Over the past 10 years we have successfully isolated and identified 2658 strains of bacteria from middle ear otorrhea. Broadly classified, 1698 gram-positive cocci (63.8%), 822 gram-negative bacilli (30.9%), and 138 other strains (5.2%) were detected. Staphylococcus aureus and Pseudomonas aeruginosa accounted for the majority of gram-positive cocci (50.9%) and gram-negative bacilli (57.8%), respectively.
S. aureus was detected most frequently (37.0%) in cases of acute otitis media. In recent years, S. aureus has surpassed the identified number of pneumococcal and hemolytic streptococcal strains, highly prevalent in past years. However, pneumococci and hemolytic streptococci continued to be frequently found in children under 6 years of age, while S. aureus was most often isolated from children of age 6 and over.
Among 2813 strains isolated from cases of chronic otitis media, S. aureus accounted for 31.8%, Ps. aeruginosa for 19.2% and S. epidermidis for 17.0%.
Comparison of yearly fluctuations revealed the detection rate to be unchanged for S. aureus and reduced from 25% in 1963 to 16% in 1972 for Ps. aeruginosa.
S. aureus and Ps. aeruginosa were more frequently detected in cases undergoing surgery than those not. Mixed infections were present in 11.8% of patients with acute otitis media and 38.6% of patients with chronic otitis media.
Diptheroids were related to mixed infections in many patients and were found along with another type of bacteria in 95% of postoperative cases.
Substitution of the bacterial flora occurred about twice as frequently in postoperative cases than in those not operated on. The type of bacterial substitution was varied, but there was a tendency towards a transition from gram-positive cocci to gram-negative bacilli.
Drug sensitivity was determined using discs containing 3 drug concentrations. Susceptibility was higher than that in other reports. Although (+++) and (++) sensitive bacteria were regarded to be effective, clinically it is more reliable to consider (+++) sensitive bacteria as being susceptible. Sensitivity tests were carried out for S. aureus and Ps. aeruginosa. S. aureus was highly sensitive to cephaloridine and chloramphenicol. Hemolytic streptococci and pneumonocci were highly sensitive to every drug tested. Ps. aeruginosa exhibited high susceptibily to colistin and gentamicin. Colistin was effective for all gram-positive bacilli tested except Proteus and Proteus inconstans.
