Abstract
This study was organized to investigate the prevalence, antibiotic and disinfectant resistance phenotypes and genotypes as well as plasmid profiles of
Shigella
species
isolated from raw cow milk and milk products in Egypt. Genotypic analysis was performed to determine the presence of
β
-lactamase encoding genes
(
bla
TEM
,
bla
CTX-M
,
bla
OXA-1
and
bla
SHV
),
tet
(A) and
qacE∆
. Forty-two (7%)
Shigella
isolates (
S. dysenteriae, S. flexneri, and S. sonnei
) were recovered, with
S. dysenteriae
as the predominant type. Antibiotic sensitivity tests showed that 71.4% of
Shigella
isolates were resistant to three or more antibiotic classes (multidrug-resistant). High
resistance rates were observed against tetracyclines (100%), ampicillin, amoxicillin-clavulanate (90.5%, each) and cefaclor (66.7%), while no resistance was detected against imipenem,
sulfamethoxazole/trimethoprim, and azithromycin. Disinfectant susceptibility test of
Shigella
isolates revealed resistance to phenolic compound (vanillic acid), while 85.7%
of the
Shigella
isolates were resistant to benzalkonium chloride. Uniplex PCR analysis declared the existence of
β
-lactamase encoding genes
(
bla
TEM
in all isolates and
bla
CTX-M
in 28.6% of isolates) and,
tet
(A) in all isolates and 85.7% of the isolates
were positive for
qacE∆1,
while all isolates were negative for
bla
OXA-1
and
bla
SHV
. All
Shigella
extended spectrum β-lactamases (ESBL) producers (12, 100%) were positive for the
bla
TEM
,
bla
CTX-M
, and
qacE∆1
genes.
Furthermore, plasmid profiling revealed seven distinct plasmid patterns (P1–P7), ranging from 1.26 to 33.61 kb, among all the
Shigella
strains;
S.
dysenteriae
exhibited the greatest variance. The co-transfer of β-lactamase genes (
bla
TEM
and
bla
CTX-M
) and
qacE∆1
genes was observed by conjugation from all ESBL producers to a recipient strain. These findings indicate the emergence of
Shigella
species in Egypt
that exhibited multi-resistance to either antibiotics (particularly ESBL producer strains) or disinfectants. Thus, the resistance of
Shigella
species should regularly be
monitored and appropriate measures should be taken to manage this problem.