Plasmids encoding resistance to aminoglycoside antibiotics have recently been found to be transferred among staphylococci by a mechanism similar to conjugation, a process not previously described in this bacterial genus. Plasmid genes may be essential for their own transfer. Conjugative transfer of aminoglycoside resistance can also mobilize or co-transfer resistance to other antibiotics and may be important in the construction of the multiply-antibiotic-resistance phenotype. Multiresistant hospital-associated staphylococci are often refractory to antibiotic therapy and are the cause of serious outbreaks of nosocomial infections. We propose to investigate the genetic basis of conjugative plasmid transfer among coagulase positive and coagulase negative staphylococci by pursuing the following lines of investigation. First, we will genetically define the transfer or tra region of conjugative plasmids by deletion and transposon insertional mutagenesis and by cloning and subcloning restriction fragments comprising the tra region. DNA will be cloned in E. coli and shuttled to S. aureus by combining plasmids resident in both bacterial hosts. Trans-complementation of cloned fragments will further define tra genes. The radiolabeled tra region will also be used as a probe to identify homologous regions of the same and different species. Second, gene products of the cloned gene will be identified in the E. coli host. Their expression as surface structures on staphylococci will be assessed by raising antibody to tra-plasmid-containing staphylococci and then by using this antibody as a probe to identify any gene products which are surface-expressed. Finally, attempts will be made to interrupt conjugal mating by treating donor or recipient cells with antibody to identified conjugal surface structures. We hope that by genetically defining conjugative antibiotic resistance transfer in staphylococci we can understand the rapid emergence of isolates of this genus that are resistant to multiple antibiotics. These studies will also produce data which may reveal strategies for interrupting transfer and thus halting the spread of nosocomial staphylococcal infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI021772-01
Application #
3132109
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1984-12-01
Project End
1987-11-30
Budget Start
1984-12-01
Budget End
1985-11-30
Support Year
1
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Virginia Commonwealth University
Department
Type
Schools of Medicine
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Morton, T M; Johnston, J L; Patterson, J et al. (1995) Characterization of a conjugative staphylococcal mupirocin resistance plasmid. Antimicrob Agents Chemother 39:1272-80
Sharma, V K; Johnston, J L; Morton, T M et al. (1994) Transcriptional regulation by TrsN of conjugative transfer genes on staphylococcal plasmid pGO1. J Bacteriol 176:3445-54
Archer, G L; Niemeyer, D M; Thanassi, J A et al. (1994) Dissemination among staphylococci of DNA sequences associated with methicillin resistance. Antimicrob Agents Chemother 38:447-54
Morton, T M; Eaton, D M; Johnston, J L et al. (1993) DNA sequence and units of transcription of the conjugative transfer gene complex (trs) of Staphylococcus aureus plasmid pGO1. J Bacteriol 175:4436-47
Rupp, M E; Soper, D E; Archer, G L (1992) Colonization of the female genital tract with Staphylococcus saprophyticus. J Clin Microbiol 30:2975-9
Thomas Jr, W D; Archer, G L (1992) Mobilization of recombinant plasmids from Staphylococcus aureus into coagulase negative Staphylococcus species. Plasmid 27:164-8
Rupp, M E; Archer, G L (1992) Hemagglutination and adherence to plastic by Staphylococcus epidermidis. Infect Immun 60:4322-7
Archer, G L; Scott, J (1991) Conjugative transfer genes in staphylococcal isolates from the United States. Antimicrob Agents Chemother 35:2500-4
Jacoby, G A; Archer, G L (1991) New mechanisms of bacterial resistance to antimicrobial agents. N Engl J Med 324:601-12
Thomas Jr, W D; Archer, G L (1989) Mobility of gentamicin resistance genes from staphylococci isolated in the United States: identification of Tn4031, a gentamicin resistance transposon from Staphylococcus epidermidis. Antimicrob Agents Chemother 33:1335-41

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