Improved Selective BIN Agar for a Better Rate of Yersinia pestis Isolation from Primary Clinical Specimens in Suspected Madagascar Plague Cases

Moshe Aftalion,Voahangy Andrianaivoarimanana,Shlomo Shmaya,Minoarisoa Rajerison,Orly Laskar,Ronit Aloni-Grinstein,David Gur,Alice Lantoniaina Iharisoa,Emanuelle Mamroud,Nathan A Ledeboer

doi:10.1128/jcm.00564-21

Moshe Aftalion, Voahangy Andrianaivoarimanana + Show 8 more

Open Access

https://doi.org/10.1128/jcm.00564-21

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Abstract

ABSTRACTAccording to the WHO, 75% of the world’s plague cases are found in Madagascar, with an average of 200 to 700 cases suspected annually (mainly bubonic plague). In 2017, a pneumonic plague epidemic of unusual proportions occurred, which raised several challenges for laboratory confirmation of cases, pointing to the need for the development of Yersinia pestis isolation procedures, especially those that can be performed in remote areas. As the WHO gold standard for plague diagnosis is bacterial culture, we sought to develop a simple method to prepare a highly selective medium, fit for use in remote areas where plague is endemic. The performance of the new medium, named improved BIN, was examined in terms of growth support and selectivity with spiked samples as well in isolating Y. pestis from clinical specimens, and it was compared to the results obtained with commercially available selective media. The preparation of the new medium is less complex and its performance was found to be superior to that of first-generation BIN medium. The growth support of the medium is higher, there is no batch diversity, and it maintains high selectivity properties. In 55 clinical specimens obtained from patients suspected to be infected with Y. pestis, approximately 20% more Y. pestis-positive isolates were identified by the improved BIN medium than were identified by commercially available selective media. The improved BIN medium is notably advantageous for the isolation of Y. pestis from clinical specimens obtained from plague patients, thus offering better surveillance tools and proper promotion of medical treatment to more patients suspected of being infected with Y. pestis.

Highlights

Yersinia pestis, the causative agent of the plague, is designated by the CDC as a tier 1 agent, mainly because of rapid progression and severity of the disease and the person-to-person transmission rate (1)
The variability in different batches of BHI agar (BHIA) used for BIN preparation (Fig. 1, first-generation BIN) together with the reduction in growth support compared to that obtained by nutrient-rich BHIA (7) were challenges to overcome in producing the improved medium
As prompt isolation and identification of Y. pestis from clinical specimens of potentially infected patients is crucial for proper life-saving treatment, we evaluated the beneficial isolation features of the improved BIN medium over those obtained by CIN, the standard Y. pestis isolation medium used in Madagascar

Summary

Introduction

The causative agent of the plague, is designated by the CDC as a tier 1 agent, mainly because of rapid progression and severity of the disease and the person-to-person transmission rate (1). Immunological, and biochemical approaches have been implemented for pathogen identification; these techniques are not feasible for use in remote locations around the world where plague is endemic. According to the World Health Organization, bacteriological culture with Y. pestis strain isolation remains the gold standard for a plague diagnosis (6). 7 17 improved, and simple protocol for producing selective BIN agar plates for the isolation of Y. pestis from various contaminated clinical and environmental samples. The improved BIN agar plates allow the isolation of clinical Y. pestis isolates in Madagascar that were not isolated by other means

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