LITERATURE UPDATE
Bordetella pertussis infection: testing for the re-emergence of whooping cough
Despite the high vaccination coverage in developed countries, Bordetella pertussis infection is considered a re-emerging disease that is underreported and underdiagnosed. Here, Pathology in Practice Science Editor Brian Nation compiles a selection of research interest.
Microfluidic point-of-care testing for the detection of Bordetella pertussis: A mini-review Yılmaz Çolak Ç. Diagn Microbiol Infect Dis. 2024 Jun; 109 (2): 116239. doi: 10.1016/j.diagmicrobio.2024.116239.
Bordetella pertussis is a bacterial pathogen responsible for pertussis, which is a highly contagious respiratory disease. Despite the relatively high vaccination coverage, pertussis is considered a re-emerging disease that necessitates enhanced strategies for identification, prevention and control. The diagnosis of pertussis typically involves a combination of clinical evaluation, laboratory tests, and a thorough medical history. The current technologies for pertussis diagnosis have their own limitations, prompting the exploration of alternative diagnostic approaches that offer enhanced sensitivity, specificity and speed. Microfluidic technology is considered
a very promising tool for the diagnosis of infectious diseases, as it offers more rapid and accurate outputs. It allows point-of-care testing (POCT) at or near the patient site, which can be critical, especially for an outbreak or pandemic. In this paper, current pertussis diagnostic tools with their limitations are discussed, and microfluidic approaches for the diagnosis of pertussis are highlighted.
Pertussis toxin IgA testing over- diagnoses recent pertussis infection May ML, Evans J, Holgate T, Doi SA, Ross P, Robson JM. Pathology. 2017 Dec; 49 (7): 770–5. doi: 10.1016/
j.pathol.2017.08.005.
The importance of pertussis toxin (PT) IgA testing in the diagnosis of recent pertussis infection remains unclear. The
contribution of PT IgA to the diagnosis of recent pertussis was reviewed in two separate analyses. Firstly, an evaluation of two new automated assays (DiaSorin Liaison [DL], Italy) for PT IgG and PT IgA provided an opportunity to assess the contribution of PT IgA testing to PT IgG results. Secondly, a retrospective review of results from the PT IgA assay currently in use (Sullivan Nicolaides Pathology [SNP] PT IgA] was performed from 2013 to 2015 (n=63,474). For both the DL and SNP assays, the combination of PT IgG and PT IgA resulted in reduced specificity as compared to PT IgG results alone. For DL assays, an algorithm restricting DL PT IgA testing to samples with equivocal PT IgG results,
demonstrated superior specificity to routinely testing both assays. The retrospective review indicated that only a minority of patients had an SNP PT IgA response without an accompanying rise in SNP PT IgG. There was also evidence of an age-related increase in the prevalence of isolated positive SNP PT IgA results, which did not appear to be associated with recent pertussis infection.
In general, PT IgA appears to contribute little diagnostic value to an accurate PT IgG assay in a community- based, Australian population. Reflex testing of PT IgA in the context of equivocal PT IgG results may be worthwhile if laboratory workflow permits.
Medical illustration of drug-resistant Bordetella pertussis bacteria.
WWW.PATHOLOGYINPRACTICE.COM AUGUST 2024 47
Dan Higgins; CDC/CDC-Antibiotic Resistance Coordination and Strategy Unit
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