Diagnosis of Whooping Cough in Switzerland: Differentiating Bordetella pertussis from Bordetella holmesii by Polymerase Chain Reaction

Abstract

Bordetella holmesii, an emerging pathogen, can be misidentified as Bordetella pertussis by routine polymerase chain reaction (PCR). In some reports, up to 29% of the patients diagnosed with pertussis have in fact B. holmesii infection and invasive, non-respiratory B. holmesii infections have been reported worldwide. This misdiagnosis undermines the knowledge of pertussis' epidemiology, and may lead to misconceptions on pertussis vaccine's efficacy. Recently, the number of whooping cough cases has increased significantly in several countries. The aim of this retrospective study was to determine whether B. holmesii was contributing to the increase in laboratory-confirmed cases of B. pertussis in Switzerland. A multiplex species-specific quantitative PCR assay was performed on 196 nasopharyngeal samples from Swiss patients with PCR-confirmed Bordetella infection (median age: 6 years-old, minimum 21 days-old, maximum 86 years-old), formerly diagnosed as Bordetella pertussis (IS481+). No B. holmesii (IS481+, IS1001−, hIS1001+) was identified. We discuss whether laboratories should implement specific PCR to recognize different Bordetella species. We conclude that in Switzerland B. holmesii seems to be circulating less than in neighboring countries and that specific diagnostic procedures are not necessary routinely. However, as the epidemiological situation may change rapidly, periodic reevaluation is suggested.

False-Positive Diagnostics of Bordetella Pertussis using IS481 PCR is Limited in Danish Patients

“…In other European countries, no B. holmesii DNA was detected in nasopharyngeal samples from Finnish (n=2804), Dutch (n=6903) and Belgian (n=1493) patients with pertussislike illness [3,11]. Moreover, in Swiss patients, no B. holmesii DNA was detected in 194 B. pertussis positive samples [2].…”

Characterization of two Achromobacter xylosoxidans isolates from patients with pertussis-like symptoms

“…However, different members of the genus Bordetella, such as Bordetella bronchiseptica and Bordetella parapertussis, which have been involved as etiological causes of this illness, possess closely related non-functional genes [22]. Other Bordetella genus members, such as B. holmesii, which account for 0.4%-29% of all diagnosed pertussis cases [23,24], do not present the either pertussis toxin gene or close-related genes, a characteristic which has been used in different studies to facilitate the differentiation between B. pertussis and B. holmesii [25] . Thus, pertussis toxin functionality, although relevant, is not essential for the presence of pertussis-like symptoms.…”

Clinical Experiences in Pertussis in a Population with High Vaccination Rate

“…It is the most ill-controlled vaccine-preventable bacterial disease in countries with high vaccination coverage, in which disease peaks occur every 3-5 years. Although routine childhood vaccination has produced a substantial reduction in the number of cases, it continues to cause high morbidity and mortality in children in countries across the globe [6][7][8]. In developed countries with pertussis vaccination coverage above 90-95%, such as the USA, the UK, several European countries, and Australia, pertussis has manifested in children under 6 months of age when they have not yet completed their primary series and in adolescents and adults who lost their immunity induced by the vaccine (the last booster is given at the age of 5 years).…”