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Moraxella catarrhalis Might Be More Common than Expected in Acute Otitis Media in Young Finnish Children.

ABSTRACT: According to studies based on bacterial cultures of middle ear fluids, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis have been the most common pathogens in acute otitis media. However, bacterial culture can be affected by reduced viability or suboptimal growth of bacteria. PCR detects bacterial DNA from samples with greater sensitivity than culture. In the present study, we analyzed the middle ear pathogens with both conventional culture and semiquantitative real-time PCR in 90 middle ear fluid samples obtained from children aged 5 to 42 months during acute otitis media episodes. Samples were tested for the presence of S. pneumoniae, H. influenzae, M. catarrhalis, Alloiococcus otitidis, Staphylococcus aureus, and Pseudomonas aeruginosa One or more bacterial pathogens were detected in 42 (47%) samples with culture and in 69 (77%) samples with PCR. According to PCR analysis, M. catarrhalis results were positive in 42 (47%) samples, H. influenzae in 30 (33%), S. pneumoniae in 27 (30%), A. otitidis in 6 (6.7%), S. aureus in 5 (5.6%), and P. aeruginosa in 1 (1.1%). Multibacterial etiology was seen in 34 (38%) samples, and M. catarrhalis was detected in most (85%) of those cases. Fifteen signals for M. catarrhalis were strong, suggesting a highly probable etiological role of the pathogen. In conclusion, even though M. catarrhalis is often a part of mixed flora in acute otitis media, a considerable proportion of cases may be primarily attributable to this pathogen.

SUBMITTER: Sillanpaa S

PROVIDER: S-EPMC5005485 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Moraxella catarrhalis Might Be More Common than Expected in Acute Otitis Media in Young Finnish Children.

Sillanpää Saara S Oikarinen Sami S Sipilä Markku M Kramna Lenka L Rautiainen Markus M Huhtala Heini H Aittoniemi Janne J Laranne Jussi J Hyöty Heikki H Cinek Ondrej O

Journal of clinical microbiology 20160713 9

According to studies based on bacterial cultures of middle ear fluids, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis have been the most common pathogens in acute otitis media. However, bacterial culture can be affected by reduced viability or suboptimal growth of bacteria. PCR detects bacterial DNA from samples with greater sensitivity than culture. In the present study, we analyzed the middle ear pathogens with both conventional culture and semiquantitative real-ti ...[more]

PMID: 27413187

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Project description:Limiting the duration of antimicrobial treatment constitutes a potential strategy to reduce the risk of antimicrobial resistance among children with acute otitis media.We assigned 520 children, 6 to 23 months of age, with acute otitis media to receive amoxicillin-clavulanate either for a standard duration of 10 days or for a reduced duration of 5 days followed by placebo for 5 days. We measured rates of clinical response (in a systematic fashion, on the basis of signs and symptomatic response), recurrence, and nasopharyngeal colonization, and we analyzed episode outcomes using a noninferiority approach. Symptom scores ranged from 0 to 14, with higher numbers indicating more severe symptoms.Children who were treated with amoxicillin-clavulanate for 5 days were more likely than those who were treated for 10 days to have clinical failure (77 of 229 children [34%] vs. 39 of 238 [16%]; difference, 17 percentage points [based on unrounded data]; 95% confidence interval, 9 to 25). The mean symptom scores over the period from day 6 to day 14 were 1.61 in the 5-day group and 1.34 in the 10-day group (P=0.07); the mean scores at the day-12-to-14 assessment were 1.89 versus 1.20 (P=0.001). The percentage of children whose symptom scores decreased more than 50% (indicating less severe symptoms) from baseline to the end of treatment was lower in the 5-day group than in the 10-day group (181 of 227 children [80%] vs. 211 of 233 [91%], P=0.003). We found no significant between-group differences in rates of recurrence, adverse events, or nasopharyngeal colonization with penicillin-nonsusceptible pathogens. Clinical-failure rates were greater among children who had been exposed to three or more children for 10 or more hours per week than among those with less exposure (P=0.02) and were also greater among children with infection in both ears than among those with infection in one ear (P<0.001).Among children 6 to 23 months of age with acute otitis media, reduced-duration antimicrobial treatment resulted in less favorable outcomes than standard-duration treatment; in addition, neither the rate of adverse events nor the rate of emergence of antimicrobial resistance was lower with the shorter regimen. (Funded by the National Institute of Allergy and Infectious Diseases and the National Center for Research Resources; ClinicalTrials.gov number, NCT01511107 .).

Project description:BACKGROUND:Moraxella catarrhalis is a leading cause of otitis media (OM) and chronic obstructive pulmonary disease (COPD). M. catarrhalis contains a Type III DNA adenine methyltransferase (ModM) that is phase-variably expressed (i.e., its expression is subject to random, reversible ON/OFF switching). ModM has six target recognition domain alleles (modM1-6), and we have previously shown that modM2 is the predominant allele, while modM3 is associated with OM. Phase-variable DNA methyltransferases mediate epigenetic regulation and modulate pathogenesis in several bacteria. ModM2 of M. catarrhalis regulates the expression of a phasevarion containing genes important for colonization and infection. Here we describe the phase-variable expression of modM3, the ModM3 methylation site and the suite of genes regulated within the ModM3 phasevarion. RESULTS:Phase-variable expression of modM3, mediated by variation in length of a 5'-(CAAC)n-3' tetranucleotide repeat tract in the open reading frame was demonstrated in M. catarrhalis strain CCRI-195ME with GeneScan fragment length analysis and western immunoblot. We determined that ModM3 is an active N6-adenine methyltransferase that methylates the sequence 5'-ACm6ATC-3'. Methylation was detected at all 4446 5'-ACATC-3' sites in the genome when ModM3 is expressed. RNASeq analysis identified 31 genes that are differentially expressed between modM3 ON and OFF variants, including five genes that are involved in the response to oxidative and nitrosative stress, with potential roles in biofilm formation and survival in anaerobic environments. An in vivo chinchilla (Chinchilla lanigera) model of otitis media demonstrated that transbullar challenge with the modM3 OFF variant resulted in an increased middle ear bacterial load compared to a modM3 ON variant. In addition, co-infection experiments with NTHi and M. catarrhalis modM3 ON or modM3 OFF variants revealed that phase variation of modM3 altered survival of NTHi in the middle ear during early and late stage infection. CONCLUSIONS:Phase variation of ModM3 epigenetically regulates the expression of a phasevarion containing multiple genes that are potentially important in the progression of otitis media.

Dataset Information

Moraxella catarrhalis Might Be More Common than Expected in Acute Otitis Media in Young Finnish Children.

Publications

Moraxella catarrhalis Might Be More Common than Expected in Acute Otitis Media in Young Finnish Children.

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