Detection of unrelated Escherichia coli strains harboring genes of CTX-M-15, OXA-1, and AAC(6')-Ib-cr enzymes in a Tunisian hospital and characterization of their integrons and virulence factors.
Beta-lactamase characterization was carried out in a collection of 18 extended-spectrum beta-lactamase (ESBL)-positive Escherichia coli isolates from blood (n=8) and urine (n=10) obtained in 2007 in a tunisian Hospital. All isolates were clonally unrelated according to PFGE analysis. Seventeen strains presented the bla(CTX-M-)₁₅ gene associated with bla (OXA-)₁ and four of these strains with the (TEM-)₁(b) gene. The remaining ESBL-positive strain contained the bla (CTX-M-)₉ gene associated with the bla (OXA-)₁ and bla (TEM-)₁(b) genes. The orf477 sequence was identified downstream of the bla(CTX-M-)₁₅ gene in all 17 bla(CTX-M-)₁₅-positive strains, and ISEcp1 upstream in 15 of them (in eight cases truncated by IS26). The presence of a class 1 integron was demonstrated in 4 of the 18 ESBL-positive strains (22.2%), with dfrA17 + aadA5 (3 strains) and dfrA12 + orfF + aadA2 (1 strain) being the gene cassettes identified. The variant aac(6´)-Ib-cr was found in 15 bla(CTX-M-)₁₅-containing strains. All 18 ESBL-positive strains were typed as phylogroup B2 and contained at least three of the eight tested virulence genes (fimA, papGIII, hlyA, cnf1, papC, aer, eae and bfp). Six bla(CTX-M-)₁₅-positive strains were included in the serotype O25b and one of them was typed as ST131. Another bla(CTX-M-)₁₅-positive strain serotype-O25 was typed as ST638. The bla(CTX-M-)₁₅, aac(6')- Ib-cr, and aac(3)-II genes were co-transferred by conjugation from 7 donor strains to E. coli CSH26 recipient strain. The bla(CTXM-)₁₅ gene is prevalent among ESBL-positive E. coli strains in the studied hospital, that is frequently found together with aac(6')- Ib-cr, and aac(3)-II genes. The detection of the clone O25b-St131 in a bla(CTX-M-)₁₅ strain corroborates its worldwide dissemination.
Département de Biologie, Tunis, Tunisia.
A
A
Jouini
K
K
Ben Slama
L
L
Vinué
E
E
Ruiz
Y
Y
Saenz
S
S
Somalo
N
N
Klibi
M
M
Zarazaga
M
M
Ben Moussa
A
A
Boudabous
C
C
Torres
D001769:Blood / Q000382:microbiology; D003227:Conjugation, Genetic; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D032023:Integrons; D008826:Microbial Sensitivity Tests; D014416:Tunisia; D014556:Urine / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics*; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*
D037521:Virulence Factors; C473109:beta-lactamase CTX-M-15; C039404:beta-lactamase OXA-2; D001618:beta-Lactamases