Abstract:
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Background and purpose: Invasive nontyphoidal salmonellosis,
mostly caused by serovars Typhimurium and Enteritidis of
Salmonella enterica, has emerged as a major public health
problem in sub-Saharan Africa. The aim of this study was the
clinical and microbiological characterization of nontyphoidal
salmonellosis episodes affecting febrile children in Mozambique.
Patients and methods: The clinical records of the patients were
evaluated, and S. enterica isolates were characterized with
regard to serovar, phage type, antimicrobial resistance
(phenotype/responsible genes), plasmid content, pulsed-field gel
electrophoresis, and multilocus sequence typing. Results:
Fifteen S. Typhimurium and 21 S. Enteritidis isolates were
recovered from blood samples of 25 children, the majority with
underlying risk factors. With regard to phage typing, most
isolates were either untypeable or reacted but did not conform,
revealing that a number of previously unrecognized patterns are
circulating in Mozambique. Most isolates were
multidrug-resistant, with nearly all of the responsible genes
located on derivatives of serovar-specific virulence plasmids.
ST313 and ST11 were the predominant sequence types associated
with S. Typhimurium and S. Enteritidis, respectively, and the
uncommon ST1479 was also detected in S. Enteritidis. A distinct
XbaI fragment of ~350 kb was associated with pulsed-field gel
electrophoresis patterns of multidrug-resistant isolates of S.
Enteritidis. Nearly half of the children were coinfected with
both serovars, a fact expected to aggravate the disease and
hamper the treatment. However, particularly poor outcomes were
not observed for the coinfected patients. Conclusion: Mixed
Salmonella infections could frequently occur in febrile children
in Mozambique. Additional studies are required to determine
their actual impact and consequences, not only in this country,
but also in other African countries. |