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[Identification of bacterial strain at each episode of recurrent acute otitis media]
M Suetake1, M Irimada, S Takahashi
1Department of Otolaryngology, Tohoku Rosai Hospital, Sendai.
Abstract:
This study was undertaken to investigate whether each episode of recurrent acute otitis media (rAOM) is caused by the same strain of bacteria or different strains at each episode. Seventy infants less than 3-years of age, having experienced rAOM for a period shorter than 8 weeks, were selected and included in the present study. The total number of AOM episodes experienced by this group was 282. At each subsequent episode of AOM, otorrhea and nasopharyngeal swabs were taken for bacterial culture and determination of the MIC for antibiotics. When S. pneumoniae was identified, its serotype, and its pbp, ermAM, and mefE genes were also investigated to determine the bacterial species and strains. S. pneumoniae was the most frequently cultured bacteria with 26 penicillin-sensitive S. pneumoniae (PSSP), 65 penicillin-insensitive S. pneumoniae (PISP), and 50 penicillin-resistant S. pneumoniae (PRSP). H. influenzae was the next most frequently cultured bacteria of which 65 were sensitive to penicillin, 27 were found to be beta-bactamase-negative-ampicillin-resistant (BLNAR) and 17 were found to be beta-bactamase positive. Bacteria cultured from each pair of two successive episodes of AOM were compared as to the identity of the bacteria during the two episodes. In 150 out of 202 pairs (74%), the cultured pathogen was different. In 22 cases in which either PISP or PRSP was the pathogen detected in two consecutive AOM episodes, 15 cases (68%) were found in which the involved strain differed between the two episodes. This study indicates that the pathogen involved in rAOM is likely to differ at each episode of AOM, not only in cases caused by PSSP, but also in those caused by PRSP.
Insights
Recurrent acute otitis media (rAOM) in infants is often caused by different bacterial strains in each episode, even with resistant bacteria like penicillin-resistant Streptococcus pneumoniae. This suggests varied microbial causes for recurring ear infections.
Area of Science:
- Microbiology
- Pediatric Infectious Diseases
Background:
- Recurrent acute otitis media (rAOM) poses a significant challenge in pediatric care.
- Understanding the microbial etiology of rAOM is crucial for effective treatment and prevention strategies.
Purpose of the Study:
- To investigate whether recurrent acute otitis media (rAOM) episodes are caused by the same or different bacterial strains.
- To analyze bacterial pathogens and their antibiotic resistance profiles in infants with rAOM.
Main Methods:
- Collected otorrhea and nasopharyngeal swabs from 70 infants with rAOM for bacterial culture.
- Determined antibiotic minimum inhibitory concentrations (MICs).
- Characterized Streptococcus pneumoniae strains by serotype and specific resistance genes (pbp, ermAM, mefE).
Main Results:
- In 74% of successive AOM episodes, the cultured pathogen differed.
- Even in cases involving penicillin-insensitive S. pneumoniae (PISP) or penicillin-resistant S. pneumoniae (PRSP), 68% of consecutive episodes involved different strains.
- Streptococcus pneumoniae was the most frequent pathogen, followed by Haemophilus influenzae.
Conclusions:
- The bacterial pathogen causing recurrent acute otitis media (rAOM) frequently differs between episodes.
- This finding applies to both susceptible and resistant bacterial strains, highlighting the dynamic nature of rAOM etiology.