. The advantages of working with agar embedded organisms in a multistep labelling procedure are discussed. In membrane fractions of M. gallisepticum, prepared by osmolysis and freeze-thawing, only sealed membranes retained their antibody-binding capacity. Electron microscopical examination of "break-through" colonies from immune growth inhibition zones revealed that the majority of cells in these colonies were destroyed, sometimes limited only by a single-layered membrane and without extracellular antibody coat. An exception from this was the presumedly young cells in the periphery of colonies and in microcolonies which appeared to be intact and had a heavy antibody layer surrounding the cells. Based on these characteristics, a possible sequence of events is suggested eventually leading to destruction of mycoplasma organisms in immune growth inhibition zones.

Serological typing of Ureaplasma urealyticum isolates from urethritis patients by an agar growth inhibition method

An agar growth inhibition method for serotyping Ureaplasma urealyticum is described, and the results of applying this method to serotyping 338 strains of the organism are presented. The serotyped strains consisted of cloned isolates from male patients with primary and recurrent nongonococcal urethritis (NGU), isolates from symptomatic patients with other genitourinary tract infections and disorders, and isolates from asymptomatic carriers of U. urealyticum in the genitourinary tract (controls). Among 122 male patients with NGU, serotype 4 was associated most frequently (52%) with this disease at Camp Lejeune, N.C. Seventeen percent of the isolates were type 2. The remaining isolates consisted of types 1, 3, 6, and 8 and accounted for 6 to 9% each of the serotypes isolated from the NGU group. Types 5 and 7 were not isolated. Among 91 symptomatic patients with other genitourinary tract infections and disorders, U. urealyticum type 4 also was associated most frequently (37%) with these disorders. The remaining isolates, represented by types 1, 2, 3, 6, 7, and 8, accounted for 9 to 15% each of the types isolated from this group. Type 5 was not isolated. Among 125 symptomfree carriers of U. urealyticum in the genitourinary tract, type 8 was recovered most frequently (30%), whereas type 4 was isolated next most frequently (24%). The remaining isolates consisted of types 1, 2, 3, 5, and 6 and accounted for 2 to 15% each in this asymptomatic control group. Type 7 was not isolated. Of the present eight serotypes of U. urealyticum studied in this investigation, type 4 was associated most frequently with disease (NGU) and certain other disorders of the genitourinary tract at Camp Lejeune. A previously unknown association of U. urealyticum with frequently abacteriuric, unexplained pyuria (with or without urethral pruritus and dysuria) is reported, suggesting the existence of asymptomatic Ureaplasma urethritis.

The metabolic inhibition test for mycoplasmas based on phosphatase production

A metabolic inhibition test based upon phosphatase production is described. This is of value for those Mycoplasma species which produce phosphatase but which cannot be examined by the previously published metabolic inhibition techniques.

Antibodies to Acholeplasma laidlawii membrane lipids in normal guinea pig serum

Acholeplasma laidlawii is killed and lysed by fresh normal guinea pig serum (GPS) without additional antibodies. Prior incubation of GPS with whole A. laidlawii organisms abolishes the killing activity of GPS. In the present study it was demonstrated that antibodies are present in normal GPS. The classical pathway, not the alternative pathway, of the complement sequence was activated by these antibodies in fresh normal GPS. The antibodies in GPS belong to the IgG class of immunoglobulins. They are directed predominantly against the membrane phospholipids of A. laidlawii. These antibodies may be induced either by natural infection of guinea pigs with A. laidlawii or by antigenic determinants of other microorganisms of food antigens.

Immunological analysis of plasma membranes of a T-strain of mycoplasma (Ureaplasma urealyticum)

The cell membranes of a T-strain of mycoplasma, obtained by ultrasonic disruption, were as effective as whole organisms in eliciting metabolism-inhibiting and complement-fixing antibodies. The soluble fraction separated from cell membranes by centrifugation at 35,000 X g showed a minor ability to elicit an antibody response as measured by metabolism inhibition and complement fixation tests. After a further centrifugation at 100,000 X g, the immunogenic activity of the soluble fraction was completely lost. Immunogenic determinants in mycoplasma membranes could also be demonstrated by adsorption tests; cell membranes were more effective than soluble fractions in adsorbing antibody capacity from the immune sera against whole cells. It has been shown by further experiments that cell membranes have at least two major antigenic determinants, which differ either in chemical nature or in capacity to adsorb and evoke antibodies, characterized by different serological behaviors.

Etiology of nongonococcal urethritis. Evidence for Chlamydia trachomatis and Ureaplasma urealyticum

Chlamydia trachomatis, Ureaplasma urealyticum (T-mycoplasma), and Hemophilus vaginalis have previously been considered possible etiological agents in nongonococcal urethritis (NGU). In this study, current C. trachomatis infection was confirmed by culture and (or) micro-immunofluorescence serology in 26 of 69 men experiencing afirst episode of NGU, and 1 of 39 with no urethritis. Serum IgM immunofluorescent antibody to chlamydia was demonstrated in 16 of 20 men with chlamydia culture positive NGU, and 3 of 39 with chlamydia culture negative NG, and none of 34 with no urethritis. 9 of 10 culture positive men with less than or equal to 10 days symptoms developed immunofluorescent antibody seroconversion in paired sera. U. realyticum was isolated significantly more often and in significantly higher concentration from first voided urine from chlamydia-negative cases of NGU than from chlamydia-positive NGU. Ureaplasmacidal antibody titers increased fourfold in six men, four of whom had negative cultures for for unreaplasma. H. vaginalis was isolated from c9 of 33 men with no urethritis and 2 of 69 with NGU. C. trachomatis is susceptible, and U. urealyticum is resistant to sulfonamides. A 10-day course of sulfisoxazole therapy produced improvement in 13 of 13 chlamydia-positive, unreaplasma-negative, and only 14 of 29 chlamydia-negative, unreaplasma-positive NGU cases (P less than 0.002). Thus, culture, serology, and response to therapy support the etiologic role of chlamydia in NGU. Quantitative culture and response to therapy suggest U. unrealyticum may cause many cases of chlamydia-netative NGU.

Effects of carbon dioxide, urea, and ammonia on growth of Ureaplasma urealyticum (T-strain mycoplasma)

By use of a simple device for continuous CO2 gassing of Ureaplasma urealyticum cultures growing in a liquid medium, we have been able to separate some of the effects of urea, CO2, ammonia, and pH on growth. The CO2 acted as a superior buffer in the pH range 5.7 to 6.8, which is optimal for Ureaplasma growth. It was, therefore, possible to observe the effect of repeated additions of urea to the culture without alkalinization of the growth medium. We found that the repeated additions of urea did not enhance Ureaplasma growth, and the resultant accumulation of ammonium ions (greater than 2,000 microng/ml) did not cause more rapid death under these conditions. By abruptly changing the gaseous environment from CO2 to N2, it was possible to cause a rapid pH change in the culture to a value above 8.0. This resulted in a more rapid death of the organisms.

Morphology of Ureaplasma urealyticum (T-mycoplasma) organisms and colonies

The morphology of Ureaplasm urealyticum in broth cultures was studied by phase-contrast microscopy. Most organisms appeared singly or in pairs. Long filaments and long chains of cocci, common in classical mycoplasma cultures, were not observed. On solid medium, U. urealyticum produced "fried-egg" colonies which developed according to the scheme suggested by Razin and Oliver (J. Gen. Microbiol., 1961) for the morphogenesis of the classical mycoplasma colonies. The formation of the peripheral zone of the colonies followed that of the central zone only when growth conditions were adequate, Hence, the appearance of peripheral zones, and consequently the larger colony size, can be taken as an indicator of improved growth conditions. Incubation in an atmosphere of 100% CO2 resulted in significantly larger colonies than in an atmosphere of N2, O2, or air. CO2 acts as a buffer, keeping the pH at the optimal range for Ureaplasma growth (pH 6.0 to 6.5) in the presence of the ammonia produced from the urea hydrolyzed by the organisms. The addition to the medium of 0.01 M urea together with 0.01 M putrescine enabled better growth than with urea alone. Small amounts of phosphate improved growth in an atmosphere of CO2, apparently fulfilling a nutritional role. Under nitrogen, higher phosphate concentrations were required for good growth, apparently serving as a buffer as well as a nutrient. Sodium chloride and sucrose which had been added to increase the tonicity of the medium inhibited growth above 0.1 M. An increase in the agar concentration above 2% resulted in decreased colony size. Likewise, prolonged drying of the agar plates caused a marked decrease in colony size, mostly affecting the peripheral zone. The addition of both urea and putrescine to the growth medium and incubation in a humidified CO2 atmosphere are recommended for improved growth and formation of fried-egg colonies of U. ureaplyticum on agar. It must be emphasized that these experiments were carried out with a laboratory-adapted strain.

Localization of enzymes in Ureaplasma urealyticum (T-strain mycoplasma)

Ureaplasma urealyticum cells were lysed by osmotic shock or by digitonin. The membrane fraction contained four to ten times as much protein as the cytoplasmic fraction. These values are in large excess of those reported for classical mycoplasmas, suggesting that the Ureaplasma membrane fraction was heavily contaminated with proteins derived from the growth medium. The U. urealyticum urease activity was localized in the cytoplasmic fraction, whereas the adenosine triphosphatase activity was localized in the membrane fraction. Significant urease activity could be detected also in nonviable cells. Urea, at concentrations above 0.25 M, was mycoplasmastatic to Acholeplasma laidlawii, Mycoplasma hominis, and U. urealyticum, so that the Ureaplasma urease did not afford preferential protection against urea toxicity. The intracellular localization of the urease would be expected to release ammonia from urea in the cytoplasm. The ammonia will take up protons to become ammonium ions. It can be hypothesized that the intracellular NH4+ plays a role in proton elimination or acid-base balance, which might be coupled to an energy producing ion gradient and/or transport mechanisms.

Serum antibody levels against T mycoplasmas in two North American Indian populations predisposed to spondylitis

Serum antibody levels against T mycoplasmas (Ureaplasma urealyticum) were determined by the metabolic inhibition method in several populations. A higher prevalence of antibody was found in Haida Indians and Bella Coola Indians than in blood donors, patients with rheumatoid arthritis, and patients attending a VD clinic. Antibody levels did not correlate with the presence of spodylitis or the histocompatibility antigen HLA-B27, although both these Indian populations have a high prevalence of spondylitis and HLA-B27.

Differential agar medium (A7) for identification of Ureaplasma urealyticum (human T mycoplasmas) in primary cultures of clinical material

A differential agar medium for the identification of Ureaplasma urealyticum in primary cultures of clinical specimens is described. The differential medium (no. A7) is specific for the identification of U. urealyticum and other members of the genus Ureaplasma. Large-colony, classical Mycoplasma and Acholeplasma species and Proteus L colonies are unreactive on this differential medium. The medium incorporates the biochemical principle of the direct spot test for urease in colonies of Ureaplasma and contains added urea and a sensitive indicator of ammonia, manganous sulfate. Ureaplasma colonies on this medium are identified as dark golden-brown or rich deep-brown colonies, in sharp contrast to the light background of the medium, when viewed by direct transmitted illumination under the low power of the microscope.

Urea-hydrolyzing activity of a T-strain mycoplasma: Ureaplasma urealyticum

The urea-hydrolyzing activity of a T-strain mycoplasma was studied in experiments using whole cells and cell-free enzyme preparations by measuring the release of 14CO2 from [14C]urea. Under the conditions used, the urea concentration optimum is approximately 5.6 X 10(-3) M urea. The activity is soluble and not membrane bound. It is stable at -70 C for several weeks but is more labile at higher temperatures. The pH optimum is between 5.0 and 6.0. The effect of several inhibitors on the activity was tested and revealed similarities, as well as differences, between T-strain mycoplasma urease activity and the urease activity of other organisms and plants.

Effect of cerulenin on growth and lipid metabolism of mycoplasmas

Cerulenin markedly inhibited the growth of Acholeplasma laidlawii. A. axanthum and A. granularum were less susceptible, whereas the sterol-requiring Mycoplasma species examined showed very little susceptibility. The inhibition was not reversed by the addition of long-chain fatty acids to the medium. At a concentration of 20 mug/ml, cerulenin inhibited the incorporation of [(14)C]acetate into A. laidlawii membrane lipids, but it had no effect on either protein or nucleic acid biosynthesis. Cerulenin inhibited both the de novo synthesis of long-chain fatty acids and the elongation of medium-chain fatty acids. As a result, carotenoid biosynthesis was stimulated, and increased amounts of oleic and elaidic acids were incorporated into membrane polar lipids. Our studies support the concept that cerulenin can serve as a useful tool for obtaining better control of fatty acid composition of A. laidlawii membranes.

Interactions between Mycoplasma pneumoniae and guinea pig complement

The "toxic" effect of guinea pig serum (GPS) on Mycoplasma pneumoniae cells was tested under various conditions, using rounding and killing of the cells as test systems. Both activities could be inhibited by heat inactivation (56 C, 30 min). Killing required both Ca2+ and Mg2+, rounding only Mg2+. Both activities were temperature dependent and no rounding or killing occurred at 4C. Incomplete complement sequences with natural of artificial defects in C1, C4, or C6 resulted in lost or reduced killing. The rounding activity was only slightly affected. Anti-C3 antiserum blocked both phenomena; incubation of GPS with 10 mg of inulin per ml reduced the rounding activity, and the same treatment of GPS deficient in C4 inhibited rounding totally. Properdin factor D was shown to be necessary for rounding by GPS, with defects in either C1 or C4. By immune adherence bound C3b could be demonstrated on M. pneumoniae cells after GPS treatment, no antibodies against M. pneumoniae could be found in GPS by immune fluorescence. The results give evidence for complement being the toxic factor in GPS. Efficient killing requires the intact complement sequence. Furthermore, M. pneumoniae cells are able to activate the alternate pathway of complement. Activation of this pathway results in rounding of the cells, which are partly able to recover after this reaction. Biological consequences for the mycoplasmas are death or damage and possibly opsonization, even in the absence of specific antibodies. The host, too, is possibly affected by products of the reaction. The interaction of M. pneumoniae and complement could be involved in the early stages of the development of M. pneumoniae disease.

Some effects of growth medium composition on the antigenicity of a T-strain mycoplasma

T-strain 960 was passaged through 24 serial 10-fold dilutions in media without added urea and with porcine serum albumin fraction V as the only protein enrichment. The organism, either grown in this manner or passaged an additional three times in medium containing horse serum and 0.1 per cent urea, was inoculated into rabbits. Resultant antisera were tested for activity against T-960 growing in these different media by: (i) growth curve analysis in the presence of antiserum, (ii) metabolic inhibition in the presence or absence of complement (fresh guinea pig serum), (iii) complement-dependent killing curves, (iv) double diffusion in gel (Ouchterlong), and (v) a new visual method for the detection of antigen-antibody reactions on glass slides coated with a thin film of indium metal. Our results indicate that the reactivity of the antisera, as assayed by the above methods, is significantly affected by the composition of the growth medium used for preparation of the antigen. In addition, it was possible to determine that the guinea pig serum-dependent killing of T960 was not affected by the presence of ammonium ion.

The persistence of mycoplasmas in the urogenital tract of men in the Antarctic

A series of meatal swabs, taken from 17 men over a period of 17 months during their tour at an Antarctic base was examined for mycoplasmas. The number of organisms isolated never exceeded 10(4) and not every specimen from each man yielded mycoplasmas. Nevertheless, Mycoplasma hominis was isolated from 71% and T-mycoplasmas from 59% of the men at some time during their stay. M. hominis persisted in the presence of serum IHA antibody titres of 1/64. Three subjects yielded only M. hominis and one only T-mycoplasmas.Six men had already spent a year at the base when the study began and mycoplasmas were still being isolated from some of them at the end of a 31 month period of isolation. The persistence of mycoplasmas in the male genital tract can therefore be independent of sexual contact. Two modes of persistence are suggested; either a few men act as carriers and reinfect the others by contaminating their environment, or as seems more likely, most men have chronic infections.

Dialysis culture of T-strain mycoplasmas

Using dialyzing cultures of T-strain mycoplasmas, it was possible to make some observations relevant to the growth and metabolism of these organisms which would not be possible in nondialyzing cultures due to growth inhibition of the organisms by elevated pH and increased ammonium ion concentration in media containing urea. The rate of ammonia accumulation was found to be related to the initial urea concentration in the medium and could not be accounted for by any change in the multiplication rate of the organisms. More ammonia was generated than could be accounted for by the added urea alone, suggesting that an ammonia-producing activity other than urease may be present in T-strain mycoplasmas. Titers above 10(7) color change units per ml were achieved in dialysis cultures of a T-strain mycoplasma in the presence of urea, and such titers were maintained for approximately 60 h during dialysis culture in the absence of added urea.

Immunity in experimental T-mycoplasma mastitis

Immunity to reinfection with the homologous T-mycoplasma strain has been demonstrated in the bovine mammary gland. This immunity was generalized throughout the udder and was not confined to previously infected quarters. Two out of three cows which were immune to reinfection with the homologous strain were not immune to reinfection with a serologically distinct T-mycoplasma strain. Animals varied in their ability to resolve experimental mastitis with T-mycoplasmas: those which resolved the initial infection without antibiotic therapy were immune to challenge with the homologous strain, but those which needed to be given antibiotics to clear the first infection were not all immune to such challenge.

Growth of T-strain mycoplasmas in medium without added urea: effect of trace amounts of urea and of a urease inhibitor

Urea is currently considered to be a requirement for the propagation of T-strain mycoplasmas. We report here the replication of T-strain 960 (ATCC 25023) in media prepared from dialyzed components with added putrescine and allantoin but without added urea, or in dialyzed medium containing small amounts of added urea. The least amount of urea which allowed growth in the medium without allantoin was above 10 mug/ml. The amount of urea estimated to contaminate the added allantoin or putrescine was 5 mug/ml or less, which is insufficient to support T-strain replication. T-strain 960 was grown in the presence of urea and the urease inhibitor acetohydroxamic acid AHA where the organisms multiplied at a slower rate in the presence of AHA than in its absence. Urea hydrolysis occurred with concomitant ammonia accumulation and pH increase in cultures with AHA added.

Detection and characterization of defective mycoplasmacidal antibody produced by rodents against Mycoplasma arthritidis

A procedure has been developed for the detection of mycoplasmacidal antibody in the serum of rats and mice infected with Mycoplasma arthritidis. Antibody activity can apparently be measured only by using resting mycoplasma cells. The reaction is complement dependent and is usually complete within 3 h. Early antibody (5 days) could be detected only within the immunoglobulin (Ig)M fraction, whereas late antibody (42 days) is found within the IgG fraction. The mycoplasmacidal antibody was highly specific and cross reactions were not observed with other mycoplasma species. Antibody activity could be removed from serum by absorption with either viable or nonviable M. arthritidis. Cidal antibody produced by rats against other mycoplasma species was active against both resting and multiplying cells. Mycoplasmacidal antibody against M. arthritidis was detected in rats 2 days after injection of the organisms and persisted at least through 300 days. Mice usually developed antibodies by 3 days after injection of the organisms and moderate titers have been observed for as long as 487 days. Since viable mycoplasmas can persist in the peripheral circulation in the presence of antibody, it is likely that viable mycoplasma-antibody complexes are also present.

Modifications of the growth inhibition test and its application to human T-mycoplasmas

Several factors were found to influence the growth inhibition test. Inoculum size and amount of antiserum are well known variables, but the method of applying the antiserum, the incubation temperature, and the pH of the agar medium also play significant roles. The growth inhibition test modified according to these findings was found to be specific and well suited for the classification and identification of human T-mycoplasmas.

The virulence of T-mycoplasmas, isolated from various animal species, assayed by intramammary inoculation in cattle

The virulence of T-mycoplasmas for cattle was tested by examining their ability to produce mastitis in cows. It was found that both virulent and avirulent strains of T-mycoplasmas can be isolated from cattle. All of four strains from pneumonic calf lungs and a strain from a case of bovine kerato-conjunctivitis caused mastitis but only two of four strains isolated from the urogenital tract of cows were virulent. None of the human, simian or canine T-mycoplasmas examined were able to cause mastitis in cattle. However, a bovine strain was found to be capable of causing mastitis in goats. Virulent and avirulent strains from the same and different species contain common antigens detected by the metabolic inhibition test. Pathogenicity could not be shown to be characteristic of any particular serotype. The possibility is raised of some species barrier being responsible for the inability of non-bovine strains to infect cattle.

The production of mastitis in cows by the intramammary inoculation of T-mycoplasmas

Six milking cows were inoculated with bovine and human T-mycoplasmas and control materials into the udder via the teat canal. Control materials produced only a slight transient cell response in the milk. Bovine T-mycoplasmas produced clinical mastitis in nine out of ten quarters inoculated. Seven developed clinical mastitis together with visible changes in the milk, excretion of T-mycoplasmas and greatly increased cell counts in the milk. In three of these quarters, in two different cows, milk secretion ceased completely. Two quarters in a different cow showed visible milk changes, excretion of T-mycoplasmas and increased cell counts. Two quarters were inoculated with human T-mycoplasmas and neither produced any signs of mastitis.Infection of the udder with T-mycoplasmas did not stimulate high-titre serum antibody levels as measured by the metabolic inhibition test, but whey samples gave high titres in two of the cows that were able to control and resolve the infection.

Urease color test medium U-9 for the detection and identification of "T" mycoplasms in clinical material

A urease color test fluid medium (U-9) for the detection and identification of T (T-strain) mycoplasmas in clinical material is described which is sensitive and specific for this group of mycoplasmas. The medium was prepared from commercially available components and contained 95% half-strength, tryptic digest broth (pH 5.5), 4% unheated horse serum, 0.05% highest-purity urea, 0.001% sodium phenolsulfonphthalein, and 1,000 units of potassium penicillin G per ml. The final reaction of medium U-9 was pH 6.0. The overall agreement (positive and negative) between urease reactions in U-9 urease color test medium and culture findings in a standard agar primary culture system among 686 clinical specimens was 98.1%. The disagreement consisted of 13 false-positive urease reactions which were recognized visually as false-positive reactions due to other microorganisms. For specimens from the female genitourinary tract, the inclusion of 2.5 mug of amphotericin B (Fungizone) per ml of medium U-9 is recommended for the suppression of growth of Candida species and filamentous fungi.

Acholeplasma axanthum, sp. n.: a new sterol-nonrequiring member of the Mycoplasmatales

Mycoplasmas recovered from tissue cultures and previously shown to belong to the sterol-nonrequiring group of mycoplasmas have been further characterized. The biological and serological properties of these strains show them to be clearly distinct from Acholeplasma laidlawii and A. granularum, two species of sterol-nonrequiring mycoplasmas recently reclassified. It is proposed that the newly described mycoplasmas be designated Acholeplasma axanthum, sp. n.

Susceptibility of genital mycoplasmas to antimicrobial agents

The susceptibility of 11 T-strains, 12 strains of Mycoplasma hominis, and a single strain of M. fermentans to 15 antimicrobial agents was determined by study of inhibition of metabolic activity in a broth dilution system. All three species were inhibited by tetracycline, chloramphenicol, streptomycin, gentamicin, and kanamycin, and were relatively resistant to cephalothin, cephaloridine, polymyxin, vancomycin, and ampicillin. Three antimicrobial agents had significant differential effects on these species. Erythromycin was more active against T-strains than against M. hominis or M. fermentans. Lincomycin, clindamycin, and nitrofurantoin had greater activity against M. hominis and M. fermentans than against T-strains. The activity of the drugs tested was generally uniform over a wide range of inocula. The effect of pH and the difference between minimal inhibiting and minimal mycoplasmacidal concentrations of the drugs tested were consistent with expectations based on the effects of these drugs on bacteria.

Previously Uncharacterized Mycoplasma Isolates from an Investigation of Canine Pneumonia

Mycoplasmas recovered from the respiratory tract and genitourinary system of dogs, with and without respiratory infection, have been characterized by biological and immunological methods. Some of the isolates were indentified as being similar to the three species of canine mycoplasmas described earlier under the designation Mycoplasma spumans, M. canis , and M. maculosum . Other mycoplasmas placed in three groups (A, C, and D) were found to be clearly distinct from the three classified species. Group A strains fermented glucose but not mannose and were serologically distinct from other canine mycoplasmas recovered in this study. These strains were subsequently found to be biologically and serologically related to a previously reported, but unclassified, canine mycoplasma. Group D strains differed in some biological properties but were serologically related. These were found to be nonfermenting mycoplasmas representing isolations from the throat and bladder of dogs. They were serologically distinct from other canine mycoplasmas and were apparently unrelated to other known mycoplasma serotypes. Group C mycoplasmas were recovered only from the lungs of dogs. Within the group, they differ in some immunological properties but appear to be serologically distinct from other canine strains. They can also be separated from other dog strains in their ability to ferment glucose and mannose. Group B strains were found to have biological properties similar to M. canis strains but seemed to be only partially related to this serotype when examined in several serological techniques. It is suggested that these strains might represent antigenic variants of M. canis .

Enhanced growth of T-strain mycoplasmas with N-2-hydroxyethylpiperazone-N'-2-ethanesulfonic acid buffer

The small size of T-strain mycoplasma colonies obtained on agar medium has been a drawback to the study of these organisms. The incorporation of 0.05 mN-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES), a new hydrogen ion buffer, into agar medium at pH 6.8 led to the production of colonies at least 60% greater in diameter than those obtained on media without HEPES at pH 6.5 or 6.0. In addition, the colonies often had the "fried-egg" appearance typical of "classical" large-colony-forming mycoplasmas. The addition of HEPES to liquid medium in the presence of 0.1% urea resulted in a slightly higher number of viable organisms and a corresponding increase in ammonia production. Rapid death of the mycoplasmas occurred on continued incubation of the liquid medium cultures even in the presence of HEPES. The larger colony size facilitated the study of hemadsorption and tissue-culture cell adsorption. Preliminary results of such tests in which these phenomena have been demonstrated are presented. The advantages and disadvantages of having larger colonies are discussed, and the terminology of T-strain mycoplasmas is considered in the light of the present findings.