Biology subjects

Sunmonu, G. T.

Publications and source records attributed to Sunmonu, G. T..

4 recordsLinked to original sources

bioRxiv2024

Slow-growing Salmonella enterica Typhi mis-identified as Salmonella Gallinarum in Ibadan, Nigeria

Salmonella enterica serovar Typhi is endemic in Nigeria where S. Gallinarum is rarely reported. Probable S. Gallinarum was blood-cultured from three Ibadan patients within 10-days leading to suspicion of an outbreak. All three isolates were re-identified using VITEK-2, whole genome sequenced on Illumina and Oxford Nanopore platforms and confirmed as S. Typhi genotype 3.1.1. Two isolates from the same household had no single nucleotide polymorphisms, suggesting a point-source, but the third was an independent infection event. The isolates formed small colonies, were negative for motility by hanging drop method, and in Sulphide-Indole-Motility medium at 24h, but positive after 48h incubation. Hybrid genome assemblies revealed chromosomal fragment arrangements with imbalances on either side of ori and ter, which has been shown to slow S. Typhi growth. Suspected S. Gallinarum isolates in typhoid endemic areas should be evaluated biochemically and for motility after extended incubation, and verified by serological or molecular methods. Main contributions of the researchO_LIThis study demonstrates that slow-growing Salmonella Typhi can be mis-identified as S. Gallinarum in resource-limited endemic countries. C_LIO_LIExtended motility testing and confirmatory testing can avoid S. Gallinarum miss-calls. C_LIO_LIThe genetic basis for slow-growth may be chromosomal rearrangements at rrn operons, which are known to occur in S. Typhi C_LI

microbiology↗

bioRxiv2024

Genomic Analysis of Salmonella enterica from cattle, beef and humans in the Greater Tamale Metropolis of Ghana

Salmonella enterica is a bacterial foodborne pathogen notorious for infecting humans and animals. Proper control of Salmonella requires routine surveillance and interventions across the food-production chain. However, due to limited resources the dynamics and transmission of non-typhoidal Salmonella serotypes remain poorly understood in several African settings, including within Ghana. Here, we employed bacterial culture and whole genome sequencing (WGS) to investigate the prevalence, virulence and antimicrobial resistance determinants of Salmonella enterica isolates from beef, cattle blood and human patient stool in Greater Tamale Metropolis, Ghana. Enrichment and culture of the specimens yielded 62 isolates in total from beef (31), bovine blood (28) and human diarrhoeal specimens (3). We identified at least 15 STs and 18 different Salmonella serovars. The most common serovars detected were Poona (n=13), Montevideo (n=10) and Poano (n=7) with S. Montevideo being the most common from cattle blood. Thirty-two isolates belonged to novel sequence types (STs), with ST2609 (n=9) being most common. Four raw beef isolates harboured at least one gene conferring resistance to beta-lactam (blaTEM-1), chloramphenicol (catA), fosfomycin (fosA7), quinolone (qnrD1) or tetracycline (tet(A)). Eight isolates carried at an IncF, IncI and/orCol3M plasmid replicon. This study recovered Salmonella, often belonging to previously undocumented STs, at high frequencies from cattle and beef and demonstrated that isolates from human diarrhoeal patients are closely related to bovine isolates. The data highlight the need for broader and sustained surveillance and the urgent need for food safety interventions in Ghana.

microbiology↗

bioRxiv2024

Typhi Mykrobe: fast and accurate lineage identification and antimicrobial resistance genotyping directly from sequence reads for the typhoid fever agent Salmonella Typhi

BackgroundTyphoid fever results from systemic infection with Salmonella enterica serovar Typhi (Typhi) and causes 10 million illnesses annually. Disease control relies on prevention (water, sanitation, and hygiene interventions or vaccination) and effective antimicrobial treatment. Antimicrobial resistant (AMR) Typhi lineages have emerged and become established in many parts of the world. Knowledge of local pathogen populations informed by genomic surveillance, including of lineages (defined by the GenoTyphi scheme) and AMR determinants, is increasingly used to inform local treatment guidelines and to inform vaccination strategy. Current tools for genotyping Typhi require multiple read alignment or assembly steps and have not been validated for analysis of data generated with Oxford Nanopore Technologies (ONT) long-read sequencing devices. Here, we introduce Typhi Mykrobe, a command line software tool for rapid genotyping of Typhi lineages, AMR determinants, and plasmid replicons direct from sequencing reads. ResultsWe validated Typhi Mykrobe lineage genotyping by comparison with the current standard read mapping-based approach and demonstrated 99.8% concordance across nearly 13,000 genomes sequenced with Illumina platforms. For the few isolates with discordant calls, we show that Typhi Mykrobe results are better supported by the evidence from raw sequence read data than the results generated using the mapping-based approach. We also demonstrate 99.9% concordance for detection of AMR determinants compared with the current standard assembly-based approach, with similar results for plasmid marker detection. Typhi Mykrobe predicts clinical resistance categorisation (S/I/R) for eight drug classes, and we show strong agreement with phenotypic categorisations generated from reference laboratory minimum inhibitory concentration (MIC) data for n=1,572 Illumina-sequenced isolates (>99% agreement within one doubling dilution). We show strong concordance (>96% for genotype and >98% for AMR and plasmid) between calls made from ONT reads and those made from Illumina reads for isolates sequenced on both platforms (n =93 genomes). Typhi Mykrobe takes less than a minute per sample and is available at https://github.com/typhoidgenomics/genotyphi. ConclusionsTyphi Mykrobe provides rapid and sensitive genotyping of Typhi genomes direct from Illumina and ONT reads, although lower accuracy was observed for R9 ONT data. It demonstrated accurate assignment of GenoTyphi lineage, detection of AMR determinants and prediction of corresponding AMR phenotypes, and identification of plasmid replicons.

microbiology↗

bioRxiv2024

Genomic characterization of foodborne Salmonella enterica and Escherichia coli isolates from Saboba district and Bolgatanga Municipality Ghana

Salmonella enterica and Escherichia coli are well-known bacteria commonly associated with foodborne illnesses in humans and animals. Genomic characterization of these pathogens provides valuable insights into their evolution, virulence factors and resistance determinants. This study aimed to characterized previously isolated Salmonella (n = 14) and E. coli (n = 19) from milk, meat and its associated utensils in Ghana using whole-genome sequencing. Most of the Salmonella serovars (Fresno, Plymouth, Infantis, Give and Orleans) identified in this study are yet to be reported in Ghana. Most Salmonella isolates were pan-sensitive, but genes conferring resistance to fosfomycin (fosA7.2) and tetracycline (tet(A)) were detected in one and three isolates, respectively. Seven of the Salmonella isolates carry the IncI1-I(Gamma) plasmid replicon. Although antimicrobial resistance was not common among Salmonella strains, most (11/19) of the E. coli strains had at least one resistance gene, with nearly half (8/19) being multidrug resistant and carrying mobile elements. Three of the 19 E. coli strains belong to serovars commonly associated with enteroaggregative E. coli (EAEC) pathotype. While strains belonging to virulence-associated lineages lacked key plasmid-encoded virulence plasmids, several plasmid replicons were detected in most of the E. coli (14/19) strains. Food contaminated with these pathogens can serve as a vehicle for disease transmission, posing a significant public health risk and necessitating stringent food safety and hygiene practices to prevent outbreaks. Hence, there is need for continuous surveillance and preventive measures to stop the spread of foodborne pathogens and reduce the risk of associated illnesses in Ghana.

microbiology↗