Nasopharyngeal flora and acute otitis media

No evidence from a systematic review for the use of probiotics to prevent otitis media

AIM

This systematic review evaluates the current evidence for the use of probiotics in the prevention of acute otitis media (AOM) in children.

METHODS

This study is registered with PROSPERO prior to commencement. PubMed, MEDLINE, EMBASE and Cochrane database were searched using relating keywords. All literature was screened to determine relatability to the topic. Review articles were also screened for additional literature.

RESULTS

Thirteen studies were found on probiotics and their role in preventing AOM in children. They ranged in quality from poor to moderate. Half (2/4) of the studies that used nasal probiotic formulations showed a significant difference in reducing otitis media, while only a third (3/9) of the studies using oral formulations suggest benefit in reducing AOM. None of the studies demonstrated significant adverse effects from probiotics.

CONCLUSION

The evidence for any effect of probiotics on the prevention of AOM is limited, and the overall low quality of studies makes it difficult to draw definitive conclusions. No serious adverse events were noted, and there is some evidence to suggest possible benefit with nasal probiotic administration.

Streptococcus pneumoniae Otitis Media Pathogenesis and How It Informs Our Understanding of Vaccine Strategies

PURPOSE OF REVIEW

This study aimed to review the literature regarding the mechanisms of transition from asymptomatic colonization to induction of otitis media and how the insight into the pathogenesis of otitis media has the potential to help design future otitis media-directed vaccines.

RECENT FINDINGS

Respiratory viruses have long been shown to predispose individuals to bacterial respiratory infections, such as otitis media. Recent information suggests that Streptococcus pneumoniae, which colonize the nasopharynx asymptomatically, can sense potentially "threatening" changes in the nasopharyngeal environment caused by virus infection by upregulating specific sets of genes involved in biofilm release, dissemination from the nasopharynx to other sites, and protection against the host immune system. Furthermore, an understanding of the transcriptional and proteomic changes occurring in bacteria during transition to infection has led to identification of novel vaccine targets that are disease-specific and will not affect asymptomatic colonization. This approach will avoid major changes in the delicate balance of microorganisms in the respiratory tract microbiome due to elimination of S. pneumoniae.

SUMMARY

Our recent findings are reviewed in the context of the current literature on the epidemiology and pathogenesis of otitis media. We also discuss how other otopathogens, such as Haemophilus influenzae and Moraxella catarrhalis, as well as the normal respiratory microbiome, can modulate the ability of pneumococci to cause infection. Furthermore, the unsatisfactory protection offered by the pneumococcal conjugate vaccines is highlighted and we review potential future strategies emerging to confer a more specific protection against otitis media.

Recent epidemiology of Streptococcus pneumoniae in nasopharynxes of Korean children with acute otitis media

BACKGROUND

This prospective study was performed to evaluate serotype distribution, multilocus sequence typing, and antibiotic susceptibility of Streptococcus pneumoniae identified in Korean children with acute otitis media (AOM) after the introduction of a 7-valent pneumococcal conjugate vaccine (PCV7).

METHODS

Nasopharyngeal aspirates were collected from children diagnosed with AOM in seven hospitals in Korea. The bacteria identified in these samples and the serotypes, sequence types (STs), and antibiotic susceptibilities of S. pneumoniae isolates were evaluated.

RESULTS

A total of 390 children were enrolled, and bacteria were identified in 376 (96.4%) children. S. pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were identified in 155 (39.7%), 127 (32.6%) and 86 (22.1%) children, respectively. Serotype 19A (22.4%) was the most common S. pneumoniae serotype, with serogroups 11 (14.7%) and 15 (13.5%) following. ST320 (23.5%) was the most common ST; ST166 (17.0%) and ST83 (8.5%) followed. The overall susceptibility rates of S. pneumoniae to oral penicillin V and amoxicillin/clavulanate were 2.6% and 53.2%, respectively. The susceptibility rate to cefditoren was 91.0%; however, the rates for other cephalosporins were less than 10.0%. Compared with other serogroups, S. pneumoniae serogroups 19, 11, and 15 showed significantly lower susceptibility rates to all the antibiotics tested.

CONCLUSION

S. pneumoniae serotype 19A, serogroups 11 and 15 were the major nasopharyngeal-colonizing bacteria in Korean children with AOM after the introduction of PCV7. These relatively prevalent serotype/serogroups showed lower antibiotic susceptibility rates.

Otopathogens Detected in Middle Ear Fluid Obtained during Tympanostomy Tube Insertion: Contrasting Purulent and Non-Purulent Effusions

Otitis media is a prominent disease among children. Previous literature indicates that otitis media is a polymicrobial disease, with Haemophilus influenzae, Streptococcus pneumoniae, Alloiococcus otitidis and Moraxella catarrhalis being the most commonly associated bacterial pathogens. Recent literature suggests that introduction of pneumococcal conjugate vaccines has had an effect on the etiology of otitis media. Using a multiplex PCR procedure, we sought to investigate the presence of the aforementioned bacterial pathogens in middle ear fluid collected from children undergoing routine tympanostomy tube placement at Wake Forest Baptist Medical Center during the period between January 2011 and March 2014. In purulent effusions, one or more bacterial organisms were detected in ~90% of samples. Most often the presence of H. influenzae alone was detected in purulent effusions (32%; 10 of 31). In non-purulent effusions, the most prevalent organism detected was A. otitidis (26%; 63 of 245). Half of the non-purulent effusions had none of these otopathogens detected. In purulent and non-purulent effusions, the overall presence of S. pneumoniae was lower (19%; 6 of 31, and 4%; 9 of 245, respectively) than that of the other pathogens being identified. The ratio of the percentage of each otopathogen identified in purulent vs. non-purulent effusions was >1 for the classic otopathogens but not for A. otitidis.

The Lung Immune Response to Nontypeable Haemophilus influenzae (Lung Immunity to NTHi)

Haemophilus influenzae is divided into typeable or nontypeable strains based on the presence or absence of a polysaccharide capsule. The typeable strains (such as type b) are an important cause of systemic infection, whilst the nontypeable strains (designated as NTHi) are predominantly respiratory mucosal pathogens. NTHi is present as part of the normal microbiome in the nasopharynx, from where it may spread down to the lower respiratory tract. In this context it is no longer a commensal and becomes an important respiratory pathogen associated with a range of common conditions including bronchitis, bronchiectasis, pneumonia, and particularly chronic obstructive pulmonary disease. NTHi induces a strong inflammatory response in the respiratory tract with activation of immune responses, which often fail to clear the bacteria from the lung. This results in recurrent/persistent infection and chronic inflammation with consequent lung pathology. This review will summarise the current literature about the lung immune response to nontypeable Haemophilus influenzae, a topic that has important implications for patient management.

Impact of respiratory viral infections on α-hemolytic streptococci and otopathogens in the nasopharynx of young children

BACKGROUND

We studied nasopharyngeal (NP) colonization in a cohort of children to determine the impact of viral upper respiratory infections (URIs) on nonpneumococcal α-hemolytic streptococci (AHS) and otopathogen colonization in association with acute otitis media (AOM).

METHODS

NP samples were collected routinely when children were aged 6, 9, 12, 15, 18, 24 and 30 months and during episodes of AOM. NP samples were prospectively obtained from 248 children during a 5-year time span: 1018 during routine visits, 161 at the time of AOM and 59 at follow-up visits 3 weeks after AOM.

RESULTS

The overall NP colonization rate of AHS was 50.8% during a non-AOM visit but declined to 38.3% during a viral URI with concurrent AOM (P = 0.0006). Of 56 AOM visits with paired follow-ups, 6 (10.7%) had AHS in the NP at the time of viral URI and concurrent AOM whereas 29 (51.8%) had AHS at the follow-up (P < 0.001). Lower NP colonization rates with AHS were associated with significant increases in Streptococcus pneumoniae carriage during non-AOM visits (P < 0.001) and during viral URI and concurrent AOM visits (P = 0.003). AHS NP colonization rates were not different when children had a viral URI without AOM versus when they were URI negative, but NP colonization with nontypeable Haemophilus influenzae rates increased (P < 0.001) and Moraxella catarrhalis decreased (P < 0.001) during viral URI.

CONCLUSION

Respiratory viral infections alter NP carriage rates of commensal AHS and otopathogens, including before AOM.

Haemophilus influenzae and the lung (Haemophilus and the lung)

Haemophilus influenzae is present as a commensal organism in the nasopharynx of most healthy adults from where it can spread to cause both systemic and respiratory tract infection. This bacterium is divided into typeable forms (such as type b) or nontypeable forms based on the presence or absence of a tough polysaccharide capsule. Respiratory disease is predominantly caused by the nontypeable forms (NTHi). Haemophilus influenzae has evolved a number of strategies to evade the host defense including the ability to invade into local tissue. Pathogenic properties of this bacterium as well as defects in host defense may result in the spread of this bacterium from the upper airway to the bronchi of the lung. This can result in airway inflammation and colonization particularly in chronic obstructive pulmonary disease. Treatment of respiratory tract infection with Haemophilus influenzae is often only partially successful with ongoing infection and inflammation. Improvement in patient outcome will be dependent on a better understanding of the pathogenesis and host immune response to this bacterium.

Aggregatibacter actinomycetemcomitans-induced bone loss and antibody response in three rat strains

BACKGROUND

The aim of this study is to compare the colonization, immunoglobulin (Ig) G response, and alveolar bone loss in Aggregatibacter actinomycetemcomitans (Aa)-inoculated Fawn Hooded Hypertensive (FHH), Dahl Salt-Sensitive (DSS), and Brown Norway (BN) rats.

METHODS

Each rat strain was divided into wild-type Aa-inoculated and non-inoculated control groups. Blood taken at 12 weeks after inoculation was assessed for Aa-specific IgG antibodies by an enzyme-linked immunosorbent assay. Colonization was assessed 12 weeks postinoculation. Bone loss was estimated by measuring the distance from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 20 molar sites. Colonization and antibody levels were compared by using the Student t test. Diseased rats were defined as having two sites per quadrant with CEJ-ABC distances that were significantly greater than the control CEJ-ABC distances.

RESULTS

The Aa colonization of FHH rats was significantly higher than in other strains (P <0.05). The Aa-specific IgG levels in the DSS Aa-inoculated group were significantly higher than in its control group (P <0.05). Only FHH rats showed Aa disease-associated bone loss (P = 0.0021).

CONCLUSIONS

Aa colonized and caused more disease in FHH rats than in the other rat strains. The rat strains each responded differently to the same Aa strain.

New patterns in the otopathogens causing acute otitis media six to eight years after introduction of pneumococcal conjugate vaccine

OBJECTIVE

To describe NP and AOM otopathogens during the time frame 2007 to 2009, 6 to 8 years after the introduction of 7-valent pneumococcal conjugate (PCV7) in the United States and to compare nasopharyngeal (NP) colonization and acute otitis media (AOM) microbiology in children 6 to 36 months of age having first and second AOM episodes with children who are otitis prone.

METHODS

Prospectively, the microbiology of NP colonization and AOM episodes was determined in 120 children with absent or infrequent AOM episodes. NP samples were collected at 7 routine visits between 6 and 30 months of age and at the time of AOM. For first and subsequent AOM episodes, middle ear fluid (MEF) was obtained by tympanocentesis. Eighty otitis prone children were comparatively studied. All 200 children received age-appropriate doses of PCV7.

RESULTS

We found PCV7 serotypes were virtually absent: (0.9% isolated from both NP and MEF) in both study groups. However, non-PCV7 serotypes replaced PCV serotypes such that the frequency of isolation of S. pneumoniae (Spn) was nearly equal to that of non-typeable Haemophilus influenzae (NTHi). M. catarrhalis (Mcat) was less common and Staphylococcus aureus infrequent in the NP and MEF from the 2 groups. The proportion of Spn, NTHi and Mcat causing AOM was similar in children with first and second AOM episodes compared to otitis prone children. However, oxacillin-resistant Spn isolated from the NP and MEF was 19% for the absent/infrequent and 58% for the otitis prone groups, P < 0.0001. Beta-lactamase producing NTHi occurred more frequently in the otitis prone group, P = 0.04.

CONCLUSIONS

Six to 8 years after widespread use of PCV7, Spn strains expressing vaccine-type serotypes have virtually disappeared from the NP and MEF of vaccinated children. NP colonization and AOM has changed to non-PCV7 strains of Spn. NTHi continues to be a major AOM pathogen. The otopathogens in first and second AOM and in otitis prone children are very similar although Spn and NTHi are more often antibiotic resistant in the otitis prone.

Colonization and turnover of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in otitis-prone children

Recurrent otitis media are frequently intractable during childhood. It is unclear whether recurrent otitis media is caused by etiological bacteria colonization or by new infections. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were isolated from the nasopharynx of 7 otitisprone and 2 non-prone children with recurrent otitis media. Plural bacterial species and strains were found in all children while affected by otitis media. The same strain was repeatedly isolated from all otitisprone children even after administration of antibiotics but was not from the non-prone children. Antibiotic susceptibility did not differ significantly among the same repeatedly isolated strains. This pilot study suggests that the etiological bacteria tend to colonize and is hard to eliminate in otitis-prone children.

Predictors for Haemophilus influenzae colonization, antibiotic resistance and for sharing an identical isolate among children attending 16 licensed day-care centers in Michigan

BACKGROUND

Nontypable Haemophilus influenzae is an important cause of otitis media in children. Children attending day-care centers are at an increased risk for nontypable H. influenzae colonization and otitis media. We describe the prevalence of nontypable H. influenzae colonization, antibiotic resistance and predictors for colonization and sharing an identical isolate with at least 1 other child in the same day-care centers among children attending 16 day-care centers.

METHODS

Throat swabs of 198 children < 3 years old attending 16 day-care centers were cultured for H. influenzae. Day-care center directors and parents completed risk factors questionnaires. Nontypable H. influenzae isolates were screened for antibiotic resistance and genotyped. Statistics were performed using SAS software (SAS Institute, Inc., Cary, NC).

RESULTS

We isolated 179 unique nontypable H. influenzae strains from 127 participants. Colonization ranged from 0% to 95% among day-care centers. As individual factors, exposure to tobacco smoke was associated with colonization (P = 0.05), and racial self-identifications as "other" (nonwhite, nonblack) was protective (P = 0.035), whereas as "black" was protective for sharing (P = 0.03). Pacifier use was associated with sharing (P = 0.04), but not with colonization. As day-care centers factors, rates of colonization and sharing were higher in day-care centers with > or = 5 classrooms (P < 0.01 and P = 0.03), with such suboptimal hygiene habits as minimal hand washing by staff after eating (P < 0.002 and P < 0.01) or by children after wiping their own nose (P = 0.01 and P = 0.003). Of colonized children, 41% presented a beta-lactamase-producing strain. Colonized children were more likely to carry resistant strains if they were taking an antibiotic (P = 0.02).

CONCLUSION

Although day-care center colonization varied, the overall colonization rate was high. Colonization with nontypable H. influenzae, with beta-lactamase-producing strain and sharing were, mostly, associated with modifiable risk factors.

Amoxicillin-sulbactam versus amoxicillin-clavulanic acid for the treatment of non-recurrent-acute otitis media in Argentinean children

Streptococcus pneumoniae (Sp) and Haemophilus influenzae (Hi) are the leading bacterial cause of acute otitis media (AOM), having the nasopharynx (NP) as their reservoir. In October 2001 we began a prospective, multicenter, randomized, evaluator blind study, comparing the efficacy of amoxicillin-sulbactam (Ax/S) and amoxicillin-clavulanic acid (Ax/C) for the treatment of non-recurrent AOM (nr-AOM). Both antimicrobial susceptibility (AS) to Ax/S and Ax/C from Sp and Hi carried by study children (aged 6-48 months with nr-AOM) and, clinical outcome after treatment with high dose of either Ax/C (7:1) or Ax/S (4:1) (amoxicillin dose: 80 mg/(kg day), b.i.d. for 10 days) were assessed. Nasal cultures (NCs) were taken at Day 0. Follow-up NCs, were done only for Sp carriers. On final analysis 247/289 pts (85.5%) were fully evaluable (120 Ax/S and 127 Ax/C). NP carriage rate of Hi and Sp at Day 0 was 32.2% (93/289 pts) and 28.7% (83/289 pts), respectively. Persistent Sp carriage was detected only in 2 pts. Hi betalactamase positive rate was 13% (12/93). MICs for Ax/S and Ax/C were identical when tested against Sp and Hi isolates (range < or = 0.016-1.0 and < or = 0.016-0.25 mg/L, respectively). Clinical efficacy at Days 12-14 and 28-42 were 98.3% (115/117) and 94.2% (97/103) for Ax/S; and 98.3% (115/117) and 95.1% (98/103) for Ax/C, respectively (pNS). We conclude, that Sp and Hi isolated from NCs of nr-AOM pts were highly sensitive to both drugs and correlated with high clinical efficacy rate.

Identification, distribution, and expression of novel genes in 10 clinical isolates of nontypeable Haemophilus influenzae

We hypothesize that Haemophilus influenzae, as a species, possesses a much greater number of genes than that found in any single H. influenzae genome. This supragenome is distributed throughout naturally occurring infectious populations, and new strains arise through autocompetence and autotransformation systems. The effect is that H. influenzae populations can readily adapt to environmental stressors. The supragenome hypothesis predicts that significant differences exist between and among the genomes of individual infectious strains of nontypeable H. influenzae (NTHi). To test this prediction, we obtained 10 low-passage NTHi clinical isolates from the middle ear effusions of patients with chronic otitis media. DNA sequencing was performed with 771 clones chosen at random from a pooled genomic library. Homology searching demonstrated that approximately 10% of these clones were novel compared to the H. influenzae Rd KW20 genome, and most of them did not match any DNA sequence in GenBank. Amino acid homology searches using hypothetical translations of the open reading frames revealed homologies to a variety of proteins, including bacterial virulence factors not previously identified in the NTHi isolates. The distribution and expression of 53 of these genes among the 10 strains were determined by PCR- and reverse transcription PCR-based analyses. These unique genes were nonuniformly distributed among the 10 isolates, and transcription of these genes in planktonic cultures was detected in 50% (177 of 352) of the occurrences. All of the novel sequences were transcribed in one or more of the NTHi isolates. Seventeen percent (9 of 53) of the novel genes were identified in all 10 NTHi strains, with each of the remaining 44 being present in only a subset of the strains. These genic distribution analyses were more effective as a strain discrimination tool than either multilocus sequence typing or 23S ribosomal gene typing methods.

Acquisition of Streptococcus pneumoniae and nonspecific morbidity in infants and their families: a cohort study

BACKGROUND

Most children are believed to acquire Streptococcus pneumoniae asymptomatically, with only a few developing overt S. pneumoniae disease. This study investigates the relationship between acquisition of S. pneumoniae and mild nonspecific infection leading to general practitioner (GP) consultation.

METHODS

A prospective birth cohort study of 213 infants assessed at home 9 times during 24 weeks by nasopharyngeal swab and parental interview was conducted.

RESULTS

All positive S. pneumoniae swabs (including acquisition and carriage) were significantly associated with GP consultations for infection by the study infant compared with infants with negative swabs [odds ratio (OR), 1.6; 95% confidence interval (CI) 1.1-2.2; P = 0.005]. There was a stronger association with S. pneumoniae acquisition alone (OR 2.1; 95% CI 1.3-3.4; P = 0.001) than with carriage only (OR 1.4; 95% CI 0.9-2.0; P = 0.1). Multivariate analysis confirmed that S. pneumoniae acquisition by the study subject was independently associated with GP consultations: adjusted hazard ratio, 1.8 (95% CI 1.1-2.9); P = 0.02. A similar and independent association was found between S. pneumoniae acquisition by the study subject, and GP consultations for infection by the family (adjusted hazard ratio, 1.8; 95% CI 1.1-2.8; P = 0.01).

CONCLUSION

Acquisition of S. pneumoniae by the study infant was significantly associated with GP consultations for infection by the infant or family.

Genotyping of Streptococcus pneumoniae and Haemophilus influenzae Isolated from Paired Middle Ear Fluid and Nasopharynx by Pulsed-Field Gel Electrophoresis

Twenty-eight isolates of Streptococcus pneumoniae and 30 isolates of Haemophilus influenzae from paired nasopharynx and middle ear fluids of 21 children with acute otitis media (AOM) were evaluated to determine genotypes by polymerase chain reaction and pulsed-field gel electrophoresis (PFGE). Among the 28 isolates of S. pneumonaie, 21 isolates (75.0%) possessed mutations in the pbp1a,pbp2x, and pbp2b genes, and 7 isolates (25%) had mutations in the pbp2x gene. Nineteen isolates (67.9%) expressed the mefE gene, and 5 isolates (17.9%) possessed the ermB gene. Among the 30 isolates of H. influenzae, 5 isolates (16.7%) had mutations in pbp3 genes, 3 isolates (10.0%) produced beta-lactamase, and 2 (6.7%) isolates possessed mutations both in the pbp3 gene and the beta-lactamase gene. Ten out of the 14 pairs (71.4%) of the restriction fragment patterns of S. pneumoniae from paired nasopharynx and middle ear fluids were indistinguishable following PFGE analysis. The same patterns were identified among 5 children of unrelated families. The restriction fragment patterns of H. influenzae isolated by PFGE were also indistinguishable in 13 out of the 15 pairs (86.7%) of nasopharynx and middle ear fluids. The genetic similarity between nasopharyngeal and middle ear isolates suggests that the causative bacteria migrate from the nasopharynx into the middle ear cavity via the Eustachian tube. Some resistant strains might be prevalent. In children with AOM, the nasopharynx could have been colonized by a virulent strain of bacteria that replaced the benign, commensal bacteria and then progressed to the middle ear, where they caused AOM.

Nasopharyngeal pathogens in children with acute otitis media in a low-antibiotic use country

OBJECTIVE

Acute otitis media (AOM) is one of the most common diseases of childhood. Knowledge, of which bacteria are the most common pathogens in AOM and their susceptibilities towards antibiotics, is essential for the reasonable empiric treatment. With rapidly increasing frequencies of antibiotic resistance surveillance of the common etiologic pathogens has become pertinent. The purpose of this paper is to present the bacteriological findings and antibiotic susceptibilities, in cultures from nasopharyngeal swabs, in Danish children with AOM.

METHODS

Children aged up to 10 years who had AOM diagnosed in general practice in Denmark were swabbed in nasopharynx, cultures were incubated and susceptibility testing was performed as tablet diffusion and minimal inhibitory concentrations (MICs) were determined by E-test.

RESULTS

We included 331 patients, in 257 bacteria were found, which could be classified as commonly ear pathogenic. The most frequent bacteria found was Streptococcus pneumoniae followed by Haemophilus influenzae and Moraxella catarrhalis. Ninety-six percent of the tested S. pneumoniae were susceptible towards penicillin and 99% towards erythromycin. Eighty-nine percent of the H. influenzae were susceptible to ampicillin and all tested M. catarrhalis were susceptible towards erythromycin. In more than 30% of H. influenzae MIC of phenoxymethylpenicillin were above the level that could be achieved in middle ear fluid.

CONCLUSION

Antimicrobial resistance is still infrequent in pathogens that might cause AOM in children in Denmark; this is probably due to minimal use of antibiotics as well as the use of phenoxymethylpenicillin as primary drug for treatment of AOM. Phenoxymethylpenicillin and azithromycin are not efficient for treating the majority of infections due to H. influenzae.

Bacteriocin-like inhibitory substance (BLIS) production by the normal flora of the nasopharynx: potential to protect against otitis media?

The normal bacterial flora of the upper airways provides an important barrier to invading pathogens. This study investigated the production of bacteriocin-like inhibitory substances (BLIS) by streptococci isolated from the nasopharyngeal flora of children who either do or do not experience recurrent acute otitis media (AOM). Twenty children with recurrent AOM and 15 controls were tested. Swabs from the nasopharynx were evaluated for streptococci having BLIS activity against two representative strains of each of the AOM pathogens Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis. Streptococci displaying strong BLIS activity were characterized further and tested for known streptococcal bacteriocin structural genes. Sixty-five per cent of children had nasopharyngeal streptococcal isolates that were inhibitory to strains of one or more of the AOM pathogens. Six children (17 %) had streptococci that demonstrated strong BLIS activity against strains of at least three of the pathogenic species. Three of these inhibitory isolates were Streptococcus salivarius, two were S. pneumoniae and one was S. pyogenes. The inhibitory S. salivarius and S. pyogenes were shown to have structural genes for known streptococcal bacteriocins. No statistically significant difference was found between the two groups of children with respect to the presence of inhibitory streptococci in their nasopharyngeal floras. The finding of S. salivarius with strong inhibitory activity against several AOM pathogens in the nasopharyngeal flora of children is unique. Although there is no clear evidence from the present study that these organisms protect against AOM, their low pathogenicity and strong in-vitro BLIS production capability indicate that they should be incorporated in future trials of bacteriotherapy for recurrent AOM.

Nasopharyngeal carriage of anaerobes during health and acute otitis media by two years of age

The nasopharyngeal acquisition of anaerobic bacteria was longitudinally examined among a homogeneous group of Caucasian infants by 2 years of age. Nasopharyngeal swab (NP) samples were collected at scheduled healthy visits at 2, 6, 12, 18, and 24 months of age, and nasopharyngeal aspirates (NPA) during every visit for acute otitis media (AOM). The infants were divided into 4 groups according to the number (0, 1, 2-3, and > 3) of AOM episodes experienced by 2 years of age. At 2 years, the cumulative carriage rates of anaerobic species in these infant groups were 29%, 62%, 89%, and 89%, respectively. Anaerobic species were found in 15/220 (6.8%) of the NP samples and in 34/71 (47.9%) of the NPA samples. Our present results indicate that anaerobic species do not belong to the indigenous nasopharyngeal microflora but only transiently colonize the nasopharynx during AOM.

Serotypes of respiratory tract isolates of Streptococcus pneumoniae from Jamaican children

BACKGROUND

Data are lacking on the pneumococcal serotypes present in many developing regions, including the Caribbean. We examined the serotypes of nasopharyngeal (NP) isolates of pneumococci obtained from Jamaican children.

METHODS

We obtained NP samples from children seen in the Emergency Department at the Bustamante Children's Hospital. The samples were transported to Canada for isolation and serotyping of pneumococci.

RESULTS

We obtained 94 isolates from 276 children; median age 3.4 years. The majority (57%) had symptoms of acute respiratory infection at the time of sampling. The main serotypes carried were 6B (20.5%), 19F (14.5%), and 14 (8.4%). Non-typable isolates accounted for 10.8% of the isolates. Fifty-nine per cent of the serotypes were present among the 11 being considered for candidate pneumococcal conjugate vaccines (95% CI 48-70%); the corresponding proportion present in the recently licensed 7-valent vaccine was 57% (95% CI 45-67%). A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines (P<0.0001; reference=85% expected serotype representation). Less than 5% of isolates were non-susceptible to penicillin (3.2%), cefotaxime-ceftriaxone (3.2%) and cefuroxime (3.2%), while 8.4% and 1.l% of isolates were resistant to trimethoprim-sulfamethoxazole and erythromycin respectively. There were three isolates with resistance to two or more classes of drug. These isolates were all resistant to penicillin (MIC 2 micro g/mL); the serotypes were 14, 23F, and 19F.

CONCLUSION

A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines.

Effect of 23 valent pneumococcal polysaccharide and Haemophilus influenza conjugated vaccines on the clinical course of otitis media with effusion

OBJECTIVE

To determine if there is any clinical effect of 23-valent pneumococcal and type B conjugate vaccine on prognosis of otitis media with effusion.

METHOD

All children who have middle ear effusion despite long-standing antibiotherapy with a beta lactamase stable agent were offered for tympanostomy tube insertion between February 1999 and December 2001. Patients who accepted the surgical intervention were operated under general anesthesia and a Shepard grommet-type tympanostomy tube was inserted. Those who refused the surgical intervention were vaccinated with 23-valent pneumococcal and type B conjugate vaccine. State of the middle ear effusion was evaluated at the end of the 12th month in the vaccine group and 1 month after the myringotomy site was healed in the tympanostomy tube insertion group.

RESULTS

Twenty-six children in the vaccine group and 37 children in the tympanostomy tube insertion group proved the inclusion criteria at the end of study. Complete or partial resolution of middle ear effusion was observed in 73.1% of 26 children in the vaccine group and 59.5% of children in the tympanostomy tube insertion group. There was no significant difference between the two groups.

CONCLUSION

Vaccination against and type b seems to aid resolution of middle ear effusion in children with otitis media with effusion.

Effects of large dosages of amoxicillin/clavulanate or azithromycin on nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, nonpneumococcal alpha-hemolytic streptococci, and Staphylococcus aureus in children with acute otitis media

Prior use of antibiotics is associated with carriage of resistant bacteria. Colonization by Streptococcus pneumoniae, Haemophilus influenzae, nonpneumococcal alpha-hemolytic streptococci (NPAHS), and Staphylococcus aureus was evaluated in children receiving antibiotic therapy for acute otitis media and in untreated, healthy control subjects. Children were randomly assigned to receive either amoxicillin/clavulanate (90 mg/kg per day) or azithromycin. Swabs were obtained before initiating therapy and again 2 weeks and 2 months after initiating therapy. We also obtained swabs from control subjects at the time of enrollment and 2 weeks and 2 months after enrollment. The decrease in the rate of carriage of S. pneumoniae and H. influenzae at 2 weeks was significant only in the amoxicillin/clavulanate group (P<.001 and P=.005, respectively). The rate of nasopharyngeal colonization with NPAHS among treated patients increased from 23% to 39% at 2 months (P=.01). This increase was similar for both treatment groups. These results suggest that the competitive balance between organisms is altered by antibiotic therapy.

Household transmission of Streptococcus pneumoniae among siblings with acute otitis media

Nasopharyngeal transmission of Streptococcus pneumoniae was evaluated among 23 siblings with acute otitis media (AOM). Restriction fragment length polymorphism revealed that the nasopharyngeal strains were identical between siblings in 12 of 13 clusters of AOM experienced in 11 families. This study demonstrated person-to-person transmission of S. pneumoniae, especially drug-resistant strains, among siblings with AOM.

Bacterial interference between pathogens in otitis media and alpha-haemolytic Streptococci analysed in an in vitro model

Bacterial interference studied by means of agar methods has shown a decreased number of inhibitory alpha-haemolytic Streptococci among otitis-prone children. Additional information was gained regarding the interplay between alpha-haemolytic Streptococci (AHS) and otitis media (OM) pathogens by comparing the bacterial interference in broth with the interference activity studied using agar overlay methods. We found, that non-typeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis are readily inhibited by AHS in broth. Streptococcus pneumoniae was more bacteriostatically inhibited. If two OM pathogens were inoculated simultaneously, an isolate of AHS with poor inhibitory activity was not able to inhibit the growth, in contrast to an isolate of AHS with good inhibitory activity. The initial amount of AHS inoculated with M. catarrhalis seemed to play a decisive role with respect to the inhibitory activity. M. catarrhalis developed reduced susceptibility against AHS both in vivo and in vitro. In vivo studies showed that children with secretory otitis media had fewer isolates of AHS in their nasopharynx with the ability to inhibit all the test pathogens than healthy children (p < 0.001). Although the factor(s) responsible for the inhibitory activity have thus far not been defined, we could exclude low pH and nutrition depletion as the inhibitory mechanism of AHS with good inhibitory activity.

A comprehensive model for the aetiology of otitis media with effusion

Otitis media with effusion is highly prevalent among young children. Adverse effects of this disorder are mainly restricted to the group of children with a history of recurrent or persistent otitis media with effusion. Early identification, assessment and intervention might prevent these adverse effects. Up to now it is not possible to distinguish these children from those with transient otitis media with effusion. This article presents a comprehensive model for the aetiology of otitis media with effusion. Eustachian tube functioning and the immunological response to environmental pathogens are the two core elements. This model can be used to formulate specific hypotheses about the interaction of several factors that may lead to the early identification of children who are likely to develop persistent or recurrent otitis media with effusion.

Nasopharyngeal colonization by Haemophilus influenzae in children living in an orphanage

AIM

To study colonization and transmission of Haemophilus influenzae in a cohort of children <2 years old living in the unique epidemiologic conditions of a closed community of an orphanage.

METHODS

Fifty-three children, ages 0 to 24 months, were followed for 1 year. All children >2 months were vaccinated against H. influenzae serotype b. Nasopharyngeal cultures were collected monthly or, in children <6 months of age, every 2 weeks. Antibiotic susceptibility, serotype, biotype and genotype (pulsed field gel electrophoresis) of each isolate were determined. As control, 39 H. influenzae isolates were recovered from various regions in France.

RESULTS

The mean monthly rate of carriage was 45% ranging from 17 to 70%. Most isolates belonged to biotype II (62%), 4 isolates to serotype f (3.6%) and none to serotype b, and 60% of the 111 isolates produced beta-lactamase. A complete concordance was found among biotype, serotype, pulsotype and antimicrobial susceptibility. On average children were sequentially colonized by 3 different isolates. The mean duration of carriage for a given isolate was approximately 1.4 months. In younger children the mean age of primary colonization was 2 months. Contrasting with the high genetic heterogeneity of 39 control isolates, most isolates (82%) belonged to only 5 pulsotypes. Three main H. influenzae clones rapidly spread in the community and colonized children in waves.

CONCLUSION

During early life nasopharyngeal colonization by H. influenzae is a dynamic phenomenon with sequential carriage of various clones spreading in the community.

Treatment of acute otitis media - challenges in the era of antibiotic resistance

The last decade is characterized by the increase in antibiotic resistance among respiratory bacterial pathogens in the presence of only modest progress in the development of new antibacterial agents to overcome this resistance. A series of recent studies show clearly that the increased resistance among the main AOM pathogens (namely Streptococcus pneumoniae and Haemophilus influenzae) is associated with a dramatic decrease in bacteriologic response to antibiotic treatment, which in turn has an impact on clinical response. Thus, the individual patient is affected by the increasing antibiotic resistance. Moreover, the society as a whole is now also affected because the carriage and spread of antibiotic resistant AOM pathogens is remarkably impacted by antibiotic treatment. New studies show the remarkable ability of antibiotics to rapidly promote nasopharyngeal carriage and spread of antibiotic-resistant AOM pathogens. In these studies, the increase in carriage of antibiotic resistant S. pneumoniae is shown already after 3-4 days from initiation of antibiotic treatment and may last for weeks to months after treatment. Children carrying antibiotic-resistant organisms transmit those organisms to their family and to their day care centers and thus a vicious cycle is created in which increased antibiotic resistance with decreased response leads to increased antibiotic use, which in turn leads to further increase in resistance. New antibiotics are not likely to improve this situation. It is clear that the challenge in the next decade is to prevent AOM rather than to treat it. Efforts to prevent AOM include improved environmental factors, immunization with bacterial and viral vaccines and some creative measures such as prevention of colonization and attachment to epithelium of AOM pathogens. Whether these efforts will prove successful or, even if successful, will only modify the clinical and bacteriologic picture presenting new challenges, only time will tell.

The pathogenesis of nontypable Haemophilus influenzae otitis media

Nontypable Haemophilus influenzae is a common cause of otitis media and initiates infection by colonizing the upper respiratory tract. In this article, I review our current understanding of the molecular determinants of H. influenzae colonization and discuss the relationship between colonization and otitis media.

Effects of amoxicillin/clavulanate or azithromycin on nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae in children with acute otitis media

The effect of antibiotic therapy on nasopharyngeal colonization by Streptococcus pneumoniae and Haemophilus influenzae was evaluated in children diagnosed with acute otitis media. Children were randomly assigned to receive either amoxicillin/clavulanate or azithromycin therapy, and nasopharyngeal swabs were obtained for culture before and after starting therapy. Amoxicillin/clavulanate therapy eradicated or suppressed all strains of S. pneumoniae susceptible to penicillin, 75% of strains with intermediate resistance, and 40% of strains resistant to penicillin. Azithromycin therapy cleared two-thirds of azithromycin-susceptible strains of S. pneumoniae but none of azithromycin-nonsusceptible strains. Selection for antibiotic-resistant strains in individual children was not observed in children who received amoxicillin/clavulanate therapy but was observed in 2 children who received azithromycin therapy. Carriage of H. influenzae was also reduced by antimicrobial therapy but more so by amoxicillin/clavulanate. Antibiotic therapy does not directly increase the number of resistant strains in the population but, by eradicating susceptible strains, allows greater opportunity for carriage and spread of resistant strains.

Increased carriage of resistant non-pneumococcal alpha-hemolytic streptococci after antibiotic therapy

OBJECTIVE

We compared colonization and resistance rates of non-pneumococcal alpha-hemolytic streptococci (AHS) and Streptococcus pneumoniae in children receiving antibiotic therapy for acute otitis media.

STUDY DESIGN

Between December 1997 and September 1998, children 6 months to 6 years of age, diagnosed with acute otitis media were randomly assigned to receive amoxicillin/clavulanate (Augmentin) 45 mg/kg/d in 2 divided doses for 10 days or azithromycin (Zithromax), 10 mg/kg, once on the first day, followed by 5 mg/kg daily for 4 days. Nasopharyngeal swabs for culture were obtained before and at 2 weeks and 2 months after the start of therapy. Streptococci were identified by species, and antibiotic susceptibility was determined by the epsilometric test.

RESULTS

One hundred six children completed the 2-week follow-up and 2-month follow-up, respectively. The nasopharyngeal carriage rate of non-pneumococcal AHS increased from 14% before treatment to 32% at the 2-week follow-up (P =.02) and was similar in both treatment groups. In contrast, the carriage of S pneumoniae decreased from 51% before therapy to 27% at the 2-week follow-up (P =.002). The carriage of penicillin-resistant AHS strains (minimum inhibitory concentration > 1 microg/mL) increased from 9% before treatment to 26% at 2 weeks and 36% at 2 months.

CONCLUSIONS

Amoxicillin/clavulanate and azithromycin therapy resulted in increased isolation of nasopharyngeal non-pneumococcal AHS, many of which were multidrug-resistant, in contrast to a decrease in pneumococcal carriage. This suggests that the competitive balance between these 2 groups of organisms was disturbed as a result of differential antibiotic susceptibility. The importance of drug-resistant AHS as a reservoir for resistance genes for S pneumoniae warrants further investigation.

Evaluation of the patient with sore throat, earache, and sinusitis: an evidence based approach

Sore throat, earache, and sinusitis are common presenting complaints in the emergency department, and all fall within the top ten in the United States. These complaints usually have a benign course but rarely can be a symptom of a serious disease process. This article provides an evidence-based review of the literature regarding the diagnosis of pharyngitis, otitis media, and sinusitis.

A systematic review of clinical research addressing the prevalence, aetiology, diagnosis, prognosis and therapy of otitis media in Australian Aboriginal children

The objective of this review was to systemically identify and summarize all the clinically relevant evidence available from studies addressing the prevalence, aetiology, diagnosis, prognosis and therapy of otitis media in Australian Aboriginal children. Electronic searching of Medline, the Australian Medical Index and the Aboriginal and Torres Strait Islander Health Bibliographic Index was performed. This was supplemented by hand searching the Menzies School of Health Research otitis media collection, the Aboriginal and Torres Strait Islander Health Information Bulletin and Aboriginal Health: an annotated bibliography. Data were extracted and placed in a series of evidence tables relevant to clinical practice. There were 59 studies that met the inclusion criteria. The majority were surveys, and only 19 addressed diagnosis, prognosis or therapy. Severe otitis media in rural Aboriginal children does not occur in isolation but as part of a spectrum of chronic bacterial infections of the respiratory tract. Although the aspects of poverty that result in this condition remain to be clarified, exposure to other young children with chronic nasal discharge is likely to be important. Whilst there is a considerable amount of literature on otitis media in Australian Aboriginal children, the number of studies most relevant to improving health outcomes is small. A systematic approach to disease surveillance, diagnosis, and application of medical interventions is required urgently. Future medical research should be concerned with the evaluation of interventions and the generalisabilty of studies from different populations.

The Haemophilus influenzae Hap serine protease promotes adherence and microcolony formation, potentiated by a soluble host protein

Haemophilus influenzae initiates infection by colonizing the upper respiratory mucosa. The process of colonization involves adherence to epithelium and evasion of host immunity. In this study, we examined the H. influenzae Hap adhesin, which has serine protease activity and undergoes autoproteolytic cleavage and extracellular release in broth. We found that the uncleaved cell-associated form of Hap mediates adherence to cultured epithelial cells and promotes bacterial aggregation and microcolony formation. Adherence and aggregation are augmented by secretory leukocyte protease inhibitor, a natural component of respiratory secretions that inhibits Hap autoproteolysis. These observations suggest a novel paradigm in host-pathogen relations, in which a soluble host protein whose primary function is to protect host epithelium potentiates properties that facilitate bacterial colonization.

Mucosal Immunity and Bacteriology of the Eustachian Tube

The pathogenesis of otitis media is a multifaceted process that is not completely understood. Eustachian tube dysfunction plays a central but uncertain role, as do viral and bacterial microorganisms. Of the latter, the three most important are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. This article reviews the various mechanisms of infection and the immune system's response to them.

Nasopharyngeal colonization in Costa Rican children during the first year of life

BACKGROUND

The establishment of the nasopharyngeal flora was followed in Costa Rican children from birth to 1 year of age.

METHODS

Nasopharyngeal cultures were obtained at 1 (n = 413), 3 (n = 393), 6 (n = 376) and 12 months (n = 356) of age from children representative of the population in the Puriscal district. Weekly cultures were obtained from a subcohort of these children (n = 101). Mother-infant diads (n = 95) and preschool children (n = 208) attending day-care centers were also studied.

RESULTS

The estimated proportion of colonized children in the population differed markedly depending on the frequency of culture. Quarterly cultures showed a slow increase in carrier rates from 3.9% for Haemophilus influenzae, 3.1% for Streptococcus pneumoniae and 6.5% for Moraxella catarrhalis at 1 month of age to 10.1% carrying H. influenzae and 19.4% carrying S. pneumoniae by the end of the first year. By quarterly culture the proportion of children colonized at least once was 36% for S. pneumoniae, 26% for H. influenzae and 28% for M. catarrhalis. In contrast weekly sampling showed that 95 to 100% of the children were colonized at least once during the first year of life with H. influenzae, S. pneumoniae or M. catarrhalis. Nasopharyngeal carriage of H. influenzae, S. pneumoniae and M. catarrhalis was low in the mothers, and very few mother-infant pairs carried identical bacteria at the same time. In contrast carrier rates were high in the siblings attending day care (H. influenzae 27.9%, S. pneumoniae 39.4%, both organisms 26.6%). Infants with siblings had significantly higher bacterial carriage at all ages than infants without siblings.

CONCLUSIONS

Quarterly nasopharyngeal cultures showed that Costa Rican infants acquire their nasopharyngeal flora at a rate comparable with that for infants in developed countries and that siblings are an important source of the bacteria. Weekly samplings showed that virtually all children were colonized at least once during the first year of life.

Role of adenoids in the pathogenesis of otitis media: a bacteriologic and immunohistochemical analysis

Adenoidectomy is frequently performed in children suffering from recurrent or chronic otitis media with effusion and is thought to produce a long-term effect in preventing further episodes of otitis media. Bacteriologic analysis of adenoids from 60 patients revealed a significantly elevated colonization rate of middle ear pathogens in children with a present or previous history of ear disease compared to children with adenoidal hypertrophy only. The predominant pathogen was nontypeable Haemophilus influenzae, followed by Streptococcus pneumoniae and Moraxella catarrhalis. Quantitative analysis did not demonstrate a bacterial overload in the otitis group. Lectin histochemical analysis of the adenoids revealed no significant differences between the three groups; nevertheless, colonization with S pneumoniae demonstrated an increased labeling pattern with succinylated wheat germ agglutinin, indicating the exposure of N-acetyl-glucosamine as part of its own receptor structure. On the basis of these results, we support the concept of adenoidectomy in order to remove a bacterial focus; however, we could not verify the hypothesis of bacterial overgrowth in the nasopharynx.

The tympanic membrane and middle ear mucosa during non-typeable Haemophilus influenzae and Haemophilus influenzae type b acute otitis media: a study in the rat

Non-typeable Haemophilus influenzae (NTHi) and encapsulated Haemophilus influenzae type b (Hib) were inoculated into the middle ears of Sprague-Dawley rats. Tympanic membrane (TM) status was assessed otomicroscopically and specimens from various middle ear areas were prepared for light microscopy at various times during the acute phase and up to 6 months after inoculation. Irrespective of bacteria strain, acute otitis media (AOM) was present in all ears 4 days after inoculation. The Hib-infected ears showed initially a severe course of AOM, but all were otomicroscopically resolved by day 12, at which time a few NTHi-inoculated ears still exhibited middle ear effusion. The TMs infected with Hib had normalized without scar formation, whereas NTHi induced a persistent thickening of the TMs in half of all cases. The middle ear mucosa of NTHi-infected ears initially showed vigorous activity among the goblet cells, but the mucosa normalized after the acute phase. Hib, by contrast, induced prominent changes in the middle ear mucosa. Initially, no goblet cell granules or ciliated cells could be observed in the mucosa. Later on, the epithelium contained large, active goblet cells. Glands appeared beneath the mucosa which persisted as streaks of epithelial cells throughout the study period. The findings show that NTHi and Hib both induce AOM but with differing clinical courses, and affect different targets in the middle ear.

Antibodies to pneumococcal polysaccharides in human milk: lack of relationship to colonization and acute otitis media

BACKGROUND

This study analyzed antibodies to pneumococcal polysaccharides in human milk and their effect on nasopharyngeal colonization and acute otitis media in breast-fed infants.

METHODS

A total of 503 milk samples were collected from 310 mothers. Nasopharyngeal cultures were obtained from their children at 2, 6 and 10 months postpartum, and the capsular groups/types of the Streptococcus pneumoniae isolates were determined.

RESULTS

Types 6A, 6B, 19A, 19F and 23F accounted for 54% of the pneumococcal isolates, but type 3 isolates were uncommon. Milk samples were analyzed for antibody activity to the common capsular polysaccharide types 6A, 19F and 23F; to the type 3 polysaccharide; to C-polysaccharide; and to phosphorylcholine (PC), a major component of the pneumococcal cell wall polysaccharide (CWPS). Anti-capsular antibody activity was low or absent in > 90% of the milk samples. In contrast anti-PC antibody activity was detected in 88% and anti-CWPS in 84% of the samples. The frequency of acute otitis media did not vary with the milk anti-capsular, anti-PC or anti-CWPS antibody activity.

CONCLUSIONS

There was no reduction in nasopharyngeal carriage of S. pneumoniae among children fed milk with anti-capsular or anti-PC antibody activity, but carriage was increased in those children who received milk with anti-CWPS antibody activity. A protective role of antipolysaccharide or anti-CWPS antibodies in milk was not detected under the study conditions.

Streptococcus pneumoniae colonization in the young child: association with otitis media and resistance to penicillin

OBJECTIVE

To determine the nasopharyngeal colonization rate of penicillin-susceptible and penicillin-resistant strains of Streptococcus pneumoniae in young children, and to assess its relationship with the incidence of otitis media.

DESIGN

Observational study in 215 children younger than 6 years of age who received care in the Vanderbilt Vaccine Clinic from September 1, 1992, to August 31, 1993.

RESULTS

Of 842 nasopharyngeal cultures obtained, results for 44% of the cultures were positive for S. pneumoniae; 73% of the isolates were serotypes 6, 14, 19, or 23. Younger children had significantly higher rates of pneumococcal colonization than older children, with a peak at 1 year of age. By microdilution susceptibility testing, 37% of the cultures with positive results were intermediately or highly resistant to penicillin. Significantly more serotype 19 and 23 isolates were penicillin resistant than organisms of other serotypes. Children younger than 2 years of age had a twofold higher percentage of resistant isolates than those older than 2 years of age. A significant association was noted between nasopharyngeal carriage of S. pneumoniae and acute otitis media (p = 0.0002); however, the incidence of acute otitis media did not differ significantly between children colonized with penicillin-susceptible or penicillin-resistant strains. Unresolved otitis media was diagnosed more often in children who were colonized with resistant organisms than in children colonized with susceptible strains (p = 0.04).

CONCLUSIONS

There was a high rate of nasopharyngeal carriage of penicillin-resistant S. pneumoniae in this population of young children. Nasopharyngeal colonization was associated with an increased incidence of acute otitis media, and penicillin resistance was associated with an increased incidence of unresolved otitis media.

Prevalence of bacterial respiratory pathogens in the nasopharynx in breast-fed versus formula-fed infants

In several studies, breast-feeding has been associated with decreased frequency or duration of otitis media episodes. If a causal relationship exists, the mechanism of protection of breast-feeding has not been established. We hypothesized that infants who are breast-fed, compared with infants who are formula-fed, have a lower prevalence of nasopharyngeal colonization with the bacterial respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes) commonly isolated from the middle ear effusions of children with acute otitis media. In two private pediatric practices, we obtained specimens from the nasopharynx for culture from 211 infants at 1 month of age and from 173 of these infants at 2 months of age. A swab was left in place in the nasopharynx for 45 s and was then immediately transferred onto appropriate culture media. Exclusively breast-fed (n = 84) and exclusively formula-fed (n = 76) infants were similar regarding the number of persons in the household, the number of children in the household, the number of siblings in day care, and the proportion with a recent upper respiratory tract infection. The two groups did not differ significantly in the proportions found to have one or more respiratory pathogens at 1 month of age (10.7 versus 18.4%; P = 0.12) or 2 months of age (34.8 versus 35.1%; P = 0.57). We conclude that during the first 2 months after birth, the exclusive receipt of breast milk appears not to substantially influence the prevalence of nasopharyngeal colonization with common bacterial respiratory pathogens.

Micro-ecology of the nasopharyngeal bacterial flora in otitis-prone and non-otitis-prone children

The quantitative bacteriology of the adenoid was studied in otitis-prone and non-otitis-prone children. alpha-hemolytic Streptococci (Viridans Streptococci) appeared to be predominant normal flora in the healthy nasopharynx. There was a decrease in alpha-hemolytic Streptococci in the otitis-prone child compared to the non-otitis-prone child. Concomitantly, there appears to be an increase in both nontypable Haemophilus influenzae (NTHI) and S. pneumoniae in the nasopharyngeal flora in the otitis-prone child. The mechanisms responsible for this alteration of the micro-ecology of bacteria of the nasopharynx may be related, in part, to factors that alter mucociliary function. These factors could be viral infection, allergy, local and systemic immunological deficiency and the indiscriminate use of antibiotics. An understanding of the relationship between the normal flora and the potential pathogens may be important in the understanding of both the pathogenesis of otitis media (OM) and possibly the treatment of this disease entity.

Inhibition of nasopharyngeal colonization of Hemophilus influenzae by oral immunization

Nontypeable Hemophilus influenzae organisms were inoculated into the nasopharynx of BALB/c mice immunized by oral administration of formalin-killed bacteria. Salivary antibodies and the colonization of H influenzae in the nasopharynx were investigated in order to clarify the effect of oral immunization. Salivary immunoglobulin A antibody titers against H influenzae were significantly increased by oral immunization, but salivary immunoglobulin G antibody titers were not. The bacteria inoculated into the nasopharynx were more rapidly eliminated in immunized mice than in control mice. The results suggest that oral immunization might be useful in preventing otitis media with effusion by inhibiting the colonization of the nasopharynx by pathogenic bacteria.

Recurrent otitis media with non-typable Haemophilus influenzae: the role of serum bactericidal antibody

The effect of serum bactericidal antibody on colonization with non-typable Haemophilus influenzae (NTHI) was studied in 26 children. Serum bactericidal antibody did not prevent colonization with NTHI in the nasopharynx. Antibody was present in 53% before, 91% during and 100% after documented colonization of the nasopharynx with NTHI. In addition, 5 children with recurrent otitis media with effusion (OME) due to NTHI were observed for bactericidal serum antibody during a 4-year period. Bactericidal antibody against the causative NTHI strain was not detected in the acute sera of any patient during each episode, but was observed in the convalescent sera of all of the patients. The bactericidal antibody in the convalescent serum did not appear to be protective against colonization and recurrence of disease by a different heterologous strain of NTHI. However, bactericidal antibody was augmented in some cases by a heterologous infection with NTHI. We confirmed the emergence of new strains of NTHI with DNA fingerprinting and outer membrane protein (OMP) analysis. The data suggest that the immune response to NTHI in OME is usually strain-specific, and furthermore, the results demonstrate that strain-specific bactericidal antibody does not prevent colonization in the nasopharynx with the homologous or heterologous bacterial strains. In general, bactericidal antibody is not cross-protective against heterologous strains of NTHI causing a second or third episode of otitis media with NTHI.