The role of antibiotics in treating chronic rhinosinusitis.

Chronic rhinosinusitis (CRS) is an inflammatory disease of the paranasal sinuses that occurs in 1% to 5% of the U.S. It may significantly decrease quality of life. CRS is defined as an inflammatory condition of the paranasal sinuses that persists for 12 weeks or longer, despite medical management. Treatment is directed at enhancing mucociliary clearance, improving sinus drainage/outflow, eradicating local infection (with antibiotics) and inflammation (with steroids), and improving access for topical medications.

The microbiology of rhinosinusitis evolves through several stages. The early phase (acute) is generally caused by a virus that may be followed by an aerobic bacterial infection in 2% to 10% of patients. Aerobic (Staphylococcus aureus) and anaerobic (Prevotella and Fusobacteria) members of the oral flora emerge as predominant sinus cavity isolates.

Antimicrobials are one component of comprehensive medical and surgical management for this disorder. Antimicrobialtherapy of chronic rhinosinusitis should be adequate against the potential aerobic and anaerobic pathogens. Because most of these infections are polymicrobial and many include beta-lactamase producing aerobic and anaerobic organisms, amoxicillin-clavulanate is the first-line regimen for most patients. Clindamycin is adequate for penicillin-allergic individuals and is also generally appropriate for methicillin resistant Staphylococcus aureus treatment is administered for at least three weeks and may be extended for up to 10 weeks in refractory cases. Treatment can be guided by a culture preferably from the sinus cavity obtained from individuals who have not shown improvement or deteriorated despite therapy.

Chronic sinusitis is associated with higher risk of some head and neck cancers

Chronic rhino-sinusitis (CRS) may be involved in causing of certain head and neck cancers (HNCs), because of immunodeficiency or inflammation.

Several studies explored this issue. Tsou et al. who studied the Taiwan Longitudinal Health Insurance Database found a 3.55-fold increased risk of developing nasopharyngeal cancer (NPC) compared with individuals without rhinosinusitis associations between and CRS throughout a 3-year period. 

Riley et al. conducted a systematic review found a 2.7- fold increased risk of developing NPC in patients with CRS compared with patients without sinusitis.  

Beachler and Engels of the National Institutes of Health, Bethesda, Maryland evaluated the associations of chronic sinusitis with subsequent HNC, including NPC, human papillomavirus-related oropharyngeal cancer (HPV-OPC), and nasal cavity and paranasal sinus cancer (NCPSC), in an elderly US individuals. They evaluated 483 546 Medicare beneficiaries treated from 2004 through 2011. CRS was associated with increased risk of developing particularly NPC, HPV-OPC, and NCPSC within 1 year of the chronic sinusitis diagnosis. Overall, the risk of any HNC type was 8% higher in patients with CRS than individuals without chronic sinusitis.

Future studies are warranted to evaluate whether inflammation in patients with sinusitis contributes to emergence of cancer, especially in middle-aged adults.

Bacteriology of normal non-Inflamed sinuses and its significance

Attempts to recover organisms from non-inflamed tonsils were carried out for over seven decades. Some studies failed to find any microorganisms and others recovered them only in a portion of the cases. Only three studies identified bacteria in all sinus sample. 

Brook evaluated the microbiology of maxillary sinuses of 12 adults and found an average of 4 isolates/sinus  of aerobic and anaerobic bacteria. The predominant anaerobes were Prevotella  Fusobacterium ,and Peptostreptococcus spp., and Propionibactreium acnes. The most common aerobic bacteria were beta-hemolytic Streptococcoci, Staphylococcus aureus, Streptococcus pneumoniae, and Haemophillus parainfluenzae.

Ramakrishnanet al. collected middle meatus specimens from 28 individuals with no sinusitis. Bacterial colonization was assessed in these specimens using quantitative PCR and 16S rRNA pyrosequencing. All subjects were positive for bacterial colonization of the middle meatus. S. aureus, S. epidermidis and P. acnes were the most prevalent and abundant microorganisms detected. The authors found rich and diverse bacterial assemblages in all of the individuals, including opportunistic pathogens typically found in the nasopharynx.

Aurora et al. compared the microbiome and immune response from 30 patients with chronic rhino-sinusitis (CRS) and 12 healthy controls. The microbiome was analyzed by deep sequencing of the bacterial 16S and fungal 18S ribosomal RNA genes. Although quantitative increase in most bacterial and fungal species was observed in patients with CRS relative to controls, the microbiomes of patients with CRS were qualitatively similar to the controls. The predominate aerobic organisms were Cyanobacterium , Curtobacterium, and  Pseudomonas spp., and staphylococcus aureus. The commonest anaerobes were Propionbacterium, and Prevottela spp.

Patients with CRS had increased levels of the following cytokines: IL-4, IL-5, IL-8, and IL-13, along with increased levels of eosinophils and basophils in the lavage. Furthermore, peripheral blood leukocytes obtained from some patients with CRS responded to control lavage samples (ie, to commensals) to produce IL-5. In contrast, the same lavage sample evoked no IL-5 production in leukocytes from healthy controls. These results may explain why systemic steroid treatment provides relief for some patients with CRS.

Colonization of non-inflamed “normal “ sinus is possible because there is direct communication between the sinuses nasal cavity through the ostia which could enable organisms that reside in the nasopharynx to spread into the sinus. The presence of bacteria in the sinus can explain why following closure of the ostium, these organisms may become involved in the emerging inflammatory process.

The study by Aurora et al. that the host response or lack of response to the normal sinus flora may be key to the development of sinus inflammation. Modulation the sinus flora by topical antimicrobial and/or probiotic organisms that may interfere with the growth of pathogens may be used to prevent and treat sinus inflammation. Future studies that would explore these modalities are warranted. 

                                                      

                                                       CT of normal sinuses