Aboratory Diagnosis of Pertussis

Abstract

Listen

Translate article

Background: The resurgence of pertussis highlights the importance of standardized, sensitive, and specific laboratory diagnoses, the lack of which is responsible for the large differences in pertussis notifications between countries. Accurate laboratory diagnosis is also important for distinguishing between the several etiologic agents of pertussis-like diseases, which involve both viruses and bacteria. If pertussis is diagnosed in a timely manner, antibiotic treatment of the patient can mitigate the symptoms and prevent transmission. The aim was to evaluate the relationship between reported and confirmed cases in patients treated at Zona Norte Children's Hospital, to analyze the methods used for the diagnosis of pertussis and to study the susceptibility of the isolates to erythromycin as the drug of choice to treatment of pertussis. Methods & Materials: A retrospective study of pertussis notifications and confirmations in patients treated from 1 January 2007 until 30 september 2017 was carried. All nasopharyngeal aspirate specimens for diagnosis of pertussis were assay by amplification of 481 insertion sequence and pertussis toxin by PCR and culture on Regan Lowe and Bordet Gengou agar. To all those strains that remained viable MICs to erythromycin were performed using the Etest method. Results: It was observed that of 1670 notifications only 6.8% (114) were confirmed. It is noted that in 2007, 2008,2011 and 2012 there was a marked increase in notifications and confirmations. The same was in the order of 8,1%; 14,6%, 16,1% and 7% respectively of the reported cases. 57.0% (65) of the diagnoses were performed by both methods (PCR + Culture); 37.7% (43) of the samples were diagnosed only by PCR and 5.3% (6) were positive only by culture. Erythromycin resistance was tested in 81.6% (58) of the recovered strains, all of which were sensitive. Conclusion: The increase in notifications and confirmations in 2007; 2008; 2011 and 2012 coincides with the detected epidemic situation in our province .PCR is most sensitive and should always be included to complement culture. This observation confirms the need for maintaining the ability to culture to analyze the antimicrobial drug resistance. Erythromycin can be a good drug for empirical treatment.