A retrospective evaluation of microbiology of acute otitis media complicated by spontaneous otorrhea in children living in Milan, Italy

PURPOSE: To evaluate the microbiology of acute otitis media (AOM) with otorrhea due to spontaneous tympanic membrane perforation (STMP) in children living in Milan, Italy. METHODS: We evaluated middle ear fluid (MEF) specimens taken from children affected by AOM associated with STMP and otorrhea between January 2001 and December 2011. The fluid was collected by means of direct swab sampling, sent for culture, and processed within 4 h. RESULTS: A total of 705 specimens were obtained from 458 children (233 boys; mean age ± SD 28.3 ± 19.9 months), and were positive for bacteria in 487 cases (69.1 %). The most frequently cultured infectious agent in single-pathogen cultures was Haemophilus. influenzae (51.0 %), followed by Streptococcus pneumoniae (19.4 %), Streptococcus pyogenes (17.4 %), and Staphylococcus aureus (10.7 %). After adjusting for the sub-period of data collection, age, gender, and previous full heptavalent pneumococcal conjugate vaccine (PCV-7) schedule, it was found that the prevalence of H. influenzae slightly increased in 2008-2010, and the prevalence of S. pneumoniae significantly decreased over time (p = 0.02). CONCLUSIONS: AOM with STMP is a particular form of AOM in which S. pyogenes plays a significant causative role although, as in uncomplicated cases, H. influenzae and S. pneumoniae retain their etiological importance. The frequency of the detection of S. aureus in MEF deserves further study because this pathogen can give rise to severe clinical problems. Finally, although the use of PCV-7 was relatively efficacious, the benefit of pneumococcal vaccination would be increased by vaccines including a larger number of serotypes