A Survey of Antimicrobial Resistance Determinants in Category A Select Agents, Exempt Strains, and Near-Neighbor Species.

A dramatic increase in global antimicrobial resistance (AMR) has been well documented. Of particular concern is the dearth of information regarding the spectrum and prevalence of AMR within Category A Select Agents. Here, we performed a survey of horizontally and vertically transferred AMR determinants among Category A agents and their near neighbors. Microarrays provided broad spectrum screening of 127 Francisella spp., Yersinia spp., and Bacillus spp. strains for the presence/absence of 500+ AMR genes (or families of genes). Detecting a broad variety of AMR genes in each genus, microarray analysis also picked up the presence of an engineered plasmid in a Y. pestis strain. High resolution melt analysis (HRMA) was also used to assess the presence of quinolone resistance-associated mutations in 100 of these strains. Though HRMA was able to detect resistance-causing point mutations in B. anthracis strains, it was not capable of discriminating these point mutations from other nucleotide substitutions (e.g., arising from sequence differences in near neighbors). Though these technologies are well-established, to our knowledge, this is the largest survey of Category A agents and their near-neighbor species for genes covering multiple mechanisms of AMR.

Francisella spp. detected in Dermacentor ticks in Malaysian forest reserve areas.

Limited information is available on tropical ticks and tick-borne bacteria affecting the health of humans and animals in the Southeast Asia region. Francisella tularensis is a tick-borne bacterium which causes a potentially life-threatening disease known as tularemia. This study was conducted to determine the occurrence of Francisella spp. in questing ticks collected from Malaysian forest reserve areas. A total of 106 ticks (mainly Dermacentor and Haemaphysalis spp.) were examined for Francisella DNA using a Polymerase chain reaction (PCR) assay targeting the bacterial 16S rDNA. Francisella DNA was detected from 12 Dermacentor ticks. Sequence analysis of the amplified 16S rDNA sequences (1035 bp) show >99% identity with that of Francisella endosymbiont reported in a tick from Thailand. A dendrogram constructed based on the bacterial 16S rDNA shows that the Francisella spp. were distantly related to the pathogenic strains of F. tularensis. Three Francisella-positive ticks were identified as Dermacentor atrosignatus, based on sequence analysis of the tick mitochondrial 16S rRNA gene. Further screening of cattle and sheep ticks (Haemaphysalis bispinosa and Rhipicephalus microplus) and animal samples (cattle, sheep, and goats) did not yield any positive findings. Our findings provide the first molecular data on the occurrence of a Francisella strain with unknown pathogenicity in Dermacentor questing ticks in Malaysia.

First detection of Francisella-like endosymbionts in Hyalomma asiaticum asiaticum from China-Kazakhstan border / 中国人兽共患病学报

We conducted the detection the Francisella spp.nucle acid from Hyalomma asiaticum asiaticum that main distribution is on railway line area from China-Kazakhstan border.The free-living ticks were collected and then identified by morphological and molecular methods.After species identification,they were detected by PCR targeting 16S rRNA and sdhA of Francisella spp.The amplified products were sequenced and the sequences was analyzed by using the Blast.A phylogenetic tree was constructed using MEGA 6 software.A total of 243 fleas were identified as H.asiaticum asiaticum.Only 35 samples were detected for Francisella spp.positive and the positive rate was 14.4％.Sequence analysis showed that two different sequences (seql and seq2) and all belong to Francisella-like endosymbionts (FLEs).Phylogenetic analyses showed that two FLEs were belong to the same cladd.This is first detection of FLEs nucleic acid from H.asiaticum Railway line area of China-Kazakhstan border.