Downregulation of RNAIII in vancomycin-intermediate Staphylococcus aureus strains regardless of the presence of agr mutation.
Reduced vancomycin susceptibility in Staphylococcus aureus can cause serious problems relating to treatment failure and persistent infection. We investigated vancomycin susceptibility, genetic relationships and transcriptional changes of the accessory gene regulator (agr) in vancomycin-intermediate S. aureus (VISA) strains isolated from South Korea compared with vancomycin-susceptible S. aureus (VSSA) strains. Molecular characterization, population analysis profiling, agr sequencing and transcriptional profiling of RNAIII by real-time RT-PCR were performed. Of 16 VISA strains tested, eight exhibited ST5, agr II and type II SCCmec. The others exhibited ST239, agr I and type III SCCmec. A point mutation in AgrA (Asp8Gly or Ile238Lys) was found in only five VISA strains; no mutations were detected in the other strains. However, RNAIII levels markedly decreased in all VISA strains (mean of 1.39-fold change) compared with the VSSA strains (31.51-fold change) in late-exponential phases (P<0.0001). The downregulation of RNAIII could be an important genetic event in the VISA strains, regardless of the presence or absence of the agr mutation.
Catholic Research Institutes of Medical Science, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Chulmin
C
Park
Catholic Research Institutes of Medical Science, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Na-Young
NY
Shin
Catholic Research Institutes of Medical Science, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Ji-Hyun
JH
Byun
Catholic Research Institutes of Medical Science, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Hyun-Ho
HH
Shin
Catholic Research Institutes of Medical Science, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Eun-Young
EY
Kwon
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Su-Mi
SM
Choi
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Si-Hyun
SH
Kim
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Jae-Chul
JC
Kwon
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Sun Hee
SH
Park
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Jung-Hyun
JH
Choi
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Jin-Hong
JH
Yoo
Division of Antimicrobial Resistance, Korea National Institute of Health, Center for Infectious Diseases, Osong, Chungcheongbuk-do Province, Republic of Korea.
Jae Il
JI
Yoo
Division of Antimicrobial Resistance, Korea National Institute of Health, Center for Infectious Diseases, Osong, Chungcheongbuk-do Province, Republic of Korea.
Gyung Tae
GT
Chung
Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea.
Dong-Gun
DG
Lee
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015536:Down-Regulation; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D058889:Molecular Typing; D020125:Mutation, Missense; D056910:Republic of Korea; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics*; D014640:Vancomycin / Q000494:pharmacology; D020713:Vancomycin Resistance
C095698:Agr protein, Staphylococcus aureus; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015534:Trans-Activators; D014640:Vancomycin