Direct association between rainfall and non-typhoidal <i>Salmonella</i> bloodstream infections in hospital-admitted children in the Democratic Republic of Congo

Abstract Non-typhoidal Salmonella (NTS) ranks first among causes of bloodstream infection in children under five years old in the Democratic Republic of Congo and has a case fatality rate of 15%. Main host-associated risk factors are Plasmodium falciparum malaria, anemia and malnutrition. NTS transmission in sub-Saharan Africa is poorly understood. NTS bloodstream infections mostly occur during the rainy season, which may reflect seasonal variation in either environmental transmission or host susceptibility. We hypothesized that environment- and host-associated factors contribute independently to the seasonal variation in NTS bloodstream infections in children under five years old admitted to Kisantu referral hospital in 2013–2019. We used remotely sensed rainfall and temperature data as proxies for environmental factors and hospital data for host-associated factors. We used principal component analysis to disentangle the interrelated environment- and host-associated factors. With timeseries regression, we demonstrated a direct association between rainfall and NTS variation, independent of host-associated factors. While the latter explained 17.5% of NTS variation, rainfall explained an additional 9%. The direct association with rainfall points to environmental NTS transmission, which should be explored by environmental sampling studies. Environmental and climate change may increase NTS transmission directly or via host susceptibility, which highlights the importance of preventive public health interventions

Phylogeographical analysis of the dominant multidrug-resistant H58 clade of Salmonella Typhi identifies inter- and intracontinental transmission events.

The emergence of multidrug-resistant (MDR) typhoid is a major global health threat affecting many countries where the disease is endemic. Here whole-genome sequence analysis of 1,832 Salmonella enterica serovar Typhi (S. Typhi) identifies a single dominant MDR lineage, H58, that has emerged and spread throughout Asia and Africa over the last 30 years. Our analysis identifies numerous transmissions of H58, including multiple transfers from Asia to Africa and an ongoing, unrecognized MDR epidemic within Africa itself. Notably, our analysis indicates that H58 lineages are displacing antibiotic-sensitive isolates, transforming the global population structure of this pathogen. H58 isolates can harbor a complex MDR element residing either on transmissible IncHI1 plasmids or within multiple chromosomal integration sites. We also identify new mutations that define the H58 lineage. This phylogeographical analysis provides a framework to facilitate global management of MDR typhoid and is applicable to similar MDR lineages emerging in other bacterial species

Antimicrobial Resistance in Invasive Non-typhoid Salmonella from the Democratic Republic of the Congo: Emergence of Decreased Fluoroquinolone Susceptibility and Extended-spectrum Beta Lactamases

Background: Co-resistance against the first-line antibiotics ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole or multidrug resistance (MDR) is common in non typhoid Salmonella (NTS). Use of alternative antibiotics, such as fluoroquinolones or third generation cephalosporins is threatened by increasing resistance, but remains poorly documented in Central-Africa. Methodology/Principal findings: As part of a microbiological surveillance study in DR Congo, blood cultures were collected between 2007 and 2011. Isolated NTS were assessed for serotype and antimicrobial resistance including decreased ciprofloxacin susceptibility and extended-spectrum beta-lactamase (ESBL) production. In total, 233 NTS isolates (representing 23.6% of clinically significant organisms) were collected, mainly consisting of Salmonella Typhimurium (79%) and Salmonella Enteritidis (18%). The majority of NTS were isolated in the rainy season, and recovered from children ≤2 years old. MDR, decreased ciprofloxacin susceptibility, azithromycin and cefotaxime resistance were 80.7%, 4.3%, 3.0% and 2.1% respectively. ESBL production was noted in three (1.3%) isolates. Decreased ciprofloxacin susceptibility was associated with mutations in codon 87 of the gyrA gene, while ESBLs all belonged to the SHV-2a type. Conclusions/Significance: Presence of almost full MDR among NTS isolates from blood cultures in Central Africa was confirmed. Resistance to fluoroquinolones, azithromycin and third generation cephalosporins is still low, but emerging. Increased microbiological surveillance in DR Congo is crucial for adapted antibiotic therapy and the development of treatment guidelines. © 2013 Lunguya et al

Salmonella typhi in the Democratic Republic of the Congo: fluoroquinolone decreased susceptibility on the rise

BACKGROUND: Drug resistance of Salmonella enterica serovar Typhi (Salmonella Typhi) to first-line antibiotics is emerging in Central Africa. Although increased use of fluoroquinolones is associated with spread of resistance, Salmonella Typhi with decreased ciprofloxacin susceptibility (DCS) has rarely been reported in Central Africa. METHODOLOGY/PRINCIPAL FINDINGS: As part of a microbiological surveillance study in the Democratic Republic of the Congo (DR Congo), Salmonella Typhi isolates from bloodstream infections were collected prospectively between 2007 and 2011. The genetic relationship of the Salmonella Typhi isolates was assessed by pulsed-field gel electrophoresis (PFGE). The antimicrobial resistance profile of the isolates was determined and mutations associated with DCS were studied. In total, 201 Salmonella Typhi isolates were collected. More than half of the Salmonella Typhi isolates originated from children and young adults aged 5-19. Thirty different PFGE profiles were identified, with 72% of the isolates showing a single profile. Multidrug resistance, DCS and azithromycin resistance were 30.3%, 15.4% and 1.0%, respectively. DCS was associated with point mutations in the gyrA gene at codons 83 and 87. CONCLUSIONS/SIGNIFICANCE: Our study describes the first report of widespread multidrug resistance and DCS among Salmonella Typhi isolates from DR Congo. Our findings highlight the need for increased microbiological diagnosis and surveillance in DR Congo, being a prerequisite for rational use of antimicrobials and the development of standard treatment guidelines

Multidrug-resistant Salmonella enterica, Democratic Republic of the Congo [letter]

Not available</p

Presence of black and red colored test lines.

<p>Samples applied to both tests (<i>Salmonella</i> Ag Rapid Test, Creative diagnostics) contained <i>Salmonella</i> Enteritidis and both were scored as a positive test result. The test above shows a red colored control line and a black colored test line. The picture below shows a red colored control and test line.</p

Diagnostic accuracy of antigen-based immunochromatographic rapid diagnostic tests for the detection of <i>Salmonella</i> in blood culture broth

<div><p>Background</p><p>In low resource settings, <i>Salmonella</i> serovars frequently cause bloodstream infections. This study investigated the diagnostic performance of immunochromatographic rapid diagnostic tests (RDTs), which detect <i>Salmonella</i> antigens, when applied to stored grown blood culture broth.</p><p>Material/Methods</p><p>The SD Bioline One Step <i>Salmonella</i> Typhi Ag Rapid Detection Kit (Standard Diagnostics, Republic of Korea), marketed for the detection of <i>Salmonella enterica</i> serovar Typhi (<i>Salmonella</i> Typhi) in stool and the <i>Salmonella</i> Ag Rapid Test (Creative Diagnostics, USA), marketed for the detection of all <i>Salmonella</i> serotypes in stool, were selected for evaluation based on a pre-test evaluation of six RDT products. The limits of detection (LOD) for culture suspensions were established and the selected RDT products were assessed on 19 freshly grown spiked blood culture broth samples and 413 stored clinical blood culture broth samples, collected in Cambodia and the Democratic Republic of the Congo.</p><p>Results</p><p>The LOD of both products was established as 10⁷−10⁸ CFU/ml. When applied to clinical blood culture broth samples, the diagnostic sensitivity and specificity of the SD Bioline RDT were respectively 100% and 79.7% for the detection of <i>Salmonella</i> Typhi; 94.4% (65/69) of false-positive results were caused by <i>Salmonella</i> Enteritidis. When considering the combined detection of <i>Salmonella</i> Typhi and Enteritidis (both group D <i>Salmonella</i>), sensitivity and specificity were 97.9% and 98.5% respectively. For Creative Diagnostics, diagnostic sensitivity was 78.3% and specificity 91.0% for all <i>Salmonella</i> serotypes combined; 88.3% (53/60) of false negative results were caused by <i>Salmonella</i> Paratyphi A.</p><p>Conclusions</p><p>When applied to grown blood culture broths, the SD Bioline RDT had a good sensitivity and specificity for the detection of <i>Salmonella</i> Typhi and <i>Salmonella</i> Enteritidis. The Creative Diagnostics product had a moderate sensitivity and acceptable specificity for the detection of all <i>Salmonella</i> serovars combined and needs further optimization. A RDT that reliably detects <i>Salmonella</i> Paratyphi A is needed.</p></div