ABSTRACT
BACKGROUND: Non-typhoidal Salmonella (NTS) are a major cause of bloodstream infection (BSI) in sub-Saharan Africa. This study aimed to assess its longitudinal evolution as cause of BSI, its serotype distribution and its antibiotic resistance pattern in Kisantu, DR Congo. METHODS: As part of a national surveillance network, blood cultures were sampled in patients with suspected BSI admitted to Kisantu referral hospital from 2015-2017. Blood cultures were worked-up according to international standards. Results were compared to similar data from 2007 onwards. RESULTS: In 2015-2017, NTS (n = 896) represented the primary cause of BSI. NTS were isolated from 7.6% of 11,764 suspected and 65.4% of 1371 confirmed BSI. In children <5 years, NTS accounted for 9.6% of suspected BSI. These data were in line with data from previous surveillance periods, except for the proportion of confirmed BSI, which was lower in previous surveillance periods. Salmonella Typhimurium accounted for 63.1% of NTS BSI and Salmonella Enteritidis for 36.4%. Of all Salmonella Typhimurium, 36.9% did not express the O5-antigen (i.e. variant Copenhagen). O5-negative Salmonella Typhimurium were rare before 2013, but increased gradually from then onwards. Multidrug resistance was observed in 87.4% of 864 NTS isolates, decreased ciprofloxacin susceptibility in 7.3%, ceftriaxone resistance in 15.7% and azithromycin resistance in 14.9%. A total of 14.2% of NTS isolates, that were all Salmonella Typhimurium, were multidrug resistant and ceftriaxone and azithromycin co-resistant. These Salmonella isolates were called extensively drug resistant. Compared to previous surveillance periods, proportions of NTS isolates with resistance to ceftriaxone and azithromycin and decreased ciprofloxacin susceptibility increased. CONCLUSION: As in previous surveillance periods, NTS ranked first as the cause of BSI in children. The emergence of O5-negative Salmonella Typhimurium needs to be considered in the light of vaccine development. The high proportions of antibiotic resistance are worrisome.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteremia/epidemiology , Bacteremia/microbiology , Drug Resistance, Multiple, Bacterial/drug effects , Salmonella Infections/epidemiology , Salmonella Infections/microbiology , Salmonella typhimurium/drug effects , Salmonella typhimurium/isolation & purification , Adolescent , Adult , Azithromycin , Ceftriaxone , Child , Child, Preschool , Ciprofloxacin , Congo/epidemiology , Female , Humans , Infant , Infant, Newborn , Male , Microbial Sensitivity Tests , Salmonella/drug effects , Salmonella Infections/diagnosis , Salmonella enteritidis/drug effects , Serogroup , Typhoid Fever/drug therapy , Young AdultABSTRACT
BACKGROUND: This study gives an overview of a decade (2007-2017) of hospital-based Salmonella Typhi bloodstream infection (BSI) surveillance in the Democratic Republic of the Congo (DRC), at 4 main sampling sites. METHODS: Blood cultures were sampled in hospital-admitted patients with suspected BSI, according to standardized clinical indications. The results of the surveillance period 2015-2017 were compiled with those of previous surveillance periods (2007-2010 and 2011-2014). Whole genome sequencing of isolates with decreased ciprofloxacin susceptibility (DCS) was performed. RESULTS: Salmonella Typhi was isolated in 1.4% (531/37 388) and 10.3% (531/5177) of suspected and culture-confirmed BSI episodes, respectively. Salmonella Typhi ranked first among the BSI pathogens in adults (n = 220), but was mostly (n = 301 [56.7%]) isolated from children, of which 72.1% (217/301) and 31.6% (95/301) were <10 years and <5 years old, respectively. Multidrug resistance (MDR), DCS, and combined MDR/DCS were found in 38.3% (n = 180), 24.5% (n = 115), and 11.9% (n = 56) of 470 first isolates, respectively. MDR and DCS rates had increased since 2007, but remained stable during 2015-2017 with no geographical clustering at the province level. Most (91/93 [97.8%]) DCS isolates sequenced belonged to Genotyphi genotype 2.5.1, and gyr S83 was the most frequent DCS mutation (76/93 [81.7%]). Infections occurred perennially, but increased during the rainy season. CONCLUSIONS: Salmonella Typhi was a frequent cause of BSI in adults and children in DRC, with high rates of antibiotic resistance. Sustainable surveillance and implementation of vaccination are compelling.
