Differences in Primary Sites of Infection between Zoonotic and Human Tuberculosis: Results from a Worldwide Systematic Review

Tuberculosis (TB) is one of the most devastating infectious diseases worldwide. Whilst global burden estimates for M. tuberculosis infection (MtTB) are well established, accurate data on the contribution of zoonotic TB (zTB) caused by M. bovis or M. caprae to human TB are scarce. The association of M. bovis infection with extrapulmonary tuberculosis has been suggested repeatedly, though there is little scientific evidence available to support this relationship. The present study aimed to determine globally the occurrence of extrapulmonary TB and the primary site (i.e. primary body location affected) of zTB in comparison with MtTB, based on previously published reports. A systematic literature review was conducted in 32 different bibliographic databases, selecting reports on zTB written in English, French, German, Spanish or Portuguese. Data from 27 reports from Africa, America, Europe and the Western Pacific Region were extracted for analyses. Low income countries, in Africa and South-East Asia, were highly underrepresented in the dataset. The median proportion of extrapulmonary TB cases was significantly increased among zTB in comparison with data from registries of Europe and USA, reporting mainly MtTB cases (47% versus 22% in Europe, 73% versus 30% in the USA). These findings were confirmed by analyses of eight studies reporting on the proportions of extrapulmonary TB in comparable populations of zTB and MtTB cases (median 63% versus 22%). Also, disparities of primary sites of extrapulmonary TB between zTB and MtTB were detected. Our findings, based on global data, confirm the widely suggested association between zTB and extrapulmonary disease. Different disability weights for zTB and MtTB should be considered and we recommend separate burden estimates for the two diseases.     

Cytokines in Mycoplasma pneumoniae infections

Mycoplasma pneumoniae (M. pneumoniae) is one of the smallest free-living bacteria known. Along with other unique characteristics of this genus, it lacks the typical peptidoglycan cell wall of most eubacteria. Best known for causing tracheobronchitis and atypical pneumonia in humans, this pathogen also causes a number of extrapulmonary syndromes such as meningitis/encephalitis and arthritis. Recent studies also suggest that infection may be associated with chronic conditions such as asthma. Although the mechanisms of M. pneumoniae pathogenesis remain to be elucidated, one important component of M. pneumoniae infections is the induction of proinflammatory and other cytokines in both acute and chronic conditions. In this review, we survey the induction of cytokines by M. pneumoniae in different model systems, and we discuss the possible role of induced cytokines in M. pneumoniae pathogenesis.     

Manifestations and complications of Mycoplasma pneumoniae disease: a review

Over the past 20 years the annual number of reports on extrapulmonary symptoms during Mycoplasma (M.) pneumoniae disease has increased. Clinical and epidemiological data indicate that symptoms from the skin and mucous membranes, from the central nervous system, from the heart, and perhaps from other organs as well are not quite uncommon manifestations of M. pneumoniae disease. Reports on unusual courses of the disease have also accumulated, including cases of severe respiratory symptoms, sometimes seen in patients with underlying disease or with a concomitant viral infection. Serious extrapulmonary manifestations have been common in fatal cases of M. pneumoniae disease. Some observations and experimental data on these manifestations and on the possible pathogenic mechanisms are dealt with. The conclusion is that such mechanisms are still largely unknown.     

A comparison of glycan expression and adhesion of mouse-adapted strains and clinical isolates of Helicobacter pylori

The role of Mycoplasma pneumoniae infection as a trigger for asthma exacerbations is well supported in previous studies. This study was designed to investigate the role of M. pneumoniae infection in acute exacerbation of asthma in children. A total of 150 patients (110 males, 40 females) were studied and immunoglobulin M (IgM) antibodies to M. pneumoniae were detected by enzyme-linked immunosorbent assay (ELISA), and PCR amplification was performed for the P1 gene to associate M. pneumoniae infection with asthma. As compared with 33 children with asthma, only two of the control subjects had positive IgM titers for M. pneumoniae , which was statistically significant ( P =0.002). A total of 15 children with asthma were positive by PCR for the P1 gene while none of the controls had a positive PCR. Of these positive cases, 24 cases were positive only by ELISA, six were positive only by PCR and nine patients were found to be positive by both ELISA and PCR. All the clinical characteristics of the patients at baseline were comparable between the moderate and the severe group of patients statistically, except for the peak expiratory flow rate. Mycoplasma pneumoniae infection was found to have a significant association with acute exacerbation in the moderate group of asthma patients by PCR ( P =0.01). These data suggest that M. pneumoniae infection may contribute to asthma exacerbation.     

The spread of Mycoplasma pneumoniae is polyclonal in both an endemic setting in France and in an epidemic setting in Israel

Mycoplasma pneumoniae infections occur both endemically and epidemically, and macrolide resistance has been spreading for 10 years worldwide. A substantial increased incidence of M. pneumoniae infections has been reported in several countries since 2010. Whether this increased incidence is attributed to different or to the same M. pneumoniae genotype is unknown. We have developed a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) for the molecular typing of M. pneumoniae isolates. In this study, the MLVA typing method was modified and validated to be applicable directly to respiratory tract specimens without culture. This method was applied to 34 M. pneumoniae-positive specimens received at the Bordeaux Hospital, France, between 2007 and 2010 in an endemic setting, and to 63 M. pneumoniae-positive specimens collected during an epidemic surge of M. pneumoniae infections in 2010 in Jerusalem, Israel. The M. pneumoniae endemic spread was shown to be polyclonal in France, with 15 MLVA types identified. Strikingly, the Israeli epidemic surge was also a multi-clonal phenomenon, with 18 circulating MLVA types. The macrolide resistance-associated substitution, A2058G, was found in 22% of the Israeli patients. Macrolide-resistant M. pneumoniae belonged to four MLVA types, the MLVA type Z being the most frequent one. An association between the MLVA type Z and macrolide resistance might exist since macrolide resistance was present or generated during the course of illness in all patients infected with this MLVA type. In conclusion, the discriminatory power of the MLVA showed that the spread of M. pneumoniae strains in France in an endemic setting was polyclonal as well as the surge of M. pneumoniae infections in Israel in 2010.     

Proteogenomic mapping as a complementary method to perform genome annotation

The accelerated rate of genomic sequencing has led to an abundance of completely sequenced genomes. Annotation of the open reading frames (ORFs) (i.e., gene prediction) in these genomes is an important task and is most often performed computationally based on features in the nucleic acid sequence. Using recent advances in proteomics, we set out to predict the set of ORFs for an organism based principally on expressed protein-based evidence. Using a novel search strategy, we mapped peptides detected in a whole-cell lysate of Mycoplasma pneumoniae onto a genomic scaffold and extended these "hits" into ORFs bound by traditional genetic signals to generate a "proteogenomic map". We were able to generate an ORF model for M. pneumoniae strain FH using proteomic data with a high correlation to models based on sequence features. Ultimately, we detected over 81% of the genomically predicted ORFs in M. pneumoniae strain M129 (the originally sequenced strain). We were also able to detect several new ORFs not originally predicted by genomic methods, various N-terminal extensions, and some evidence that would suggest that certain predicted ORFs are bogus. Some of these differences may be a result of the strain analyzed but demonstrate the robustness of protein analysis across closely related genomes. This technique is a cost-effective means to add value to genome annotation, and a prerequisite for proteome quantitation and in vivo interaction measures.     

Susceptibility of newly established mouse strain MPS to Mycoplasma pneumoniae infection

A newly established mouse strain, MPS, which is more sensitive to Mycoplasma pulmonis than ICR, ddY and other mouse strains was examined for its susceptibility to Mycoplasma pneumoniae. In experimental infections with M. pneumoniae, it was observed that M. pneumoniae attached to tracheas of MPS mice, and M. pneumoniae cells were isolated from tracheas and lungs of MPS mice even after four weeks of infection, while no mycoplasmas were isolated from ICR and ddY mice after one week of infection. Specific antibodies against M. pneumoniae were also observed by the Western blotting in the sera of MPS mice infected with M. pneumoniae. Although any lung lesion could not be observed in this work, this newly established mouse strain MPS may be useful for experiments of M. pneumoniae infection, especially for the analysis of strain differences in susceptibility to M. pneumoniae infection.     

Epidemiologic aspects of M. pneumoniae disease complications: a review

As early as the 1940s, erythema multiforme exudativum (Stevens-Johnson syndrome) and hemolytic anemia were associated with outbreaks of atypical pneumonia, a disease later found to be caused by Mycoplasma pneumoniae. Epidemiologic evidence has also associated neurological complications, especially aseptic meningitis and meningoencephalitis, with M. pneumoniae infections. Urticarial and morbilliform skin rashes often appear late in the course of M. pneumoniae pneumonia. A multitude of other complications have been ascribed to M. pneumoniae infections, often reported as case reports diagnosed by serologic antibody titers only. More systematic investigations are needed to assess the frequency of complications to M. pneumoniae infections. Isolation of the agent, not only serologic titer rises, should be required before a syndrome is attributed to M. pneumoniae infection.     

Observations on the occurrence of mycoplasmas in the central nervous system of some laboratory animals

Mycoplasma pulmonis was isolated from the brains of 6 (23%) of 26 mice which had a naturally-occurring respiratory infection with this mycoplasma, and from the brains of 6 (8%) of 71 mice which had been inoculated intranasally or intravenously. The incidence of natural infection was greater in older mice, but there was no obvious mouse strain difference except for higher incidence in athymic nudes. There was no evidence that the organisms passed the blood-brain barrier. Some isolations, especially from nudes, may have been extraneous contaminants, as these were fewer when the mouse skulls were sterilized with ignited methanol. M. pneumoniae was not isolated from the brains of 14 hamsters which had a respiratory infection after intranasal inoculation nor were ureaplasmas isolated from the cerebrospinal fluids of 12 marmosets with a natural oropharyngeal infection. The aetiology of M. pneumoniae encephalitis in man is discussed.     

Tuberculosis in patients with human immunodeficiency virus infection. Review of current concepts.

Tuberculosis is a frequent complication of human immunodeficiency virus (HIV)-induced immunosuppression. The diagnosis of extrapulmonary tuberculosis in patients with evidence of HIV infection qualifies as a criterion of the acquired immunodeficiency syndrome. Demographic characteristics of patients with tuberculosis and HIV infection vary by region and reflect the degree to which patients with Mycobacterium tuberculosis infection adopt behaviors that put them at risk for HIV infection. The clinical features of tuberculosis in patients with HIV infection are atypical. Extrapulmonary disease, tuberculin anergy, and unusual findings on chest radiographs occur most frequently when tuberculosis afflicts patients with other clinical evidence of HIV infection at the time tuberculosis is diagnosed. Treatment is effective for tuberculosis in HIV-seropositive patients, and isoniazid prophylaxis is recommended for HIV-infected patients with positive tuberculin skin tests.     

Interactions between Streptococcus pneumoniae and influenza virus: a mutually beneficial relationship?

Historically, most research on infectious diseases has focused on infections with single pathogens. However, infections with pathogens often occur in the context of pre-existing viral and bacterial infections. Clinically, this is of particular relevance for coinfections with Streptococcus pneumoniae and influenza virus, which together are an important cause of global morbidity and mortality. In recent years new evidence has emerged regarding the underlying mechanisms of influenza virus-induced susceptibility to secondary pneumococcal infections, in particular regarding the sustained suppression of innate recognition of S. pneumoniae. Conversely, it is also increasingly being recognized that there is not a unidirectional effect of the virus on S. pneumoniae, but that asymptomatic pneumococcal carriage may also affect subsequent influenza virus infection and the clinical outcome. Here, we will review both aspects of pneumococcal influenza virus infection, with a particular focus on the age-related differences in pneumococcal colonization rates and invasive pneumococcal disease.     

Protective immune responses in mice induced by intramuscular and intranasal immunization with a Mycoplasma pneumoniae P1C DNA vaccine

Mycoplasma pneumoniae is an important causative agent of atypical pneumonia. This study was to determine the ability of a DNA expression vector, which encodes the carboxy terminal region of the M. pneumoniae P1 protein (P1C), to induce humoral and cellular immune responses and to protect against M. pneumoniae infection in BALB/c mice. Mice were immunized with pcDNA3.1/P1C by either intramuscular injection (i.m.) or intranasal inoculation (i.n.). Our results showed that p1c DNA immunization generates detectable antibodies specific to M. pneumoniae, and elicits high levels of IgG1, IgG2a, and IgG2b isotypes (P?< 0.01). The levels of IFN-γ and IL-4 in spleen cells of the immunized mice were significantly elevated by immunization via both the i.m. and i.n. methods. Moreover, p1c DNA-immunized mice exhibited detectable protection against M. pneumoniae infection. The lung tissue inflammation was relieved and the histopathologic score (HPS) of pcDNA3.1/P1C-immunized mice was significantly decreased than those in phosphate-buffed saline (PBS) or vaccine-vector-immunized mice (P?< 0.01), whereas there were no significant differences in HPS between i.m. and i.n. vaccination (P?> 0.05). Our results suggest that pcDNA3.1/P1C could be useful for developing a vaccine against M. pneumoniae infection.     

Comparison of the efficacy of egg yolk extract and horse serum for growth of Mycoplasma pneumoniae

The usefulness of chicken egg yolk extract as a substitute for horse serum in culture media for Mycoplasma pneumoniae was investigated. As a growth-supporting factor in the growth medium for M. pneumoniae and some other mycoplasmal species, the primary isolation medium for M. pneumoniae, and the metabolism-inhibition test medium for diagnosis of M. pneumoniae infection, egg yolk extract may be an excellent substitute for horse serum. The particular superiority of egg yolk extract to horse serum is that egg yolk extract, unlike horse serum, did not show any inhibitory effect on the growth of M. pneumoniae.     

T-bet deficiency facilitates airway colonization by Mycoplasma pulmonis in a murine model of asthma

Epidemiological and clinical evidence suggest a correlation between asthma and infection with atypical bacterial respiratory pathogens. However, the cellular and molecular underpinnings of this correlation remain unclear. Using the T-bet-deficient (T-bet(-/-)) murine model of asthma and the natural murine pathogen Mycoplasma pulmonis, we provide a mechanistic explanation for this correlation. In this study, we demonstrate the capacity of asthmatic airways to facilitate colonization by M. pulmonis and the capacity of M. pulmonis to exacerbate symptoms associated with acute and chronic asthma. This mutual synergism results from an inability of T-bet(-/-) mice to mount an effective immune defense against respiratory infection through release of IFN-gamma and the ability of M. pulmonis to trigger the production of Th2-type cytokines (e.g., IL-4 and IL-5), and Abs (e.g., IgG1, IgE, and IgA), eosinophilia, airway remodeling, and hyperresponsiveness; all pathophysiological hallmarks of asthma. The capacity of respiratory pathogens such as Mycoplasma spp. to dramatically augment the pathological changes associated with asthma likely explains their association with acute asthmatic episodes in juvenile patients and with adult chronic asthmatics, >50% of whom are found to be PCR positive for M. pneumoniae. In conclusion, our study demonstrates that in mice genetically predisposed to asthma, M. pulmonis infection elicits an inflammatory milieu in the lungs that skews the immune response toward the Th2-type, thus exacerbating the pathophysiological changes associated with asthma. For its part, airways exhibiting an asthmatic phenotype provide a fertile environment that promotes colonization by Mycoplasma spp. and one which is ill-equipped to kill and clear respiratory pathogens.     

Antibodies anti-Chlamydia pneumoniae and anti-Mycoplasma pneumoniae in patients with negative serology for hantavirus. Retrospective study.

The seroprevalence of Chlamydia pneumoniae and Mycoplasma pneumoniae in hantavirus seronegative patients, who had symptoms and signs compatible with pneumonia was established. For this purpose we used the indirect fluorescent antibody test. Titers > or = 1:16 for C. pneumoniae and M. pneumoniae were found in 8.6% and 17.1% of the serum, respectively, showing evidence of recent or current infection.     

A latex agglutination test for the detection of Mycoplasma pneumoniae in respiratory exudates: a comparative study with a commercially available DNA-probe test.

We prepared polyclonal antibody specific to Mycoplasma pneumoniae. Using this antibody, we developed a latex agglutination test (LAT) for detecting the organism in respiratory exudates as rapid diagnosis of M. pneumoniae infection. Further, LAT was compared with DNA-probe test (DP) which was the only commercially available test for the rapid detection of the organism. In LAT, both M. pneumoniae and M. genitalium give positive agglutination, but the titer of M. genitalium was significantly lower than that of M. pneumoniae. The detection limit of LAT was 2 x 10(5) CFU/ml and that of DP was 5 x 10(4) CFU/ml in vitro. It was considered that target molecules in LAT were accumulated in the pharyngeal portion of the patients, because of their long half-life at 37 C. However, ribosomal RNA which was target molecule in DP was destroyed at 37 C much sooner, and the accumulation could not be expected. Actually, positive rate in LAT was higher than that in DP among clinical specimens in which M. pneumoniae was detected by culture method. The procedure of LAT is much easier and more rapid than that of DP in which radioactive isotope is required. LAT could be the choice of test for rapid diagnosis of M. pneumoniae infection.     

Mycoplasma pneumoniae infection induces a neutrophil-derived antimicrobial peptide, cathelin-related antimicrobial peptide

In innate immunity, cationic antimicrobial peptides including cathelin-related antimicrobial peptide (CRAMP) are known to play critical roles in protecting the host from infection by invasive microbes, including Gram-positive and -negative bacteria. However, little is known about the interactions between CRAMP and mycoplasmas. In the present study, the antimicrobial activity of CRAMP against M. pneumoniae and the expression of CRAMP in bronchoalveolar lavage fluid (BALF) of M. pneumoniae-infected mice was examined. CRAMP at 10-20 μg/mL reduced the growth of two strains of M. pneumoniae by 100 to 1000-fold. The amount of CRAMP in the BALF of M. pneumoniae-infected mice was 20～25 ng/mL by ELISA. The presence of mature CRAMP in BALF was observed by Western blotting. Neutrophils in BALF showed a fair amount of CRAMP in their cytoplasm by immunofluorescence. Furthermore, the addition of M. pneumoniae resulted in the release of a large amount of CRAMP from neutrophils induced by thioglycolate. These results suggest that CRAMP from neutrophils may play an important role in protection against M. pneumoniae infection.     

Role of Mincle in Alveolar Macrophage-Dependent Innate Immunity against Mycobacterial Infections in Mice

The role of macrophage-inducible C-type lectin Mincle in lung innate immunity against mycobacterial infection is incompletely defined. In this study, we show that wild-type (WT) mice responded with a delayed Mincle induction on resident alveolar macrophages and newly immigrating exudate macrophages to infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG), peaking by days 14-21 posttreatment. As compared with WT mice, Mincle knockout (KO) mice exhibited decreased proinflammatory mediator responses and leukocyte recruitment upon M. bovis BCG challenge, and they demonstrated increased mycobacterial loads in pulmonary and extrapulmonary organ systems. Secondary mycobacterial infection on day 14 after primary BCG challenge led to increased cytokine gene expression in sorted alveolar macrophages of WT mice, but not Mincle KO mice, resulting in substantially reduced alveolar neutrophil recruitment and increased mycobacterial loads in the lungs of Mincle KO mice. Collectively, these data show that WT mice respond with a relatively late Mincle expression on lung sentinel cells to M. bovis BCG infection. Moreover, M. bovis BCG-induced upregulation of C-type lectin Mincle on professional phagocytes critically shapes antimycobacterial responses in both pulmonary and extrapulmonary organ systems of mice, which may be important for elucidating the role of Mincle in the control of mycobacterial dissemination in mice.     

A deficient TLR2 signaling promotes airway mucin production in Mycoplasma pneumoniae-infected allergic mice

The original hygiene hypothesis suggests that early childhood respiratory infections preceding allergen exposure may decrease the prevalence of allergic diseases. We have recently demonstrated that Mycoplasma pneumoniae infection preceding allergen exposure reduced allergic responses in mice. However, the molecular mechanisms underlying the protective role of M. pneumoniae in allergic responses, particularly airway mucin production, remain unclear. Wild-type and Toll-like receptor 2 (TLR2)-deficient mice with a respiratory M. pneumoniae infection preceding allergen (ovalbumin) challenge were utilized to determine the regulatory role of TLR2-IFN-gamma signaling pathway in airway mucin expression. Furthermore, air-liquid interface cultures of mouse primary tracheal epithelial cells were performed to examine the effects of IFN-gamma on mucin expression. In wild-type mice, M. pneumoniae infection preceding allergen challenge significantly reduced airway mucins but increased IFN-gamma. In sharp contrast, in TLR2-deficient mice, M. pneumoniae preceding allergen challenge resulted in increased mucin protein without a noticeable change of IFN-gamma. In cultured mouse primary tracheal epithelial cells, IFN-gamma was shown to directly inhibit mucin expression in a dose-dependent manner. Our study demonstrates for the first time that a respiratory M. pneumoniae infection preceding allergen challenge reduces airway epithelial mucin expression in part through TLR2-IFN-gamma signaling pathway. A bacterial infection in asthmatic subjects with weakened TLR2-IFN-gamma signaling may result in an exaggerated airway mucin production.     

The landscape of extrapulmonary manifestations of human parainfluenza viruses: A systematic narrative review

Human parainfluenza virus (HPIV) infection is associated with every kind of respiratory tract illnesses, including the common cold, laryngotracheobronchitis (i.e. croup), tracheobronchitis, bronchiolitis, and pneumonia, in both children and adults. Although HPIVs are common respiratory pathogens, there are increasing reports about extrapulmonary manifestations of HPIVs infection. Each of the HPIVs could produce infection of other organs (central nervous system, heart, myocardium, etc.) in all age groups who are either immunocompetent or immunocompromised. This review aimed at summarizing the available data on clinical manifestations of HPIV infection outside the respiratory tract from 1961 to 2020. The findings support the possibility of extrapulmonary infections that were thought to be due to rare host genetic or immunologic defects in infected patients. These findings highlight the fact that extrapulmonary dissemination of HPIV can occur, but the association is not clearly demonstrated. Our data support the hypothesis that HPIV infection is one of the possible causes of these alterations and may even be the direct cause in some cases.