Nasopharyngeal carriage of Haemophilus influenzae

Microbiological Characterization of Haemophilus influenzae Isolated from Patients with Lower Respiratory Tract Infections in a Tertiary Care Hospital, South India

INTRODUCTION

Haemophilus influenzae is responsible for wide range of localized and invasive lower respiratory tract infections (LRTI) with the highest burden of disease in low and middle income countries.

AIM

The aim of the present study was to characterize the H.influenzae isolates from suspected LRTI.

MATERIALS AND METHODS

A prospective study was conducted over a period of one and half years (December 2012 to May 2014) including patients with LRTI. H.influenzae was isolated from lower respiratory specimens following standard procedures. Complete characterization of the isolates was performed by bio typing, capsular serotyping, molecular genotyping and antibiotic susceptibility testing. The predisposing factors and clinical presentation were studied in the infected patients.

RESULTS

A total of 8995 samples were received during the study period, out of which growth was significantly observed in 2848 (31.7%) samples. Among the various respiratory pathogens, H.influenzae was isolated from 175 (6.14%) patients. Majority (78.9%) of the patients presented with acute exacerbations of chronic obstructive pulmonary disease. The isolates most frequently were of Biotype II (35.42%). Only four of the 50 isolates subjected to capsular serotyping were typeable and were of type b, e and f. All the 50 isolates tested were found to be non-typeable by PCR for capsular genotyping. Maximum resistance was found against ampicillin (9.71%).

CONCLUSION

H.influenzae was found to be a significant cause of LRTI. Majority of the isolates were found to be non typeable strains. Non typeable H. influenzae isolates should not be neglected as they can colonize the respiratory tract in COPD patients and can lead to biofilm formation and treatment failure.

Carriage of Streptococcus pneumoniae and other respiratory bacterial pathogens in low and lower-middle income countries: a systematic review and meta-analysis

BACKGROUND

Infection with Streptococcus pneumoniae is a major cause of childhood morbidity and mortality worldwide, especially in low income countries where pneumococcal conjugate vaccines (PCVs) are still underused. In countries where PCVs have been introduced, much of their efficacy has resulted from their impact on nasopharyngeal carriage in vaccinated children. Understanding the epidemiology of carriage for S. pneumoniae and other common respiratory bacteria in developing countries is crucial for implementing appropriate vaccination strategies and evaluating their impact.

METHODS AND FINDINGS

We have systematically reviewed published studies reporting nasopharyngeal or oropharyngeal carriage of S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and Neisseria meningitidis in children and adults in low and lower-middle income countries. Studies reporting pneumococcal carriage for healthy children <5 years of age were selected for a meta-analysis. The prevalences of carriage for S. pneumoniae, H. influenzae, and M. catarrhalis were generally higher in low income than in lower-middle income countries and were higher in young children than in adults. The prevalence of S. aureus was high in neonates. Meta-analysis of data from young children before the introduction of PCVs showed a pooled prevalence estimate of 64.8% (95% confidence interval, 49.8%-76.1%) in low income countries and 47.8% (95% confidence interval, 44.7%-50.8%) in lower-middle income countries. The most frequent serotypes were 6A, 6B, 19A, 19F, and 23F.

CONCLUSIONS

In low and lower-middle income countries, pneumococcal carriage is frequent, especially in children, and the spectrum of serotypes is wide. However, because data are limited, additional studies are needed to adequately assess the impact of PCV introduction on carriage of respiratory bacteria in these countries.

50 years of pediatric pulmonology, progress and future

Development of Pediatric Pulmonology as a speciality in India is steadily improving over past few decades. Present profile of Indian pediatric chest services include: asthma, recurrent infections, bronchiectasis, etc. It is expected to change and the emerging pulmonary illnesses include: human immunodeficiency virus (HIV infection) associated pulmonary illnesses, cystic fibrosis, primary ciliary dyskinesia, bronchopulmonary dysplasia, interstitial lung diseases, gastroesophageal reflux diseases, neuromuscular illnesses, sleep disorders, disorders due to malformations and opportunistic pulmonary infections. Respiratory infections constitute major load in pediatric outpatient services and are the leading cause of mortality in under-five children. To reduce morbidity and mortality due to respiratory tract infections, Indian Academy of Pediatrics (IAP) has developed Respiratory Tract Infection Group Education Module (RTIGEMS). After initial increase in prevalence of asthma, it seems to have stabilized now but going by the numbers, it will remain a major health problem in India. Diagnosis of pulmonary tuberculosis was always a challenge to pediatricians and with emergence of drug resistant tuberculosis, it is even more challenging. Presently few centers are providing specialized Pediatric pulmonology services in India. There is a need to develop more centers to enhance services including (a) assessment of pulmonary physiology by performing pulmonary function testing in all age groups, (b) improving diagnostic and therapeutic role of bronchoscopy and bronchoalveolar lavage, (c) sweat testing, (d) molecular diagnostics for various respiratory illnesses, and (e) utilizing advance imaging and minimally invasive technologies for diagnosis and treatment of respiratory illnesses. At present there is no degree course in Pediatric Pulmonology in India. Initially middle level pediatricians wanting to pursue their career in pediatric pulmonology should undergo training in existing centers. Trained persons should develop a network to collect data and answer relevant research questions.

Pentavalent vaccine: a major breakthrough in India's Universal Immunization Program

Immunization is one of the most important public health interventions and a cost effective strategy to control the infectious diseases especially in children. Complete immunization coverage in India has increased from below 20% in the 1980s to nearly 61% at present, but still more than 1/3rd children remain un-immunized. Advent of combination vaccines has facilitated incorporation of additional vaccines into immunization schedule. Pentavalent vaccine, against five killer diseases-diphtheria, pertussis, tetanus, hepatitis B and Hemophilus influenza type B (Hib), has been introduced in almost all GAVI eligible countries by 2011. Government of India introduced the vaccine in two states in pilot phase and has given green signal to six more states. The use of pentavalent vaccine automatically raises the coverage level of hepatitis B and Hib vaccines. If the vaccines are provided individually, the coverage of hepatitis B and Hib vaccines usually lags behind DPT coverage. This gap can be filled by using pentavalent vaccine in routine immunization programmes.

High rates of colonization with drug resistant hemophilus influenzae type B and Streptococccus Pneumoniae in unvaccinated HIV infected children from West Bengal

OBJECTIVE

To determine nasopharyngeal colonization rates of two vaccine preventable bacterial pathogens Hemophilus influenzae type b (Hib), and Streptococcus pneumoniae (Pneumococcus), antibiotic susceptibility of isolates, factors associated with their colonization, and immunization history in a cohort of HIV infected children.

METHODS

The authors conducted a cross-sectional nasopharyngeal swab survey of 151 children affected with HIV presenting for routine outpatient care in West Bengal, India.

RESULTS

151 HIV affected children were enrolled. The median age was 6, 148/151 children were HIV positive, 65% had moderate to severe malnutrition, 53% were moderately to severely immunosuppressed, 17% were on antiretroviral therapy (ART), 90% were on cotrimoxazole prophylaxis (TMP/SMX). None had received the pneumococcal or Hib conjugate vaccines. Hib prevalence was 13% and pneumococcal prevalence was 28%. Children with normal or moderate immune suppression had high rates of colonization compared to those with severe immunosuppression (71% Hib, 61% pneumococcus). Hib and pneumococcal isolates had high rates of resistance to tested antibiotics including TMP/SMX and third generation cephalosporins. Neither ART nor TMP/SMX prevented colonization. Children colonized with multidrug resistant isolates had high rates of exposure to TMP/SMX.

CONCLUSIONS

HIV infection, late access to ART, high rates of colonization to resistant organisms and lack of access to vaccines makes this population vulnerable to invasive disease from Hib and pneumococcus.

Effectiveness of 3-day amoxycillin vs. 5-day co-trimoxazole in the treatment of non-severe pneumonia in children aged 2-59 months of age: a multi-centric open labeled trial

This cluster randomized, open labeled trial was conducted to compare the effectiveness of 3 days of oral amoxycillin and 5 days of co-trimoxazole treatment in terms of clinical failure in children with World Health Organization (WHO) defined non-severe pneumonia in primary health centers in rural India. Participants were children aged 2-59 months with WHO defined non-severe pneumonia, with or without wheeze, who were accessible to follow up. From seven primary health centers in each arm, 2009 cases were randomized, 993 and 1016 in treatment with amoxycillin and co-trimoxazole, respectively. Fever was present in 1247 (62.1%) and wheeze in 443 (22.1%). There was good adherence and low loss to follow-up. Clinical failure on amoxycillin and co-trimoxazole on intention to treat analysis was 137 and 97, respectively (absolute difference = 0.04, 95% confidence interval: - 0.035-0.12). We conclude that there was no difference in effectiveness of oral co-trimoxazole or amoxycillin in treating non-severe pneumonia.

Haemophilus influenzae type b antibodies in vaccinated and non-vaccinated children

BACKGROUND

Invasive Haemophilus influenzae type b (Hib) infection has a high morbidity among young children, but the burden of disease and rate of Hib are different in different regions. The aim of the present study was to investigate the levels of Hib antibodies and the oropharyngeal Hib prevalence in young children.

METHODS

One hundred-fifty nine healthy children aged 19-36 months of age were included in this cross-sectional study. Anti-polyribosylribitol phosphate (anti-PRP) antibody concentrations were measured using commercially available enzyme-linked immunosorbent assay (ELISA), and serotyping of isolated Hib strains was conducted by slide agglutination with specific antisera.

RESULTS

Of the study participants, 57 (35.8%) were fully vaccinated (group 1A); 17 (10.7%) were incompletely vaccinated (group 1B), and 85 (53.5%) were non-vaccinated (group 2). Geometric mean titer (GMT) of anti-PRP antibody was 3.8 microg/mL, 2.2 microg/mL and 0.49 microg/mL in group 1A, group 1B and group 2, respectively. While all children in group 1 (n = 74) had seroprotective antibody concentrations (>/=0.15 microg /mL), of the children in group 2 (n = 85) 31.8% did not have seroprotective anti-PRP levels (P < 0.0001). A total of 68.2% in group 2 had natural immunity. Nineteen children (33.3%) in group 1, and 46 (54.1%) in group 2 had oropharyngeal Hib colonization (P = 0.0004).

CONCLUSIONS

Hib conjugate vaccine is immunogenic and reduces Hib colonization. Each country should investigate the burden of Hib disease and the natural immunity in young children, and should determine antigenic dose, number of doses administered and dose intervals before deciding whether to introduce Hib conjugate vaccine in routine immunization programs.

Haemophilus influenzae colonization and its risk factors in children aged <2 years in northern India

The disease burden and the age group of children most affected by Haemophilus influenzae remain controversial particularly in many countries of South Asia. Nasopharyngeal carriage of H. influenzae can indicate the transmission dynamics in these settings. In a prospective population-based study, nasopharyngeal swabs from 1000 children aged <2 years, belonging to various socioeconomic groups from rural and urban areas of northern India were taken. The prevalence of H. influenzae carriage was found to be 11·2%. Among these isolates, 69% belonged to type b and the rest were non-typable. The age group most affected was 18–21 months. The carriage rate was influenced by age and socioeconomic factors namely type of housing, overcrowding, and season. Hib carriage is quite common in northern India and it is associated with age, type of housing, overcrowding, and season. Since carriage gets established early, Hib vaccination should target children in early infancy.

High ampicillin resistance in different biotypes and serotypes of Haemophilus influenzae colonizing the nasopharynx of healthy school-going Indian children

Haemophilus influenzaeis one of the main causes of otitis media, sinusitis, meningitis, pneumonia and septicaemia in children, and the development of ampicillin resistance inH. influenzaeis a cause of serious concern. The aim of the present study was to determine the prevalence of ampicillin resistance inH. influenzaecolonizing the nasopharynx of school-going healthy North Indian children, and to compare the distribution of different biotypes and serotype b in this population. A total of 2400 school-going healthy children from 45 rural and 45 urban schools were enrolled. Nasopharyngeal swabs were collected from the children and cultured.H. influenzaewas isolated from 1001 (41·7 %) of the 2400 nasopharyngeal swabs collected. All theseH. influenzaeisolates were biotyped and serotyped, and their antibiotic susceptibility tested. All eight biotypes were present in this population. The most prevalent biotypes were I (19·6 %), II (16·8 %) and III (25·0 %). Of the 1001 isolates, 316 (31·6 %) wereH. influenzaetype b and 685 (68·4 %) were non-type bH. influenzae, and 22·9 % were resistant to ampicillin, 41·9 % to chloramphenicol, 27·5 % to erythromycin and 67·3 % to co-trimoxazole. Of the 316H. influenzaetype b isolates, 44·0 % were ampicillin resistant, while only 13·1 % non-type bH. influenzaeisolates were ampicillin resistant. Of the 229 ampicillin-resistantH. influenzaeisolates, 196 (85·6 %) were positive forβ-lactamase; 93·4 % (214/229) were biotypes I, II and III, of which 49 % were biotype I, 27·9 % were type II and 16·6 % were type III. Most of the strains belonging to biotypes III–VIII were ampicillin sensitive. Ampicillin resistance is significantly more common in biotype I and serotype b than in other biotypes and serotypes.

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.

High nasopharyngeal carriage of drug resistant Streptococcus pneumoniae and Haemophilus influenzae in North Indian schoolchildren

OBJECTIVES

To determine the carriage rate of Streptococcus pneumoniae and Haemophilus influenzae in healthy Indian schoolchildren. The prevalence of antibiotic resistant strains in the community may be used to assess the trends of antibiotic resistance in invasive strains. Prevalence of resistance to various antimicrobial drugs among S. pneumoniae and H. influenzae was estimated.

METHODS

Two thousand four hundred subjects, aged 5-10 years, were enrolled from 45 rural and 45 urban schools. A nasopharyngeal swab was collected from each child, after taking informed written consent. Swabs were processed to isolate S. pneumoniae and H. influenzae. All isolates were tested for resistance to chloramphenicol, erythromycin and co-trimoxazole. Streptococcus pneumoniae isolates were also tested against tetracycline and oxacillin while H. influenzae isolates were tested against ampicillin.

RESULTS

Nasopharyngeal carriage of S. pneumoniae and H. influenzae was high in healthy schoolchildren. Stratified analysis showed that nasal carriage of pneumococci in urban children was significantly lower than in rural children [46.8% vs. 53.2%, P<0.001]. Carriage rates of H. influenzae in male and female populations were significantly different (47.8% vs. 52.3%, P<0.04). Penicillin resistance in S. pneumoniae was found low (3.3%), but 22.9% of H. influenzae isolates were ampicillin resistant. Resistance to co-trimoxazole was very high in both S. pneumoniae (81.8%) and H. influenzae (67.3%).

CONCLUSION

There is high nasopharyngeal carriage of drug resistant S. pneumoniae and H. influenzae in schoolchildren of north India. Currently, in India, co-trimoxazole for 5 days is recommended for treatment of non-severe pneumonia and third generation cephalosporins are drug of choice for management of severe pneumococcal/H. influenzae diseases. We found high co-trimoxazole resistance and low penicillin resistance in pneumococcal isolates. This justifies empirical use of penicillin in management of invasive pneumococcal infections in India.

Respiratory infections caused by non-typeable Haemophilus influenzae

PURPOSE OF REVIEW

This review will consider recent developments in the clinical aspects of infections due to non-typeable Haemophilus influenzae. In addition, newer developments in the areas of mechanisms of pathogenesis, host pathogen interaction, immune responses and efforts toward vaccine development will be reviewed briefly.

RECENT FINDINGS

Non-typeable H. influenzae continues to be a common cause of otitis media in infants and children, sinusitis in children and adults, pneumonia in adults, and lower respiratory tract infection in adults with chronic obstructive pulmonary disease. While the rate of beta-lactamase production by isolates of H. influenzae varies geographically, most regions show a rate of 20-35% of isolates producing beta-lactamase. Recent studies have highlighted the possible role of bacterial biofilms formed by H. influenzae as a cause of otitis media. Several lines of evidence indicate that H. influenzae causes intracellular infection in the lower respiratory tract in chronic obstructive pulmonary disease and this observation has important implications in understanding the human immune response to the bacterium. Lipooligosaccharide is an important virulence factor for H. influenzae and research is generating new information on the complex role of this molecule in colonization and infection of the respiratory tract. Several surface molecules are under active evaluation as vaccine antigens.

SUMMARY

Non-typeable H. influenzae is an important cause of respiratory tract infections in children and adults. Most strains are susceptible to amoxicillin/clavulanate, fluoroquinolones and the newer macrolides. Research in the next decade promises substantial progress in the challenge of developing vaccines for nontypeable H. influenzae.