Abstract:
ABSTRACT
In Africa, non-typhoid Salmonella (NTS) infections are common and self
limiting, however, they present life-threatening complications especially in
children and adults who are immunosuppressed. In these individuals,
antimicrobial treatment maybe required. The increasing antimicrobial resistance
in NTS contributes to its spread and threatens the use of commonly available and
clinically important antimicrobial agents. Over the last decade or more, resistance
to commonly available antimicrobials including ampicillin, cotrimoxazole,
streptomycin, chloramphenicol and tetracycline rose remarkably.
This study used 116 culture confirmed isolates of NTS from bacteremic
patients admitted in the medical ward of Aga Khan University Hospital, examined
over a 12-month period, 2007. NTS isolates were identified by culture methods,
and confirmed by slide agglutination tests according to Kauffmann-White scheme
utilizing the Salmonella poly-O, H1 and H2 agglutination antisera. Antimicrobial
susceptibility tests were done using the disk diffusion method. Conjugation
experiment was done to determine genetic basis of resistance and polymerase
chain reaction was done to detect presence of genes encoding the quinolone
resistance-determining region.
Resistant isolates contained plasmids of various sizes. Some isolates had
only one plasmid while others had up to five plasmids of varying sizes. The large
plasmids extracted ranged from 90 kb to slightly over 147 kb in size; while the
small size plasmids ranged from about 2.1 kb to 5.6 kb. The isolates that had
16
plasmids all had a 43.5kb plasmid size. Some isolates in Salmonella serotype group
B and group C3 had the largest plasmid size, slightly above 147 kb. The gyrB, parC
and parE had 500bp products.
The resistance to ampicillin, tetracycline, cotrimoxazole and
chloramphenicol was low, but there was an increase in quinolone and
fluoroquinolone antimicrobials.
The study concluded that, there is a decrease in resistance to conventional
drugs of choice for treatment of invasive NTS in Kenya, but there is an increase in
resistance to quinolone and flouroquinolone; and a new resistance to cefotaxime
and ceftriaxone.
