Background:
Shigella
spp. are primary pathogens of diarrhea in children worldwide. Emergence of resistance to fluoroquinolones and third-generation cephalosporins is crucial in the management of pediatric shigellosis. We determined the prevalence and the antibiotic resistance patterns of
Shigella
species isolated from pediatric patients in central Iran.
Materials and methods:
Pediatric diarrhea samples (n=230) were cultured on MacConkey and XLD agar media and in GN broth. Genus-specific PCR for
ipaH
was also used for detection directly from fecal specimens. Antibiotic resistance and the frequency of ESBL and AmpC genes were determined.
Results:
Out of the 230 samples, 19 (8.2%) cases of
Shigella
spp. were identified using culture. Twenty-six samples were positive by PCR (11.3%),
S. flexneri
(4/19; 21%) and
S. sonnei
(15/19; 78.9%) being the most detected. The highest antibiotic resistance rates were found for cotrimoxazole (19/19; 100%), ampicillin (16/19; 84.2%), cefixime (13/19; 68.4%) and ceftriaxone (12/19; 63.1%). Ten cases showed phenotypic ESBL presence and all these strains were positive for
bla
TEM
,
bla
CTX-M-1
, and
bla
CTX-M-15
. Three strains were AmpC positive, all of which harbored
bla
CMY-2
and two contained
bla
CIT
. Of the 19
Shigella
isolates 5 (26.3%), 2 (10.5%), and 1 (5.2%) were phenotypically resistant to nalidixic acid, ciprofloxacin, and norfloxacin, respectively. Class 1 integron was found in 18 (94.7%) isolates whereas class 2 integron was found in 19 (100%) strains.
Conclusion:
We found a considerable presence of
Shigella
species with elevated antibiotic resistance levels. In particular, the resistance to third-generation cephalosporins (ESBL) and ciprofloxacin must be taken seriously.