Genotypic and demographic characterization of invasive isolates of Salmonella Typhimurium in HIV co-infected patients in South Africa.
BACKGROUND
Non-typhoidal Salmonella are frequently food-borne zoonotic pathogens that may cause invasive disease in HIV-positive individuals.


METHODS
Invasive isolates (n = 652) of Salmonella Typhimurium from human patients in Gauteng Province of South Africa were investigated for the years 2006 and 2007. Bacteria were identified using standard microbiological techniques and serotyping was performed using commercially available antisera. Susceptibility testing to antimicrobial agents was determined by the E-test. Genotypic relatedness of isolates was investigated by pulsed-field gel electrophoresis analysis of digested genomic DNA.


RESULTS
Forty-five clusters of isolates were identified, of which four (clusters 3, 5, 6 and 11) were major clusters. Most isolates originated from hospital H2 and most were isolated from patients in the age range of 15 to 64 years. Ninety-three percent (213/230) of patients with a known HIV status were HIV-positive. Most isolates showed resistance to multiple antibiotics. The most commonly expressed antibiotic resistance profiles were ACSSuNa (14%; 75/555) and ACSSuTNa (13%; 72/555). Some evidence was found for nosocomial acquisition of isolates. Of the isolates from the major clusters 3, 5, 6, and 11, 33% (8/24), 6% (7/117), 4% (1/26) and 6% (3/52) were of nosocomial origin, respectively.


CONCLUSIONS
In South Africa, Salmonella Typhimurium remains a major opportunistic infection of predominantly HIV-positive patients. Clonally diverse strains that are resistant to multiple antibiotics may circulate in patients aged between 15 and 64 years over prolonged periods within the hospital environment, adding to the health care burden.
Enteric Diseases Reference Unit, National Institute for Communicable Diseases, Johannesburg, South Africa. karenk@nicd.ac.za
Karen H
KH
Keddy
Sarika
S
Dwarika
Penny
P
Crowther
Olga
O
Perovic
Jeanette
J
Wadula
Anwar
A
Hoosen
Arvinda
A
Sooka
Heather H
HH
Crewe-Brown
Anthony M
AM
Smith
D017088:AIDS-Related Opportunistic Infections / Q000453:epidemiology* / Q000382:microbiology; D000293:Adolescent; D000328:Adult; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D008875:Middle Aged; D017720:Molecular Epidemiology; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000145:classification* / Q000187:drug effects / Q000235:genetics; D013019:South Africa / Q000453:epidemiology
D004269:DNA, Bacterial