Diagnostic Accuracy of Nasopharyngeal Swab Cultures in Children Less Than Five Years with Chronic Wet Cough

Abstract

Background: It is necessary to find a non-invasive and accurate procedure to predict persistent bacterial bronchitis (PBB) causative organisms and guide antibiotic therapy. The study objective was to compare the diagnostic accuracy of nasopharyngeal swab cultures with bronchoalveolar lavage (BAL) cultures in children with PBB. Methods: Nasopharyngeal swab and BAL fluid specimens were collected and cultured for bacterial pathogens prospectively from less than five-year-old children undergoing flexible bronchoscopy for chronic wet cough. Results: Of the 59 children included in the study, 26 (44.1%) patients had a positive BAL bacterial culture with neutrophilic inflammation. Prevalence of positive cultures for any of the four common respiratory pathogens implicated in PBB (Moraxella catarrhalis, Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae) was significantly higher (p = 0.001) in NP swabs compared to BAL fluids (86.4% and 44.1% of PBB cases, respectively). NP swab cultures for any of the four main bacterial pathogens had 85% (95% CI: 65–96%) and 48% (95% CI: 31–66%) sensitivity and specificity of detecting PBB, respectively. Positive and negative predictive values were 56% (95% CI: 47–65%) and 80% (95% CI: 60–91%), respectively. In conclusion, in children less than 5 years of age with chronic wet cough (PBB-clinical), a negative NP swab result reduces the likelihood of lower airway infection; however, a positive NP swab does not accurately predict the presence of lower airway pathogens. Flexible bronchoscopy should be considered in those with recurrent PBB-clinical or with clinical pointers of central airway anomalies.

Validation of nasal tracheal aspiration in children with lung disease

“…Previous literature has described several non-invasive “upper airway sampling” methods to obtain information about lower airway tract infection. These methods include oropharyngeal swab, nasopharyngeal swab, nasopharyngeal aspiration, nasotracheal aspiration, oropharyngeal suction, induced sputum, all of which have all been compared to the gold standard bronchoalveolar lavage (BAL) [ 2 – 9 ]. Sampling is performed by inserting the swab into either (1) the nasopharynx through a single nostril or (2) the oropharynx through the mouth until it reaches the posterior pharynx where a gentle rotation is performed for 2–3 s following withdrawal of the swab [ 2 , 3 ].…”

“…These methods include oropharyngeal swab, nasopharyngeal swab, nasopharyngeal aspiration, nasotracheal aspiration, oropharyngeal suction, induced sputum, all of which have all been compared to the gold standard bronchoalveolar lavage (BAL) [ 2 – 9 ]. Sampling is performed by inserting the swab into either (1) the nasopharynx through a single nostril or (2) the oropharynx through the mouth until it reaches the posterior pharynx where a gentle rotation is performed for 2–3 s following withdrawal of the swab [ 2 , 3 ]. Nasopharyngeal aspiration (NPA), nasotracheal aspiration (NTA) or oropharyngeal suction (OPS) is performed by inserting a catheter into either (1) the nostril or (2) the mouth to reach into the posterior pharynx or to the proximity of the open trachea, withdrawing the catheter while applying a gentle suction with an electric suction device [ 4 – 6 ].…”

“…followed by oropharyngeal suction by catheter inserted into the mouth to reach into the posterior pharynx or to the proximity of the open trachea, withdrawing the catheter while applying a gentle suction with an electric suction device [ 7 – 9 ]. The validity of these methods has been investigated in various settings with different results [ 2 – 9 ].…”

“…In 1995, Avital et al in a small study sample concluded that NTA may be helpful in the diagnosis and treatment of recurrent or chronic pulmonary infection [ 6 ]. However, the following studies (Asseri et al [ 2 ], Hare et al [ 3 ], Lu et al [ 5 ]) concluded that a negative swab and/or negative NPA/NTA result reduces the likelihood of lower airway infection. A positive sample, however, does not accurately predict the presence of lower airway pathogens [ 2 , 3 , 5 ].…”

“…However, the following studies (Asseri et al [ 2 ], Hare et al [ 3 ], Lu et al [ 5 ]) concluded that a negative swab and/or negative NPA/NTA result reduces the likelihood of lower airway infection. A positive sample, however, does not accurately predict the presence of lower airway pathogens [ 2 , 3 , 5 ]. All previous studies have attempted to validate the above-mentioned methods by comparing with BAL in intubated patients.…”