High rate of nasopharyngeal carriage of potential pathogens among children in Greenland: results of a clinical survey of middle-ear disease

The unsolved problem of otitis media in indigenous populations: a systematic review of upper respiratory and middle ear microbiology in indigenous children with otitis media

BACKGROUND

Otitis media (OM) imposes a great burden of disease in indigenous populations around the world, despite a variety of treatment and prevention programs. Improved understanding of the pathogenesis of OM in indigenous populations is required to advance treatment and reduce prevalence. We conducted a systematic review of the literature exploring the upper airway and middle ear microbiota in relation to OM in indigenous children.

METHODS

Papers targeting microbiota in relation to OM in children < 18 years indigenous to Australia, New Zealand, North America, and Greenland were sought. MEDLINE, CINAHL, EMBASE, Cochrane Library, and Informit databases were searched using key words. Two independent reviewers screened titles, abstracts, and then full-text papers against inclusion criteria according to PRISMA guidelines.

RESULTS

Twenty-five papers considering indigenous Australian, Alaskan, and Greenlandic children were included. There were high rates of nasopharyngeal colonization with the three main otopathogens (Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis) in indigenous children with OM. Middle ear samples had lower rates of otopathogen detection, although detection rates increased when molecular methods were used. Pseudomonas aeruginosa and Staphylococcus aureus were commonly detected in middle ear discharge of children with chronic suppurative OM. There was a significant heterogeneity between studies, particularly in microbiological methods, which were largely limited to culture-based detection of the main otopathogens.

CONCLUSIONS

There are high rates of otopathogen colonization in indigenous children with OM. Chronic suppurative OM appears to be associated with a different microbial profile. Beyond the main otopathogens, the data are limited. Further research is required to explore the entire upper respiratory tract/middle ear microbiota in relation to OM, with the inclusion of healthy indigenous peers as controls.

Effect of the 13-valent pneumococcal conjugate vaccine on nasopharyngeal carriage by respiratory pathogens among Greenlandic children

Background: In 2010, Greenland introduced the 13-valent pneumococcal conjugate vaccine (Prevnar 13®– PCV-13) in the childhood immunisation program. The authors aimed to evaluate the impact of PCV-13 on nasopharyngeal carriage of bacteria frequently associated with respiratory infections in children.

Method: In 2013 a cross-sectional population-based study of nasopharyngeal carriage was conducted among Greenlandic children aged 0–6 years and results were compared with an equivalent study from 2011. Nasopharyngeal swab samples were tested for Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus. Pneumococcal serotyping was performed by Quellung reaction and serotype-specific antisera. Statistical analysis included logistic regression models, adjusting for known risk factors.

Result: A total of 377 nasopharyngeal samples were collected. Overall carriage rate of S. pneumoniae remained unchanged from 2011 to 2013 (51% and 56%, p=0.13), but significant serotype shifts were observed among both vaccinated and unvaccinated children with marked reductions in carriage of vaccine-type pneumococci, counterbalanced by increasing carriage of non-vaccine types. Carriage rate of S. aureus decreased significantly among vaccinated children whereas that of M. catarrhalis increased.

Conclusion: PCV-13 introduction in Greenland is associated with significant changes in nasopharyngeal bacterial carriage. Continued surveillance is warranted to clarify whether these changes are persistent, and affect the pattern of respiratory and invasive diseases in Greenland.

Epidemiology and Molecular Characteristics of Mycoplasma pneumoniae During an Outbreak of M. pneumoniae-associated Stevens-Johnson Syndrome

BACKGROUND

An increase in Mycoplasma pneumoniae-associated Stevens-Johnson syndrome (SJS) cases at a Colorado pediatric hospital led to an outbreak investigation. We describe the epidemiologic and molecular characteristics of M. pneumoniae among SJS case-patients and surrounding community members during the outbreak.

METHODS

M. pneumoniae polymerase chain reaction-positive respiratory specimens from 5 Colorado hospitals and 4 referral laboratories underwent confirmatory polymerase chain reaction testing; positive specimens then underwent multilocus variable-number tandem-repeat analysis (MLVA) and macrolide resistance testing. Three SJS-M. pneumoniae case-patient households were surveyed using a standardized questionnaire, and nasopharyngeal/oropharyngeal swabs were obtained from all consenting/assenting household contacts. International Classification of Diseases, 9th revision codes were used to identify pneumonia cases among Colorado patients 5-21 years of age from January 2009 to March 2014.

RESULTS

Three different M. pneumoniae MLVA types were identified among the 5 SJS case-patients with confirmed infection; MLVA type 3-X-6-2 was seen more commonly in SJS case-patients (60%) than in 69 non-SJS community specimens (29%). Macrolide resistance was identified in 7% of community specimens but not among SJS case-patients. Of 15 household contacts, 5 (33%) were M. pneumoniae positive; all MLVA types were identical to those of the corresponding SJS case-patient, although the specimen from 1 contact was macrolide resistant. Overall pneumonia cases as well as those caused by M. pneumoniae specifically peaked in October 2013, coinciding with the SJS outbreak.

CONCLUSIONS

The outbreak of M. pneumoniae-associated SJS may have been associated with a community outbreak of M. pneumoniae; clinicians should be aware of the M. pneumoniae-SJS relationship. Household transmission of M. pneumoniae was common within the households investigated.

The effects of ventilation tubes versus no ventilation tubes for recurrent acute otitis media or chronic otitis media with effusion in 9 to 36 month old Greenlandic children, the SIUTIT trial: study protocol for a randomized controlled trial

Background

The prevalence of otitis media in Greenlandic children is one of the highest in the world. International studies have shown that otitis-prone children may benefit from tubulation of the tympanic membrane. However, it is unknown whether these results can be applied to Greenlandic children and trials on the effects of ventilation tubes in high-risk populations have, to our knowledge, never been conducted.

Methods

The trial is an investigator-initiated, multicentre, randomized, blinded superiority trial of bilateral ventilation tube insertion versus treatment as usual (no tube) in Greenlandic children aged 9–36 months with chronic otitis media with effusion or recurrent acute otitis media. With randomization stratified by otitis media subtype and trial site, a type 1 error of 5% and a power of 80%, a total of 230 participants are needed to detect a decrease of two visits to a health clinic during 2 years, which is considered the minimal clinical relevant difference. The primary outcome measure will be assessed blindly by investigating medical records. Secondary outcome measures are number of episodes of acute otitis media, quality of life, number of episodes of antibiotics administration and proportion of children with tympanic membrane perforations.

Discussion

This trial will provide evidence-based knowledge of the effects of ventilation tubes in children with middle ear infections from the high-risk Greenlandic population. Furthermore, this trial will improve the understanding of conducting randomized clinical trials in remote areas, where management of logistical aspects is particularly challenging.

Trial registration

ClinicalTrials.gov, NCT02490332. Registered on 14 February 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1770-x) contains supplementary material, which is available to authorized users.

Nasopharyngeal bacterial carriage in young children in Greenland: a population at high risk of respiratory infections

The incidence of childhood respiratory infections in Greenland is among the highest globally. We performed a population-based study of 352 Greenlandic children aged 0-6 years aiming to describe rates and risk factors for carriage of four key bacteria associated with respiratory infections, their antimicrobial susceptibility and inter-bacterial associations. Nasopharyngeal swabs were tested for Streptococcus pneumoniae grouped by serotypes included (VT) or not included (NVT) in the 13-valent pneumococcal conjugate vaccine, non-typable Haemophilus influenzae (NTHi), Staphylococcus aureus and Moraxella catarrhalis. S. pneumoniae was detected from age 2 weeks with a peak carriage rate of 60% in 2-year-olds. Young age and having siblings attending a daycare institution were associated with pneumococcal carriage. Overall co-colonization with ⩾2 of the studied bacteria was 52%. NTHi showed a positive association with NVT pneumococci and M. catarrhalis, respectively, M. catarrhalis was positively associated with S. pneumoniae, particular VT pneumococci, whereas S. aureus were negatively associated with NTHi and M. catarrhalis. Nasopharyngeal bacterial carriage was present unusually early in life and with frequent co-colonization. Domestic crowding increased odds of carriage. Due to important bacterial associations we suggest future surveillance of pneumococcal conjugate vaccine's impact on carriage in Greenland to also include other pathogens.

Study of Two Separate Types of Macrolide-Resistant Mycoplasma pneumoniae Outbreaks

To study the complete natural process of a Mycoplasma pneumoniae outbreak in a semiclosed room such as a primary school room, we investigated two separate M. pneumoniae outbreaks involving 81 students in total in two primary schools in Hangzhou, China. M. pneumoniae isolates from pharyngeal swabs were detected by fluorescence quantitative real-time PCR (RT-PCR) and culture. The class in school M had 39 students, with 12 (30.8%) with positive M. pneumoniae detection results. The class from school J had 42 students, with 13 (31.0%) positive. The strains from two classes were confirmed to represent two clones (3/4/5/7/2 and 5/4/5/7/2) and to be macrolide resistant (A2063G) according to P1 and multilocus variable-number tandem-repeat analysis (MLVA) genotyping, determination of MIC of antibiotics, and sequencing. Students with M. pneumoniae isolates detected were divided into three groups: those carrying the isolates, those with upper respiratory tract infection (URI), and those with pneumonia. Longitudinal sampling performed using pharyngeal swabs showed that the persistence of M. pneumoniae was longest in the group of students with pneumonia. M. pneumoniae causes pneumonia outbreaks in schools, and the incidence of pneumonia has a higher rate than that of URI. The persistence of M. pneumoniae, with a median duration of 79.50 days in the group of students with pneumonia, differs from that of the infection state.

Respiratory infections in Eñepa Amerindians are related to malnutrition and Streptococcus pneumoniae carriage

OBJECTIVES

High acute respiratory tract infection (ARTI) rates are observed in indigenous populations. We assessed the role of viral infections and nasopharyngeal bacterial carriage in ARTIs in Eñepa Amerindians from Venezuela.

METHODS

In 40 children aged 0-10 years with ARTIs, healthy nearest-age sibling controls and their mothers the presence of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, Mycoplasma pneumoniae, Chlamydophila pneumoniae/psittachi and 15 respiratory viruses was investigated.

RESULTS

S. pneumoniae was the most frequently detected pathogen, with carriage rates of 75% and 38% in children and mothers respectively. In children, S. pneumoniae carriage was associated with ARTI risk in multivariate analysis (OR 14.1, 95% CI 1.4-137.7). Viral infections were not associated with ARTI risk. S. pneumoniae carriage was common in children of all ages while viral co-infections were more frequently present in children under 4 years compared to older children (46% vs. 17%, p < 0.01). An increase of one unit height-for-age Z score (i.e. improved chronic nutritional status) was associated with decreased odds of S. pneumoniae colonization in multivariate analysis (OR 0.66, 95% CI 0.44-0.99).

CONCLUSIONS

In Eñepa children high S. pneumoniae carriage rates associated with a poor nutritional status contribute to the development of ARTIs.

Pathogen diversity and hidden regimes of apparent competition

Competition through cross-reacting host immune responses, a form of apparent competition, is a major driver of pathogen evolution and diversity. Most models of pathogens have focused on intraspecific interactions to explain observed patterns. Two recent experiments suggested that Haemophilus influenzae, a common nasopharyngeal colonizer of humans, might alter the immune environment in a way that favors otherwise less fit serotypes of another common pathogen, pneumococcus. Using a computational model, we demonstrate that H. influenzae, if it consistently raises the fitness of the less fit serotypes, can strongly promote pneumococcal diversity. However, the effects of H. influenzae are so sensitive to the prevalence of H. influenzae that this species is unlikely to be the main driver of serotype coexistence. Interactions that significantly affect diversity could furthermore be extremely difficult to detect through co-occurrence analysis alone. These results suggest that small differences in strains' adaptations to different immunological regimes, which are shaped by coinfections with other pathogens, can have dramatic effects on strain dynamics and patterns of phenotypic variation. Studies of microbial communities might therefore benefit from the use of varied approaches to infer the presence of indirect interactions.

Chronic suppurative otitis media in a birth cohort of children in Greenland: population-based study of incidence and risk factors

BACKGROUND

Inuits of the Arctic experience very high rates of chronic suppurative otitis media (CSOM), yet world-wide, very little is known about the epidemiology of CSOM. The study aims were to determine incidence, median age at debut, risk factors, and associated population attributable risks for CSOM in young children in Sisimiut, the second biggest town of Greenland (population 5400), where living conditions are relatively western and approximately 90% are Inuits.

METHODS

A population-based birth cohort of 465 children aged between 0 and 4 years was followed for a 2-year period (1996 to 1998), and cases of CSOM were registered based on medical history and clinical examinations. Kaplan-Meier curves were used for estimations of cumulative risk and Cox regression analyses for hazard rates associated with risk factors.

RESULTS

Cumulative risk of CSOM at 4 years of age was 14%, and median age at debut was 336 days. Risk factors were attending childcare centers (hazard ratio [HR]: 3.18, 95% confidence interval [CI]: 1.53- 6.61), having smokers in the household (HR: 4.56, 95% CI: 1.07-19.4), having a mother who reported a history of purulent ear discharge (3.27, 95% CI: 1.74-6.13), having a high burden of upper respiratory tract infections (HR: 1.19, 95% CI: 1.03-1.37), and being Inuit (HR: 5.56, 95% CI: 0.78-50).

CONCLUSIONS

Greenlandic children have high rates of CSOM with debut early in life, but the identified risk factors and the associated population attributable risks indicate that preventive measures regarding use of childcare centers and passive smoking may reduce the high frequency of CSOM in this high-risk population.

Acute and chronic otitis media

Otitis media (OM) is a common illness in young children. OM has historically been associated with frequent and severe complications. Nowadays it is usually a mild condition that often resolves without treatment. For most children, progression to tympanic membrane perforation and chronic suppurative OM is unusual (low-risk populations); this has led to reevaluation of many interventions that were used routinely in the past. Evidence from a large number of randomized controlled trials can help when discussing treatment options with families. Indigenous children in the United States, Canada, Northern Europe, Australia, and New Zealand experience more OM than other children. In some places, Indigenous children continue to suffer from the most severe forms of the disease. Communities with more than 4% of the children affected by chronic tympanic membrane perforation have a major public health problem (high-risk populations). Higher rates of invasive pneumococcal disease, pneumonia, and chronic suppurative lung disease (including bronchiectasis) are also seen. These children will often benefit from effective treatment of persistent (or recurrent) bacterial infection.

Frequent Haemophilus influenzae type B colonization in rural Thailand

In Asia, there is uncertainty regarding whether the burden of Haemophilus influenzae type b (Hib) disease is great enough to warrant vaccination. In this nasopharyngeal carriage study in rural Thailand, 7% of children younger than 5 years of age carried Hib, a prevalence similar to that found in countries with high rates of Hib disease before vaccine introduction.

Acute otitis media and season of birth

INTRODUCTION

This study examines the question whether season of birth is associated with acute otitis media (AOM) and recurrent AOM (rAOM) and whether season of birth is associated with early age of AOM onset.

METHODS

This was done in a population-based survey of 591 unselected Greenlandic children aged 3-5 and 8 years, living in the two largest towns in Greenland. The overall attendance rate was 86%. Information of AOM episodes was obtained from the parents and cross-checked in medical records available for 95% of the children. In total, 67% reported AOM at least once and 30% of those had rAOM.

RESULTS

According to season of birth, the frequency of history of AOM in general varied between 63% and 70% lowest for birth in the autumn and highest for birth in the spring but without any significant statistical difference (p=0.51). The similar variation in rAOM according to season of birth was between 21% and 35%, highest for children born in autumn and winter and lowest for children born in the spring (p=0.09). Additionally, there was no difference in age at onset of the first AOM episode according to season of birth. However, AOM children born in the summer and autumn periods have a significantly higher relative risk (RR=1.44, CI=1.04-1.99) of attracting rAOM than AOM children born in the winter and spring periods. This may be due to a higher risk of being quickly reinfected in the late autumn and winter period with another episode of upper respiratory tract infection.

CONCLUSION

Season of birth do not seem to be a predictor of AOM episodes or early onset of AOM but children born in the summer and autumn periods who attracts AOM have a higher risk of developing rAOM.

Respiratory tract infections in Greenland: results of an audit project

OBJECTIVES

To elucidate and improve quality of diagnosis and treatment of respiratory tract infections in Greenland.

STUDY DESIGN

All district medical officers and nursing staff in the Greenlandic coastal health services were invited to participate in the study. Twenty-five district medical officers and the nursing staff from nine districts completed the project and registered in a 3-week period 1,163 contacts involving respiratory tract infections.

METHODS

Self-registration according to the Audit Project Odense (APO) method on a simple APO registration chart. All contacts involving respiratory tract infections were registered with regard to sex, type of contact, contact form, infection focus, diagnosis and treatment, origin of infection, antibiotic treatment, choice of antibiotics and possible sick-leave.

RESULTS

Of the 1,163 registered contacts lung infections represented 26%, throat infections 22% and otitis media 16%. Paraclinical tests were performed in 32% of the cases, 47% of the cases were treated with antibiotics, in 2/3 of the cases with penicillin V. The use of paraclinical tests was somewhat lower and the use of antibiotics was higher than in Denmark.

CONCLUSION

The study showed that it is possible to carry out an APO audit in Greenland, and that there was a moderate difference in the diagnosis and treatment between Greenland and Denmark. An increased use of paraclinical tests may result in quality improvement.

[Evolution of Streptococcus pneumoniae antibiotic resistance in Abidjan: update on nasopharyngeal carriage, from 1997 to 2001]

The emerging antibiotic resistance and worldwide diffusion of Streptococcus pneumoniae strains is an important public health problem.

OBJECTIVES

The aims of this study were to study the evolution of S. pneumoniae resistance rates to penicillin G and other antimicrobials from nasopharyngeal carriage.

METHOD

Four hundred and eighty-two nasopharyngeal samples of S. pneumoniae were studied from 1997 to 2001. The Kirby-Bauer technique was used to screen the susceptibility of samples and completed with the determination of penicillin G minimal inhibitory concentration using the E-test.

RESULTS

Resistance to penicillin increased from 1997 to 2001: 8.5% in 1997, 20.7% in 1998, 16% in 1999, and 23.5% in 2001. However, the resistance to other beta-lactam antibiotics was low. The rate of resistance to cotrimoxazole increased from 52.2% in 1997 to 84.3% in 2001, with a higher degree of resistance in 2001. The resistance of S. pneumoniae to tetracycline increased. In contrast, the prevalence of erythromycin-resistant pneumococcal samples decreased from 11.6% in 1997 to 8% in 2001. The resistance to three or more antibiotics (multi-drug resistant) was also increased from 9.4% in 1997 to 23.5% in 2001.

CONCLUSION

This data shows that carriage of antibiotic-resistant pneumococci is increasing in Abidjan. It will be interesting to assess the current bacterial resistance patterns by a national epidemiological observatory.

Pattern of drug prescription for children under the age of four years in a population in Greenland

AIM

To provide knowledge of drug prescription patterns in general and of antibiotics in particular, and number of consultations and diagnoses leading to prescriptions among children aged 0-4 y in the Arctic.

METHODS

A population-based cohort of children aged 0-4 y, living in Sisimiut, the second largest town in Greenland, was followed from August 1996 to December 1998. Information on consultations, diagnoses and drug prescriptions was obtained from medical files at the local health centre.

RESULTS

Among 280 participating children, the mean number of consultations per child was 5.64 per year at risk (range 0-17), of prescriptions 4.02 per year at risk (range 0-17.2), and of prescribed systemic antibiotics per child 1.47 per year at risk (range 0-7.25). Systemic antibiotics formed the therapeutic subgroup most often issued for children, constituting 33.5% of all prescriptions. Of the systemic antibiotics, 50% were broad-spectrum penicillins, 34% penicillin V, 14% macrolides and 2% other antibiotics. The most frequent diagnoses leading to drug prescription in general as well as to prescription of systemic antibiotics were respiratory tract infections, accounting for 59% of all prescriptions and 81% of prescriptions of systemic antibiotics. Children aged 1/2-1 y of age had the highest prescription rates of drugs in general and of systemic antibiotics.

CONCLUSIONS

Compared to other countries, prescription rates of drugs in general and of systemic antibiotics in particular were high. The use of broad-spectrum penicillins was higher than recommended in Greenlandic national guidelines, and might be reduced.

Activated T cells in the surface secretion on the adenoid--a flow cytometric study

We previously demonstrated the presence of leucocytes in the adenoid surface secretion with the ability of immunoglobulin A (IgA), IgM and IgG production as well as production of cells with phagocytic capacity. In the present study, we investigated the presence of activated T cells in the secretion. Adenoid surface secretion from 12 children subjected to adenoidectomy was obtained with an imprint method. From six children, peripheral blood was also obtained. By flow cytometry, the number of lymphocytes, granulocytes, epithelial cells and red blood cells was analysed as well as the expression on lymphocyte subsets of the following antigens: CD3, CD4, CD8, CD19, CD25, CD38, CD45RO, CD45RA, HLA-DR, TcRgd, CD161 and l-selectin. The majority of T cells were activated and to a significantly higher degree were CD45RO+, CD161+ and l-selectin-, as compared with the corresponding peripheral blood. The median percentage of B cells and T cells in the secretion were 81 and 13%, respectively. In conclusion, the proportion of B and T cells in the adenoid surface secretion is significantly different as compared with the peripheral blood. The T cells in the adenoid surface secretion are to a high degree activated. The results suggest that the leucocytes in the surface secretion are part of the mucosal defence.

Population-based study of acute respiratory infections in children, Greenland

Acute respiratory infections (ARI) are frequent in Inuit children, in terms of incidence and severity. A cohort of 294 children <2 years of age was formed in Sisimiut, a community on the west coast of Greenland, and followed from 1996 to 1998. Data on ARI were collected during weekly visits at home and child-care centers; visits to the community health center were also recorded. The cohort had respiratory symptoms on 41.6% and fever on 4.9% of surveyed days. The incidence of upper and lower respiratory tract infections was 1.6 episodes and 0.9 episodes per 100 days at risk, respectively. Up to 65% of the episodes of ARI caused activity restriction; 40% led to contact with the health center. Compared with studies from other parts of the world, the incidence of ARI appears to be high in Inuit children.

The role of bacterial toxins in sudden infant death syndrome (SIDS)

There is increasing evidence for the involvement of bacterial toxins in some cases of sudden infant death syndrome (SIDS), particularly the pyrogenic toxins of Staphylococcus aureus. This had led to the hypothesis that some SIDS deaths are due to induction of inflammatory mediators by infectious agents or their products during a period in which the infant is unable to control these normally protective responses. The genetic, developmental and environmental risk factors identified for SIDS are assessed in relation to frequency or density of mucosal colonisation by toxigenic bacteria and their effects on induction and control of inflammatory responses to the toxins.

Bacterial pathogens of otitis media and sinusitis: detection in the nasopharynx with selective agar media

Carriage rates for the bacterial pathogens associated with otitis media (Streptococcus pneumoniae [SP], Hemophilus influenzae [HI], and Moraxella catarrhalis [MC]) are of interest. Culture on three selective agars was compared with culture on two standard agars to determine the more accurate method for detection of these species in the nasopharynx of healthy children. Weekly samples were obtained in winter from 18 healthy children (ages 1 through 9 years) as part of a longitudinal study. A 0.1-mL sample of 116 nasopharyngeal aspirate/washes was inoculated onto each of five agars. Two were standard (sheep blood and chocolate), and three were selective (blood with gentamicin for SP; chocolate with vancomycin, bacitracin, and clindamycin for HI; blood with amphotericin B, vancomycin, trimethoprim, and acetazolamide for MC). One technician read the standard plates and another the selective; both were blinded to the results of the other. SP was found in 44% of samples with selective agar versus 25% with standard agar; HI was found in 31% with selective versus 9% with standard; MC was found in 56% with selective versus 37% with standard. Overall, 80% of samples had one or more pathogens detected with selective agars as compared with 58% with standard agars (P =.0004). Selective agars were more accurate than standard agars for detecting otitis pathogens in the nasopharynx, where they are a common part of normal flora in healthy children.

Quantitative analysis of the effect of xylitol on pneumococcal nasal colonisation in rats

Xylitol possesses anti-bacterial effects on pneumococci in vitro. To study the effect in vivo, the nostrils of 80 rats were inoculated with pneumococci. Intervention groups (n = 20) received either a xylitol diet or xylitol nasal sprays. The control groups were on a normal diet or had saline sprays. After 3 days, a quantitative bacterial culture and a PCR were done from the mucosal suspension. Neither the mean colony-forming unit counts nor the PCR counts differed statistically significant between the xylitol and control groups. Thus, we found that xylitol had no significant effect on pneumococcal mucosal colonisation.

Acute otitis media and sociomedical risk factors among unselected children in Greenland

OBJECTIVE

To describe the sociomedical risk factors associated with episodes of acute otitis media (AOM), recurrent AOM (rAOM), and chronic otitis media (COM) in Greenlandic children and especially to point out children at high risk of rAOM (defined as > 5 AOM episodes since birth) and COM which are prevalent among Inuit children all over the Arctic.

METHODS

The study design was cross-sectional and included 740 unselected children, 3, 4, 5, and 8-years-old, living in two major Greenlandic towns, Nuuk and Sisimiut. All children were otologically examined and the parents answered a questionnaire containing sociomedical variables including ethnicity, family history of OM, housing, insulation, crowding, daycare, passive cigarette smoking, breast feeding, type of diet, allergy, and chronic diseases. Historical data were cross-checked in medical records which also formed the basis for the drop-out analyses. Statistical analyses included frequency tests, calculation of odds ratio (OR), and multiple logistic regression.

RESULTS

The attendance rate was 86%. Former episode of AOM was reported by 2/3 of the children, rAOM by 20%, and COM by 9%. The following variables were found significantly more often in children with AOM by simple frequency testing: Parental (OR = 1.83), sibling (OR = 1.62), and parental plus sibling (OR = 2.56) history of OM, crowding (OR = 5.55), long period of exclusive breast feeding ( > 4 months) (OR = 2.47), and recent acute disease (P = 0.034). The following variables were found significantly more often in children with rAOM or COM by simple frequency testing: Parental history of OM (OR = 1.60; OR = 2.11, respectively) and no recall of breast feeding (P = 0.005; P = 0.003, respectively). Also, COM was found significantly more often in children with two Greenlandic parents (OR = 3.07). A multiple logistic regression test denoted only parental history of OM (OR = 1.82) and long period of exclusive breast feeding (OR = 1.14) as significant predictors of AOM.

CONCLUSIONS

Many of the risk factors usually associated with AOM could not be confirmed as risk factors in this survey. Parental history of OM and long period of exclusive breast feeding were the strongest factors associated with AOM in Greenlandic children and ethnicity was associated with COM. However, the study confirms that AOM is a multifactorial disease determined by a number of genetic and environmental factors.

Nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae among children with acute respiratory tract infections in Thailand: a molecular epidemiological survey

The prevalence of penicillin-resistant Streptococcus pneumoniae in Thailand has dramatically increased over the last decade. During a national survey, which was conducted from 1992 to 1994, 37.2% of the pneumococci isolated from the nasopharynges of children with acute respiratory tract infections were penicillin resistant (MIC, >/=0.1 microg/ml). In order to investigate the prevalence and clonal relatedness of nasopharyngeal carriage of penicillin-resistant S. pneumoniae in Thailand, a molecular epidemiological survey was undertaken. To this end, 53 penicillin-resistant pneumococcal isolates from children who suffered from acute respiratory tract infections and who originated from five distinct regions of the country were characterized in detail. DNA fingerprint analysis demonstrated 13 clusters, i.e., genotypes shared by two or more strains, and 14 unique genotypes. The cluster size varied from 2 (nine clusters) to 11 strains (one cluster). Six of the 13 restriction fragment end labeling clusters consisted of two or more distinct serotypes, indicating frequent horizontal transfer of capsular genes. Geographical distribution of the genotypes among the five regions of Thailand demonstrated that only four genetic clusters were restricted to single areas of the country, whereas the other nine clusters represented isolates collected in two or more districts. These observations demonstrate that the majority of the genetic clusters are spread throughout the country. The most predominant genetic cluster, representing 21% of the isolates, was identical to the Spanish pandemic clone 23F. In addition, the second largest cluster matched the Spanish-French international clone 9V. These data indicate that the genetic clones 23F and 9V, which are widely spread throughout the world, are the most predominant multidrug-resistant pneumococcal clones in Thailand. Therefore, we conclude that these pandemic clones are primarily responsible for the increase in the prevalence of pneumococcal penicillin resistance in Thailand.

Multidrug-resistant Streptococcus pneumoniae in Poland: identification of emerging clones

Penicillin resistance among Streptococcus pneumoniae isolates has rapidly emerged in Poland during the last decade and has reached prevalence levels of up to 14.4% in 1997. In order to investigate the nature of this increase, a molecular epidemiological analysis of non-penicillin-susceptible multidrug-resistant pneumococci isolated in 1995 and 1996 was conducted. Thirty-seven patients who suffered mainly from upper respiratory tract infections and pneumococcal pneumonia were enrolled in this study. The medical centers to which the patients were admitted were located in 16 Polish towns across the country. Eight distinct BOX PCR types were observed, representing 14 subtypes. Restriction fragment end labeling (RFEL) analysis divided the pneumococcal strains into 16 distinct types. By combining the BOX PCR and RFEL data, four genetically distinct clusters of strains were identified. Two clusters represented the genetic clones 23F and 9V, which have recently emerged all over the world. The two other genetic clusters, which represented serotypes 23F and 6B, clearly predominated in the analyzed collection of Polish non-penicillin-susceptible pneumococcal strains. Since the latter clusters did not match any of the 133 RFEL types of non-penicillin-susceptible pneumococci collected in 15 other countries, their Polish clonal origin is most likely.

Infection, inflammation and sleep: more pieces to the puzzle of sudden infant death syndrome (SIDS)

Risk factors for sudden infant death syndrome (SIDS) parallel those for respiratory tract infections; however, infectious agents suggested to be involved in SIDS do not fulfil Koch's postulates. No single agent has been identified in all cases and there is no suitable animal model for SIDS which could be used to test the candidate organisms. Based on epidemiological and experimental work by our group and others, we suggested some SIDS deaths are due to pathophysiological responses elicited by combinations of microbial products and/or cigarette smoke during a developmental stage when infants' endocrine responses are less able to "damp down" the effects of inflammatory mediators. Here we review evidence from studies on interactions between developmental and environmental risk factors that could affect 1) mucosal colonization of infants by potentially pathogenic bacteria, and 2) induction and control of infants', inflammatory responses to infectious agents. New evidence suggests that there are genetic factors involved in the induction of inflammatory responses to some bacterial antigens implicated in SIDS. Further investigation of the role of infection, exposure to cigarette smoke and inflammation in infants, particularly differences in ethnic groups at increased risk of SIDS, could lead to new insights into the events leading to a fatal outcome and perhaps to new intervention schemes to reduce further the incidence of these deaths.

Acute otitis media and age at onset among children in Greenland

This survey examines the age at onset of acute otitis media (AOM) in 591 unselected Greenlandic children aged 3, 4, 5 and 8 years from the two largest towns in Greenland. The attendance rate was 86%. Parental information about episodes of AOM was cross-checked in medical records, which were available for 95% of the children. AOM was defined as episodes with earache, otorrhoea or previous treatment for AOM, with written otoscopic evidence of AOM resulting in treatment with weak analgetics or antibiotics. Recurrent AOM (rAOM) was defined as > or = 5 AOM episodes since birth. In total, 66% of the children had experienced AOM at least once. Of all children, 40% had AOM during the first year of life. Median age of the first episode was 10 months (range: 1-84 months), and there was no sex difference. Children between 7 and 12 months of age were at highest risk of AOM. Children with rAOM had their first AOM episode at a significantly younger age than children with < 5 AOM episodes (median: 7 months, range: 2-48 months). In addition, 83% of children with rAOM had their first AOM episode before 12 months of age compared with 53% of children with < 5 episodes (p < 0.0001). The relative risk of rAOM was eight times greater if the first episode of AOM occurred before six months of age compared to more than 24 months of age. Thirty-five percent of children with rAOM had chronic otitis media as well, compared to only 4% of children with < 5 AOM episodes. We conclude that early onset of AOM (before one year of age) occurs frequently in Greenlandic children compared to others, and a high proportion of these children develop rAOM.

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.

Molecular characterization of pneumococcal nasopharynx isolates collected from children during their first 2 years of life

Pneumococcal colonization was studied in 19 children monitored from birth through the age of 2 years. For this purpose, pneumococcal isolates were characterized by capsular typing, restriction fragment end labeling (RFEL), and penicillin-binding protein (PBP) genotyping. Fifty-eight isolates were collected and were found to belong to 10 capsular types, 31 RFEL types, and 7 PBP genotypes. Thirty-nine percent of the isolates had reduced susceptibility to penicillin. All seven highly resistant strains (MICs, > 1 microgram/ml) were identical to the pandemic clone 23F. Children were culture positive between one and eight times at 13 scheduled visits. Although the infants were frequently recolonized with different strains, colonization with one particular strain often persisted for several months. Isolation of a previously detected capsular type was common, and the chromosomal homogeneity tended to be high when it occurred. Horizontal transfer of capsular genes between strains of different RFEL types was demonstrated in one child. The ecological advantage of transfer of capsular genes is unclear unless survival of the organism on a mucosal surface may be linked to immunoprotective pressure against particular capsular types.

Cloning and expression of the Moraxella catarrhalis lactoferrin receptor genes

The lactoferrin receptor genes from two strains of Moraxella catarrhalis have been cloned and sequenced. The lfr genes are arranged as lbpB followed by lbpA, a gene arrangement found in lactoferrin and transferrin receptor operons from several bacterial species. In addition, a third open reading frame, orf3, is located one nucleotide downstream of lbpA. The deduced lactoferrin binding protein A (LbpA) sequences from the two strains were found to be 99% identical, the LbpB sequences were 92% identical, and the ORF3 proteins were 98% identical. The lbpB gene was PCR amplified and sequenced from a third strain of M. catarrhalis, and the encoded protein was found to be 77% identical and 84% similar to the other LbpB proteins. Recombinant LbpA and LbpB proteins were expressed from Escherichia coli, and antisera raised to the purified proteins were used to assess antigenic conservation in a panel of M. catarrhalis strains. The recombinant proteins were tested for the ability to bind human lactoferrin following gel electrophoresis and electroblotting, and rLbpB, but not rLbpA, was found to bind lactoferrin. Bactericidal antibody activity was measured, and while the anti-rLbpA antiserum was not bactericidal, the anti-rLbpB antisera were found to be weakly bactericidal. Thus, LbpB may have potential as a vaccine candidate.

Extremely high prevalence of nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae among children in Kaohsiung, Taiwan

Resistance (intermediate and high) to penicillin among Streptococcus pneumoniae strains is an emerging problem worldwide. From 1995 to 1997, isolates of S. pneumoniae not susceptible to penicillin were seen with increasing frequency from blood, cerebrospinal fluid, pleural fluid, and middle ear fluid from pediatric patients at the Veterans General Hospital-Kaohsiung. To determine the prevalence of carriage of these penicillin-nonsusceptible S. pneumoniae isolates, we obtained nasopharyngeal swab specimens from 2,905 children (ages, 2 months to 7 years) attending day-care centers or kindergartens or seen in our outpatient clinic. S. pneumoniae was isolated from 611 children, and 584 strains were available for analysis. The oxacillin disc test was used as a screening test to evaluate penicillin susceptibility. The MICs of 11 antibiotics (penicillin, cefaclor, cefuroxime, ceftriaxone, cefotaxime, imipenem, chloramphenicol, clarithromycin, rifampin, vancomycin, and teicoplanin) were determined by the E-test. Only 169 (29%) of the strains were susceptible to penicillin; 175 (30%) strains were intermediately resistant and 240 (41%) were highly resistant. The isolates also demonstrated high rates of resistance to other beta-lactams (46% were resistant to cefaclor, 45% were resistant to cefuroxime, 45% were resistant to ceftriaxone, 31% were resistant to cefotaxime, and 46% were resistant to imipenem). The rate of resistance to macrolide antimicrobial agents was strikingly high; 95% of the isolates were not susceptible to clarithromycin. However, 97% were susceptible to rifampin and 100% were susceptible to the two glycopeptides (vancomycin and teicoplanin). While reports of penicillin-resistant S. pneumoniae increased worldwide through the 1980s, the high prevalence (71%) of resistance reported here is astonishing. Surveillance of nasopharyngeal swab specimen cultures may provide useful information on the prevalence of nonsusceptible strains causing invasive disease. Such information could be used to guide therapy of pneumococcal infections.

Epidemiology and pathogenesis of chronic suppurative otitis media: implications for prevention and treatment

Despite advances in public health and medical care, chronic suppurative otitis media is still prevalent around the world. It is most common in developing countries and in certain high risk populations in developed nations, as well as among children who have tympanostomy tubes inserted. Since this chronic infection is caused by persistent acute otorrhea, which in turn is usually secondary to acute otitis media, prevention should be directed toward prompt and appropriate treatment of the acute middle-ear infection. Repair of chronic perforations should prevent recurrence, since reinfection is due either to reflux of pathogenic organisms from the nasopharynx into the middle ear, or water contamination from the external canal. Information from epidemiological studies, which show that populations can be categorized into highest, high, low and lowest prevalence, can be helpful in setting national priorities for prevention and treatment.