Outbreak of Mycoplasma pneumoniae infection among hospital personnel studied by a nucleic acid hybridization test.

An outbreak of Mycoplasma pneumoniae (MP) infection occurred during the period March-May 1989 among the personnel of the Accident and Emergency Department of the Kuopio University Hospital, Kuopio, Finland. The index patient was a young male orderly, who fell ill with severe pneumonia. His tracheal mucus sample proved to be strongly positive for MP when tested by a commercial DNA-RNA hybridization test (Gen-Probe). After the index patient two additional staff members (an orderly and a nurse) fell ill with pneumonia and 66 others showed symptoms of upper respiratory infection or fever. The most frequent symptoms were a sore throat, a cough, rhinitis and headaches. All 97 employees of the department were tested for the presence of MP in April-May 1989 using throat swabs as test material. Forty-three (44%) were found to be positive for MP by the 'Gen-Probe' test. Eight (19%) of the MP positive staff were completely asymptomatic. The MP positive staff were retested about 3 weeks later, whereupon 40 (93%) had become negative. Most of the persons involved in this outbreak suffered only from mild respiratory symptoms, suggesting that MP outbreaks like the present one may easily pass unnoticed.