Distribution of tetracycline and streptomycin resistance genes and class 1 integrons in Enterobacteriaceae isolated from dairy and nondairy farm soils.
The prevalence of selected tetracycline and streptomycin resistance genes and class 1 integrons in Enterobacteriaceae (n = 80) isolated from dairy farm soil and nondairy soils was evaluated. Among 56 bacteria isolated from dairy farm soils, 36 (64.3%) were resistant to tetracycline, and 17 (30.4%) were resistant to streptomycin. Lower frequencies of tetracycline (9 of 24 or 37.5%) and streptomycin (1 of 24 or 4.2%) resistance were observed in bacteria isolated from nondairy soils. Bacteria (n = 56) isolated from dairy farm soil had a higher frequency of tetracycline resistance genes including tetM (28.6%), tetA (21.4%), tetW (8.9%), tetB (5.4%), tetS (5.4%), tetG (3.6%), and tetO (1.8%). Among 24 bacteria isolated from nondairy soils, four isolates carried tetM, tetO, tetS, and tetW in different combinations; whereas tetA, tetB, and tetG were not detected. Similarly, a higher prevalence of streptomycin resistance genes including strA (12.5%), strB (12.5%), ant(3'') (12.5), aph(6)-1c (12.5%), aph(3'') (10.8%), and addA (5.4%) was detected in bacteria isolated from dairy farm soils than in nondairy soils. None of the nondairy soil isolates carried aadA gene. Other tetracycline (tetC, tetD, tetE, tetK, tetL, tetQ, and tetT) and streptomycin (aph(6)-1c and ant(6)) resistance genes were not detected in both dairy and nondairy soil isolates. A higher distribution of multiple resistance genes was observed in bacteria isolated from dairy farm soil than in nondairy soil. Among 36 tetracycline- and 17 streptomycin-resistant isolates from dairy farm soils, 11 (30.6%) and 9 (52.9%) isolates carried multiple resistance genes encoding resistance to tetracycline and streptomycin, respectively, which was higher than in bacteria isolated from nondairy soils. One strain each of Citrobacter freundii and C. youngae isolated from dairy farm soils carried class 1 integrons with different inserted gene cassettes. Results of this small study suggest that the presence of multiple resistance genes and class 1 integrons in Enterobacteriaceae in dairy farm soil may act as a reservoir of antimicrobial resistance genes and could play a role in the dissemination of these antimicrobial resistance genes to other commensal and indigenous microbial communities in soil. However, additional longer-term studies conducted in more locations are needed to validate this hypothesis.
Srinivasan
Velusamy
V
Department of Animal Science and the Food Safety Center of Excellence, The University of Tennessee, Knoxville, TN 37996, USA.
Nam
Hyang-Mi
HM
Sawant
Ashish A
AA
Headrick
Susan I
SI
Nguyen
Lien T
LT
Oliver
Stephen P
SP
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial / Q000187:drug effects; D032023:Integrons; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012988:Soil Microbiology; D013307:Streptomycin / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D013752:Tetracycline; D013307:Streptomycin
Appl Environ Microbiol. 2004 Apr;70(4):2503-7
15066850
FEMS Microbiol Ecol. 2002 Nov 1;42(2):277-88
19709288
Appl Environ Microbiol. 2001 Jan;67(1):22-32
11133424
Antimicrob Agents Chemother. 2000 Jun;44(6):1479-84
10817696
FEMS Microbiol Ecol. 2000 Apr 1;32(1):77-85
10779622
Clin Infect Dis. 2003 Feb 15;36(4):462-7
12567304
Environ Int. 2004 Mar;30(1):117-22
14664871
FEMS Microbiol Lett. 1998 Dec 15;169(2):391-5
9868786
Appl Environ Microbiol. 2003 Sep;69(9):5336-42
12957921
Microbiol Mol Biol Rev. 2001 Jun;65(2):232-60 ; second page, table of contents
11381101
Environ Int. 2003 Jan;28(7):587-95
12504155
Appl Environ Microbiol. 2001 Apr;67(4):1494-502
11282596
J Dairy Sci. 2005 Apr;88(4):1391-8
15778307
Vet Microbiol. 2003 Jan 2;91(1):73-84
12441233
Appl Environ Microbiol. 1993 May;59(5):1467-72
8517740
Clin Infect Dis. 2002 Jun 1;34 Suppl 3:S93-S106
11988879
Antimicrob Agents Chemother. 2003 Mar;47(3):878-82
12604515
Antimicrob Agents Chemother. 2001 Mar;45(3):723-6
11181350
Antimicrob Agents Chemother. 1991 Nov;35(11):2253-61
1803998
Plasmid. 1996 Mar;35(2):98-107
8700971
Antimicrob Agents Chemother. 1995 Jan;39(1):185-91
7695304
J Clin Microbiol. 2002 Aug;40(8):2813-22
12149335
Appl Environ Microbiol. 2005 Dec;71(12):7941-7
16332771
Can J Microbiol. 2003 Sep;49(9):538-48
14608420
Res Microbiol. 2006 Apr;157(3):220-6
16239097
Mol Cell Probes. 2001 Aug;15(4):209-15
11513555
Cell Mol Life Sci. 1999 Nov 30;56(9-10):742-54
11212334
Antimicrob Agents Chemother. 1999 Mar;43(3):686-9
10049290
Appl Environ Microbiol. 2004 Dec;70(12):7372-7
15574938
J Antimicrob Chemother. 1999 Apr;43(4):503-9
10350379
Appl Environ Microbiol. 1997 Nov;63(11):4604-7
9361446
Can J Microbiol. 1995 Sep;41(9):792-9
7585356
Eur J Clin Microbiol Infect Dis. 1999 Nov;18(11):761-70
10614949
Proc Natl Acad Sci U S A. 2002 Apr 30;99(9):6434-9
11972035