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Laboratory: Clinical Microbiology
Test Name:
Test Code: MRES
Clinical Information:
Test Indications:
Rhinosinusitis is a common medical condition.  Acute sinusitis is frequently caused by viruses, but bacterial infection may also occur.  Rhinosinusitis is typically managed symptomatically, with antimicrobials selected empirically for patients having clinical features suggestive of a bacterial infection.  Obtaining a specimen for bacterial culture is generally indicated only for patients with complicated infections or chronic disease.  This would include patients who are critically ill, immunocompromised, failing to respond (or deteriorating) despite multiple courses of empiric antimicrobial therapy, and those who have recurrent episodes of rhinosinusitis with clearing between bouts.  Obtaining a specimen would also be indicated for patients with suspected intracranial extension of infection.  Aerobic bacterial culture of an aseptically collected sinus aspirate can help in determining the pathogen(s) involved, and susceptibility testing performed on recovered pathogens can assist in choosing appropriate therapy.

A sinus aspirate for aerobic bacterial culture may be obtained from patients with complicated and/or chronic sinus infections to help guide therapy.  Swabs are not recommended.  The volume of specimen obtained using a swab as a collection device is suboptimal.  Do not sent a swab dipped in fluid obtained by sinus aspiration.
Clearly indicate on the microbiology requisition the specimen site, the specimen type, and the test(s) requested (e.g., bacterial culture - aerobic).  If other tests (e.g., bacterial culture - anaerobic, fungal culture) are also required based on the clinical presentation of the patient, these may be requested using the same requisition.
The laboratory will automatically perform a Gram stain when appropriate.  This does not need to be requested on the microbiology requisition.
Indicate the current antimicrobial therapy the patient is receiving on the requisition.

Patient Preparation Instructions:
The sample must be obtained using aseptic technique.  Follow protocols outlined by your healthcare facility for this sample type.
Accurate patient identification must be made prior to sample collection.  Patient identification should be done in accordance with site policy.
Samples and requisitions must be labeled/completed in accordance with the Shared Health Specimen Acceptance Policy.
Collection Devices:
Specimen Required: Sinus Aspirate - Fluid obtained by sinus aspiration, preferred minimum volume of at least 1 mL (Adult and Pediatric)
Reference Values:
A descriptive report will be sent.  The microbiology laboratory will culture for bacteria commonly implicated as a cause of sinus infections.  If any of the following pathogens are recovered, they will be identified and susceptibility results will be provided: Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, Streptococcus pneumoniae, Group A Streptococcus, Gram-negative bacilli.  Other isolates that are recovered will be listed without further work-up unless requested by the ordering professional.
For specimens from which no organisms are recovered, a report of "No organism isolated." will be issued by the microbiology laboratory.
The anticipated turn-around-time is two to four days from receipt of the specimen in the microbiology laboratory.
See Also:
More Information:
Specimen Handling:
Local: Transport as soon as possible, hold at room temperature.
Courier/local storage: ≤24 hours at room temperature.  Ensure samples that are being sent to a referral laboratory are packaged in accordance with Transport of Dangerous Goods recommendations for diagnostic samples.