Non-typeable Haemophilus influenzae and Streptococcus pneumoniae as primary causes of acute otitis media in colombian children: a prospective study

Abstract

Background: Acute otitis media (AOM) is one of the most frequently encountered bacterial infections in children aged < 5 years; Streptococcus pneumoniae (S. pneumoniae) and non-typeable Haemophilus influenzae (NTHi) are historically identified as primary AOM causes. Nevertheless, recent data on bacterial pathogens causing AOM in Latin America are limited. This prospective study aimed to identify and characterize bacterial etiology and serotypes of AOM cases including antimicrobial susceptibility in < 5 year old Colombian children.

Methods: From February 2008 to January 2009, children ≥3 months and < 5 years of age presenting with AOM and for whom a middle ear fluid (MEF) sample was available were enrolled in two medical centers in Cali, Colombia. MEF samples were collected either by tympanocentesis procedure or spontaneous otorrhea swab sampling. Bacteria were identified using standard laboratory methods, and antimicrobial resistance testing was performed based on the 2009 Clinical and Laboratory Standards Institute (CLSI) criteria. Most of the cases included in the study were sporadic in nature.

Results: Of the 106 enrolled children, 99 were included in the analysis. Bacteria were cultured from 62/99 (63%) of samples with S. pneumoniae, H. influenzae, or S. pyogenes. The most commonly isolated bacteria were H. influenzae in 31/99 (31%) and S. pneumoniae in 30/99 (30%) of samples. The majority of H. influenzae episodes were NTHi (27/31; 87%). 19F was the most frequently isolated pneumococcal serotype (10/30; 33%). Of the 30 S. pneumoniae positive samples, 8/30 (27%) were resistant to tetracycline, 5/30 (17%) to erythromycin and 8/30 (27%) had intermediate resistance to penicillin. All H. influenzae isolates tested were negative to beta-lactamase.

Conclusions: NTHi and S. pneumoniae are the leading causes of AOM in Colombian children. A pneumococcal conjugate vaccine that prevents both pathogens could be useful in maximizing protection against AOM.

Figure 1

Seasonal distribution of AOM episodes (ATP cohort). The stacked line graph shows the number of episodes enrolled in each month and the simple bar graph shows the number of S. pneumoniae and H. influenzae isolated each month.

Figure 2

Etiology of bacteria identified from samples cultured from middle ear fluid. Number of positive bacterial episodes is represented in the stacked column bar. The bar for H. influenzae also includes serotypes of H. influenzae positive episodes. * H. influenzae type b ** H. influenzae type f

Figure 3

Serotype distribution of S. pneumoniae (N = 30) positive isolates cultured from middle ear fluid samples. The pie chart shows each serotypes of S. pneumoniae with their respective percentage of positive episodes.

Figure 4

Antibacterial susceptibility of S. pneumoniae positive samples to penicillin (ATP cohort). The susceptibility of each S. pneumoniae serotype to penicillin for categories sensitive, intermediate and resistant. *Minimum Inhibitory Concentration