Growth on artificial medium of an agent associated with atypical pneumonia and its identification as a PPLO

Mycoplasma fermentans and TNF-beta interact to amplify immune-modulating cytokines in human lung fibroblasts

Mycoplasma can establish latent infections and are associated with arthritis, leukemia, and chronic lung disease. We developed an experimental model in which lung cells are deliberately infected with Mycoplasma fermentans. Human lung fibroblasts (HLF) were exposed to live M. fermentans and immune-modulating cytokine release was assessed with and without known inducers of cytokine production. M. fermentans increased IL-6, IL-8/CXCL8, MCP-1/CCL2, and Gro-alpha/CXCL1 production. M. fermentans interacted with TNF-beta to release more IL-6, CXCL8, and CXCL1 than predicted by the responses to either stimulus alone. The effects of live infection were recapitulated by exposure to M. fermentans-derived macrophage-activating lipopeptide-2 (MALP-2), a Toll-like receptor-2- and receptor-6-specific ligand. The synergistic effect of combined stimuli was more pronounced with prolonged incubations. Preexposure to TNF-beta sensitized the cells to subsequent MALP-2 challenge, but preexposure to MALP-2 did not alter the IL-6 response to TNF-beta. Exposure to M. fermentans or MALP-2 did not enhance nuclear localization, DNA binding, or transcriptional activity of NF-kappaB and did not modulate early NF-kappaB activation in response to TNF-beta. Application of specific inhibitors of various MAPKs suggested that p38 and JNK/stress-activated protein kinase were involved in early IL-6 release after exposure to TNF-beta and M. fermentans, respectively. The combined response to M. fermentans and TNF-beta, however, was uniquely sensitive to delayed application of SP-600125, suggesting that JNK/stress-activated protein kinase contributes to the amplification of IL-6 release. Thus M. fermentans interacts with stimuli such as TNF-beta to amplify lung cell production of immune-modulating cytokines. The mechanisms accounting for this interaction can now be dissected with the use of this in vitro model.

Mycoplasma pneumoniae subtype-independent induction of proinflammatory cytokines in THP-1 cells

Mycoplasma pneumoniae can be divided into two main subtypes depending on the amino acid sequences of the P1 adhesin and the P65 protein, both located in the attachment organelle. Differences between these subtypes in infectivity, virulence and interaction with host cells have not been extensively studied. Using ELISA to measure released protein and real-time PCR to quantify mRNA, we have demonstrated that both M. pneumoniae subtypes significantly increased tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8) at comparable levels in THP-1 cells over a 72 h period of time. However, subtype 2 induced a statistically significant increase (P<0.001) in the release of interleukin-1beta at 24 h post-infection compared to subtype 1. These data provide evidence that the induction of proinflammatory cytokine gene and protein expression by M. pneumoniae is not dependent on the infecting subtype.

IDENTIFICATION OF MYCOPLASMATACEAE BY THE FLUORESCENT ANTIBODY METHOD

Clark, Harold W. (The George Washington University, Washington, D.C.), Jack S. Bailey, Richard C. Fowler, and Thomas McP. Brown. Identification of Mycoplasmataceae by the fluorescent antibody method. J. Bacteriol. 85:111-118. 1963.-The conditions of the fluorescent antibody reactions were studied in relation to their application to Mycoplasmataceae or pleuropneumonia-like organisms (PPLO). Mycoplasma hominis type 1 and 2 antigens and their homologous antisera were used to determine the activity and specificity of these and other strains. Fluorescein isothiocyanate conjugated antiserum globulin preparations were used in both the direct and indirect fluorescent antibody methods. A direct tube technique was used for the detection and measurement of growth in broth cultures by the addition of conjugated antiserum. The specific fluorescent staining and recognition of hot water fixed M. hominis colonies was presented as a suitable identification standard. The antigenic activity was found to remain in the insoluble residue after exposure of M. hominis strains to sonic vibration (9 kc) for 30 min and centrifugation. Brief 2-min exposures of tissue cells to vibration (9 kc) caused the disruption of tissues, with the release of viable and "bound" nonwashable strains that reacted specifically with fluorescent antibody. It is proposed to apply both the sonic vibration and the fluorescent antibody techniques for the identification of Mycoplasmataceae in human tissues.

CYTOPATHIC EFFECT OF THE ATYPICAL PNEUMONIA ORGANISM IN CULTURES OF HUMAN TISSUE

Eaton, Monroe D. (Harvard Medical School, Boston, Mass.), Ann E. Farnham, Jeana D. Levinthal, and Anthony R. Scala. Cytopathic effect of the atypical pneumonia organism in cultures of human tissue. J. Bacteriol. 84:1330-1337. 1962.-Three strains of the atypical pneumonia agent were adapted to grow in continuous cell cultures of human amnion or human embryonic lung, with production of initial increased acidity followed by destruction of the cells. Evidence is presented that cytopathic effects of the organism were associated with intracellular growth and formation of microcolonies. Clumps of organisms stained specifically with fluorescein-labeled antibody, and showed distinctive tinctorial reactions with the May Grünwald-Giemsa stain. The cytopathic effect was prevented by fresh serum from a rabbit immunized with an egg-passage strain of the atypical pneumonia agent. Heating the immune serum to 56 C for 30 min abolished the neutralizing effect. The significance of heat-labile serum constituents in killing or inhibition of mycoplasma is discussed.

Identification of a virulence-associated determinant, dihydrolipoamide dehydrogenase (lpd), in Mycoplasma gallisepticum through in vivo screening of transposon mutants

To effectively analyze Mycoplasma gallisepticum for virulence-associated determinants, the ability to create stable genetic mutations is essential. Global M. gallisepticum mutagenesis is currently limited to the use of transposons. Using the gram-positive transposon Tn4001mod, a mutant library of 110 transformants was constructed and all insertion sites were mapped. To identify transposon insertion points, a unique primer directed outward from the end of Tn4001mod was used to sequence flanking genomic regions. By comparing sequences obtained in this manner to the annotated M. gallisepticum genome, the precise locations of transposon insertions were discerned. After determining the transposon insertion site for each mutant, unique reverse primers were synthesized based on the specific sequences, and PCR was performed. The resultant amplicons were used as unique Tn4001mod mutant identifiers. This procedure is referred to as signature sequence mutagenesis (SSM). SSM permits the comprehensive screening of the M. gallisepticum genome for the identification of novel virulence-associated determinants from a mixed mutant population. To this end, chickens were challenged with a pool of 27 unique Tn4001mod mutants. Two weeks postinfection, the birds were sacrificed, and organisms were recovered from respiratory tract tissues and screened for the presence or absence of various mutants. SSM is a negative-selection screening technique whereby those mutants possessing transposon insertions in genes essential for in vivo survival are not recovered from the host. We have identified a virulence-associated gene encoding dihydrolipoamide dehydrogenase (lpd). A transposon insertion in the middle of the coding sequence resulted in diminished biologic function and reduced virulence of the mutant designated Mg 7.

Correlates of immune protection in chickens vaccinated with Mycoplasma gallisepticum strain GT5 following challenge with pathogenic M. gallisepticum strain R(low)

Colonization of the avian respiratory tract with Mycoplasma gallisepticum results in a profound inflammatory response in the trachea, air sacs, conjunctiva, and lungs. A live attenuated M. gallisepticum vaccine strain, GT5, was previously shown to be protective in chickens upon challenge; however, the mechanisms by which this vaccine and others confer protection remain largely unknown. The current study evaluated several potential correlates of GT5 vaccine-mediated immune protection following challenge with the pathogenic M. gallisepticum strain R(low). GT5-vaccinated chickens developed mild tracheal lesions, consisting of few and scattered, discrete, lymphofollicular aggregates in the lamina propria. In addition, low numbers of aggregated B, CD4(+), and CD8(+) cells were observed to infiltrate the trachea, in stark contrast to the large numbers infiltrating the tracheas of sham-vaccinated chickens challenged with R(low). Lymphofollicular aggregates were rarely observed prior to day 12 postchallenge in sham-vaccinated chickens. Instead, they contained an increasingly more cellular inflammatory response characterized by expansion of the lamina propria by lymphoplasmacytic and histiocytic infiltrates. This was due in part to expansion of interfollicular zones by large numbers of infiltrating CD4(+) and CD8(+) cells and a sizeable population of immunoglobulin A (IgA)- and IgG-secreting plasma cells. GT5-vaccinated chickens also had higher serum IgG concentrations, and significantly higher numbers of M. gallisepticum-specific IgG- and IgA-secreting plasma/B cells within the trachea, than did sham-vaccinated chickens. These responses were observed as early as day 4 postchallenge, indicating the importance of antibody-mediated clearance of mycoplasma in GT5-vaccinated chickens.

Mycoplasma pneumoniae and central nervous system complications: a review

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia. Little is known about the extrapulmonary manifestations of this organism. Numerous central nervous system (CNS) manifestations have been described with M. pneumoniae. CNS involvement is probably the most common site of involvement in addition to the respiratory system. Up to 7% of patients hospitalized with M. pneumoniae may have CNS symptoms. Common CNS presentations include encephalitis, aseptic meningitis, polyradiculitis, cerebellar ataxia, and myelitis. The mechanism behind these CNS manifestations remains unclear. Direct invasion, neurotoxin production, or an immune-mediated mechanism has been proposed. Newer diagnostic techniques for the direct detection of the antigen and the microorganism are proving useful for the detection of extrapulmonary disease. This review comprehensively reviews the CNS complications that have been reported with M. pneumoniae.

Mycoplasma pneumoniae and its role as a human pathogen

Mycoplasma pneumoniae is a unique bacterium that does not always receive the attention it merits considering the number of illnesses it causes and the degree of morbidity associated with it in both children and adults. Serious infections requiring hospitalization, while rare, occur in both adults and children and may involve multiple organ systems. The severity of disease appears to be related to the degree to which the host immune response reacts to the infection. Extrapulmonary complications involving all of the major organ systems can occur in association with M. pneumoniae infection as a result of direct invasion and/or autoimmune response. The extrapulmonary manifestations are sometimes of greater severity and clinical importance than the primary respiratory infection. Evidence for this organism's contributory role in chronic lung conditions such as asthma is accumulating. Effective management of M. pneumoniae infections can usually be achieved with macrolides, tetracyclines, or fluoroquinolones. As more is learned about the pathogenesis and immune response elicited by M. pneumoniae, improvement in methods for diagnosis and prevention of disease due to this organism may occur.

Microbial stimulation by Mycoplasma fermentans synergistically amplifies IL-6 release by human lung fibroblasts in response to residual oil fly ash (ROFA) and nickel

Mycoplasma (MP), such as the species M. fermentans, possess remarkable immunoregulatory properties and can potentially establish chronic latent infections with little signs of disease. Atmospheric particulate matter (PM) is a complex and diverse component of air pollution associated with adverse health effects. We hypothesized that MP modulate the cellular responses induced by chemical stresses such as residual oil fly ash (ROFA), a type of PM rich in transition metals. We assessed the release of interleukin-6 (IL-6), a prototypic immune-modulating cytokine, in response to PM from different sources in human lung fibroblasts (HLF) deliberately infected with M. fermentans. We found that M. fermentans and ROFA together synergistically stimulated production of IL-6 compared to either stimuli alone. Compared to several other PM, ROFA appeared most able to potentiate IL-6 release. The potentiating effect of live MP infection could be mimicked by M. fermentans-derived macrophage-activating lipopeptide-2 (MALP-2), a known Toll-like receptor-2 agonist. The aqueous fraction of ROFA also contained potent IL-6 inducing activity in concert with MALP-2, and exposure to several defined metal salts indicated that Ni and, to a lesser extent V, (but not Cu) could synergistically act with MALP-2 to induce IL-6. These data indicate that microorganisms like MP can interact with environmental stimuli such as PM-derived metals to synergistically activate signaling pathways that control lung cell cytokine production and, thus, can potentially modulate adverse health effects of PM exposure.

Colistin sulfate as a suitable substitute of thallium acetate in culture media intended for mycoplasma detection and culture

Thallium acetate in concentrations of 500 to 1000 mg/l is tolerated in the culture by the most mollicutes of the orders Mycoplasmatales and Acholeplasmatales and by this reason it is added in the culture media as a selective element for the detection and propagation of mycoplasmas and acholeplasmas. Because of the high toxicity of thallium acetate and its accumulation in the environment, thallium acetate is not biodegradable, an alternative was searched. The results and analysis of tests with nine mollicute species are presented here. It is recommended to replace thallium acetate in the formulations where it is used and colistin sulfate is proposed as its substitute.

The role of atypical pathogens in community-acquired pneumonia

The atypical pathogens in community-acquired pneumonia traditionally have included Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. Recent studies documenting their epidemiology and clinical characteristics have shown that these organisms are indistinguishable from the pneumococcus. Furthermore, therapy no longer depends on the specific bacterial cause of community-acquired pneumonia. Etiologic diagnosis is still difficult, although new methods are becoming available. This article focuses on these issues and on why the term atypical is no longer meaningful.

Do mycoplasmas cause human cancer?

A linkage between mycoplasmas and malignancy was mainly proposed in the 1960s when human-associated mycoplasmas were becoming of interest given the novel characterization of the human respiratory pathogen Mycoplasma pneumoniae. Associations with leukemia and other malignancies, however, were largely ascribed to tissue-culture contamination, which is now recognized as a significant potential problem in molecular biology circles. A few epidemiological studies, however, continue to raise concern over such a linkage. As well, in vitro data have demonstrated the potential for some mycoplasmas to induce karyotypic changes and malignant transformation during chronic tissue-culture infestation. As cellular and molecular mechanisms for such transformation become studied, a resurgence of interest in this area is inevitable. A role for mycoplasmas in malignancy of any sort is conjectural, but there remains a need to continue with focussed epidemiological and laboratory investigations.Key words: mycoplasma, cancer, oncogenesis, leukemia.

Comparison of in-vitro activities of SCH27899 and other antibiotics against Mycoplasma pneumoniae

We examined the in-vitro activities of various antibiotics against 25 strains of Mycoplasma pneumoniae (22 clinical isolates and 3 standard strains). In the 22 clinical isolates, the 90% minimum inhibitory concentrations (MIC 90) of SCH27899, ofloxacin, levofloxacin, ciprofloxacin, erythromycin, clarithromycin, roxithromycin, clindamycin, and minocycline were 16, 2, 2, 4, 0.0039, 0.0039, 0.016, 2, and 4 microg/ml, respectively. The minimum bactericidal concentrations (MBC 90) of SCH27899, ofloxacin, levofloxacin, ciprofloxacin, erythromycin, clarithromycin, roxithromycin, clindamycin, and minocycline were 64, 4, 2, 8, 0.0625, 0.0625, 0.125, 8, and 64 microg/ml, respectively. The low sensitivity of M. pneumoniae to SCH27899 may be a result of the impermeability of the bacteria to this molecule. The results of this study suggest that SCH27899 would not be a suitable antimicrobial agent to use in the alternative chemotherapy of M. pneumoniae infection.

Ether lipids in the cell membrane of Mycoplasma fermentans

Two new ether lipids, 1-O-alkyl/alkenyl-2-O-acyl-glycero-3-phosphocholine and its lyso form, 1-O-alkyl/alkenyl-glycero-3-phosphocholine, were identified in the cell membrane of Mycoplasma fermentans using chemical analyses, GLC-MS, MALDI-TOF MS, and 1D and 2D NMR spectroscopy. The lipids are heterogeneous with respect to both acyl and alkyl/alkenyl residues. The acyl residues at position 2 of glycerol are hexadecanoyl and octadecanoyl in a molar ratio of 3.6 : 1 with a trace amount of octadecenoyl. The alkyl/alkenyl residues at position 1 of glycerol are hexadecyl (78%), octadecyl (7%), octadecenyl (14%), and hexadecenyl (traces). In the octadecenyl residue, the double bond has a cis configuration and is located at either position 1' (plasmalogen-type lipid) or 9' in a ratio approximately 1 : 1. This is the first report of the presence of alkyl and vinyl (alk-1'-enyl) ether lipids in the cell membrane of aerobically grown mycoplasmas. Lipids of this type have been found in some Gram-positive bacteria, thus supporting the hypothesized close taxonomical relationship of these bacteria to mycoplasmas. The ether lipids of M. fermentans are structurally similar to platelet activating factor; it was demonstrated that the 2-O-acetylated lyso form lipid can mimic platelet-activating factor activity in isolated perfused and ventilated rat lungs.

Hayflick, his limit, and cellular ageing

Almost 40 years ago, Leonard Hayflick discovered that cultured normal human cells have limited capacity to divide, after which they become senescent -- a phenomenon now known as the 'Hayflick limit'. Hayflick's findings were strongly challenged at the time, and continue to be questioned in a few circles, but his achievements have enabled others to make considerable progress towards understanding and manipulating the molecular mechanisms of ageing.

Evaluation of in-vitro activity of new quinolones, macrolides, and minocycline against Mycoplasma pneumoniae

We made a comparative study of the in-vitro activities of grepafloxacin (GPFX), ofloxacin (OFLX), erythromycin (EM), clarithromycin (CAM), roxithro-mycin (RXM), and minocycline (MINO) against 20 strains of Mycoplasma pneumoniae (17 clinical isolates and 3 standard strains). The minimum inhibitory concentration (MIC)90-to-minimum bactericidal concentration (MBC)90 ratio showed that the new quinolones have bactericidal effects on M. pneumoniae. Thus, it is expected that the new quinolones, especially grepafloxacin, will be clinically useful antimicrobial agents for the treatment of M. pneumoniae infection because of their good pharmacokinetic properties and bactericidal action.

Identification and expression of a Mycoplasma gallisepticum surface antigen recognized by a monoclonal antibody capable of inhibiting both growth and metabolism

In order to identify antigenic proteins of Mycoplasma gallisepticum, monoclonal antibodies (MAbs) against virulent M. gallisepticum R strain were produced in mice. MAb 35A6 was selected for its abilities to inhibit both growth and metabolism of M. gallisepticum in vitro. The MAb recognized a membrane protein with an apparent molecular mass of 120 kDa. The corresponding gene, designated the mgc3 gene, was cloned from an M. gallisepticum genomic DNA expression library and sequenced. The mgc3 gene is a homologue of the ORF6 gene encoding 130-kDa protein in the P1 operon of M. pneumoniae and is localized downstream of the mgc1 gene, a homologue of the P1 gene. To assess the characteristics of MGC3 protein, all 10 TGA codons in the mgc3 gene, which encode a tryptophan in the Mycoplasma species, were replaced with TGG codons, and recombinant fowlpox viruses (FPV) harboring the altered mgc3 gene were constructed. One of the recombinant FPVs was improved to express MGC3 protein on the cell surface in which the signal peptide of MGC3 protein was replaced with one from Marek's disease virus gB. These results should provide the impetus to develop a vaccine based on MGC3 protein which can induce antibodies with both growth inhibition and metabolic-inhibition activities using a recombinant FPV.

In vitro activity of telithromycin (HMR3647), a new ketolide, against clinical isolates of Mycoplasma pneumoniae in Japan

The in vitro activity of telithromycin (HMR3647), a new ketolide, against Mycoplasma pneumoniae was determined by the broth microdilution test using 41 clinical isolates obtained in Japan, as compared with those of five macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin, and josamycin), minocycline, and levofloxacin. Telithromycin was less potent than azithromycin, but it was more active than four other macrolides, minocycline, and levofloxacin; its MICs at which 50 and 90% of the isolates tested were inhibited were both 0.00097 microg/ml, justifying clinical studies to determine its efficacy for treatment of M. pneumoniae.

An outbreak of acute respiratory disease caused by Mycoplasma pneumoniae and adenovirus at a federal service training academy: new implications from an old scenario

Outbreaks of Mycoplasma pneumoniae and adenovirus have been reported in military institutions for several decades. During a recent outbreak in a federal service training academy, we performed an epidemiological and laboratory investigation to better characterize and control the outbreak. Of 586 students responding to a questionnaire, 317 (54%) reported having a respiratory illness during the outbreak period. Among 42 students who underwent complete laboratory testing, 24 (57%) had evidence of M. pneumoniae infection, 8 (19%) had evidence of adenovirus infection, and 4 (10%) had evidence of both. Polymerase chain reaction testing of oropharyngeal swabs revealed more acute M. pneumoniae infections (57% positive) than did serology or culture. Multivariate analysis revealed that visiting the campus health clinic >3 times for a nonrespiratory condition, such as injury, was a significant risk factor for illness among freshmen early in the course of the outbreak, whereas having an ill roommate was a risk factor throughout the duration of the outbreak.

Atypical pathogens in community-acquired pneumonia

The atypical pathogens are an important and significant cause of CAP. The clinical and radiologic manifestations of CAP caused by these pathogens are modulated by the immunologic and physiologic status of the host, and therefore are not pathogen-specific. The range of frequencies found in various studies for the atypical pathogens among the causes of CAP is broad. These frequencies are affected by very important factors that should be recognized. In a significant percentage of patients, an atypical pathogen can be identified together with an additional cause. The significance of multiple causes has not been clarified sufficiently. The principal diagnostic techniques in use today for the causative diagnosis of CAP are serologic tests. Different serologic methods have been used in various studies and diagnostic criteria are not standardized. In the future it is likely that diagnostic testing will be based on the PCR technique on serum samples. The effectiveness and importance of antimicrobial therapy in some patients with atypical pathogen CAP are unclear. The accepted therapy today for atypical pathogen CAP, which is based on erythromycin, will probably be changed in the near future in favor of the new generations of fluoroquinolone or the new macrolide preparations.

Beijerinck's work on tobacco mosaic virus: historical context and legacy

Beijerinck's entirely new concept, launched in 1898, of a filterable contagium vivum fluidum which multiplied in close association with the host's metabolism and was distributed in phloem vessels together with plant nutrients, did not match the then prevailing bacteriological germ theory. At the time, tools and concepts to handle such a new kind of agent (the viruses) were non-existent. Beijerinck's novel idea, therefore, did not revolutionize biological science or immediately alter human understanding of contagious diseases. That is how bacteriological dogma persisted, as voiced by Loeffler and Frosch when showing the filterability of an animal virus (1898), and especially by Ivanovsky who had already in 1892 detected filterability of the agent of tobacco mosaic but kept looking for a microbe and finally (1903) claimed its multiplication in an artificial medium. The dogma was also strongly advocated by Roux in 1903 when writing the first review on viruses, which he named 'so-called "invisible" microbes', unwittingly including the agent of bovine pleuropneumonia, only much later proved to be caused by a mycoplasma. In 1904, Baur was the first to advocate strongly the chemical view of viruses. But uncertainty about the true nature of viruses, with their similarities to enzymes and genes, continued until the 1930s when at long last tobacco mosaic virus particles were isolated as an enzyme-like protein (1935), soon to be better characterized as a nucleoprotein (1937). Physicochemical virus studies were a key element in triggering molecular biology which was to provide further means to reveal the true nature of viruses 'at the threshold of life'. Beijerinck's 1898 vision was not appreciated or verified during his lifetime. But Beijerinck already had a clear notion of the mechanism behind the phenomena he observed. Developments in virology and molecular biology since 1935 indicate how close Beijerinck (and even Mayer, Beijerinck's predecessor in research on tobacco mosaic) had been to the mark. The history of research on tobacco mosaic and the commitments of Mayer, Beijerinck and others demonstrate that progress in science is not only a matter of mere technology but of philosophy as well. Raemaekers' Mayer cartoon, inspired by Beijerinck, artistically represents the crucial question about the reliability of our images of reality, and about the scope of our technological interference with nature.

Hemolysis in identifying Eaton's pleuro-pneumonia-like organism

A method for readily demonstrating hemolysis of mammalian erythrocytes by Eaton's pleuropneumonia-like organism is described. This reaction may be useful in preliminary identification of this organism, since other strains from human sources are not known to have this property.

Studies on L forms and protoplasts of group A streptococci. II. Chemical and immunological properties of the cell membrane

Intact bacterial membranes have been isolated from protoplasts prepared from Group A streptococci by a cell wall-dissolving enzyme. A membrane fraction with identical chemical and serological properties has been obtained by differential centrifugation of mechanically disrupted streptococci. The membrane is chemically distinct from the cell wall and is composed of 72 per cent protein, 26 per cent lipid, and 2 per cent carbohydrate. Capillary precipitin tests and analysis by microdiffusion have demonstrated that the membrane contains antigens distinct from those of the cell wall and from those of the cytoplasm which it envelops. Evidence is presented which demonstrates that this antigenic material is common to the membranes of Group A streptococci, and that it can be distinguished by immunodiffusion from related antigenic substances present in membranes of several other serological groups of hemolytic streptococci. This antigenic material does not cross-react with the membrane antigens of other Gram-positive cocci.

In vitro activities of quinupristin-dalfopristin and the streptogramin RPR 106972 against Mycoplasma pneumoniae

The in vitro activities of quinupristin-dalfopristin and streptogramin RPR 106972 were determined with 44 strains of Mycoplasma pneumoniae and compared to those of macrolides, minocycline, and quinolones. All isolates tested were highly susceptible to macrolides and to quinupristin-dalfopristin (MIC at which 90% of the isolates are inhibited [MIC90], 0.0625 microg/ml), followed by RPR 106972 (MIC90, 0.5 microg/ml), quinolones, and minocycline.

A seroepidemiological study of Mycoplasma pneumoniae infections in Denmark over the 50-year period 1946-1995

The epidemiological pattern of Mycoplasma pneumoniae infections in Denmark over the 50-year period 1946-1995 is described. The study is based on blood specimens received at the central laboratory at Statens Serum Institut for titration of cold agglutinins (CA), initially for the diagnosis of CA positive primary atypical pneumonia, and during the 1960s of M. pneumoniae infection; in addition, specimens from the last 38 years were tested for antibodies specific to M. pneumoniae. By retrospective analysis of the test results compiled over the years it was found that intervals of regular periodicity have been interrupted by an era of changes in the pattern. Attention is paid to the significance of CA for this study, and the possible background of the epidemiological pattern is described.

STARCH GEL ELECTROPHORESIS OF A FRACTION OF CERTAIN OF THE PLEUROPNEUMONIA-LIKE GROUP OF MICROORGANISMS

Fowler, Richard C. (George Washington University School of Medicine, Washington, D.C.), Don W. Coble, Norman C. Kramer, and Thomas McP. Brown. Starch gel electrophoresis of a fraction of certain of the pleuropneumonia-like group of microorganisms. J. Bacteriol. 86:1145-1151. 1963.-Starch gel electrophoresis is suggested as a means of further characterizing strains of the pleuropneumonia-like group of microorganisms (PPLO), defined herein as including both the various "L" forms of bacteria and the Mycoplasmataceae. The techniques used may be varied to "select" other groups of proteins or classes of compounds (e.g., glycoproteins, lipoproteins, and enzymes). Only the results by starch gel electrophoresis on the soluble portion of sonically treated, washed cultures, grown in a pancreatic digest of beef heart enriched with bovine serum, are reported. As yet, differences appear more significant than similarities among the electrophoretically separable proteins. The demonstration of characteristic protein patterns for each strain studied suggests possibilities of further dividing serological groups into sero-logically distinct subtypes. Tentative migration values (E(f)) have been assigned to the protein bands for convenience in designation. Numerous interrelationships are thereby suggested.

CYTOPATHOGENIC MYCOPLASMAS ASSOCIATED WITH TWO HUMAN TUMORS. I. ISOLATION AND BIOLOGICAL ASPECTS

Armstrong, D. (The Children's Hospital of Philadelphia, Philadelphia, Pa.), G. Henle, N. L. Somerson, and L. Hayflick. Cytopathogenic mycoplasmas associated with two human tumors. I. Isolation and biological aspects. J. Bacteriol. 90:418-424. 1965.-Mycoplasmas were isolated from cell cultures of two benign human tumors. The first isolate contained two mycoplasmas, one a well-known human species (Mycoplasma hominis type I) and frequent tissue culture contaminant, and the other a recently reported new type. The second isolate was a mycoplasma of the newly described type. The mycoplasmas could be reisolated, after one or more passages through tissue culture, from extracts of the original tumor tissue. The relationship of the organisms to the neoplasms remains obscure. Both isolates produce cytopathic effect (CPE) and acidification of medium in a variety of tissue cultures. The CPE may be diminished, but not abolished, by increasing concentrations of arginine in the tissue culture media. Infection of various tissue cultures with the mycoplasmas did not result in interference to super-infection with vesicular stomatitis virus.

AEROSOLS AS A SOURCE OF WIDESPREAD MYCOPLASMA CONTAMINATION OF TISSUE CULTURES

Mycoplasma isolates were cultured from 15 antibiotic-free cell cultures obtained from a single laboratory. Complement-fixation tests showed that these isolates were antigenically related to each other but were unrelated to M. hominis type 1, M. hominis type 2, M. arthritidis, M. laidlawii type B, Mycoplasma sp. H.Ep. #2 (Barile), or M. salivarium. Examination of serum used to feed the infected cell lines revealed no Mycoplasma. Infection resulting from cross-contamination by a single Mycoplasma strain from one cell culture to another was investigated. Although the organisms were not found in the air over the work area, aerosols containing these contaminants were produced in tissue culture bottles during the trypsinization of cell monolayers. The minimal infectious dose of Mycoplasma for tissue cultures was measured, and it was determined that one organism was capable of initiating an infection in a tissue culture. The pattern of contamination and the small dose required for infection indicated that Mycoplasma contamination was spread from one tissue culture to another via aerosols. It was demonstrated that Mycoplasma can be transferred from one cell culture to another through the use of a common burette for dispensing medium.

REPLICATION OF MYCOPLASMA PNEUMONIAE IN BROTH CULTURE

Low, Iolanda E. (Harvard Medical School, Boston, Mass.), and Monroe D. Eaton. Replication of Mycoplasma pneumoniae in broth culture. J. Bacteriol. 89:725-728. 1965.-Reproducible growth curves of Mycoplasma pneumoniae can be obtained with the use of shaking cultures, which allows earlier and higher yields of the organism than stationary or roller cultures. Decreasing oxygen tension clearly decreases the growth of M. pneumoniae to barely detectable levels, with or without glucose or pyruvate as substrates. The use of phenol red as a pH indicator in the medium is helpful in judging the replication of a culture so that log-phase organisms can be harvested in large amounts.

LYSIS OF PLEUROPNEUMONIA-LIKE ORGANISMS BY STAPHYLOCOCCAL AND STREPTOCOCCAL TOXINS

Six strains representing three species of Mycoplasma were examined for susceptibility to lysis by staphylococcal and streptococcal toxins. All were sensitive to staphylococcal alpha-toxin, two to streptolysin S, and three to streptolysin O. The results support the concept that the limiting membrane of pleuropneumonia-like organisms is basically similar to those of many other cell types and provide additional evidence for the participation of cholesterol in cytolysis induced by streptolysin O.

Characterization of the recA gene regions of Spiroplasma citri and Spiroplasma melliferum

In previous studies (A. Marais, J. M. Bove, and J. Renaudin, J. Bacteriol. 178:862-870, 1996), we have shown that the recA gene of Spiroplasma citri R8A2 was restricted to the first 390 nucleotides of the N-terminal part. PCR amplification and sequencing studies of five additional strains of S. citri have revealed that these strains had the same organization at the recA region as the R8A2 strain. In contrast to S. citri, Spiroplasma melliferum was found to contain a full-length recA gene. However, in all five S. melliferum strains tested, a TAA stop codon was found within the N-terminal region of the recA reading frame. Our results suggest that S. melliferum, as well as S. citri, is RecA deficient. In agreement with the recA mutant genotype of S. citri and S. melliferum, we have shown that these organisms are highly sensitive to UV irradiation.

EFFECT OF PH ON HUMAN MYCOPLASMA STRAINS

Shepard, Maurice C. (U.S. Naval Medical Field Research Laboratory, Camp Lejeune, N.C.), and Carl D. Lunceford. Effect of pH on human Mycoplasma strains. J. Bacteriol. 89:265-270. 1965.-The optimal reaction of culture media for the cultivation of T-strain Mycoplasma of human origin was investigated. By use of a recently modified tryptic digest medium, the optimal reaction in either agar or fluid medium was found to be pH 6.0. In contrast, human classic (large-colony) Mycoplasma could be cultivated in agar or fluid medium over a rather broad pH range, and the influence of the reaction of the medium appeared to be primarily species-dependent. M. salivarium, for example, grew best in agar from pH 5.5 through 6.5. M. pneumoniae (Easton's agent) yielded largest colony numbers in agar and highest titers in broth at pH 8.0. In the case of T-strain Mycoplasma, both maximal colony numbers in agar and highest titers in fluid media were achieved at a reaction of pH 6.0. In addition, largest colony size of T-strain Mycoplasma was also achieved in agar at pH 6.0, and averaged 50 to 100% larger than that obtained by cultivation at pH 8.0 with the same medium. Although T-strains will develop in agar media over a pH range of from 5.0 through 10.0, the extremely small colony size and poor staining properties resulting from growth in an alkaline medium make their recognition in agar cultures difficult. Aerobic cultivation of T-strains was first achieved in agar adjusted to pH 5.5 to 6.0. In fluid medium, multiplication of T-strains occurred only within the limits of pH 5.0 through 8.0, with highest titers being reached at pH 6.0. Greater attention to the reaction of complete Mycoplasma media is stressed.

PREPARATION OF COMPLEMENT-FIXING ANTIGEN FOR ROUTINE USE IN DIAGNOSIS OF EATON PNEUMONIA

A technique by which Eaton P.P.L.O. complement-fixing antigen, suitable for routine use, can be prepared in an ordinary bacteriological laboratory is described in detail.

EXPERIMENTAL INFECTION WITH MYCOPLASMA PNEUMONIAE (EATON'S AGENT)

The pathogenesis of Mycoplasma pneumoniae infection was studied in the Syrian hamster with qualitative and quantitative culture methods and special histopathologic techniques. The animals were readily infected with the mycoplasma, which multiplied throughout the respiratory tract. Sensitivity of this experimental host to infection was indicated by the 50 per cent infective dose, which was 10 colony-forming units of the organism. Inoculation consistently resulted in the production of peribronchial pneumonitis which was induced by the mycoplasma. The organisms were visualized in a superficial location in the mucosa of involved bronchi, by means of indirect fluorescent antibody staining and by a modification of the Brown and Brenn technique. The data indicate applicability of the hamster to the study of problems concerned with M. pneumoniae disease which are impractical or impossible to resolve in the human host.

Fulminant Mycoplasma pneumoniae pneumonia

The frequency of fulminant pneumonia due to Mycoplasma pneumoniae is relatively rare despite the high prevalence of Mycoplasma species infection in the general population. We recently encountered such a case and have reviewed the English-language literature on cases of M pneumoniae pneumonia that have resulted in respiratory failure or death. Due to host factors or on epidemiologic grounds, fulminant cases seem to be more common in young healthy adults, in males, and possibly in smokers among the 46 patients we found. An enhanced host cellular immune response may be responsible for the development of severe cases. A spectrum of small airways disease is characteristic, including cellular bronchiolitis and bronchiolitis obliterans with and without organizing pneumonia. Based largely on anecdotal experience, corticosteroid use may be salutary in patients with respiratory failure. For reasons that are not well known, the incidence of pulmonary thromboembolism is increased in fatal cases.