Ceftriaxone-Resistant Salmonella enterica Serotype Typhimurium Sequence Type 313 from Kenyan Patients Is Associated with the bla _CTX-M-15 Gene on a Novel IncHI2 Plasmid

Abstract

Multidrug-resistant bacteria pose a major challenge to the clinical management of infections in resource-poor settings. Although nontyphoidal Salmonella (NTS) bacteria cause predominantly enteric self-limiting illness in developed countries, NTS is responsible for a huge burden of life-threatening bloodstream infections in sub-Saharan Africa. Here, we characterized nine S. Typhimurium isolates from an outbreak involving patients who initially failed to respond to ceftriaxone treatment at a referral hospital in Kenya. These Salmonella enterica serotype Typhimurium isolates were resistant to ampicillin, chloramphenicol, cefuroxime, ceftriaxone, aztreonam, cefepime, sulfamethoxazole-trimethoprim, and cefpodoxime. Resistance to β-lactams, including to ceftriaxone, was associated with carriage of a combination of blaCTX-M-15, blaOXA-1, and blaTEM-1 genes. The genes encoding resistance to heavy-metal ions were borne on the novel IncHI2 plasmid pKST313, which also carried a pair of class 1 integrons. All nine isolates formed a single clade within S. Typhimurium ST313, the major clone of an ongoing invasive NTS epidemic in the region. This emerging ceftriaxone-resistant clone may pose a major challenge in the management of invasive NTS in sub-Saharan Africa.

Antimicrobial resistance pattern: a report of microbiological cultures at a tertiary hospital in Tanzania

“…In this study, a significant proportion of Salmonella species isolates were resistant to third generation cephalosporins. Similar findings have been observed in Europe from people who travelled from Asian countries [29, 30] and in Kenya [31]. However, these findings are in contrast with the previous study conducted three years ago in the same hospital which observed all Salmonella species to be susceptible to ceftriaxone [28]; suggesting the presence of emerging multidrug-resistant Salmonella species in Northwestern Tanzania.…”

Travelers Can Import Colistin-Resistant Enterobacteriaceae, Including Those Possessing the Plasmid-Mediated mcr-1 Gene

“…LN794248), pAPEC-O1-R from avian-pathogenic E. coli (GenBank accession no. DQ517526) (26,27), and pSA26 carrying ISApl1-mcr-1 from an ST68 E. coli strain (GenBank accession no. KU743384).…”

Emergence of Community-Acquired, Multidrug-Resistant Invasive NontyphoidalSalmonellaDisease in Rural Western Kenya, 2009–2013

“…The case fatality rate (CFR) is high, ranging from 21% to 36% in hospitalized children in East Africa, highest in infants [3,7,8]. Strains of NTS that are multidrug resistant to recommended first-line antibiotics, including chloramphenicol and ampicillin, have emerged in several African countries over the past 20 years [9,10]; however, resistance to ceftriaxone and ciprofloxacin had not been documented until recently [11,12]. A distinct phylogenetic lineage of Salmonella Typhimurium, sequence type 313 (ST313), is a significant cause of iNTS disease in Africa.…”