Distribution of tetracycline resistance genes in genotypically related and unrelated multiresistant Acinetobacter baumannii strains from different European hospitals.
The presence of tetracycline (TET) resistance genes was investigated in 49 genotypically related and unrelated multidrug-resistant Acinetobacter baumannii (MDRAB) strains from European hospitals including representatives of pan-European clones I and II. Except for one strain, all MDRAB strains displayed resistance to tetracycline (MIC range of 16 to > 512 microg/ml) but were susceptible (MIC < 4 microg/ml) or exhibited intermediate resistance (MIC of 4-8 microg/ml) to minocycline (MIN). In 37 strains, either tet(A) or tet(B) was detected and one of these strains possessed both tet(A) and tet(M). In addition, all MDRAB strains contained the aspecific efflux gene adeB irrespectively of whether they harbored tet genes or not. Repetitive DNA element (rep)-PCR fingerprinting using the (GTG)5 primer [(GTG)5-PCR] revealed that strains previously assigned to pan-European clones I and II were grouped into two separate clusters. In addition, these clusters also contained strains that had not been typed previously, indicating that (GTG)5-PCR is a valuable method for recognizing putative new members of MDRAB clones. Most, but not all, members of clones I and II were linked to the presence of either tet(A) or tet(B) and displayed different levels of TET resistance with MIC values of 32 to > 512 microg/ml and > 512 microg/ml, respectively. Of these two genes only tet(B) encodes an efflux of both TET and MIN, which was reflected by the relatively high MIC values for MIN (4 microg/ml) shown by the majority of the tet(B)-carrying clone II strains as opposed to the low MIC values for MIN (< 1 microg/ml) displayed by most tet(A)-containing clone I strains. Collectively, our phenotypic and genotypic resistance data support the therapeutic evaluation of second-generation tetracyclines like MIN as promising agents for treating MDRAB infections.
Huys
Geert
G
Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, Ghent, Belgium. geert.huys@UGent.be
Cnockaert
Margo
M
Vaneechoutte
Mario
M
Woodford
Neil
N
Nemec
Alexandr
A
Dijkshoorn
Lenie
L
Swings
Jean
J
D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017920:Antiporters / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology*; D013753:Tetracycline Resistance / Q000235:genetics*
C445684:AdeB protein, Acinetobacter baumannii; D000900:Anti-Bacterial Agents; D017920:Antiporters; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins; C079051:tetA protein, Bacteria; D004262:DNA Restriction Enzymes; D013752:Tetracycline; D008911:Minocycline