Chest Infections |

Reliability of the Viral PCR: A Clinical Perspective FREE TO VIEW

Johan Barretto, MD; Ibrahim Faruqi, MD; Yasser Samra, DO; Abbas Shahmohammadi, MD
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UFL, Gainesville, FL

Chest. 2015;148(4_MeetingAbstracts):114A. doi:10.1378/chest.2278145
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SESSION TITLE: Chest Infections Posters I

SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM

PURPOSE: In clinical practice the respiratory viral pcr is now being used with increasing frequency, its role is to diagnose, influence treatment and also to determine isolation status. We noticed patients with a negative nasopharyngeal swab on admission only to be found to be positive on other forms of respiratory secretion sampling or repeat nasopharyngeal swab testing. The purpose of this study was to assess the likelihood of a patient having contradictory (both a positive and negative) viral pcr testing within a 7 day period.

METHODS: A chart review of the electronic medical record was performed over a 3 month period, the results of respiratory viral pcr testing was evaluated. Patients were deemed to have a either a positive or negative nasopharyngeal swab or a positive or negative lower respiratory tract viral pcr. The following parameters were grouped as lower respiratory tract: Bronchial washing, Bronchial lavage, Bronchial Biopsy, Bronchial Wash, Bronchoalveolar lavage, Endotracheal, Endotracheal tube, Laryngotracheal, Larynx, Lobe, right upper, Lower Wedge, Lung, Lung right lower lobe, Sputum, Throat, Trachea, Transtracheal aspirate, Upper Wedge.

RESULTS: Preliminary data has indicated that of the 436 patients who had a respiratory viral pcr study performed at least 32 had conflicting (one positive and one negative) results within a 7 day period. Of the 32 patients with conflicting results 18 (56%) had at least one negative nasopharyngeal respiratory viral study which was contradicted by a positive study within 7 days.

CONCLUSIONS: The nasopharyngeal swab in clinical practice is of variable reliability. A nasopharyngeal swab is rather uncomfortable for both patients and staff. It is entirely possible that healthcare staff inadvertently perform the viral pcr in the same manner they perform another much more common swab, the MRSA nare swab. The lack of cellularity at the nare is a likely reason for lower than expected yield.

CLINICAL IMPLICATIONS: The nasopharyngeal swab which is being utilized with increasing frequency should be used as tool to supplement rather than supplant the clinicians judgment. The discontinuation of droplet isolation should not be protocolized to a negative nasopharyngeal swab, but should instead be a clinical decision, especially given the implication of placing a patient with an active respiratory virus in close proximity to patients and staff.

DISCLOSURE: The following authors have nothing to disclose: Johan Barretto, Ibrahim Faruqi, Yasser Samra, Abbas Shahmohammadi

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