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.
Highlights
Multidrug-resistant bacteria pose a major challenge to the clinical management of infections in resource-poor settings
Typhimurium strains have been reported previously in other countries in Europe [16], Asia [17, 18], and the United States [19, 20], few data are available on this phenotype in sub-Saharan Africa
Typhimurium ST313 is the dominant pathovariant of invasive nontyphoidal Salmonella (NTS) disease in immunocompromised adults and children in sub-Saharan Africa, and it is noteworthy that the acquisition of this new plasmid has occurred within this clonal population
Summary
Multidrug-resistant bacteria pose a major challenge to the clinical management of infections in resource-poor settings. 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. A significant burden of iNTS cases are found in sub-Saharan Africa [3, 4], caused mainly by Salmonella enterica serotypes Typhimurium and Enteritidis [5, 6]. Infections with these serotypes are associated with poor outcomes, including a high rate of mortality, especially among children less than 5 years of age and in HIV-infected adults who have low CD4 T-lymphocyte counts [7, 8]. Typhimurium isolates from patients seeking treatment in a tertiary-care and teaching hospital in Nairobi, Kenya, that exhibited resistance to ceftriaxone with or without combined resistance to fluoroquinolones
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