Background:
Shigella
is a major cause of gastroenteritis especially in children. In developing countries, the incidence is
frequent and results are often life threatening. Changing epidemiology and emerging antibiotic resistance warrants
continuous monitoring of susceptibility. The present study highlights the changing epidemiology and drug resistance
patterns of
Shigella isolated at different hospitals of Nepal over a period of 13 years (Jan. 2003–Dec. 2015).
Methods: This study was carried out in 12 participating laboratories. Stool specimens received at respective
laboratories were processed for isolation and identification of
Shigella species and confirmed by serotyping at National
Public Health Laboratory. Antimicrobial resistance patterns were determined by Kirby Baeur disc diffusion test.
Results: A total of 332 isolates were identified as
Shigella species of which
Shigella flexneri
(50 %) was the predominant
serotype.
Shigella dysenteriae
,
Shigella sonnei
,
Shigella boydii
, and untypable
Shigella spp. respectively, accounted for 28.6,
27.54, 10.2, 4.5, and 6.6 % of the total number. Change in prevalent serotype is noted over the years.
S. dysenteriae was
the prevalent species in Nepal in 2003 and 2004, but since 2005,
S. flexneri remained prevalent. Majority of the isolates
were recovered from children aged 1–10 years and was statistically significant (
p = 0.023) compared to the other age
groups. High resistance among all
Shigella species to the first-line drugs like ampicillin (88 %), cotrimoxazole (76 %),
ciprofloxacin (39 %,) and nalidixic acid (80 %) was observed; 46.1 % of total isolates were multidrug resistant (MDR), and
the most common MDR profile was ampicillin, nalidixic acid, and co-trimoxazole. Prevalence of MDR increased
significantly in 2010 as compared to 2003. Only few
Shigella isolates were resistant to ceftriaxone.
Conclusions: The study revealed
S. flexneri as the predominant serogroup in Nepal. Children below 10 years were
more prone to the disease. Nalidixic acid, ampicillin, co-trimoxazole, and ciprofloxacin should not be used empirically
as the first-line drugs in treatment of shigellosis. Since the distribution of different species of
Shigella and their
antibiotic susceptibility profile may vary from one geographical location to another and may also change with
time, continuous local monitoring of resistance patterns is necessary for appropriate antimicrobial therapy.
