Development, stability, and molecular mechanisms of macrolide resistance in Campylobacter jejuni.
Previous studies of macrolide resistance in Campylobacter were primarily focused on strains from various origins or used in vitro systems. In this study, we conducted both in vitro and in vivo experiments to examine the development, stability, and genetic basis of macrolide resistance in Campylobacter jejuni using erythromycin-resistant (Ery(r)) mutants derived from the same parent strain. Chickens inoculated with low-level Ery(r) mutants (MIC = 32 or 64 microg/ml) at 15 days old did not shed highly Ery(r) mutants (MIC > 512 microg/ml) after prolonged exposure to a low dose of tylosin. The low-level Ery resistance was not stable in vitro or in vivo in the absence of macrolide selection pressure. However, high-level Ery resistance displayed remarkable stability in vitro and in vivo. Ribosomal sequence analysis of 69 selected Ery(r) mutants showed that specific point mutations (A2074G or A2074C) occurred in all highly Ery(r) mutants. No mutations in ribosomal protein L4 were observed in any of the in vitro-selected Ery(r) mutants. However, three specific mutations in L4, G74D, G57D, and G57V, were widely found among in vivo-selected Ery(r) mutants. Insertion of three amino acids, TSH, at position 98 in ribosomal protein L22 was observed only in mutants selected in vitro. Inactivation of the CmeABC efflux pump dramatically reduced Ery MICs in Ery(r) mutants. Together, these findings suggest that multiple factors contribute to the emergence of highly Ery(r) Campylobacter in chicken, reveal resistance level-dependent stability of macrolide resistance in C. jejuni, and indicate that C. jejuni utilizes complex and different mechanisms to develop Ery resistance in vitro and in vivo.
Caldwell
Dave Bryson
DB
Department of Animal Science, The University of Tennessee, Knoxville, Tennessee, USA.
Wang
Ying
Y
Lin
Jun
J
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002169:Campylobacter Infections / Q000188:drug therapy / Q000382:microbiology; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000235:genetics* / Q000472:pathogenicity; D002645:Chickens; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology; D005516:Food Microbiology; D005759:Gastroenteritis / Q000188:drug therapy / Q000382:microbiology; D005798:Genes, Bacterial; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D009154:Mutation; D012329:RNA, Bacterial / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D015645:Tylosin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins; C056368:ribosomal protein L4; D004917:Erythromycin; D015645:Tylosin
Clin Infect Dis. 2001 Apr 15;32(8):1201-6
11283810
Antimicrob Agents Chemother. 2005 Jul;49(7):2753-9
15980346
Proc Natl Acad Sci U S A. 2005 Jan 18;102(3):541-6
15634738
Appl Environ Microbiol. 2005 Jan;71(1):169-74
15640184
Foodborne Pathog Dis. 2005 Spring;2(1):12-23
15992295
FEMS Microbiol Lett. 2005 Dec 1;253(1):39-46
16213669
Microbes Infect. 2006 Jun;8(7):1972-8
16714138
Antimicrob Agents Chemother. 2006 Nov;50(11):3893-6
16940070
J Antimicrob Chemother. 2006 Aug;58(2):243-55
16735431
Curr Opin Microbiol. 2003 Oct;6(5):452-6
14572536
Antimicrob Agents Chemother. 2001 Jan;45(1):371-2
11221726
Emerg Infect Dis. 2001 Jan-Feb;7(1):24-34
11266291
Antimicrob Agents Chemother. 2007 May;51(5):1678-86
17353243
Curr Opin Microbiol. 1999 Oct;2(5):489-93
10508723
J Antimicrob Chemother. 2005 Sep;56(3):491-7
16055509
Curr Opin Microbiol. 2006 Oct;9(5):461-5
16890008
Appl Environ Microbiol. 2006 Feb;72(2):1316-21
16461682