First study on characterization of virulence and antibiotic resistance genes in verotoxigenic and enterotoxigenic E. coli isolated from raw milk and unpasteurized traditional cheeses in Romania

• Published in: Folia microbiologica Vol. 62; no. 2; pp. 145 - 150
• Main Authors: Tabaran, Alexandra, Mihaiu, Marian, Tăbăran, Flaviu, Colobatiu, Liora, Reget, Oana, Borzan, Mihai Marian, Dan, Sorin Daniel
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-03-2017; Springer Nature B.V
• Subjects: Animals; Antibiotic resistance; Antibiotics; Applied Microbiology; Biomedical and Life Sciences; Cattle; Cattle Diseases - microbiology; Cattle Diseases - transmission; Cheese; Cheese - microbiology; Dairy products; Drug resistance; Drug Resistance, Bacterial - genetics; E coli; Enterotoxigenic Escherichia coli - drug effects; Enterotoxigenic Escherichia coli - genetics; Enterotoxigenic Escherichia coli - isolation & purification; Enterotoxigenic Escherichia coli - pathogenicity; Environmental Engineering/Biotechnology; Escherichia coli; Escherichia coli Infections - microbiology; Escherichia coli Infections - transmission; Escherichia coli Infections - veterinary; Food science; Gene Expression; Genes; Genes, Bacterial - genetics; Genotype; Immunology; International standards; Life Sciences; Microbial Sensitivity Tests; Microbiology; Milk; Milk - microbiology; Polymerase Chain Reaction; Romania; Shiga-Toxigenic Escherichia coli - drug effects; Shiga-Toxigenic Escherichia coli - genetics; Shiga-Toxigenic Escherichia coli - isolation & purification; Shiga-Toxigenic Escherichia coli - pathogenicity; Toxicity; Virulence; Virulence Factors - genetics; Virulence Factors - metabolism; tetA; Tetracycline Resistance; Antibiotic Resistance Gene; Traditional Cheese; Resistance Gene
• ISSN: 0015-5632; 1874-9356
• DOI: 10.1007/s12223-016-0481-8

The study focused on the incidence of enterotoxigenic
Escherichia coli
(ETEC) and verotoxigenic
E
.
coli
(VTEC) in raw milk and traditional dairy cheeses marketed in Romania, characterizing the virulence and antibiotic resistance genes of these isolates. One hundred and twenty samples of raw milk and 80 samples of unpasteurized telemy cheese were collected and cultured according to the international standard protocol. All the characteristic
E
.
coli
cultures were analyzed for the presence of
STa
,
STb
,
LT
,
stx1
, and
stx2
toxicity genes. The ETEC/VTEC strains were tested for the presence of antibiotic resistance genes, such as
aadA1
,
tetA
,
tetB
,
tetC
,
tetG
,
dfrA1
,
qnrA
,
aaC
,
sul1
,
bla
SHV
,
bla
CMY
,
bla
TEM
, and
ere(A)
, using PCR. The results showed that 27 samples (18.62%) were positive for one of the virulence genes investigated. 48.1% (
n
 = 13) tested positive at the genes encoding for tetracycline resistance,
tetA
being the most prevalent one (61.5%;
n
 = 8). A high percent (33.3%;
n
 = 9) revealed the beta-lactamase (
bla
TEM
) resistance gene, and none of the samples tested positive for
bla
CMY
and
bla
SHV
genes. The genes responsible for resistance to sulfonamides (
sul1
) and trimethoprim (
dfrA1
) were detected in rates of 14.8% (
n
 = 4) and 7.4% (
n
 = 2), respectively.
E
.
coli
is highly prevalent in raw milk and unpasteurized cheeses marketed in Romania. These strains might represent an important reservoir of resistance genes which can easily spread into other European countries, given the unique market.