Purulent suffering from persistent or recurrent sinusitis.

Purulent Sinusitis can be caused when the ciliary clearance
mechanism of the sinus is decreased, or by means of an obstructed ostium. As a
result, secretions are retained, sinus pressure is reduced to negative, along
with a decrease in oxygen partial pressure as well. Sinus blockage and ciliary
dysfunction are aggravated by allergic, non-allergic and/or viral attacks that
produce an inflammatory response in the mucosa of the nasal- and sinus
cavities, which produces an environment suitable for the growth of pathogens.

Predisposing conditions such as cystic fibrosis, ciliary
dyskinesia, allergic inflammation, immuno-compromisation and ostiomeatal
obstruction (due to drug addiction and nasal polyps) should be seriously
considered in those patients suffering from persistent or recurrent sinusitis.
1

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Acute viral rhinosinusitis

The majority of rhinosinusitis cases/episodes are caused by
viral pathogens, the most common being Rhinovirus, along with Influenza and
Parainfluenza viruses, presenting in 3-15% of acute sinusitis cases. Other
viruses include Corona virus, Respiratory Syncytial virus, Adenovirus and
enterovirus of which 0.5-2% can progress to acute bacterial sinusitis 2,3.

Of all other risk factors, Viral infections of the upper
airway appear to be the most prevailing factor predisposing individuals to acute
bacterial sinusitis. Of these patients, approximately 90% will present with
sinus involvement, but a mere 5-10% of these individuals will have a bacterial
superinfection. (4,5)

 

Acute bacterial rhinosinusitis

There is a strong correlation between acute bacterial
rhinosinusitis and upper respiratory tract infection. The following factors
contribute to impaired mucocilliary clearance and bacterial infection:

·        
Allergy

·        
Trauma

·        
Neoplasms

·        
Granulomatous and inflammatory diseases

·        
Midline destructive disease

·        
Environmental factors

·        
Dental infection

·        
Anatomic variation

S aureus, S Pneumonia
and H Influenza are the most common pathogens
contributing to sinusitis. After receiving the 7-valent pneumococcal vaccine
introduced in the year 2000, Paediatric cases infected with S Pneumonia in the United States, experienced
a decline in recovery rate, but those infected with H Influenza experienced an
increase in recovery rate. 6,7 S pneumoniae penicillin-resistant strains’
rate of recovery was different after vaccination.

 

P aeruginosa(amongst other gram-negative rods) have been observed
in acute sinusitis of nosocomial origin. Patients with nasogastric- and/or
catheters in situ; immunocompromised persons; patients with HIV infection, and
those with cystic fibrosis were all frequent hosts of P aeruginosa.

 

Sinus aspirates have produced proof that 66% of patients
diagnosed with acute sinusitis are infected with at least one pathogenic bacterial
species, while 26-30% show multiple predominant bacterial species. Normal flora
are the bacteria most commonly involved in acute sinusitis and can become sinus
pathogens when sneezing, coughing and/or direct invasion deposit these
pathogens into the sinuses, if conditions optimize their growth.

 

Streptococcus
pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are the predominate pathogens cultured from maxillary
sinus aspirates. Streptococcus pyogenes,
Staphylococcus aureus and anaerobes are found in less than 10% of patients
with acute bacterial sinusitis, despite the sufficient environment available
for their growth. In Chronic Sinusitis, and sinusitis resulting from dental sources,
anaerobic organisms were frequently isolated.

 

S Pneumonia is a gram-positive, catalase-negative,
facultative anaerobic cocci. Almost to 20- 43 % of acute bacterial
rhinosinusitis episodes in adults result from this pathogen which is proving to
become increasingly resistant to various antibiotics including penicillin. Intermediate
penicillin-resistance to Macrolides, Clindamycin, Trimethoprim-Sulfamethoxazole
and Doxycycline, than the complete penicillin resistant counter-part 8.

 

In the past, H Influenza type B(gram-negative facultative
anaerobic bacilli ) was one of the leading causes of meningitis, but this all
changed after the vaccine became extensively administered. Non-typeable strains
of H influenzae have found to be the cause of 22-35% of acute bacterial
rhinosinusitis cases amongst adults. It develops antimicrobial resistance by
means of Beta-lactamase production. Aspirates from the paranasal sinuses showed
that 32.7% of these patients, were infected with beta-lactamase–positive for H
influenza; other reports suggest a rate of 44%.

 

M catarrhalis; a gram-negative, oxidase-positive, aerobic
diplococci; is responsible for 2-10% of acute bacterial rhinosinusitis cases in
adults. It is yet another organism utilising Beta-lactamase production as the
mechanism of antimicrobial resistance. Isolates from the paranasal sinus
revealed 98% to be beta-lactamase–positive for M catarrhalis.

 

S aureus accounts for 10% of episodes of acute bacterial
rhinosinusitis, and is now acknowledged to be an increasingly common pathogen
in acute bacterial rhinosinusitis. 9 While methicillin-resistant S aureus
(MRSA) still represents only a fraction of episodes of S aureus rhinosinusitis,
increasing occurrences drug-resistant S aureus may alter future pharmacological
recommendations. 10

 

Gram-negative organisms are the leading cause in nosocomial
sinusitis and include Pseudomonas
aeruginosa (15.9%), Escherichia coli
(7.6%), Proteus mirabilis (7.2%), Klebsiella pneumoniae, and Enterobacter species. They account for
60% of cases. Polymicrobial infection is observed in 25-100% of cultures. Other
pathogenic organisms found in nosocomial patients are gram-positive organisms
(31%) and fungi (8.5%).10

Acute invasive fungal rhinosinusitis

On the rare occasion, sinusitis is caused by fungal
infections. Fungal sinusitis (eg, allergic fungal sinusitis) may appear like a
lower airway disorder and allergic bronchopulmonary aspergillosis.

 

Fungal agents associated with sinusitis include Aspergillus and Alternaria species. Bipolaris
and Curvularia species are the most
common fungi seen in allergic fungal sinusitis, accounting respectively for 60%
and 20% in most studies.

 

CHRONIC
SINUSITIS(CRS)

The etiological studies of sinusitis are gradually moving
towards focussing on ostiomeatal obstruction; allergies, polyps; occult- and
subtle immunodeficiency states; as well as dental diseases. Microorganisms are
more often recognized as secondary invaders during Chronic Rhinosinutitus

Bacterial involvement

Bacterial involvement

The bacteria involved in CRS are not the same as those involved
in acute rhinosinusitis. The following bacteria have been observed in samples
obtained via endoscopy and/or sinus puncture in those individuals with chronic
sinusitis:

•             Staphylococcus
aureus (both methicillin-susceptible S aureus MSSA and methicillin-resistant
S aureus MRSA strains) 11

•             Coagulase-negative
staphylococci

•             H
influenzae

•             M
catarrhalis

•             S
pneumoniae

•             Streptococcus
intermedius

•             Pseudomonas
aeruginosa

•             Nocardia
species

•             Anaerobic
bacteria ( Peptostreptococcus, Prevotella, Porphyromonas, Bacteroides,
Fusobacterium species 12 )

The exact roles of these microbes in the aetiology of
chronic sinusitis is uncertain, as opposed to their well-defined role in Acute
Rhinosinusitis.  Various researchers
disagree on the microbial etiology of chronic sinusitis and much of the debate
has to do with varying research methodology. Studies that have used appropriate
methods for recovery of anaerobes have demonstrated their prominence in chronic
sinusitis (50-70%), while many studies that utilised other techniques, failed
to isolate them. 13 The variety growth of microbes in samples can also be attributed
to patients’ previous exposure to various broad-spectrum antibiotics.

 

During a study,
Jyonouchi et al inoculated Bacteriodes
Fragilis in rabbits by means of intra-sinus inoculation, thereby
successfully inducing Chronic sinusitis. Following the experiment, Immunoglobulin
(IgG)was then identified against
B.Fragilis organism in the infected animals. 14 IgG antibodies to other anaerobic
organisms have been isolated in human cases of chronic sinusitis as well15, thereby
reinforcing the suspected role of anaerobes in chronic sinusitis.

 

In most cases, CRS patients present with 1-6 different
pathogens per specimen, thereby confirming the condition as a result of mostly
polymicrobial infection12. Antibiotic administration; past vaccinations; and normal
flora suppressing the emergence of pathogenic species all influence the
microbial findings of chronic sinusitis.

 

In some cases, acute exacerbation of chronic sinusitis is
often caused by polymicrobial infections, with the predominant pathogens being
anaerobic bacteria. Aerobic bacteria usually associated with acute sinusitis
(eg, S pneumoniae, H influenzae,M catarrhalis) may emerge at a later stage of
the still emerge. 16

Gram-negative facultative and aerobic bacteria, such as P
aeruginosa, are mostly found in isolated post-endoscopic sinus surgery. 17

Fungal involvement

The following fungal pathogens have been reported in samples
obtained by means of endoscopy or sinus puncture in patients with chronic
sinusitis 18 :

·        
Aspergillus
species

·        
Cryptococcus
neoformans

·        
Candida
species

·        
Sporothrix
schenckii

·        
Alternaria
species

 

Risk factors

The following conditions and risk factors are predisposing
elements in the development of chronic sinusitis:

·        
Anatomic abnormalities of the ostiomeatal
complex (eg, septal deviation, concha bullosa, deviation of uncinate process,
Haller cells)

·        
Allergic rhinitis

·        
Aspirin sensitivity

·        
Asthma

·        
Nasal polyps

·        
Nonallergic rhinitis (eg, vasomotor rhinitis,
rhinitis medicamentosa, cocaine abuse)

·        
Defects in mucociliary clearance

·        
Nasotracheal intubation

·        
Nasogastric intubation

·        
Hormonal (eg, puberty, pregnancy, oral
contraception)

·        
Obstruction by tumor

·        
Immunologic disorders (eg, common variable
immunodeficiency, immunoglobulin A IgA deficiency, IgG subclass deficiency,
AIDS)

·        
Cystic fibrosis

·        
Primary ciliary dyskinesia, Kartagener syndrome

·        
Wegener granulomatosis

·        
Repeated viral upper respiratory tract
infections

·        
Smoking

·        
Environmental irritants and pollutants

·        
Gastroesophageal reflux disease (GERD). The
reflux of gastric contents may play a contributing role in some cases of CRS;
this relationship still needs to be better defined

·        
Periodontitis/significant dental disease

·        
Systemic diseases (ie, granulomatosis with
polyangiitis (Wegener granulomatosis), Churg-Strauss vasculitis, sarcoidosis)

·        
Yellow nail syndrome