[Mechanisms of disease in Mycoplasma pneumoniae infection. Clinical manifestations and complications].
BACKGROUND
Mycoplasma pneumonia has been related to several conditions. With this study we have tried to establish the condition more frequently associated and their physiopathological mechanism.


METHODS
One-hundred and five patients admitted to Puerta de Hierro Hospital between March 1996 and July 2001, with IgM positive serology to Mycoplasma were evaluated. Thirty four cases were selected upon the basis of two criteria: patients which positivity was confirmed by seroconversion, elevation of the antibody titer, or confirmation by complement fixation were included, and patients with some intercurrent condition or with other diagnoses were ruled out.


RESULTS
26 patients (77%) showed a respiratory infection, and 20 of them showed a pneumonia. Two types of complications were observed. The first type were the complications due to an invasion of the tissue by Mycoplasma, with 5 cases of pleuropericarditis and three cases of pleuritis; in 5 of these there was simultaneously a respiratory process. The second type were the complications mediated by an autoimmune mechanism, with two cases of reactive arthritis, one case of vasculitis with cutaneous predominance, one case of urticaria a frigore, three cases of lymphocytic meningitis, one case of disseminated encephalitis, one patient with Guillain-Barré syndrome and one case of Adie's tonic pupil. Six of these patients showed a respiratory infection on the previous days with an average delay of 10 days between the beginning of the respiratory symptomatology and the appearance of one of these diseases.


CONCLUSIONS
Mycoplasma pneumoniae can give rise to disease through a mechanism of direct invasion and through autoimmunity mechanisms. The second group of complications is seen by more frequency in young women.
Servicio de Medicina Interna II, Clínica Puerta de Hierro, Madrid. hevio@msn.com
F
F
Blasco Patiño
R
R
Pérez Maestu
J M
JM
López de Letona
D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D016918:Arthritis, Reactive / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification*; D010493:Pericarditis / Q000209:etiology*; D010998:Pleurisy / Q000209:etiology*; D011019:Pneumonia, Mycoplasma / Q000150:complications* / Q000276:immunology; D012698:Serologic Tests; D014657:Vasculitis / Q000209:etiology*
D000907:Antibodies, Bacterial