Role of Mycoplasma pneumoniae in acute respiratory-tract infections in Saudi paediatric patients.

The role of Mycoplasma pneumoniae and viruses in the various clinical presentations of acute respiratory-tract infection (ARTI) was studied in Saudi children seen at King Khalid University Hospital (KKUH) between January 1995 and January 1996. The study population comprised 511 children (age < 14 years) of both sexes. Nasopharyngeal aspirates (NPA) and acute-phase sera were collected. Convalescent sera were only available from 334 of the patients (with an interval of 15-42 days between collection of the acute and corresponding convalescent sera). Respiratory syncytial virus (RSV) was the most commonly detected virus, found in 69% of patients. Mycoplasma pneumoniae, found in 9% of the patients, appeared to be the second most common causative agent (this is the first time the prevalence of this agent in ARTI among Saudi children has been studied), followed by influenza A virus (present in 8% of the patients). RSV was highly prevalent during the colder months (October-April), with a peak in January-February, whereas there was little seasonal fluctuation in the prevalence of M. pneumoniae. Although most (60%) of the M. pneumoniae infections were in patients aged > 60 months, RSV was detected in 22% of the patients aged 1-5 months of age and only in 6% of those aged > 60 months. Infection with M. pneumoniae was found mainly in children with broncho-pneumonia (12 cases) and lobar pneumonia (three cases). Most of those infected with RSV had bronchiolitis (53 cases), followed by broncho-pneumonia (24 cases) and bronchial asthma (20 cases). As their prevalences were low, it was difficult to draw any conclusions about possible associations between the other viral agents encountered (influenza, para-influenza and adenovirus) and clinical disease.