Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolated from the nasopharynges of asymptomatic children and molecular analysis of S. pneumoniae and H. influenzae strain replacement in the nasopharynx

Targeted next-generation sequencing for pulmonary infection diagnosis in patients unsuitable for bronchoalveolar lavage

Background

Targeted next-generation sequencing (tNGS) has emerged as a rapid diagnostic technology for identifying a wide spectrum of pathogens responsible for pulmonary infections.

Methods

Sputum samples were collected from patients unable or unwilling to undergo bronchoalveolar lavage. These samples underwent tNGS analysis to diagnose pulmonary infections. Retrospective analysis was performed on clinical data, and the clinical efficacy of tNGS was compared to conventional microbiological tests (CMTs).

Results

This study included 209 pediatric and adult patients with confirmed pulmonary infections. tNGS detected 45 potential pathogens, whereas CMTs identified 23 pathogens. The overall microbial detection rate significantly differed between tNGS and CMTs (96.7% vs. 36.8%, p < 0.001). Among the 76 patients with concordant positive results from tNGS and CMTs, 86.8% (66/76) exhibited full or partial agreement. For highly pathogenic and rare/noncolonized microorganisms, tNGS, combined with comprehensive clinical review, directly guided pathogenic diagnosis and antibiotic treatment in 21 patients. This included infections caused by Mycobacterium tuberculosis complex, certain atypical pathogens, Aspergillus, and nontuberculous Mycobacteria. Among the enrolled population, 38.8% (81/209) of patients adjusted their treatment based on tNGS results. Furthermore, tNGS findings unveiled age-specific heterogeneity in pathogen distribution between children and adults.

Conclusion

CMTs often fall short in meeting the diagnostic needs of pulmonary infections. This study highlights how tNGS of sputum samples from patients who cannot or will not undergo bronchoalveolar lavage yield valuable insights into potential pathogens, thereby enhancing the diagnosis of pulmonary infections in specific cases.

Oligopeptide Transporters of Nonencapsulated Streptococcus pneumoniae Regulate CbpAC and PspA Expression and Reduce Complement-Mediated Clearance

Streptococcus pneumoniae colonizes the human nasopharynx and causes several diseases. Pneumococcal vaccines target the polysaccharide capsule and prevent most serious disease, but there has been an increase in the prevalence of nonencapsulated S. pneumoniae (NESp). Previously, it was thought that a capsule was necessary to cause invasive disease. NESp strains expressing the oligopeptide transporters AliC and AliD have been isolated from patients with invasive disease. The AliC and AliD oligopeptide transporters regulate the expression of several genes, including choline binding protein AC (CbpAC) (a homolog of PspA), which aids in reducing C3b deposition. It is hypothesized that by altering CbpAC expression, AliC and AliD provide protection from classical complement-mediated clearance by reducing C-reactive protein (CRP) binding. Our study demonstrates that AliC and AliD regulate CbpAC expression in NESp and that AliD found in certain serotypes of encapsulated strains regulates PspA expression. C3b deposition was increased in the NESp ΔaliD and encapsulated mutants in comparison to the wild type. NESp strains expressing AliC and AliD have a significant decrease in C1q and CRP deposition in comparison to the ΔaliC ΔaliD mutant. The complement protein C1q is required for NESp clearance in a murine model and increases opsonophagocytosis. By regulating CbpAC expression, NESp inhibits CRP binding to the bacterial surface and blocks classical complement activation, leading to greater systemic survival and virulence. Due to the increase in the prevalence of NESp, it is important to gain a better understanding of NESp virulence mechanisms that aid in establishing disease and persistence within a host by avoiding clearance by the immune system. IMPORTANCE Streptococcus pneumoniae (pneumococcus) can cause a range of diseases. Although there is a robust pneumococcal vaccination program that reduces invasive pneumococcal disease by targeting various polysaccharide capsules, there has been an increase in the isolation of nonvaccine serotypes and nonencapsulated S. pneumoniae (NESp) strains. While most studies of pneumococcal pathogenesis have focused on encapsulated strains, there is little understanding of how NESp causes disease. NESp lacks a protective capsule but contains novel genes, such as aliC and aliD, which have been shown to regulate the expression of numerous genes and to be required for NESp virulence and immune evasion. Furthermore, NESp strains have high transformation efficiencies and harbor resistance to multiple drugs. This could be deleterious to current treatment strategies employed for pneumococcal disease as NESp can be a reservoir of drug resistance genes. Therefore, deciphering how NESp survives within a host and facilitates disease is a necessity that will allow the fabrication of improved, broad-spectrum treatments and preventatives against pneumococcal disease. Our study provides a better understanding of NESp virulence mechanisms during host-pathogen interactions through the examination of genes directly regulated by the NESp proteins AliC and AliD.

Pneumococcal carriage in unvaccinated children at the time of vaccine implementation into the national immunization program in Poland

We investigated pneumococcal carriage among unvaccinated children under five years of age at a time when the conjugate polysaccharide vaccine (PCV) was introduced in Poland into the national immunization program (NIP). Paired nasopharyngeal swab (NPS) and saliva samples collected between 2016 and 2020 from n = 394 children were tested with conventional culture and using qPCR. The carriage rate detected by culture was 25.4% (97 of 394), by qPCR 39.1% (155 of 394), and 40.1% (158 of 394) overall. The risk of carriage was significantly elevated among day care center attendees, and during autumn/winter months. Among isolates cultured, the most common serotypes were: 23A, 6B, 15BC, 10A, 11A. The coverage of PCV10 and PCV13 was 23.2% (23 of 99) and 26.3% (26 of 99), respectively. Application of qPCR lead to detection of 168 serotype carriage events, with serogroups 15, 6, 9 and serotype 23A most commonly detected. Although the highest number of carriers was identified by testing NPS with qPCR, saliva significantly contributed to the overall number of detected carriers. Co-carriage of multiple serotypes was detected in 25.3% (40 of 158) of carriers. The results of this study represent a baseline for the future surveillance of effects of pneumococcal vaccines in NIP in Poland.

Genotypic and phenotypic characteristics of Streptococcus pneumoniae from community-acquired pneumonia patients and healthy asymptomatic participants in Sichuan province, China

Background

Streptococcus pneumoniae (S. pneumoniae) is the common cause of community-acquired pneumonia (CAP) and is also found in the upper respiratory tract of healthy people. Hence, the study aimed to compare the serotypes, virulence/pili genes, and antibiotic susceptibility of S. pneumoniae from healthy asymptomatic participants and CAP patients.

Methods

Streptococcus pneumoniae were retrospectively collected from health asymptomatic participants and CAP patients in Sichuan, China. The serotypes were tested by multiplex polymerase chain reaction (PCR) or Quellung reaction. Antibiotic susceptibility testing was performed using the broth microdilution method. The molecular epidemiology of S. pneumoniae was analyzed by multilocus sequence typing (MLST). Additionally, the presence of virulence/pili genes were detected using PCR.

Results

A total of 83 pneumococcal isolates were collected in the current study. Of these, 52 and 31 isolates were from healthy asymptomatic participants and CAP patients, respectively. Most of S. pneumoniae were resistant to erythromycin (ERY), clindamycin (CLI), tetracycline (TET) and trimethoprim-sulfamethoxazole (SXT). 90.4% isolates were classified as multidrug resistant (MDR). The predominant serotypes were 3, 19F and 19A in the CAP carriers, whereas 3, 6 and 19F were the main serotypes among the asymptomatic carriers. The overall coverage rates of pneumococcal conjugate vaccine (PCV) 10 and PCV13 serotypes were 34.9% and 66.3%, respectively. The predominant sequence types (STs) were ST271, ST320, and ST3397. There were significant differences in some resistance and virulence characteristics between CAP patients and asymptomatic carriers. Additionally, clonal complex (CC) 271 strains had higher percentage in resistance to cefuroxime (CXM) and cefotaxime (CEF), meropenem (MER) and cefepime (CFP), which mainly carried the rlrA and sipA genes.

Conclusions

High coverage rate of PCV13 and high prevalence of MDR indicated the necessity to expand immunization with PCV13 and rationally use the antibiotics in Sichuan, China. Importantly, long-term surveillance should be conducted to assess effectiveness brought by vaccines. Our findings may supply new guidance for developing new pneumococcal vaccines.

Etiological and epidemiological features of acute respiratory infections in China

Nationwide prospective surveillance of all-age patients with acute respiratory infections was conducted in China between 2009‒2019. Here we report the etiological and epidemiological features of the 231,107 eligible patients enrolled in this analysis. Children <5 years old and school-age children have the highest viral positivity rate (46.9%) and bacterial positivity rate (30.9%). Influenza virus, respiratory syncytial virus and human rhinovirus are the three leading viral pathogens with proportions of 28.5%, 16.8% and 16.7%, and Streptococcus pneumoniae, Mycoplasma pneumoniae and Klebsiella pneumoniae are the three leading bacterial pathogens (29.9%, 18.6% and 15.8%). Negative interactions between viruses and positive interactions between viral and bacterial pathogens are common. A Join-Point analysis reveals the age-specific positivity rate and how this varied for individual pathogens. These data indicate that differential priorities for diagnosis, prevention and control should be highlighted in terms of acute respiratory tract infection patients' demography, geographic locations and season of illness in China.

Broadly Reactive Human Monoclonal Antibodies Targeting the Pneumococcal Histidine Triad Protein Protect against Fatal Pneumococcal Infection

Streptococcus pneumoniae remains a leading cause of bacterial pneumonia despite the widespread use of vaccines. While vaccines are effective at reducing the incidence of most serotypes included in vaccines, a rise in infection due to nonvaccine serotypes and moderate efficacy against some vaccine serotypes have contributed to high disease incidence.

Streptococcus pneumoniae remains a leading cause of bacterial pneumonia despite the widespread use of vaccines. While vaccines are effective at reducing the incidence of most serotypes included in vaccines, a rise in infection due to nonvaccine serotypes and moderate efficacy against some vaccine serotypes have contributed to high disease incidence. Additionally, numerous isolates of S. pneumoniae are antibiotic or multidrug resistant. Several conserved pneumococcal proteins prevalent in the majority of serotypes have been examined for their potential as vaccines in preclinical and clinical trials. An additional, yet-unexplored tool for disease prevention and treatment is the use of human monoclonal antibodies (MAbs) targeting conserved pneumococcal proteins. Here, we isolated the first human MAbs (PhtD3, PhtD6, PhtD7, PhtD8, and PspA16) against the pneumococcal histidine triad protein (PhtD) and the pneumococcal surface protein A (PspA), two conserved and protective antigens. MAbs to PhtD target diverse epitopes on PhtD, and MAb PspA16 targets the N-terminal segment of PspA. The PhtD-specific MAbs bind to multiple serotypes, while MAb PspA16 serotype breadth is limited. MAbs PhtD3 and PhtD8 prolong the survival of mice infected with pneumococcal serotype 3. Furthermore, MAb PhtD3 prolongs the survival of mice in intranasal and intravenous infection models with pneumococcal serotype 4 and in mice infected with pneumococcal serotype 3 when administered 24 h after pneumococcal infection. All PhtD and PspA MAbs demonstrate opsonophagocytic activity, suggesting a potential mechanism of protection. Our results identify new human MAbs for pneumococcal disease prevention and treatment and identify epitopes on PhtD and PspA recognized by human B cells.

Risk Factors for Carriage of Antibiotic-resistant Bacteria in Healthy Children in the Community: A Systematic Review

BACKGROUND

In addition to health care settings, antibiotic resistance has also been increasing in the community. Healthy children represent an important potential reservoir of antibiotic-resistant (AR) bacteria. However, strategies to reduce the spread of AR bacteria often fail to specifically address the factors that promote the carriage of AR bacteria in this population.The objective of this review was to Identify risk factors for carriage of AR bacteria by healthy children.

METHODS

We did a systematic search of MEDLINE, Embase and PubMed for studies in developed (OECD) countries that assessed risk factors for carriage of AR bacteria in healthy children in the community. We excluded studies done before 1998 and studies of AR Streptococcus pneumoniae carriage in the absence of pneumococcal conjugate vaccination.

RESULTS

Of 1234 studies identified, 30 were eligible for inclusion. These studies assessed the impact of 49 risk factors on AR strains of S. pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli. The majority of these risk factors were assessed in 2 or fewer studies per bacteria. Recent antibiotic consumption was associated with carriage of resistant respiratory bacteria (S. pneumoniae, H. influenzae); however, it was not consistently associated with carriage of AR bacteria in skin or stool (S. aureus and E. coli). For AR S. aureus, transmission within households appeared to have a greater impact than individual antibiotic use.

CONCLUSIONS

The factors that promote carriage of AR bacteria by healthy children differed between bacterial species. To reduce reservoirs of AR bacteria in the community, it is essential for intervention strategies to target the specific risk factors for different bacteria.

The characterization of bacterial communities of oropharynx microbiota in healthy children by combining culture techniques and sequencing of the 16S rRNA gene

The high incidence of bacterial respiratory infections has led to a focus on evaluating the human respiratory microbiome. Studies based on culture-based and molecular methods have shown an increase in the bacterial community that includes the bacterial phyla Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria in the oropharynx of healthy individuals. Therefore, recognizing this microbial compound and subsequently identifying those carriers of specific pathogens can be of great help in predicting future infections and their control. In this prospective study, we sought to characterize the bacterial communities of the respiratory microbiome in healthy children aged between 3 and 6 years old by combining both cultural techniques and sequencing of the 16S rRNA gene. Seventy-seven oropharynx samples using Dacron swabs were collected from 77 healthy children in the kindergartens of Ilam, Iran. Bacterial identification was performed by phenotypic methods and in house developed PCR-based sequencing (the V1-V9 hypervariable region of the bacterial 16S ribosomal RNA gene). In total, 346 bacterial isolates were characterized based on phenotypic and sequencing-based molecular methods. The 3 most predominant phyla were Firmicutes (74%), Proteobacteria (22%), and Actinobacteria (4%). At the level of the genus, Staphylococci (coagulase-positive and coagulase-negative) and Streptococci were dominant. Also, the most commonly identified potentially pathogenic colonisers were S. aureus (75%), Enterobacteriaceae spp. (40.1%), and A. baumannii (15.6%). The present study identified 3 phyla and 9 family of bacteria in the oropharyngeal microbiome. Remarkably, the presence of potential pathogenic bacteria in the nasopharynx of healthy children can predispose them to infectious diseases, and also frequent exposure to human respiratory bacterial pathogens are further risk factors.

Airway microbiome in adult survivors of extremely preterm birth: the EPICure study

Bronchopulmonary dysplasia (BPD) is a major complication of preterm birth that leads to lifelong respiratory morbidity. The EPICure study has investigated the longitudinal health outcomes of infants born extremely preterm (EP; <26 weeks gestation). Our aim was to characterise the airway microbiome in young adults born extremely preterm, with and without neonatal BPD, in comparison to matched term-born controls.Induced sputum was collected from 92 young adults aged 19 years (51 EP and 41 controls). Typical respiratory pathogens were detected using quantitative PCR. 16S rRNA gene sequencing was completed on 74 samples (29 EP with BPD; 9 EP without BPD; and 36 controls).The preterm group with BPD had the least diverse bacterial communities. The relative abundance of Bacteriodetes, particularly Prevotella melaninogenica was significantly lower in the preterm group compared to controls. This decline was balanced by a nonsignificant increase in Firmicutes. Total Prevotella relative abundance correlated with forced expiratory volume in 1 s z-score (ρ=0.272; p<0.05). Typical respiratory pathogen loads and prevalence were similar between groups.In conclusion, extremely preterm birth is associated with a significant dysbiosis in airway microbiome in young adulthood regardless of neonatal BPD status. This is characterised by a shift in the community composition away from Bacteriodetes as manifested in a significant drop in Prevotella relative abundance.

The burden of community-acquired bacterial pneumonia in the era of antibiotic resistance

INTRODUCTION

Community-acquired pneumonia (CAP) is a significant global health problem and leading cause of death and hospitalization in both the US and abroad. Increasing macrolide resistance among Streptococcus pneumoniae and other pathogens results in a greater disease burden, along with changing demographics and a higher preponderance of comorbid conditions. Areas covered: This review summarizes current data on the clinical and economic burden of CAP, with particular focus on community-acquired bacterial pneumonia (CABP). Incidence, morbidity and mortality, and healthcare costs for the US and other regions of the world are among the topics covered. Major factors that are believed to be contributing to the increased impact of CABP, including antimicrobial resistance, the aging population, and the incidence of comorbidities are discussed, as well as unmet needs in current CABP management. Expert commentary: The clinical and economic burden of CABP is staggering, far-reaching, and expected to increase in the future as new antibiotic resistance mechanisms emerge and the world's population ages. Important measures must be initiated to stabilize and potentially decrease this burden. Urgent needs in CABP management include the development of new antimicrobials, adjuvant therapies, and rapid diagnostics.

Streptococcus pneumoniae PspC Subgroup Prevalence in Invasive Disease and Differences in Contribution to Complement Evasion

The pneumococcal capsular serotype is an important determinant of complement resistance and invasive disease potential, but other virulence factors have also been found to contribute. Pneumococcal surface protein C (PspC), a highly variable virulence protein that binds complement factor H to evade C3 opsonization, is divided into two subgroups: choline-bound subgroup I and LPxTG-anchored subgroup II. The prevalence of different PspC subgroups in invasive pneumococcal disease (IPD) and functional differences in complement evasion are unknown. The prevalence of PspC subgroups in IPD isolates was determined in a collection of 349 sequenced strains of Streptococcus pneumoniae isolated from adult patients. pspC deletion mutants and isogenic pspC switch mutants were constructed to study differences in factor H binding and complement evasion in relation to capsule thickness. Subgroup I pspC was far more prevalent in IPD isolates than subgroup II pspC The presence of capsule was associated with a greater ability of bound factor H to reduce complement opsonization. Pneumococcal subgroup I PspC bound significantly more factor H and showed more effective complement evasion than subgroup II PspC in isogenic encapsulated pneumococci. We conclude that variation in the PspC subgroups, independent of capsule serotypes, affects pneumococcal factor H binding and its ability to evade complement deposition.

Role of viral and bacterial pathogens in causing pneumonia among Western Australian children: a case-control study protocol

INTRODUCTION

Pneumonia is the leading cause of childhood morbidity and mortality globally. Introduction of the conjugate Haemophilus influenzae B and multivalent pneumococcal vaccines in developed countries including Australia has significantly reduced the overall burden of bacterial pneumonia. With the availability of molecular diagnostics, viruses are frequently detected in children with pneumonia either as primary pathogens or predispose to secondary bacterial infection. Many respiratory pathogens that are known to cause pneumonia are also identified in asymptomatic children, so the true contribution of these pathogens to childhood community-acquired pneumonia (CAP) remains unclear. Since the introduction of pneumococcal vaccines, very few comprehensive studies from developed countries have attempted to determine the bacterial and viral aetiology of pneumonia. We aim to determine the contribution of bacteria and viruses to childhood CAP to inform further development of effective diagnosis, treatment and preventive strategies.

METHODS AND ANALYSIS

We are conducting a prospective case-control study (PneumoWA) where cases are children with radiologically confirmed pneumonia admitted to Princess Margaret Hospital for Children (PMH) and controls are healthy children identified from PMH outpatient clinics and from local community immunisation clinics. The case-control ratio is 1:1 with 250 children to be recruited in each arm. Nasopharyngeal swabs are collected from both cases and controls to detect the presence of viruses and bacteria by PCR; pathogen load will be assessed by quantitative PCR. The prevalence of pathogens detected in cases and controls will be compared, the OR of detection and population attributable fraction to CAP for each pathogen will be determined; relationships between pathogen load and disease status and severity will be explored.

ETHICS AND DISSEMINATION

This study has been approved by the human research ethics committees of PMH, Perth, Australia (PMH HREC REF 2014117EP). Findings will be disseminated at research conferences and in peer-reviewed journals.

Nasopharyngeal s. pneumoniae carriage and density in Belgian infants after 9 years of pneumococcal conjugate vaccine programme

BACKGROUND

In Belgium, the infant pneumococcal conjugate vaccine (PCV) programme changed from PCV7 (2007-2011) to PCV13 (2011-2015) and to PCV10 (2015-2016). A 3-year nasopharyngeal carriage study was initiated during the programme switch in 2016. Main objective of the year 1 assessment was to obtain a baseline measurement of pneumococcal carriage prevalence, carriage density, serotype distribution and antibiotic resistance.

MATERIALS/METHODS

Two infant populations aged 6-30 months and without use of antibiotics in the seven days prior to sampling were approached: (1) attending one of 85 randomly selected day-care centres (DCC); (2) presenting with AOM at study-trained general practitioners and paediatricians. Demographic and clinical characteristics were documented and a single nasopharyngeal swab was taken. S. pneumoniae were cultured, screened for antibiotic resistance and serotyped, and quantitative Taqman real-time PCR (qRT-PCR) targeting LytA was performed.

RESULTS

Culture-based (DCC: 462/760; 60.8% - AOM: 27/39; 69.2%) and LytA-based (DCC: 603/753; 80.1% - AOM: 32/39; 82.1%) carriage prevalence was high. Average pneumococcal DNA load in LytA-positive day-care samples was 6.5 × 10⁶ copies/µl (95%CI = 3.9-9.2 × 10⁶, median = 3.5 × 10⁵); DNA load was positively associated with signs of common cold and negatively with previous antibiotic use. Culture-based frequency of 13 pneumococcal vaccine (PCV) serotypes was 5.4% in DCC and 7.7% in AOM, with 19F and 14 being most frequent, and frequencies below 0.5% for serotypes 3, 6A, 19A in both populations. Predominant non-PCV serotypes were 23B and 23A in day-care and 11A in infants with AOM. In day-care, resistance to penicillin was rare (<0.5%) and absent against levofloxacin; 32.7% and 16.9% isolates were cotrimoxazole- and erythromycin-resistant respectively.

CONCLUSION

Four years after PCV13 introduction in the vaccination programme, PCV13 serotype carriage was rare in infants throughout Belgium and penicillin resistance was rare. Continued surveillance in the context of a PCV programme switch is necessary.

Phenotypic diversity of Haemophilus influenzae and Haemophilus parainfluenzae isolates depending on origin and health condition

Background. Haemophili are common human microbiota representatives. The aim of our study was to investigate a diversity of Haemophilus spp. isolates selected from clinical specimens on the basis of biochemical characteristics, biotypes distribution, protein profiles and antimicrobial resistance. Results. A total of 893/1025 (87%) of haemophili isolates were identified: 260/1025 (25%) as H. influenzae and 633/1025 (62%) as H. parainfluenzae. Moreover, a group of 107/1025 (10%) isolates without species identification (with e.g. abnormal numerical profile) was described as Haemophilus spp. Within the H. influenzae isolates, biotypes II and III were in a great majority (92/893; 10%, each), whereas among H. parainfluenzae, the most commonly occurring was biotype I and II (301/893, 34% and 178/893, 20%, respectively). A similar prevalence of biotypes was obtained regardless of the patient’s age or health condition or the type of specimen. A production of beta-lactamases was shown in 46/893 (5%) haemophili, both H. influenzae (13/46, 28%) and H. parainfluenzae (33/46, 72%) isolates. On the basis of haemophili biochemical characteristics, the cluster analysis using the UPGMA method demonstrated a high degree of phenotypic similarity due to a small distances between isolates taken from both unhealthy children and adults. Conclusion. Based on biochemical characteristics, about 90% of haemophili clinical isolates representing human-specific respiratory microbiota were positively identified as H. influenzae and H. parainfluenzae. The same differences in biotypes and antimicrobial resistance among isolates selected from healthy people or from patients with chronic and recurrent diseases were detected.

Epidemiology of Nasopharyngeal Carriage by Haemophilus influenzae in Healthy Children: A Study in the Mediterranean Coast Region

BACKGROUND

Haemophilus influenzae, a colonizer of the nasopharynx, in children causes mainly otitis and sinusitis. The primary objective of this study was to determine the prevalence of pharyngeal colonization by H. influenzae, and the secondary objectives were to identify risk factors associated with H. influenzae colonization and its antibiotic susceptibility.

METHODS

A prospective, multicenter study of nasopharyngeal carriers of H. influenzae was conducted in the pediatric consulting rooms of 10 primary healthcare centers in Murcia (Spain). The study consisted of 404 healthy children less than 5 years of age and was carried out during winter (January-March) and summer (July-September) of 2015. A nasopharyngeal sample was collected from each child, and an epidemiologic survey was completed by a pediatrician.

RESULTS

In total, 112 (27.7%) children had colonization by H. influenzae, with 73.2% of cases in winter and 26.8% of cases in summer (P < 0.001). The median (interquartile range) age in months of the colonized children (13 months, 12-47.5) was lower than that of the noncolonized children (46 months, 12-49) (P < 0.001). All H. influenzae found were nontypeable H. influenzae (NTHi). Among 112 isolates, 20% were ampicillin resistant, of which 10% produced β-lactamase, and 9% were ampicillin resistant and did not produce β-lactamase. A logistic regression analysis showed that young age (odds ratio: 0.98) and the winter period (odds ratio: 3.41; P < 0.001) were risk factors for colonization by NTHi.

CONCLUSIONS

Colonization by NTHi is high in this Mediterranean coast region with remarkable ampicillin resistant. Younger age and the winter period were facilitating factors.

Surface Proteins and Pneumolysin of Encapsulated and Nonencapsulated Streptococcus pneumoniae Mediate Virulence in a Chinchilla Model of Otitis Media

Streptococcus pneumoniae infections result in a range of human diseases and are responsible for almost one million deaths annually. Pneumococcal disease is mediated in part through surface structures and an anti-phagocytic capsule. Recent studies have shown that nonencapsulated S. pneumoniae (NESp) make up a significant portion of the pneumococcal population and are able to cause disease. NESp lack some common surface proteins expressed by encapsulated pneumococci, but express surface proteins unique to NESp. A chinchilla model of otitis media (OM) was used to determine the effect various pneumococcal mutations have on pathogenesis in both NESp and encapsulated pneumococci. Epithelial cell adhesion and invasion assays were used to examine the effects in relation to deletion of intrinsic genes or expression of novel genes. A mouse model of colonization was also utilized for comparison of various pneumococcal mutants. It was determined that pneumococcal surface protein K (PspK) and pneumolysin (Ply) affect NESp middle ear pathogenesis, but only PspK affected epithelial cell adhesion. Experiments in an OM model were done with encapsulated strains testing the importance of native virulence factors and treatment of OM. First, a triple deletion of the common virulence factors PspA, PspC, and Ply, (ΔPAC), from an encapsulated background abolished virulence in an OM model while a PspC mutant had detectable, but reduced amounts of recoverable bacteria compared to wildtype. Next, treatment of OM was effective when starting antibiotic treatment within 24 h with resolution by 48 h post-treatment. Expression of NESp-specific virulence factor PspK in an encapsulated strain has not been previously studied, and we showed significantly increased adhesion and invasion of human epithelial cells by pneumococci. Murine colonization was not significantly increased when an encapsulated strain expressed PspK, but colonization was increased when a capsule mutant expressed PspK. The ability of PspK expression to increase colonization in a capsule mutant despite no increase in adhesion can be attributed to other functions of PspK, such as sIgA binding or immune modulation. OM is a substantial economic burden, thus a better understanding of both encapsulated pneumococcal pathogenesis and the emerging pathogen NESp is necessary for effective prevention and treatment.

Nonencapsulated Streptococcus pneumoniae: Emergence and Pathogenesis

While significant protection from pneumococcal disease has been achieved by the use of polysaccharide and polysaccharide-protein conjugate vaccines, capsule-independent protection has been limited by serotype replacement along with disease caused by nonencapsulated Streptococcus pneumoniae (NESp). NESp strains compose approximately 3% to 19% of asymptomatic carriage isolates and harbor multiple antibiotic resistance genes. Surface proteins unique to NESp enhance colonization and virulence despite the lack of a capsule even though the capsule has been thought to be required for pneumococcal pathogenesis. Genes for pneumococcal surface proteins replace the capsular polysaccharide (cps) locus in some NESp isolates, and these proteins aid in pneumococcal colonization and otitis media (OM). NESp strains have been isolated from patients with invasive and noninvasive pneumococcal disease, but noninvasive diseases, specifically, conjunctivitis (85%) and OM (8%), are of higher prevalence. Conjunctival strains are commonly of the so-called classical NESp lineages defined by multilocus sequence types (STs) ST344 and ST448, while sporadic NESp lineages such as ST1106 are more commonly isolated from patients with other diseases. Interestingly, sporadic lineages have significantly higher rates of recombination than classical lineages. Higher rates of recombination can lead to increased acquisition of antibiotic resistance and virulence factors, increasing the risk of disease and hindering treatment. NESp strains are a significant proportion of the pneumococcal population, can cause disease, and may be increasing in prevalence in the population due to effects on the pneumococcal niche caused by pneumococcal vaccines. Current vaccines are ineffective against NESp, and further research is necessary to develop vaccines effective against both encapsulated and nonencapsulated pneumococci.

Streptococcus pneumoniae nasopharyngeal colonisation in children aged under six years with acute respiratory tract infection in Lithuania, February 2012 to March 2013

serotypes among children in Lithuania are limited. A prospective study was carried out from February 2012 to March 2013 to evaluate the circulation of SPn serotypes among young children in five cities of Lithuania before the introduction of universal vaccination with pneumococcal conjugate vaccine (PCV). A total of 900 children under six years of age who presented to primary care centres or a hospital emergency department with acute respiratory tract infection (RTI) were enrolled in the study. The SPn colonisation rate was40.8% (367/900), with a peak at two and three years old(48.8% and 45.4%, respectively). Of the 367 SPn isolates, the most common serotypes were 6B (15.8%,n = 58), 19F (13.9%, n = 51), 23F (13.9%, n = 51), 15(10.1%, n = 37), 14 (9.5%, n = 35), 6A (9.3%, n= 34),11 (4.6%, n = 17), 3 (3.0%, n = 11) and 18C (3.0%, n =11); less frequent were 23 (non-23F) (2.7%, n = 10), 19A(2.2%, n = 8) and 9V (1.6%, n = 6). Serotypes 6A and 11 were more common in children under two years-old;18C was found only in children aged two to five years.The serotypes found might be an important predictor of the likely effectiveness of the PCVs currently available in Lithuania

Respiratory viruses are associated with common respiratory pathogens in cystic fibrosis

OBJECTIVES

Test the hypothesis that the link between respiratory viruses and pulmonary exacerbation in cystic fibrosis (CF) reflects increased frequency or severity of lower airways infection.

STUDY DESIGN

Molecular respiratory viral panels (RVPs), cell counts, and quantitative bacterial cultures were assessed in 235 bronchoalveolar lavage fluid (BALF) samples from 138 children with CF. Relationships among the data were analyzed using multivariate methods.

RESULTS

RVPs were positive in 67 (28.5%) BALF samples from 52 (37.7%) patients, with rhinovirus/enterovirus most common (82.4% of RVP+). RVP+ patients were younger (5.4 years, IQR 3.0-9.7 vs. 8.0 years, IQR 3.5-12.9; P < 0.01), more likely to have respiratory symptoms (74.6% vs. 55.2%, P < 0.01), and had higher BALF percent neutrophils (70.5%, IQR 46-85% vs. 59.3%, IQR 34-77%; P < 0.05). Percent predicted FEV1 at bronchoscopy was diminished from baseline in both groups, but recovered in the RVP- (90.2 ± 22.2% vs. 89.6 ± 19.7%, P = 0.62) but not the RVP+ subjects (95.7 ± 21.1% vs. 89.1 ± 18.0%, P < 0.05). RVP status did not alter recovery rates of typical CF respiratory pathogens including Staphylococcus aureus (44.8% vs. 42.9%) and Pseudomonas aeruginosa (25.4% vs. 25.6%). However, common respiratory pathogens (Haemophilus species, Moraxella species, and Streptococcus pneumoniae) were recovered more frequently from RVP+ samples independent of age (OR 3.6, 95% CI 1.8-7.5, P < 0.001).

CONCLUSIONS

Respiratory viruses were frequently detected in BALF from CF patients and associated with markers of disease severity. Respiratory viruses did not impact frequency or severity of infection with typical CF pathogens, but rates of infection with common respiratory pathogens were increased. This finding may have treatment implications.

Relationships between rhinitis symptoms, respiratory viral infections and nasopharyngeal colonization with Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus in children attending daycare

BACKGROUND

Nasal bacterial colonization is often dubbed "asymptomatic." We hypothesized that rhinitis, common in preschool children, is associated with bacterial colonization and that respiratory viruses, which cause rhinitis, interact with bacteria in ways which promote transmission.

METHODS

Five hundred eighty-five children (4.2-73.6 months) attending daycare had clinical information, a rhinitis score and nasal swabs collected in February 2009. Swabs in soya tryptone glucose glycerine broth were cultured for Streptococcus pneumoniae (Sp), Haemophilus influenzae (Hi) and Staphylococcus aureus and analyzed by real-time polymerase chain reaction for respiratory viruses, both semiquantitatively.

RESULTS

Rhinitis symptoms, carriage of Sp and Hi and viral detection fell, whereas S. aureus carriage rates rose with age. Significant, age-independent associations between rhinitis symptoms and detection of Hi (P < 0.033) and Hi colonization density (P < 0.027) were observed. Of the 42% with detected viruses, most (78%) had picornavirus detection. There was a significant age-independent association between viral detection (and viral load, picornavirus detection and picorn aviral load) and detection of Sp (P = 0.020, 0.035, 0.005, 0.014) and between viral detection and viral load and Sp colonization density (P = 0.024, 0.028) [corrected].

CONCLUSIONS

Hi may promote its own transmission by inducing or ampli¬fying rhinitis in children. There isa close quantitative relationship between respiratory viral detection, including picornavirus detection and Spcoloni¬zation. These findings have implications for understanding disease patho¬genesis and formulating prevention strategies using vaccines [corrected].

High prevalence of Streptococcus pneumoniae in adenoids and nasopharynx in preschool children with recurrent upper respiratory tract infections in Poland--distribution of serotypes and drug resistance patterns

BACKGROUND

Streptococcus pneumoniae is one of the major bacterial pathogens colonizing nasopharynx, and often causes upper respiratory tract infections in children. We investigated the prevalence of S. pneumoniae in nasopharynx and adenoid core in 57 children aged 2-5 years who underwent adenoidectomy for recurrent pharyngotonsillitis, and we determined serotypes and antibiotic resistance patterns of the isolated pneumococci.

MATERIAL/METHODS

The nasopharyngeal specimens obtained before adenoidectomy and the adenoids after the surgery were cultured for pneumococci. All isolates were serotyped by means of Quellung reaction. Susceptibility to antibiotics was determined according to EUCAST recommendations.

RESULTS

S. pneumoniae colonization was observed in 40 (70.2%) children. From 29 (50.9%) children S. pneumoniae was isolated both from nasopharynx and adenoid core; 2 or 3 different isolates were identified in 8 (14.0%) children. In 8 (14.0%) children pneumococci were obtained from adenoid core only and in 3 (5.3%) children from nasopharynx only. Among the isolates, 35.3% were susceptible to all tested antimicrobials and 45.1% had decreased susceptibility to penicillin. Multidrug resistance was present in 52.9% of the isolates. The most frequent was serotype 19F (25.5%). The prevalence of serotypes included in pneumococcal conjugate vaccines PCV10 and PCV13 was 51.0% and 62.7%, respectively.

CONCLUSIONS

The adenoids, like the nasopharynx, can be regarded as a reservoir of pneumococci, including multidrug resistant strains, especially in children with indication for adenoidectomy due to recurrent respiratory tract infections refractory to antibiotic therapy. Good vaccine coverage among the isolated pneumococci confirmed the validity of the routine immunization by PCVs in young children.

Streptococcus pneumoniae--a review of carriage, infection, serotype replacement and vaccination

Invasive pneumococcal infection remains a leading global cause of morbidity and mortality in young children. In developed nations, a substantial decrease in the incidence of IPD has been achieved with inclusion of the 7 valent protein conjugated pneumococcal vaccines (7vPCV) into paediatric vaccine schedules. In contrast, the incidence of IPD has changed little in developing nations. This is likely due to poor access to medical care and pneumococcal vaccination, the accompanying HIV and malnutrition burden, and the fact that 7vPCV does not contain the most common serotypes (1,5, 6A) responsible for IPD in many developing nations. The battle against IPD in developed nations is not over, with the rise of non-7vPCV serotypes since routine 7vPCV vaccination. This has necessitated the development and distribution of pneumococcal vaccines containing 3 or 6 additional serotypes. This article provides an overview on pneumococcal carriage and risk factors for IPD, the rise of non-7vCPV serotypes in the era of 7vPCV vaccination, and the current and newly available broader valent pneumococcal vaccines.

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.

Characteristics of Streptococcus pneumoniae strains colonizing upper respiratory tract of healthy preschool children in Poland

Antibiotic resistant and invasive pneumococci may spread temporally and locally in day care centers (DCCs). We examined 267 children attending four DCCs located in the same city and 70 children staying at home in three seasons (autumn, winter, and spring) to determine prevalence, serotype distribution, antibiotic resistance patterns, and transmission of pneumococcal strains colonizing upper respiratory tract of healthy children without antipneumococcal vaccination. By pheno- and genotyping, we determined clonality of pneumococci, including drug-resistant strains. The average carriage of pneumococci in three seasons was 38.2%. 73.4% and 80.4% of the isolates belonged to serotypes present in 10- and 13-valent conjugate vaccine, respectively. Among the pneumococcal strains, 33.3% were susceptible to all antimicrobial tested and 39.2% had decreased susceptibility to penicillin. Multidrug resistance was common (35.7%); 97.5% of drug-resistant isolates represented serotypes included to 10- and 13-valent conjugate vaccine. According to BOX-PCR, clonality definitely was observed only in case of serotype 14. Multivariate analysis determined DCC attendance as strongly related to pneumococcal colonization in all three seasons, but important seasonal differences were demonstrated. In children attending DCCs, we observed dynamic turnover of pneumococcal strains, especially penicillin nonsusceptible and multidrug resistant, which were mostly distributed among serotypes included to available pneumococcal conjugate vaccines.

Upper respiratory colonization by Streptococcus pneumoniae in healthy pre-school children in south-east Poland

OBJECTIVE

Carriage of Streptococcus pneumoniae in upper respiratory tract of healthy children is a major factor in the horizontal transmission of pneumococcal strains, especially between children attending day-care centers and may be also the source of infection in other individuals. During 8-month prospective study including 3 seasons (autumn, winter, spring), we determined risk factors for S. pneumoniae colonization in general and colonization at 2 or 3 time points in healthy pre-school children, including penicillin non-susceptible likewise multidrug resistant strains.

METHODS

Pneumococcal cultures were obtained from 311 children aged 3-5. Finally, a total of 342 isolates were identified. Resistance of pneumococcal isolates was determined and information about potential risk factors were obtained from questionnaires.

RESULTS

A total of 72.4% children were colonized by pneumococci at least once, including 8.4% children colonized at 3 time points, 25.4% children - twice and 38.6% children - only once. Penicillin non-susceptible pneumococcal colonization was found in 36.3% children at least once while multidrug-resistant pneumococcal colonization in 34.1% children. Of the 10.9% and 10.6% children were colonized at 2 or 3 time points by penicillin non-sussceptible and multidrug-resistant isolates, respectively. Pneumococcal colonization (in general or by non-susceptible to penicillin isolates) was independently associated with day care attendance, having no siblings, frequent respiratory tract infections and higher number of antibiotic courses. Children attending day care center, with frequent respiratory tract infections, exposed to tobacco smoke were prone to colonization by multidrug-resistant isolates. Risk of colonization at 2 or 3 time points by pneumococcal isolates, including penicillin-nonsusceptible isolates, was associated with age and day care attendance while multidrug-resistant pneumococcal colonization was found to be significantly higher in children aged 3, with frequent respiratory tract infections and higher number of antibiotic courses.

CONCLUSION

These results indicate high rate of upper respiratory colonization by S. pneumoniae in healthy preschool children in Poland, including colonization by penicillin non-susceptible and multidrug-resistant pneumococci.

Nasopharyngeal Streptococcus pneumoniae carriage in Japanese children attending day-care centers

OBJECTIVES

We conducted a prospective bacteriological survey to investigate antibiotic resistance-related genetic characteristics and the turnover of nasopharyngeal Streptococcus pneumoniae carriage in healthy children in day-care centers (DCCs).

METHODS

A total of 363 nasopharyngeal mucus samples were collected from children aged 0 to 6 years attending two DCCs in the summer of 2004 (n=181) and the following winter (n=182). We obtained 157 S. pneumoniae isolates and analyzed them by antibiotic susceptibility testing, PCR assay for the penicillin-binding protein (PBP) genes and macrolide-resistance gene, and pulsed-field gel electrophoresis (PFGE).

RESULTS

The overall carriage rate was 43.3% (157/363). The percentages of penicillin-intermediately resistant S. pneumoniae (PISP) strains, penicillin-resistant S. pneumoniae (PRSP) strains, erythromycin-intermediately resistant S. pneumoniae strains and erythromycin-resistant S. pneumoniae strains were 35.7% (56/157), 0.6% (1/157), 1.9% (3/157), and 69.4% (109/157), respectively. The percentages of S. pneumoniae strains with the pbp mutation(s) and mefA and/or ermB gene(s) were 92.4% (145/157) and 71.3% (112/157), respectively. Fifty strains with different PFGE patterns were obtained from among the 157 isolates. Thirteen strains were observed in both seasons, but only one of these strains was isolated from the same carrier. Twenty-one strains (42.0%) were isolated from two or more children, and 17 of these were each isolated from children attending the same DCC.

CONCLUSIONS

These results indicate the spread of S. pneumoniae, particularly those with antibiotic-resistance genes, and the vigorous genetic turnover and substantial horizontal transmission of this pathogen in healthy children attending DCCs in Japan.

Haemophilus influenzae type b carriage and novel bacterial population structure among children in urban Kathmandu, Nepal

Haemophilus influenzae type b (Hib) is a major cause of invasive bacterial infection in children that can be prevented by a vaccine, but there is still uncertainty about its relative importance in Asia. This study investigated the age-specific prevalence of Hib carriage and its molecular epidemiology in carriage and disease in Nepal. Oropharyngeal swabs were collected from children in Kathmandu, Nepal, from 3 different settings: a hospital outpatient department (OPD), schools, and children's homes. Hib was isolated using Hib antiserum agar plates, and serotyping was performed with latex agglutination. Hib isolates from children with invasive disease were obtained during active microbiological surveillance at Patan Hospital, Kathmandu, Nepal. Genotyping of disease and carriage isolates was undertaken using multilocus sequence typing (MLST). Swabs were taken from 2,195 children, including 1,311 children at an OPD, 647 children attending schools, and 237 children in homes. Overall, Hib was identified in 5.0% (110/2,195; 95% confidence interval [95% CI], 3.9% to 6.4%). MLST was performed on 108 Hib isolates from children carrying Hib isolates and 15 isolates from children with invasive disease. Thirty-one sequence types (STs) were identified, and 20 of these were novel STs. The most common ST isolates were sequence type 6 (ST6) and the novel ST722. There was marked heterogeneity among the STs from children with disease and children carrying Hib. STs identified from invasive infections were those commonly identified in carriage. This study provides evidence of Hib carriage among children in urban Nepal with genetically diverse strains prior to introduction of universal vaccination. The Hib carriage rate in Nepal was similar to the rates observed in other populations with documented high disease rates prior to vaccination, supporting implementation of Hib vaccine in Nepal in 2009.

Immune response to the 7-valent pneumococcal conjugate vaccine in 30 asplenic children

The aim of the study was to determine the concentration of pneumococcal antibodies after a dose of 7-valent pneumococcal conjugate vaccine (PCV7) in 30 asplenic children between 4 months and 19 years of age. Fifteen children had received pneumococcal polysaccharide vaccine (PPV) approximately 5 years prior to vaccination with PCV7. The antibody concentrations against serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were measured by ELISA before and after the PCV7 vaccination. Before vaccination with PCV7, the antibody concentrations were similar in children who had or had not received PPV previously. A dose of PCV7 stimulated a good immune response in asplenic patients. Prior immunization with PPV did not affect the antibody concentration after the vaccination with PCV7. In conclusion, asplenic children vaccinated with PPV may need revaccination with PPV earlier than the recommended 3-5 years after the first dose. PCV7 induces a satisfactory immune response in asplenic patients and should be considered as an alternative vaccine in that patient group.

Nasopharyngeal Haemophilus influenzae carriage in Japanese children attending day-care centers

We conducted a prospective bacteriological survey to investigate antibiotic resistance-related genetic characteristics and the turnover of nasopharyngeal Haemophilus influenzae carriage in healthy children in day-care centers (DCCs). A total of 363 nasopharyngeal mucus samples were collected from children aged 0 to 6 years attending two DCCs in the summer of 2004 (n = 184) and the following winter (n = 179). We obtained 172 H. influenzae isolates and analyzed them by antimicrobial susceptibility testing, PCR for bla(TEM-1) and the penicillin-binding protein (PBP) gene, and pulsed-field gel electrophoresis (PFGE). The overall carriage rate was 47.4% (172/363), and 37.2% of the isolates (64/172) were ampicillin (AMP) resistant. All the resistant isolates had a PBP mutation(s), while only three isolates had TEM-1. The carriage rate was significantly higher in the winter than in the summer (56.4% and 38.6%, respectively), owing to the increase in the numbers of AMP-susceptible H. influenzae isolates in the winter. Children aged < or = 3 years showed a higher rate of carriage of H. influenzae isolates with an AMP resistance gene(s) than those aged > or = 4 years (21.9% and 12.6%, respectively). Forty-two strains with different PFGE patterns were obtained from among the 172 isolates. Only five strains were observed in both seasons. None of the strains isolated in the summer was isolated from the same carrier in the winter. Twenty-seven strains (64.3%) were isolated from two or more children, and 25 of these were each isolated from children belonging to the same DCC. These results indicate the spread of H. influenzae, particularly those with a PBP mutation(s), and the highly vigorous genetic turnover and substantial horizontal transmission of this pathogen in healthy children attending DCCs in Japan.

Virulence phenotypes of low-passage clinical isolates of nontypeable Haemophilus influenzae assessed using the chinchilla laniger model of otitis media

Background

The nontypeable Haemophilus influenzae (NTHi) are associated with a spectrum of respiratory mucosal infections including: acute otitis media (AOM); chronic otitis media with effusion (COME); otorrhea; locally invasive diseases such as mastoiditis; as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. These diverse clinical and genotypic findings suggest that each NTHi strain possesses a unique set of virulence factors that contributes to the course of the disease.

Results

The local and systemic virulence patterns of ten genomically characterized low-passage clinical NTHi strains (PittAA – PittJJ) obtained from children with COME or otorrhea were stratified using the chinchilla model of otitis media (OM). Each isolate was used to bilaterally inoculate six animals and thereafter clinical assessments were carried out daily for 8 days by blinded observers. There was no statistical difference in the time it took for any of the 10 NTHi strains to induce otologic (local) disease with respect to any or all of the other strains, however the differences in time to maximal local disease and the severity of local disease were both significant between the strains. Parameters of systemic disease indicated that the strains were not all equivalent: time to development of the systemic disease, maximal systemic scores and mortality were all statistically different among the strains. PittGG induced 100% mortality while PittBB, PittCC, and PittEE produced no mortality. Overall Pitt GG, PittII, and Pitt FF produced the most rapid and most severe local and systemic disease. A post hoc determination of the clinical origins of the 10 NTHi strains revealed that these three strains were of otorrheic origin, whereas the other 7 were from patients with COME.

Conclusion

Collectively these data suggest that the chinchilla OM model is useful for discriminating between otorrheic and COME NTHi strains as to their disease-producing potential in humans, and combined with whole genome analyses, point the way towards identifying classes of virulence genes.

Dissemination of a capsular and antibiotype variant of the England-9 pneumococcal clone in the Czech Republic

Forty-one clinical isolates of serotype 19F Streptococcus pneumoniae resistant to chloramphenicol and/or tetracycline, isolated in the Czech Republic between 1996 and 2005, were analysed by pulsed-field gel electrophoresis and multilocus sequence typing. All but two isolates belonged to a single cluster represented by sequence type 423, a double-locus variant of clone England(14)-9. Interestingly, these two isolates differed from the dominant clone in capsular type as well as antibiotic susceptibility profile.

Possible prevalence and transmission of acute respiratory tract infections caused by Streptococcus pneumoniae and Haemophilus influenzae among the internally displaced persons in tsunami disaster evacuation camps of Sri Lanka

OBJECTIVE

The objective of this prospective study was to investigate the status of acute respiratory tract infections caused by Haemophilus influenzae and Streptococcus pneumoniae in tsunami disaster evacuation camps.

METHODS

Nasopharyngeal swabs (NP) of 324 internally displaced persons (IDP) in 3 different tsunami disaster evacuation camps of Sri Lanka were collected between March 18th and 20th, 2005, and analyzed for MIC, beta-lactamase production, serotypes, PCR and pulsed-field gel electrophoresis (PFGE).

RESULTS

Many IDP had respiratory symptoms and the prevalence of cough and/or sputum was 84%, 70.5% and 64.7% in the three camps. Twenty-one H. influenzae from 20 IDP and 25 S. pneumoniae from 22 IDP were isolated from the NP. All H. influenzae isolates were nontypeable, and 5 were beta-lactamase producing. Seventeen pneumococci were susceptible, 5 showed intermediate resistance and 3 were fully resistant to penicillin G. Molecular analysis showed the 21 H. influenzae strains had 13 PFGE patterns and 25 pneumococci had 16 PFGE patterns. All 4 different PFGE patterns of H. influenzae strains were detected in a few IDP in camps 1 and 3, and 5 different PFGE patterns of serotype 3, 22A, 9A, 10A and 11A pneumococci were detected in a few IDP in camps 1 and 3.

CONCLUSION

Our data indicate acute respiratory tract infections caused by various types of H. influenzae and S. pneumoniae appear to have been prevalent, some of which were potentially transmitted from person to person in tsunami disaster evacuation camps.

Modelling the co-occurrence of Streptococcus pneumoniae with other bacterial and viral pathogens in the upper respiratory tract

Otitis media (OM) is a major burden for all children, particularly for Australian Aboriginal children. Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and viruses (including rhinovirus and adenovirus) are associated with OM. We investigated nasopharyngeal microbial interactions in 435 samples collected from 79 Aboriginal and 570 samples from 88 non-Aboriginal children in Western Australia. We describe a multivariate random effects model appropriate for analysis of longitudinal data, which enables the identification of two independent levels of correlation between pairs of pathogens. At the microbe level, rhinovirus infection was positively correlated with carriage of S. pneumoniae, H. influenzae and M. catarrhalis, and adenovirus with M. catarrhalis. Generally, there were positive associations between bacterial pathogens at both the host and microbe level. Positive viral–bacterial associations at the microbe level support previous findings indicating that viral infection can predispose an individual to bacterial carriage. Viral vaccines may assist in reducing the burden of bacterial disease.

Carriage of Streptococcus pneumoniae in healthy Norwegian children attending day-care centres

An observational study to examine Streptococcus pneumoniae carriage in Norwegian children was initiated after two cases of pneumococcal meningitis, caused by the England(14)-9 clone, occurred in one day-care centre in Oslo. All children recruited from the day-care centre where the cases occurred were vaccinated with a seven-valent pneumococcal conjugate vaccine; the other participants who attended three other day-care centres nearby were not. The children were followed for 9 months, and three samplings took place. At the first visit, 45.7% of the children were colonised by pneumococci in the nasopharynx. The children harboured a variety of serotypes, with serotypes 6A, 23F, 6B and 19F being the most frequent. The numbers of children carrying vaccine serotypes decreased in both the vaccinated and the non-vaccinated groups. Thus, no significant effect of vaccine on carriage was detected in this relatively small study.

Advances in understanding the pathogenesis of pneumococcal otitis media

In this review, a state of the art on otitis media research is provided with emphasis on the role of Streptococcus pneumoniae in the pathogenesis of this disease. Articles have been selected by MEDLINE search supplemented with a manual crosscheck of bibliographies. Pathogenic mechanisms in middle ear and eustachian tube are described. Furthermore, pneumococcal characteristics and pneumococcus-host interactions are highlighted as well as the possible role of biofilms in persistence or recurrence of otitis media. Because of the availability of new techniques, an increasing number of pneumococcal features contributing in the pathogenesis of otitis media are identified and in-depth knowledge of pneumococcus-host interactions has been gained. The present advances in research on otitis media open up new perspectives for therapeutic or preventive strategies.

Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus isolated from the nasopharynx of healthy children attending day-care centres in the Czech Republic

Nasopharyngeal carriage of potential pathogens was studied in 425 healthy 3- to 6-year-old children attending 16 day-care centres (DCCs) in nine Czech cities during the winter 2004-2005. The overall carriage of pathogens was 62.8% (Streptococcus pneumoniae, 38.1%; Haemophilus influenzae, 24.9%; Moraxella catarrhalis, 22.1%; Staphylococcus aureus, 16%). An age-related downward trend was observed for colonization with respiratory pathogens in contrast to Staph. aureus whose carriage was significantly higher among older children. The following serotypes of colonizing S. pneumoniae were the most predominant: 23F (20.6%), 6A (15.1%), 6B (12.7%), 18C (7.8%), 15B and 19F (6% each). The majority (94.3%) of H. influenzae isolates were non-typable; among capsulated isolates, serotype b was not found. Decreased susceptibility to penicillin was determined in 3% of pneumococci; 4.6% of H. influenzae strains and 85.1% of M. catarrhalis strains produced beta-lactamase. As for non-beta-lactam antibiotics, pneumococci resistant to trimethoprim-sulphamethoxazole were the most common (15.7%) among the attendees.

Natural history of drug-resistant clones of Streptococcus pneumoniae colonizing healthy children in Portugal

A total of 3,539 Streptococcus pneumoniae (Pn) were recovered from 4,969 nasopharyngeal samples of children attending 13 day-care centers (DCCs) located in Lisbon, Portugal, during a surveillance study from January, 2001, through March, 2003, integrated in the European intervention project (EURIS, European Resistance Intervention Study). All Pn isolates were tested for anti-biotyping and drug-resistant pneumococci (DRPn) were further tested by serotyping and pulsed-field gel electrophoresis (PFGE). Overall carriage of Pn was very high (71.2%) and 39.9% of the isolates were resistant to antimicrobials (22.5% with decreased susceptibility to penicillin and 17.4% susceptible to penicillin and resistant to other antimicrobials). Serotypes 6B, 14, 23 F, 19F, and 19 A were prevalent among the 1,287 DRPn and 5.8% of the isolates were non-typeable. Eighty PFGE patterns were identified among 1,285 DRPn, and 93.1% of the DRPn belonged to 26 major clonal types that comprised: Pneumococcal Molecular Epidemiology Network (PMEN) clones (76.3%), Portuguese (PT)-DCC clones, previously detected in 1996-1999 (14.3%), and EURIS PT-DCC new clones, identified for the first time in the EURIS study, during 2001-2003 (9.4%). Comparing with previous Portuguese surveillance studies carried out since 1996, we observed that carriage increased from 47% to 71%, but no major changes were detected on the prevalence of pneumococcal serotypes. Moreover, although PMEN clones were predominant in all DCCs, in the present study the majority of them were gradually decreasing in time whereas several PT-DCC and new clones seemed to be increasing.