STUDIES ON MYCOPLASMA PNEUMONIAE INFECTION IN SWEDEN

Pathogenesis of Mycoplasma pneumoniae: An update

Genus Mycoplasma, belonging to the class Mollicutes, encompasses unique lifeforms comprising of a small genome of 8,00,000 base pairs and the inability to produce a cell wall under any circumstances. Mycoplasma pneumoniae is the most common pathogenic species infecting humans. It is an atypical respiratory bacteria causing community acquired pneumonia (CAP) in children and adults of all ages. Although atypical pneumonia caused by M. pneumoniae can be managed in outpatient settings, complications affecting multiple organ systems can lead to hospitalization in vulnerable population. M. pneumoniae infection has also been associated with chronic lung disease and bronchial asthma. With the advent of molecular methods of diagnosis and genetic, immunological and ultrastructural assays that study infectious disease pathogenesis at subcellular level, newer virulence factors of M. pneumoniae have been recognized by researchers. Structure of the attachment organelle of the organism, that mediates the crucial initial step of cytadherence to respiratory tract epithelium through complex interaction between different adhesins and accessory adhesion proteins, has been decoded. Several subsequent virulence mechanisms like intracellular localization, direct cytotoxicity and activation of the inflammatory cascade through toll-like receptors (TLRs) leading to inflammatory cytokine mediated tissue injury, have also been demonstrated to play an essential role in pathogenesis. The most significant update in the knowledge of pathogenesis has been the discovery of Community-Acquired Respiratory Distress Syndrome toxin (CARDS toxin) of M. pneumoniae and its ability of adenosine diphosphate (ADP) ribosylation and inflammosome activation, thus initiating airway inflammation. Advances have also been made in terms of the different pathways behind the genesis of extrapulmonary complications. This article aims to comprehensively review the recent advances in the knowledge of pathogenesis of this organism, that had remained elusive during the era of serological diagnosis. Elucidation of virulence mechanisms of M. pneumoniae will help researchers to design effective vaccine candidates and newer therapeutic targets against this agent.

Outbreak of Mycoplasma pneumoniae-Associated Stevens-Johnson Syndrome

BACKGROUND

Stevens-Johnson syndrome (SJS) is an uncommon, sporadic disease and outbreaks are rare. In November 2013, an outbreak of SJS was identified at Children's Hospital Colorado.

METHODS

Outbreak cases were children aged 5-21 with a discharge diagnosis of SJS admitted from September 1 to November 30, 2013. Medical charts were reviewed using standardized data collection forms. Respiratory specimens were tested for viruses and Mycoplasma pneumoniae (Mp) by polymerase chain reaction (PCR). We conducted a separate 4-year retrospective case-control study comparing hospitalized SJS cases with and without evidence of Mp infection.

RESULTS

During the outbreak, 8 children met SJS criteria. Median age was 11.5 years (range 8-16 years); 5 (63%) were boys and 5 (63%) were Mp-PCR-positive. Of the 5 PCR-positive children, none had preceding medication exposure, and all had radiographic pneumonia. All outbreak Mp isolates were macrolide susceptible. The retrospective case-control analysis showed that Mp-associated SJS episodes (n = 17) were more likely to have pneumonia (odds ratio [OR] 7.5, confidence interval [CI] 1.6–35.1), preceding respiratory symptoms (OR 30.0, CI 3.3–269.4) [corrected] an erythrocyte sedimentation rate ≥35 mg/dL (OR 22.8, CI 2.1-244.9), and ≤3 affected skin sites (OR 4.5, CI 1.2-17.4) than non-Mp-associated SJS episodes (n = 23).

CONCLUSIONS

We report the largest outbreak of SJS in children, which was also predominately associated with Mp infection. Mp-associated SJS was associated with a distinct clinical presentation that included less extensive skin disease, an elevated erythrocyte sedimentation rate, and evidence of a preceding respiratory infection.

Frequency of Chlamydia pneumoniae and Mycoplasma pneumoniae infections in children

OBJECTIVE

Chlamydia pneumoniae and Mycoplasma pneumoniae are among the most important pathogens of acute respiratory infections in children between the ages of 5 and 15 years. We aimed to investigate seasonal frequency of respiratory infections caused by C. pneumoniae and M. pneumoniae, frequency of coinfection, clinical findings and to determine relationship between clinical findings and laboratory results.

MATERIAL AND METHODS

Total of 284 patients (ranging 5-15 years of age), admitted to out-patient clinic with symptoms of respiratory tract infections between January 2004 and June 2005, were enrolled in the study. IgA, IgG and IgM antibodies against C. pneumoniae were quantitatively detected in all serum samples by using microimmunofluorescence (MIF). For the M. pneumoniae infection an IgM titer in the ELISA test were analyzed. Nasopharyngeal smear samples were collected for PCR detection.

RESULTS

Mean age was 8 +/- 2.2 (range 5-14) years. Mycoplasma pneumoniae IgM in 86 (30.2%) cases, C. pneumoniae IgM in one (0.3%) case, IgA in six (2.1%) cases and IgG in 10 (3.5%) cases were found positive. In 10 (3.5%) cases, both C. pneumoniae IgG (a titer of >1/216) and M. pneumoniae IgM were found positive concomitantly. The M. pneumoniae IgM in winter was found significantly higher compared to other seasons. Mycoplasma pneumoniae PCR method was performed on a total of 203 samples in 33 (16.2%) of which M. pneumoniae was found positive. The false positive ratio of PCR technique was found 16.2%. In a total of 217 examined samples by PCR method, the DNA of C. pneumoniae was found positive in two patients.

CONCLUSION

Mycoplasma pneumoniae was a common pathogen in respiratory infections. The otherwise C. pneumoniae infections were rarely seen in children. A Comparison of serology diagnostic tests for M. pneumoniae infections was found more sensitive and specific than PCR.

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.

Severe necrotizing pneumonitis in a child with Mycoplasma pneumoniae infection

Lower respiratory tract illness due to Mycoplasma pneumoniae is typically mild and self-limited. There are, however, numerous reports of serious and life-threatening cases of mycoplasma pneumonia in adults. We present a case involving a 4-year-old girl with severe mycoplasma infection and necrotizing pneumonitis requiring lobectomy. A detailed pathological report is provided.

Central nervous system manifestations associated with serologically verified Mycoplasma pneumoniae infection

Among 560 hospitalized patients with serologically verified Mycoplasma pneumoniae infection (significant titre rise of complement-fixing antibodies in paired sera), 27 (4.8%) had central nervous system (CNS) manifestations for which no evidence incriminating any other causal agent could be found. Of these patients 18 had encephalitis or meningoencephalitis, 8 aseptic meningitis and 1 polyradiculitis. Of the patients with meningoencephalitis 4 died and 3 had permanent sequelae. The cases of aseptic meningitis were benign without any deaths or sequelae. There was a predominance of young age groups, 13 patients (48%) being below 10 years of age. Neither erythromycin nor tetracycline had a beneficial effect on the course of the illness in a few patients treated. Another 15 patients had CNS manifestations for which an alternative aetiology was suspected. The specificity of the M. pneumoniae CF test in the diagnostics of CNS manifestations is discussed, as well as the pathogenesis of the CNS complications associated with M. pneumoniae infection. Some features are summarized from 87 case reports presented earlier in the literature.

Recurrent pneumonia and encephalitis due to Mycoplasma pneumoniae

Recurrent Mycoplasma pneumoniae encephalitis in a young man is reported. The patient appeared not to be immunodeficient and despite the presence of a focal inflammatory brain lesion with a predominance of polymorphonuclear cells no direct evidence of inent in M. pneumoniae respiratory tract infection still is unknown the case strongly indicates that certain individuals are somehow predisposed to such complications. The case also illustrates that CNS complications may occur even during a mild mycoplasma respiratory tract infection and that the radiological findings can mimic cerebral haemorrhage or abscess necessitating neurosurgical exploration.

Clinical and laboratory manifestations in patients with serological evidence of Mycoplasma pneumoniae infection

139 cases of Mycoplasma pneumoniae infection (serological diagnosis) were treated at Aurora Hospital, Helsinki, between January 1975 and August 1977. In 123 patients the main diagnosis was respiratory infection; 114 of these had pneumonia. The frequency of complications was high: 8 patients had neurologic, 6 cardiac and 5 joint symptoms. Although a significant rise in titre of complement-fixing antibodies to M. pneumoniae was required, the low titre level in some patients who had manifestations less frequently associated with M. pneumoniae infection may suggest nonspecific reactions. Nearly half of the patients in this study had plasmocytosis in the peripheral blood suggesting a strong antibody response. This might be connected with some serological reactions detected in association with M. pneumoniae infections.