Mycoplasma pneumoniae-associated nephritis in children

Mycoplasma pneumoniae infection is a rare cause of acute nephritis. Six chi ldren (2 girls) aged 5-10 years, admitted for nephritis, had serological te sts showing recent Mycoplasma pneumoniae infection. The diagnosis of Mycopl asma pneumoniae infection was based on the presence of serum IgM, detected either by immunofluorescence (IF) (n=1) or enzyme-linked immunosorbent assa y (n=5). Four children had a renal biospy, with analysis of parenchymal Myc oplasma pneumoniae components by indirect IF and polymerase chain reaction. Extrarenal symptoms were: respiratory (n=3), ear, nose, and throat (n=2), gastrointestinal (n=3), hepatic (n=1), neurological (n=1), articular (n=1), and hematological (n=3). The patients presented with acute nephritis (1 ha d a nephrotic syndrome) or with acute renal failure and proteinuria. Pathol ogical findings included type 1 membranoproliferative glomerulonephritis (M PGN, n=1), proliferative endocapillary glomerulonephritis (n=2), and minima l change disease (n=1). The patient with type I MPGN progressed rapidly tow ards end-stage renal failure because of a congenital solitary kidney. Among the patients with endocapillary glomerulonephritis, 1 relapsed 6 months la ter and remained proteinuric, while the other recovered, as did the child w ith minimal change disease. The search for Mycoplasma pneumoniae antigens a nd nucleic acids in renal tissue was negative. However, the absence of the microorganism in the kidney is a common feature of post-streptococcal glome rulonephritis. We conclude that Mycoplasma pneumoniae is a rare yet potenti al cause of acute glomerulonephritis.