Abstract
Over a six-month period we studied 74 adult Nigerians who presented consecutively to Ahmadu Bello University Teaching Hospital, Zaria, with lobar or segmental pneumonia. Pneumococcal infection was diagnosed in 50% by the detection of pneumococcal polysaccharide antigen in serum or purulent sputum: 24% had pneumococcal antigenaemia. Twelve patients had evidence of Mycoplasma pneumoniae infection and half of these also had pneumococcal infection. The suggestion that M pneumoniae respiratory infection may predispose to serious bacterial pneumonia is discussed. The initial clinical and radiological features were similar in the pneumococcal and M pneumoniae groups. Raised cold agglutinin titres were not a reliable indication of M pneumoniae infection, perhaps due to altered autoantibody production in Nigerians. Pneumonia was commoner in the dry season, probably related to depressed nasopharyngeal defences caused by drying. Less common causes of lobar pneumonia that were found are also discussed and no cases of legionnaires' disease were identified.