Clinical perspectives on nasopharyngeal morphology in humans

The nasopharynx is an integral component of the upper aerodigestive tract, whose morphologic features share an intimate relationship with a vast array of clinical, functional, and quality of life conditions related to contemporary humans. Its composite architecture and central location amidst the nasal cavity, pharyngotympanic tube, palate, and skull base bears implications for basic physiologic functions including breathing, vocalization, and alimentation. Over the course of evolution, morphological modifications of nasopharyngeal anatomy have occurred in genus Homo which serve to distinguish the human upper aerodigestive tract from that of other mammals. Understanding of these adaptive changes from both a comparative anatomy and clinical perspective offers insight into the unique blueprint which underpins many clinical pathologies currently encountered by anthropologists, scientists, and otorhinolaryngologists alike. This discussion intends to familiarize readers with the fundamental role that nasopharyngeal morphology plays in upper aerodigestive tract conditions, with consideration of its newfound clinical relevance in the era of the COVID-19 pandemic.

Nasopharyngeal microbiota in hospitalized children with Bordetella pertussis and Rhinovirus infection

Despite great advances in describing Bordetella pertussis infection, the role of the host microbiota in pertussis pathogenesis remains unexplored. Indeed, the microbiota plays important role in defending against bacterial and viral respiratory infections. We investigated the nasopharyngeal microbiota in infants infected by B. pertussis (Bp), Rhinovirus (Rv) and simultaneously by both infectious agents (Bp + Rv). We demonstrated a specific nasopharyngeal microbiome profiles for Bp group, compared to Rv and Bp + Rv groups, and a reduction of microbial richness during coinfection compared to the single infections. The comparison amongst the three groups showed the increase of Alcaligenaceae and Achromobacter in Bp and Moraxellaceae and Moraxella in Rv group. Furthermore, correlation analysis between patients’ features and nasopharyngeal microbiota profile highlighted a link between delivery and feeding modality, antibiotic administration and B. pertussis infection. A model classification demonstrated a microbiota fingerprinting specific of Bp and Rv infections. In conclusion, external factors since the first moments of life contribute to the alteration of nasopharyngeal microbiota, indeed increasing the susceptibility of the host to the pathogens' infections. When the infection is triggered, the presence of infectious agents modifies the microbiota favoring the overgrowth of commensal bacteria that turn in pathobionts, hence contributing to the disease severity.

Antigen-Presenting Cells in the Airways: Moderating Asymptomatic Bacterial Carriage

Bacterial respiratory tract infections (RTIs) are a major global health burden, and the role of antigen-presenting cells (APCs) in mounting an immune response to contain and clear invading pathogens is well-described. However, most encounters between a host and a bacterial pathogen do not result in symptomatic infection, but in asymptomatic carriage instead. The fact that a pathogen will cause infection in one individual, but not in another does not appear to be directly related to bacterial density, but rather depend on qualitative differences in the host response. Understanding the interactions between respiratory pathogens and airway APCs that result in asymptomatic carriage, will provide better insight into the factors that can skew this interaction towards infection. This review will discuss the currently available knowledge on airway APCs in the context of asymptomatic bacterial carriage along the entire respiratory tract. Furthermore, in order to interpret past and futures studies into this topic, we propose a standardized nomenclature of the different stages of carriage and infection, based on the pathogen’s position with regard to the epithelium and the amount of inflammation present.

Oropharyngeal Carriage of hpl-Containing Haemophilus haemolyticus Predicts Lower Prevalence and Density of NTHi Colonisation in Healthy Adults

Nontypeable Haemophilus influenzae (NTHi) is a major respiratory pathogen that initiates infection by colonising the upper airways. Strategies that interfere with this interaction may therefore have a clinically significant impact on the ability of NTHi to cause disease. We have previously shown that strains of the commensal bacterium Haemophilus haemolyticus (Hh) that produce a novel haem-binding protein, haemophilin, can prevent NTHi growth and interactions with host cells in vitro. We hypothesized that natural pharyngeal carriage of Hh strains with the hpl open reading frame (Hh-hpl⁺) would be associated with a lower prevalence and/or density of NTHi colonisation in healthy individuals. Oropharyngeal swabs were collected from 257 healthy adults in Australia between 2018 and 2019. Real-time PCR was used to quantitatively compare the oropharyngeal carriage load of NTHi and Hh populations with the Hh-hpl⁺ or Hh-hpl⁻ genotype. The likelihood of acquiring/maintaining NTHi colonisation status over a two- to six-month period was assessed in individuals that carried either Hh-hpl⁻ (n = 25) or Hh-hpl⁺ (n = 25). Compared to carriage of Hh-hpl⁻ strains, adult (18–65 years) and elderly (>65 years) participants that were colonised with Hh-hpl⁺ were 2.43 or 2.67 times less likely to carry NTHi in their oropharynx, respectively. Colonisation with high densities of Hh-hpl⁺ correlated with a low NTHi carriage load and a 2.63 times lower likelihood of acquiring/maintaining NTHi colonisation status between visits. Together with supporting in vitro studies, these results encourage further investigation into the potential use of Hh-hpl⁺ as a respiratory probiotic candidate for the prevention of NTHi infection.

Exploiting the struggle for haem: a novel therapeutic approach against Haemophilus influenzae

Over the past decade, nontypeable Haemophilus influenzae (NTHi) has gained recognition as a major opportunistic pathogen of the respiratory tract that imposes a substantial global burden of disease, owing to a high rate of morbidity and ensuing complications. Further amplifying the global impact of NTHi infections is the increasing spectrum and prevalence of antibiotic resistance, leading to higher rates of treatment failure with first- and second-line antibiotics regimes. The threat of antibiotic resistance was recognised by the World Health Organization in 2017, listing NTHi as a priority pathogen for which new therapies are urgently needed. Despite significant efforts, there are currently no effective vaccine strategies available that can slow the growing burden of NTHi disease. Consequently, alternative preventative or therapeutic approaches that do not rely on antibiotic susceptibility or stable vaccine targets are becoming more attractive. The nutritional dependency for haem at all stages of NTHi pathogenesis exposes a vulnerability that may be exploited for the development of such therapies. This article will discuss the therapeutic potential of strategies that limit NTHi access to this vital nutrient, with particular focus on a novel bacteriotherapeutic approach under development.

Subversion of host immune responses by otopathogens during otitis media

Otitis media (OM) is one of the most common ear diseases affecting humans. Children are at greater risk and suffer most frequently from OM, which can cause serious deterioration in the quality of life. OM is generally classified into two main types: acute and chronic OM (AOM and COM). AOM is characterized by tympanic membrane swelling or otorrhea and is accompanied by signs or symptoms of ear infection. In COM, there is a tympanic membrane perforation and purulent discharge. The most common pathogens that cause AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis whereas Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with COM. Innate and adaptive immune responses provide protection against OM. However, pathogens employ a wide arsenal of weapons to evade potent immune responses and these mechanisms likely contribute to AOM and COM. Immunologic evasion is multifactorial, and involves damage to host mucociliary tract, genetic polymorphisms within otopathogens, the number and variety of different otopathogens in the nasopharynx as well as the interaction between the host's innate and adaptive immune responses. Otopathogens utilize host mucin production, phase variation, biofilm production, glycans, as well as neutrophil and eosinophilic extracellular traps to induce OM. The objective of this review article is to discuss our current understanding about the mechanisms through which otopathogens escape host immunity to induce OM. A better knowledge about the molecular mechanisms leading to subversion of host immune responses will provide novel clues to develop effective treatment modalities for OM.

Nasopharyngeal polymicrobial colonization during health, viral upper respiratory infection and upper respiratory bacterial infection

OBJECTIVES

We sought to understand how polymicrobial colonization varies during health, viral upper respiratory infection (URI) and acute upper respiratory bacterial infection to understand differences in infection-prone vs. non-prone patients.

METHODS

Nasopharyngeal (NP) samples were collected from 74 acute otitis media (AOM) infection-prone and 754 non-prone children during 2094 healthy visits, 673 viral URI visits and 631 AOM visits. Three otopathogens Streptococcus pneumoniae (Spn), Nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis (Mcat) were identified by culture.

RESULTS

NP colonization rates of multiple otopathogens during health were significantly lower than during viral URI, and during URI they were lower than at onset of upper respiratory bacterial infection in both AOM infection-prone and non-prone children. AOM infection-prone children had higher polymicrobial colonization rates than non-prone children during health, viral URI and AOM. Polymicrobial colonization rates of AOM infection-prone children during health were equivalent to that of non-prone children during viral URI, and during viral URI were equivalent to that of non-prone during AOM infection. Spn colonization was positively associated with NTHi and Mcat colonization during health, but negatively during AOM infection.

CONCLUSION

The infection-prone patients more frequently have multiple potential bacterial pathogens in the NP than the non-prone patients. Polymicrobial interaction in the NP differs during health and at onset of infection.

Collective Resistance in Microbial Communities by Intracellular Antibiotic Deactivation

The structure and composition of bacterial communities can compromise antibiotic efficacy. For example, the secretion of β-lactamase by individual bacteria provides passive resistance for all residents within a polymicrobial environment. Here, we uncover that collective resistance can also develop via intracellular antibiotic deactivation. Real-time luminescence measurements and single-cell analysis demonstrate that the opportunistic human pathogen Streptococcus pneumoniae grows in medium supplemented with chloramphenicol (Cm) when resistant bacteria expressing Cm acetyltransferase (CAT) are present. We show that CAT processes Cm intracellularly but not extracellularly. In a mouse pneumonia model, more susceptible pneumococci survive Cm treatment when coinfected with a CAT-expressing strain. Mathematical modeling predicts that stable coexistence is only possible when antibiotic resistance comes at a fitness cost. Strikingly, CAT-expressing pneumococci in mouse lungs were outcompeted by susceptible cells even during Cm treatment. Our results highlight the importance of the microbial context during infectious disease as a potential complicating factor to antibiotic therapy.

Antibiotic-resistant bacterial infections are on the rise and pose a serious threat to society. The influence of genetic resistance mechanisms on antibiotic therapy is well described. However, other factors, such as epigenetic resistance or the impact of the environment on antibiotic therapy, are less well understood. Here, we describe and characterize a mechanism of noninherited antibiotic resistance that enables the survival and outgrowth of genetically susceptible bacteria during antibiotic therapy. We show that bacteria expressing the resistance factor chloramphenicol (Cm) acetyltransferase (CAT) can potently deactivate Cm in their immediate environment. The reduced Cm concentration then allows for the outgrowth of genetically susceptible bacteria in the same environment. Mathematical modeling demonstrates the presence of a parameter space in which stable coexistence between Cm-susceptible and -resistant bacteria is possible during antibiotic therapy, which we validated using single-cell analyses. Strikingly, mixed culture experiments in which mice were infected with both Cm-susceptible and -resistant pneumococci revealed that Cm-sensitive “freeloader” bacteria even outcompeted resistant bacteria during antibiotic therapy. Together, we show that the microbial context during infection is a potential complicating factor to antibiotic treatment outcomes.

Surveillance of pneumococcal diseases in Central and Eastern Europe

Pneumococcal infection is a major cause of morbidity and mortality worldwide. The burden of disease associated with S. pneumoniae is largely preventable through routine vaccination. Pneumococcal conjugate vaccines (e.g. PCV7, PCV13) provide protection from invasive pneumococcal disease as well as non-invasive infection (pneumonia, acute otitis media), and decrease vaccine-type nasopharyngeal colonisation, thus reducing transmission to unvaccinated individuals. PCVs have also been shown to reduce the incidence of antibiotic-resistant pneumococcal disease. Surveillance for pneumococcal disease is important to understand local epidemiology, serotype distribution and antibiotic resistance rates. Surveillance systems also help to inform policy development, including vaccine recommendations, and monitor the impact of pneumococcal vaccination. National pneumococcal surveillance systems exist in a number of countries in Central and Eastern Europe (such as Croatia, Czech Republic, Hungary, Poland, Romania and Slovakia), and some have introduced PCVs (Czech Republic, Hungary, Kazakhstan, Russia, Slovakia and Turkey). Those countries without established programs (such as Kazakhstan, Russia and Ukraine) may be able to learn from the experiences of those with national surveillance systems. The serotype distributions and impact of PCV13 on pediatric pneumococcal diseases are relatively similar in different parts of the world, suggesting that approaches to vaccination used elsewhere are also likely to be effective in Central and Eastern Europe. This article briefly reviews the epidemiology of pneumococcal disease, presents the latest surveillance data from Central and Eastern Europe, and discusses any similarities and differences in these data as well the potential implications for vaccination policies in the region.

Invasive Haemophilus influenzae Disease in Adults ≥65 Years, United States, 2011

In this older age group burden of disease and CFR both increase significantly as age increases. Several underlying conditions increased risk of disease severity and patients with severe disease were more likely to die.

Background

 Since the introduction of the Haemophilus influenzae serotype b vaccine, H influenzae epidemiology has shifted. In the United States, the largest burden of disease is now in adults aged ≥65 years. However, few data exist on risk factors for disease severity and outcome in this age group.

Methods

 A retrospective case-series review of invasive H influenzae infections in patients aged ≥65 years was conducted for hospitalized cases reported to Active Bacterial Core surveillance in 2011.

Results

 There were 299 hospitalized cases included in the analysis. The majority of cases were caused by nontypeable H influenzae, and the overall case fatality ratio (CFR) was 19.5%. Three or more underlying conditions were present in 63% of cases; 94% of cases had at least 1. Patients with chronic heart conditions (congestive heart failure, coronary artery disease, and/or atrial fibrillation) (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.65–6.46), patients from private residences (OR, 8.75; 95% CI, 2.13–35.95), and patients who were not resuscitate status (OR, 2.72; 95% CI, 1.31–5.66) were more likely to be admitted to the intensive care unit (ICU). Intensive care unit admission (OR, 3.75; 95% CI, 1.71–8.22) and do not resuscitate status (OR, 12.94; 95% CI, 4.84–34.55) were significantly associated with death.

Conclusions

 Within this age group, burden of disease and CFR both increased significantly as age increased. Using ICU admission as a proxy for disease severity, our findings suggest several conditions increased risk of disease severity and patients with severe disease were more likely to die. Further research is needed to determine the most effective approach to prevent H influenzae disease and mortality in older adults.

Characterization of the nasopharyngeal microbiota in health and during rhinovirus challenge

BACKGROUND

The bacterial communities of the nasopharynx play an important role in upper respiratory tract infections (URTIs). Our study represents the first survey of the nasopharynx during a known, controlled viral challenge. We aimed to gain a better understanding of the composition and dynamics of the nasopharyngeal microbiome during viral infection.

METHODS

Rhinovirus illnesses were induced by self-inoculation using the finger to nose or eye natural transmission route in ten otherwise healthy young adults. Nasal lavage fluid samples (NLF) samples were collected at specific time points before, during, and following experimental rhinovirus inoculation. Bacterial DNA from each sample (N = 97 from 10 subjects) was subjected to 16S rRNA sequencing by amplifying the V1-V2 hypervariable region followed by sequencing using the 454-FLX platform.

RESULTS

This survey of the nasopharyngeal microbiota revealed a highly complex microbial ecosystem. Taxonomic composition varied widely between subjects and between time points of the same subject. We also observed significantly higher diversity in not infected individuals compared to infected individuals. Two genera - Neisseria and Propionibacterium - differed significantly between infected and not infected individuals. Certain phyla, including Firmicutes, Actinobacteria, and Proteobacteria, were detected in all samples.

CONCLUSIONS

Our results reveal the complex and diverse nature of the nasopharyngeal microbiota in both healthy and viral-challenged adults. Although some phyla were common to all samples, differences in levels of diversity and selected phyla were detected between infected and uninfected participants. Deeper, species-level metagenomic sequencing in a larger sample is warranted.

Bacterial pathogens in the nasopharynx, nasal cavity, and osteomeatal complex during wellness and viral infection

BACKGROUND

Viral sinusitis can precede acute bacterial sinusitis, but the influence of viral infection on bacterial colonization is unclear. The objective of this study was to evaluate the presence of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in the osteomeatal complex (OMC), nasal cavity, and nasopharynx in adults during wellness and viral upper respiratory illness (URI).

METHODS

Subjects were recruited for the study during wellness and at the time of acute viral rhinosinusitis. Swab cultures were obtained from the OMC, nasal cavity, and the nasopharynx. Swab eluates were inoculated on selective agars to detect S. pneumoniae, H. influenzae, and M. catarrhalis.

RESULTS

The study included 237 subjects, 100 adults with URI and 137 well adults. Positive culture results were found for any site in 70% (n = 70) of ill subjects and 64% (n = 88) of well subjects (p = 0.393). Of the 91 OMC cultures, positive cultures were over five times more likely to be found in ill subjects than in well subjects (31% versus 8%; p = 0.010). The nasal cavity cultures were positively statistically significant more often in ill subjects versus well subjects (39% versus 25%; p = 0.022). The overall nasopharyngeal cultures did not show a statistically significant difference (65% versus 60%; odds ratio, 1.2; p = 0.461). S. pneumoniae was positively cultured in at least one site in 15% of ill subjects and 31% of well subjects (p = 0.006). H. influenzae was positively cultured in at least one site in 45% of ill subjects and 31% of well subjects (p = 0.027). M. catarrhalis was positively cultured in at least one site in 42% of ill subjects and 27% of well subjects (p = 0.018).

CONCLUSION

This study defines the carriage rates of the three most common bacterial pathogens for acute sinusitis in the nasopharynx, nasal cavity, and OMC during illness and in the healthy state.

Bacteria in the nose of young adults during wellness and rhinovirus colds: detection by culture and microarray methods in 100 nasal lavage specimens

BACKGROUND

Patients  with  viral respiratory infections/viral rhinitis/common colds are often treated with antibiotic; however, there is little information on whether or how bacterial microbiota in the nose and nasopharynx might influence the course of viral illnesses.

METHODS

To initiate investigation of possible interaction between viral respiratory illness and microbiota of the nose/nasopharynx, we used microarray technology to examine 100 nasal lavage fluid (NLF) samples for bacterial species and recorded the bacterial titer of culturable bacteria. Rhinovirus illnesses were induced by self-inoculation using the "finger to nose or eye natural transmission route" in 10 otherwise healthy young adults. NLF samples were collected during wellness and at specific time points following experimental rhinovirus inoculation.

RESULTS

The rhinovirus infection rate was 70%. There were no consistent changes in the prevalence of different bacterial species determined by microarray and bacterial titer by culture methods during rhinovirus infection. The bacterial profile in NLF samples showed high variability between volunteers but low variability in multiple NLFs obtained before and following infection from the same volunteer. Streptococcus epidermidis/coagulase-negative staphylococcus (CNS) were identified in all 10 subjects. One or more bacterial sinus/otitis pathogens were identified by microarray in 6 of the 10 volunteers. The microarray identified a few bacteria not included in traditional bacterial cultures.

CONCLUSION

Our pilot study showed that each of the 10 volunteers had a unique bacterial profile in the nose by microarray analysis and that bacterial load did not change during experimental rhinovirus colds. Larger scale studies are warranted.

Prevention of acute otitis media using currently available vaccines

Acute otitis media (AOM) is common in infants and children. Although approximately two-thirds of cases are due to bacteria, almost all of the episodes are preceded by upper respiratory viral infection. Several viruses, among which respiratory syncytial virus is the most common, are involved in the determination of AOM. However, a significant number of AOM cases are associated with influenza infection, and influenza viruses are among the most frequently found respiratory viruses in the middle ear fluid during an acute episode of AOM. Consequently, influenza vaccination may have a favorable impact on the incidence and course of AOM. Moreover, as Streptococcus pneumoniae is one of the leading AOM bacterial pathogens and it is well known that influenza virus infection predisposes to pneumococcal infection, there is a further reason to suggest the use of influenza vaccine to reduce the risk of AOM. On the other hand, the administration of pneumococcal conjugate vaccine is considered per se a possible means of reducing the incidence of the disease. However, although a number of studies have measured the impact of both vaccines on AOM, it is still not known whether (and to what extent) they are really effective, nor what impact the more recently licensed vaccines may have. The aim of this review is to examine the clinical impact of vaccinations on AOM.

Bacterial pathogens of acute sinusitis in the osteomeatal complex during common colds and wellness

BACKGROUND

Pathogenic bacteria have been cultured from the osteomeatal complex (OMC) in one-third of adults with apparent acute bacterial sinusitis; however, it is not known whether bacteria are present in the OMC during uncomplicated viral colds in adults.

METHODS

Adult volunteers were recruited for a study during wellness and at the time of acute common cold. Swab cultures were obtained from the OMC and from the nasopharynx by 2 routes (through the nose and through the mouth). Swab eluates were inoculated on selective agars to detect S. pneumoniae, H. influenzae, and M. catarrhalis.

RESULTS

Bacterial pathogens were detected in the OMC more frequently during common colds than during wellness (31% vs 8%, p < 0.008). Pathogens detected in the OMC were always present in the nasopharynx of the subject.

CONCLUSION

Bacterial pathogens are present in the OMC in a subgroup of adult patients with uncomplicated upper respiratory illness/common cold. The nasopharynx appears to be the reservoir for bacterial pathogens in the OMC.

Mechanical non-surgical treatment of peri-implantitis: a single-blinded randomized longitudinal clinical study. II. Microbiological results

BACKGROUND

Peri-implantitis is common in patients with dental implants. We performed a single-blinded longitudinal randomized study to assess the effects of mechanical debridement on the peri-implant microbiota in peri-implantitis lesions.

MATERIALS AND METHODS

An expanded checkerboard DNA-DNA hybridization assay encompassing 79 different microorganisms was used to study bacterial counts before and during 6 months following mechanical treatment of peri-implantitis in 17 cases treated with curettes and 14 cases treated with an ultrasonic device. Statistics included non-parametric tests and GLM multivariate analysis with p<0001 indicating significance and 80% power.

RESULTS

At selected implant test sites, the most prevalent bacteria were: Fusobacterium nucleatum sp., Staphylococci sp., Aggregatibacter actinomycetemcomitans, Helicobacter pylori, and Tannerella forsythia. 30 min. after treatment with curettes, A. actinomycetemcomitans (serotype a), Lactobacillus acidophilus, Streptococcus anginosus, and Veillonella parvula were found at lower counts (p<0.001). No such differences were found for implants treated with the ultrasonic device. Inconsistent changes occurred following the first week. No microbiological differences between baseline and 6-month samples were found for any species or between treatment study methods in peri-implantitis.

CONCLUSIONS

Both methods failed to eliminate or reduce bacterial counts in peri-implantitis. No group differences were found in the ability to reduce the microbiota in peri-implantitis.

Otitis media: viruses, bacteria, biofilms and vaccines

Otitis media typically presents as either acute otitis media (AOM), with symptoms including fever, otalgia, otorrhoea or irritability and short duration; or as otitis media with effusion (OME), which is often asymptomatic and characterised by accumulation of fluid in the middle ear.

Diagnostic certainty of otitis media is challenging, given the young age of patients and variability of symptoms.

Otitis media predominantly occurs as coincident to viral upper respiratory tract infections and/or bacterial infections.

Common viruses that cause upper respiratory tract infection are frequently associated with AOM and new‐onset OME. These include respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza and coronavirus.

Predominant bacteria that cause otitis media are Streptococcus pneumoniae, Moraxella catarrhalis, and non‐typeable Haemophilus influenzae.

Antibiotic therapy does not significantly benefit most patients with AOM, but long‐term prophylactic antibiotic therapy can reduce the risk of otitis media recurrence among children at high risk.

In Australia, 84% of AOM is treated with antibiotic therapy, which contributes to development of antibiotic resistance.

Vaccine development is a key future direction for reducing the world burden of otitis media, but requires polymicrobial formulation and ongoing monitoring and modification to ensure sustained reduction in disease burden.

Biofilms in pediatric respiratory and related infections

Bacteria can grow as free-floating, planktonic bacteria or complex communities called biofilms. Biofilms promote bacterial growth and diversity and offer bacteria unique environments, including aerobic and anaerobic layers, that facilitate resistance to antimicrobial therapies. Respiratory and related structures provide ideal environments for the development of bacterial biofilms, which predispose patients to recurrent and chronic infections. Biofilms are important for the persistence of chronic rhinosinusitis, pulmonary infections in cystic fibrosis, chronic otitis media, and device-related infections. Antimicrobial therapy that is proven effective against planktonic bacteria is often insufficiently effective against the defenses of biofilms. Furthermore, biofilms modify themselves following exposure to antimicrobial therapy, thus developing increased resistance. Understanding the nature of biofilms in common pediatric infections is essential to comprehending the expected course of bacterial illness and identifying treatments that are most likely to be beneficial against more resistant biofilms.

Demonstration of Nasopharyngeal and Middle Ear Mucosal Biofilms in an Animal Model of Acute Otitis Media

Objectives:

We performed this study to determine the role of nasopharyngeal and middle ear (ME) biofilms in acute otitis media (AOM).

Methods:

Sixty female 6-month-old chinchillas, free of ME disease, were utilized. Experimental animals were inoculated with influenza A followed by Streptococcus pneumonia 7 days later. Control animals were inoculated with Sorensen's phosphate buffer. Daily otoscopy and tympanometry was performed, and the animals were painlessly sacrificed on days 1, 2, 5, 8, and 14. All mucosae were harvested and prepared for scanning electron microscopy.

Results:

The ME inflammation, initially detected on day 2 after bacterial inoculation, peaked on day 8. Eight percent of the dually inoculated chinchillas displayed type B tympanograms, and 40% displayed type C. Otoscopic evaluation of tympanic membrane inflammation was rated from 0 to 4 (0 = normal and 4 = severe drainage and/or inflammation) according to an otoscopic grading system. Ten percent of the experimental chinchillas had a grade 2 score, 20% had grade 3, and 6.7% had grade 4. The controls demonstrated no abnormal tympanometric or otoscopic findings. Scanning electron microscopic imaging showed dense biofilms on 83% of the nasopharynges and 67% of the MEs on day 8 in the experimental animals. All animals with ME biofilms had biofilms in the nasopharynx. The controls did not demonstrate biofilm formation.

Conclusions:

The study parallels the natural pathogenesis of AOM in humans. The demonstration of mucosal biofilms in both the nasopharynx (58%) and the ME (47%) of animals with ME inflammation and/or infection lends further support to the importance of mucosal biofilms in the pathogenesis of AOM.

Pharyngeal colonization dynamics of Haemophilus influenzae and Haemophilus haemolyticus in healthy adult carriers

Haemophilus influenzae is an important cause of respiratory infections, including acute otitis media, sinusitis, and chronic bronchitis, which are preceded by asymptomatic H. influenzae colonization of the human pharynx. The aim of this study was to describe the dynamics of pharyngeal colonization by H. influenzae and an intimately related species, Haemophilus haemolyticus, in healthy adults. Throat specimens from four healthy adult carriers were screened for Haemophilus species; 860 isolates were identified as H. influenzae or H. haemolyticus based on the porphyrin test and on dependence on hemin and NAD for growth. Based on tests for hemolysis, for the presence of the 7F3 epitope of the P6 protein, and for the presence of iga in 412 of the isolates, 346 (84%) were H. influenzae, 47 (11%) were H. haemolyticus, 18 (4%) were nonhemolytic H. haemolyticus, and 1 was a variant strain. Carriers A and B were predominantly colonized with nontypeable H. influenzae, carrier C predominantly with b(-) H. influenzae mutants, and carrier D with H. haemolyticus. A total of 358 H. influenzae and H. haemolyticus isolates were genotyped by pulsed-field gel electrophoresis (PFGE) following SmaI or EagI digestion of their DNA, and the carriers displayed the following: carrier A had 11 unique PFGE genotypes, carrier B had 15, carrier C had 7, and carrier D had 10. Thus, adult H. influenzae and H. haemolyticus carriers are colonized with multiple unique genotypes, the colonizing strains exhibit genetic diversity, and we observed day-to-day and week-to-week variability of the genotypes. These results appear to reflect both evolutionary processes that occur among H. influenzae isolates during asymptomatic pharyngeal carriage and sample-to-sample collection bias from a large, variable population of colonizing bacteria.

High Prevalence of Streptococcus pneumoniae with Mutations in pbp1a, pbp2x, and pbp2b Genes of Penicillin-Binding Proteins in the Nasopharynx in Children in Japan

OBJECTIVE

To evaluate the resistances of Streptococcus pneumoniae to beta-lactams developed by stepwise alterations in high-molecular-weight penicillin-binding proteins (PBPs) with a reduced binding affinity of beta-lactams. Among the numerous mutations in pbp genes that alter the affinity for beta-lactams, the decreased affinity of PBP1A, 2X and 2B is especially important in the development of resistances to beta-lactams.

STUDY DESIGN

Retrospective review.

METHODS

In this study, we investigated the mutations in pbp1a, pbp2x, and pbp2b genes evaluated by polymerase chain reaction (PCR) in 866 pneumococcal isolates collected from the nasopharynx of Japanese children with acute otitis media.

RESULTS

210 strains (24.3%) exhibited no mutations in the three pbp genes. 333 strains (38.5%) had mutations in the three pbp genes, 78 (9.0%) in two pbp genes, whereas 245 (28.3%) displayed mutations in only one pbp gene. Among the 656 strains with mutations in pbp genes, 620 (94.5%) strains had mutations in pbp2x. The annual prevalence of antimicrobial-resistant S. pneumoniae showed a gradual increase in strains with mutations in the three pbp genes and a parallel decrease in strains without mutations.

CONCLUSIONS

PCR-based genotyping can characterize the antimicrobial resistances in pneumococci along with minimal inhibitory concentrations (MICs). Physicians should pay attention to the recent increase in antimicrobial-resistant S. pneumoniae when treating pediatric acute otitis media.

Chronic rhinosinusitis and superantigens

This article discusses the potential role of bacterial superantigens (SAgs) in chronic rhinosinusitis with nasal polyposis (CRS/NP). First, it briefly describes SAgs, focusing on how they interact with the immune system by binding to T-cell receptors (TCR) and major histocompatibility complex (MHC) class II molecules. Second, it discusses the role of SAgs in other chronic inflammatory diseases.Finally, it presents evidence for the role of SAgs in the pathogenesis and maintenance of CRS/NP focusing on current research and future considerations.

Radiopaque contrast dye in nasopharynx reaches the middle ear during swallowing and/or yawning

CONCLUSION

Contrast dye in the nasopharynx reaches the middle ear during swallowing and yawning in normal adults. This suggests that displacement of bacteria in nasopharyngeal secretion to the middle ear may occur frequently during sleep.

OBJECTIVE

The middle ear is sterile under normal conditions. The purpose of this study was to examine by means of CT whether radiopaque contrast dye in the nasopharynx would reflux into the middle ear of normal adults during swallowing and/or yawning.

MATERIAL AND METHODS

Six normal adult volunteers were studied. Contrast dye was kept at the orifices of the Eustachian tube during swallowing and/or yawning by placing volunteers in either a head-down or lateral decubitus position. Reflux was determined by the presence of contrast dye in the middle ear on CT scanning of the temporal bone.

RESULTS

Two of the three volunteers in each group (four out of six in total) had contrast material detected in one or both middle ear cavities.

Weekly point prevalence of Streptococcus pneumoniae, Hemophilus influenzae and Moraxella catarrhalis in the upper airways of normal young children: effect of respiratory illness and season

The aim was to determine the effect of respiratory illness and season on carriage rates in the upper airways of Streptococcus pneumoniae, Hemophilus influenzae and Moraxella catarrhalis in normal children. Sixteen healthy children, 1-10 years old, amenable to weekly sampling were followed longitudinally for at least three seasons of the year. Respiratory symptoms were recorded daily; weekly nasal aspirate/wash samples were cultured on selective agars. Urea concentration in samples was used to define dilution of secretion. 68% of 950 samples were culture positive; 44% of positives had two or all three species. Each species was detected in about one third of samples. Bacteria were detected in 76% of samples during illness vs. 65% during wellness (p=0.004). Seasonal carriage rates varied from 56% in summer and fall to 85% in winter. There was a strong inverse correlation between dilution of secretion and bacterial detection rate in illness and wellness aspirate samples during the four seasons (r=-0.82, p=0.01). Detection of bacteria varied with the amount of secretion in the sample. This variation accounts for the apparent differences in bacterial carriage during illness vs. wellness and during different seasons.

Antimicrobial treatment guidelines for acute bacterial rhinosinusitis

Treatment guidelines developed by the Sinus and Allergy Health Partnership for acute bacterial rhinosinusitis (ABRS) were originally published in 2000. These guidelines were designed to: (1) educate clinicians and patients (or patients’ families) about the differences between viral and bacterial rhinosinusitis; (2) reduce the use of antibiotics for nonbacterial nasal/sinus disease; (3) provide recommendations for the diagnosis and optimal treatment of ABRS; (4) promote the use of appropriate antibiotic therapy when bacterial infection is likely; and (5) describe the current understanding of pharmacokinetic and pharmacodynamics and how they relate to the effectiveness of antimicrobial therapy. The original guidelines are updated here to include the most recent information on management principles, antimicrobial susceptibility patterns, and therapeutic options.

Burden of disease

An estimated 20 million cases of ABRS occur annually in the United States. According to National Ambulatory Medical Care Survey (NAMCS) data, sinusitis is the fifth most common diagnosis for which an antibiotic is prescribed. Sinusitis accounted for 9% and 21% of all pediatric and adult antibiotic prescriptions, respectively, written in 2002. The primary diagnosis of sinusitis results in expenditures of approximately $3.5 billion per year in the United States.

Definition and diagnosis of ABRS

ABRS is most often preceded by a viral upper respiratory tract infection (URI). Allergy, trauma, dental infection, or other factors that lead to inflammation of the nose and paranasal sinuses may also predispose individuals to developing ABRS.

Patients with a “common cold” (viral URI) usually report some combination of the following symptoms: sneezing, rhinorrhea, nasal congestion, hyposmia/anosmia, facial pressure, postnasal drip, sore throat, cough, ear fullness, fever, and myalgia. A change in the color or the characteristic of the nasal discharge is not a specific sign of a bacterial infection. Bacterial superinfection may occur at any time during the course of a viral URI. The risk that bacterial superinfection has occurred is greater if the illness is still present after 10 days. Because there may be cases that fall out of the “norm” of this typical progression, practicing clinicians need to rely on their clinical judgment when using these guidelines. In general, however, a diagnosis of ABRS may be made in adults or children with symptoms of a viral URI that have not improved after 10 days or worsen after 5 to 7 days. There may be some or all of the following signs and symptoms: nasal drainage, nasal congestion, facial pressure/pain (especially when unilateral and focused in the region of a particular sinus), postnasal drainage, hyposmia/anosmia, fever, cough, fatigue, maxillary dental pain, and ear pressure/fullness.

Physical examination provides limited information in the diagnosis of ABRS.

While sometimes helpful, plain film radiographs, computed tomography (CT), and magnetic resonance imaging scans are not necessary for cases of ABRS.

Microbiology of ABRS

The most common bacterial species isolated from the maxillary sinuses of patients with ABRS are Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis , the latter being more common in children. Other streptococcal species, anaerobic bacteria and Staphylococcus aureus cause a small percentage of cases.

Bacterial resistance in ABRS

The increasing prevalence of penicillin nonsusceptibility and resistance to other drug classes among S pneumoniae has been a problem in the United States, with 15% being penicillin-intermediate and 25% being penicillin-resistant in recent studies. Resistance to macrolides and trimethoprim/sulfamethoxazole (TMP/SMX) is also common in S pneumoniae . The prevalence of β-lactamase-producing isolates of H influenzae is approximately 30%, while essentially all M catarrhalis isolates produce β-lactamases. Resistance of H influenzae to TMP/SMX is also common.

Antimicrobial treatment guidelines for ABRS

These guidelines apply to both adults and children. When selecting antibiotic therapy for ABRS, the clinician should consider the severity of the disease, the rate of progression of the disease, and recent antibiotic exposure. The guidelines now divide patients with ABRS into two general categories: (1) those with mild symptoms who have not received antibiotics within the past 4 to 6 weeks, and (2) those with mild disease who have received antibiotics within the past 4 to 6 weeks or those with moderate disease regardless of recent antibiotic exposure. The difference in severity of disease does not imply infection with a resistant pathogen. Rather, this terminology indicates the relative degree of acceptance of possible treatment failure and the likelihood of spontaneous resolution of symptoms—patients with more severe symptoms are less likely to resolve their disease spontaneously. The primary goal of antibiotic therapy is to eradicate bacteria from the site of infection, which, in turn, helps (1) return the sinuses back to health; (2) decrease the duration of symptoms to allow patients to resume daily activities more quickly; (3) prevent severe complications such as meningitis and brain abscess; and (4) decrease the development of chronic disease. Severe or life-threatening infections with or without complications are rare, and are not addressed in these guidelines.

Prior antibiotic use is a major risk factor associated with the development of infection with antimicrobial-resistant strains. Because recent antimicrobial exposure increases the risk of carriage of and infection due to resistant organisms, antimicrobial therapy should be based upon the patient’s history of recent antibiotic use. The panel’s guidelines, therefore, stratify patients according to antibiotic exposure in the previous 4 to 6 weeks.

Lack of response to therapy at ≥72 hours is an arbitrary time established to define treatment failures. Clinicians should monitor the response to antibiotic therapy, which may include instructing the patient to call the office or clinic if symptoms persist or worsen over the next few days.

The predicted bacteriologic and clinical efficacy of antibiotics in adults and children has been determined according to mathematical modeling of ABRS developed by Michael Poole, MD, PhD, based on pathogen distribution, resolution rates without treatment, and in vitro microbiologic activity.

Antibiotics can be placed into the following relative rank order of predicted clinical efficacy for adults: 90% to 92% = respiratory fluoroquinolones (gatifloxacin, levofloxacin, moxifloxacin), ceftriaxone, high-dose amoxicillin/clavulanate (4 g/250 mg/day), and amoxicillin/clavulanate (1.75 g/250 mg/day); 83% to 88% = high-dose amoxicillin (4 g/day), amoxicillin (1.5 g/day), cefpodoxime proxetil, cefixime (based on H influenzae and M catarrhalis coverage), cefuroxime axetil, cefdinir, and TMP/SMX; 77% to 81% = doxycycline, clindamycin (based on gram-positive coverage only), azithromycin, clarithromycin and erythromycin, and telithromycin; 65% to 66% = cefaclor and loracarbef. The predicted spontaneous resolution rate in patients with a clinical diagnosis of ABRS is 62%.

Antibiotics can be placed into the following relative rank order of predicted clinical efficacy in children with ABRS: 91% to 92% = ceftriaxone, high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day) and amoxicillin/clavulanate (45 mg/6.4 mg per kg per day); 82% to 87% = high-dose amoxicillin (90 mg/kg per day), amoxicillin (45 mg/kg per day), cefpodoxime proxetil, cefixime (based on H influenzae and M catarrhalis coverage only), cefuroxime axetil, cefdinir, and TMP/SMX; and 78% to 80% = clindamycin (based on gram-positive coverage only), cefprozil, azithromycin, clarithromycin, and erythromycin; 67% to 68% = cefaclor and loracarbef. The predicted spontaneous resolution rate in untreated children with a presumed diagnosis of ABRS is 63%.

Recommendations for initial therapy for adult patients with mild disease (who have not received antibiotics in the previous 4 to 6 weeks) include the following choices: amoxicillin/clavulanate (1.75 to 4 g/250 mg per day), amoxicillin (1.5 to 4 g/day), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. While TMP/SMX, doxycycline, azithromycin, clarithromycin, erythromycin, or telithromycin may be considered for patients with β-lactam allergies, bacteriologic failure rates of 20% to 25% are possible. Failure to respond to antimicrobial therapy after 72 hours should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 4).When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent.

Recommendations for initial therapy for adults with mild disease who have received antibiotics in the previous 4 to 6 weeks or adults with moderate disease include the following choices: respiratory fluoroquinolone (eg, gatifloxacin, levofloxacin, moxifloxacin) or high-dose amoxicillin/clavulanate (4 g/250 mg per day). The widespread use of respiratory fluoroquinolones for patients with milder disease may promote resistance of a wide spectrum of organisms to this class of agents. Ceftriaxone (parenteral, 1 to 2 g/day for 5 days) or combination therapy with adequate gram-positive and negative coverage may also be considered. Examples of appropriate regimens of combination therapy include high-dose amoxicillin or clindamycin plus cefixime, or high-dose amoxicillin or clindamycin plus rifampin. While the clinical effectiveness of ceftriaxone and these combinations for ABRS is unproven; the panel considers these reasonable therapeutic options based on the spectrum of activity of these agents and on data extrapolated from acute otitis media studies. Rifampin should not be used as monotherapy, casually, or for longer than 10 to 14 days, as resistance quickly develops to this agent. Rifampin is also a well-known inducer of several cytochrome p450 isoenzymes and therefore has a high potential for drug interactions. Failure of a patient to respond to antimicrobial therapy after 72 hours of therapy should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 4). When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent. Patients who have received effective antibiotic therapy and continue to be symptomatic may need further evaluation. A CT scan, fiberoptic endoscopy or sinus aspiration and culture may be necessary.

Recommendations for initial therapy for children with mild disease and who have not received antibiotics in the previous 4 to 6 weeks include the following: high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day), amoxicillin (90 mg/kg per day), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. TMP/SMX, azithromycin, clarithromycin, or erythromycin is recommended if the patient has a history of immediate Type I hypersensitivity reaction to β-lactams. These antibiotics have limited effectiveness against the major pathogens of ABRS and bacterial failure of 20% to 25% is possible. The clinician should differentiate an immediate hypersensitivity reaction from other less dangerous side effects. Children with immediate hypersensitivity reactions to β-lactams may need: desensitization, sinus cultures, or other ancillary procedures and studies. Children with other types of reactions and side effects may tolerate one specific β-lactam, but not another. Failure to respond to antimicrobial therapy after 72 hours should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 5).When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent.

The recommended initial therapy for children with mild disease who have received antibiotics in the previous 4 to 6 weeks or children with moderate disease is high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day). Cefpodoxime proxetil, cefuroxime axetil, or cefdinir may be used if there is a penicillin allergy (eg, penicillin rash); in such instances, cefdinir is preferred because of high patient acceptance. TMP/SMX, azithromycin, clarithromycin, or erythromycin is recommended if the patient is β-lactam allergic, but these do not provide optimal coverage. Clindamycin is appropriate if S pneumoniae is identified as a pathogen. Ceftriaxone (parenteral, 50 mg/kg per day for 5 days) or combination therapy with adequate gram-positive and -negative coverage may also be considered. Examples of appropriate regimens of combination therapy include high-dose amoxicillin or clindamycin plus cefixime, or high-dose amoxicillin or clindamycin plus rifampin. The clinical effectiveness of ceftriaxone and these combinations for ABRS is unproven; the panel considers these reasonable therapeutic options based on spectrum of activity and on data extrapolated from acute otitis media studies. Rifampin should not be used as monotherapy, casually, or for longer than 10 to 14 days as resistance quickly develops to this agent. Failure to respond to antimicrobial therapy after 72 hours of therapy should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 5). When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent. Patients who have received effective antibiotic therapy and continue to be symptomatic may need further evaluation. A CT scan, fiberoptic endoscopy or sinus aspiration and culture may be necessary.