A nontyphoidal Salmonella serovar domestication accompanying enhanced niche adaptation

Abstract

Invasive nontyphoidal Salmonella (iNTS) causes extraintestinal infections with ~15% case fatality in many countries. However, the mechanism by which iNTS emerged in China remains unaddressed. We conducted clinical investigations of iNTS infection with recurrent treatment failure, caused by underreported Salmonella enterica serovar Livingstone (SL). Genomic epidemiology demonstrated five clades in the SL population and suggested that the international animal feed trade was a likely vehicle for their introduction into China, as evidenced by multiple independent transmission incidents. Importantly, isolates from Clade-5-I-a/b, predominant in China, showed an invasive nature in mice, chicken and zebrafish infection models. The antimicrobial susceptibility testing revealed most isolates (> 96%) in China are multidrug-resistant (MDR). Overall, we offer exploiting genomics in uncovering international transmission led by the animal feed trade and highlight an emerging hypervirulent clade with increased resistance to frontline antibiotics.

A Cross-Sectional Study of Companion Animal-Derived Multidrug-Resistant Escherichia coli in Hangzhou, China

“…Therefore, we conducted antimicrobial susceptibility testing for all 276 isolates to select a representative isolate (an E. coli isolate that showed the broadest antimicrobial resistance profile) from each animal to calculate the prevalence of MDR E. coli among dogs and cats. The phenotypic antimicrobial susceptibility of these E. coli isolates was conducted using the microdilution method according to the Clinical & Laboratory Standards Institute (CLSI) guideline as previously described ( 52 , 53 ). In the assay, we tested bacterial susceptibility to eight antimicrobials, including amoxicillin/clavulanic acid (AMC, 0.5/0.25 to 64/32 mg/L), ceftriaxone (AXO, 0.015 to 8 mg/L), trimethoprim/sulfamethoxazole (SXT, 0.125/2.375 to 16/304 mg/L), nalidixic acid (NAL, 0.5 to 64 mg/L), ciprofloxacin (CIP, 0.015 to 8 mg/L), temocillin (TEM, 0.06 to 16 mg/L), colistin (CST, 0.06 to 8 mg/L), and imipenem (IMI, 0.015 to 8 mg/L) (Sangon, Shanghai, China).…”

Climate change affects the spread of typhoid pathogens

“…A study conducted in China unveiled a gradual reduction in typhoid fever incidence from 1984 to 2007, credited to enhancements in water quality and heightened vaccination rates. These interventions have also exhibited effectiveness in diverse global regions, including sub-Saharan Africa, South and Southeast Asia and Oceania (Li et al, 2022) However, achieving enhanced S. Typhi monitoring remains challenging, primarily due to the abundance of bacterial species in the environment, including surface water, and the considerable number of carrier populations. Consequently, employing sensitive detection techniques, such as real-time polymerase chain reaction or other in-field diagnostic approaches, is a feasible alternative.…”

Genomic investigation and nationwide tracking of pediatric invasive nontyphoidal Salmonella in China

“…The third‐generation Cephalosporin and Ciprofloxacin have now been recommended as first‐line drugs to treat severe and invasive NTS infections 6 . A previous study 7 has shown that the resistance rates to third‐generation Cephalosporin and Ciprofloxacin are relatively high among iNTS isolates in China. In our study, the resistance rates of iNTS isolates to Ceftriaxone (5.6%) and Ciprofloxacin (5.6%) were all lower than the above rates; this might be because most of the iNTS isolates (83.3%) exhibited pan‐susceptibility, which renders an effective treatment.…”