[Clinical studies on acute otitis media in infants less than one year old]

Epidemiological and bacteriological studies were made on 164 infants less than 1 year old with acute otitis media (OMA) treated at the Department of Otorhinolaryngology, Matsuyama Red Cross Hospital between January 1991 and December 1993. The patients consisted of 101 males (61.6%) and 63 females (38.4%). Compared with the general population in Matsuyama city, the preponderance of male patients with OMA is statistically significant at the level of P = 0.05. In infants less than 1 year old males are likely to be more susceptible to OMA than females. One hundred and four patients among the 164 (63.4%) were referred by pediatricians. Fever was the most common symptom (57.9%) and the next was otorrhea (19.5%). Between the patients younger than 6 months (younger group) and those 6 months old or older (older group) there were epidemiological differences which were statistically significant at the level of P = 0.05. The older group contained 128 patients (78.0%) and the younger group 36 (22.0%). The difference in incidence between the two groups indicates that infants 6 months old or older are more susceptible to OMA than those younger than 6 months. In the older group 76.6% of the patients had bilateral OMA, while in 38.9% of those in the younger group the OMA was bilateral. In infants 6 months old or older bilateral involvement and, in contrast, in infants younger than 6 months unilateral involvement was more frequent. The period needed to cure OMA was confirmed for 179 ears of 106 patients. For 80 (44.7%) of the 179 ears the period extended beyond 4 weeks. Seventy-five of the 80 ears were those of patients in the older group. OMA in the older group tended to be more resistant to treatment. The middle ear secretion of 117 ears was examined bacteriologically. Specimens were collected from middle ear effusion of 99 ears following myringotomy and from otorrhea in 18 ears. Cultures of 68 specimens were positive for one species of bacteria and 13 cultures yielded two species. Streptococcus pneumoniae, Staphylococcus epidermidis and Haemophilus influenzae were the three most common microorganisms in middle ear effusion. But it was considered that S. spidermidis was not pathogenic and was a result of contamination. In otorrhea S. aureus was frequently found. No difference in the results of bacteriological study was noted between the two groups. Transplacental IgG1 and IgG2 antibodies to S. pneumoniae and H. influenzae are known to decrease after birth and their serum levels are lowest between ages 6 months and 1 year. Then the serum levels of the immunoglobulins increase gradually with active production until age 4 years. The incidence and period of restitution of OMA in infants less than 1 year old in the present study seem to reflect the above Change in the serum levels of IgG1 and IgG2 mentioned. Based on the above results emphasis is placed on close cooperation between the otolaryngologist and the pediatrician in the treatment of OMA in an infant less than 1 year old. Particularly careful follow-up is important in patients in the older age group because they tend to be more susceptible to OMA and the disease is more resistant to treatment.