Progress 10/01/00 to 09/30/04
Outputs
Macrorestriction (RFLP) analysis, using the restriction enzyme SmaI and pulsed-field gel electrophoresis (PFGE), of the chromosomes of 322 Staphylococcus aureus isolates taken from as many cases of human septicemia have identified 32 lineages and approximately 70 sublineages of this species. We are still waiting for the case report data from Dr. Vance G. Fowler (Duke University Medical Center, Durham, NC) to correlate RFLP patterns with the primary foci of infections. Likewise, RFLP analysis using PFGE was performed on the chromosomes of 90 and 590 S. aureus isolates taken from cases of bovine mastitis in Costa Rica and North Carolina, respectively. Twenty lineages and 81 sublineages of S. aureus were identified between 1988 and 2003 in three North Carolina State University dairy herds. Of these, 3 lineages (7 sublineages) persisted for a long term (10 to 15 years). One of these was common to all three herds. Two represented major strains isolated in relatively large
cell numbers. The persistent lineages were susceptible to a wide range of antibiotics. The herds were related by management and movement of cows. The North Carolina lineages were distinctly different from those of Costa Rica, though some regions of the S. aureus chromosome were conserved. The RFLP analysis proved to be a very useful tool in identifying specific lineages and following their movement between hosts.
Impacts
Macrorestiction analysis (RFLP) of the Staphylococcus aureus chromosome has successfully identified a variety of different lineages and sublineages of this opportunistic pathogen such that it can determine their persistence on and movement between hosts. S. aureus producing mastitis in dairy cattle are very difficult to eliminate, even with the use of recommended antibiotic treatment of infected cows. Although some strains of this species appear to be transient in infected herds, others can persist for many years. This investigation has identified, with the aid of DNA-based (genotypic) typing, several persistent strains in a group of three related North Carolina State University dairy herds. It is expected that future inquiries will attempt to determine the mechanisms whereby persistent strains evade host immune systems and antibiotic treatment.
Publications
- No publications reported this period
|
Progress 10/01/02 to 09/30/03
Outputs
Collaborative studies on the long-term persistence of Staphylococcus aureus strains associated with mastitis in three related dairy herds have shown that two major strains and one minor strain have persisted in the herds for at least 10 years. These herds were related by management and movement of cows. Staphylococcal strains or lineages were identified by macrorestriction analysis of chromosomal DNA using pulsed-field gel electrophoresis. The persistent strains were susceptible to all 14 different antibiotics tested using National Committee for Clinical Laboratory Standards MIC procedures. The number of new isolates examined this year was approximately equal to that examined the previous year. The long-term study has demonstrated the tenacity of certain S. aureus strain populations, even in the presence of antibiotic treatment.
Impacts
Staphylococcus aureus producing mastitis in dairy cattle are very difficult to eliminate, even with the use of recommended antibiotic treatment of infected cows. Although some strains of this species appear to be transient in infected herds, others can persist for many years. This investigation has identified, with the aid of DNA-based (genotypic) typing, several persistent strains in a group of three related dairy herds. Future inquiries will attempt to determine the mechanisms whereby persistent strains evade host immune systems and antibiotic treatment.
Publications
- Lyman, R., C. George, W. Kloos, C. Spooner, and K. Anderson. 2003. Long-term persistence of genetic types of mastitis-causing Staphylococcus aureus on three dairy herds. The American Association of Bovine Practitioners Proc. 36:168-169.
|
Progress 01/01/02 to 12/31/02
Outputs
Macrorestriction analyses of the chromosome of Staphylococcus aureus using pulsed-field gel electrophoresis have continued to identify specific lineages and sublineages responsible for human septicemia and bovine mastitis. Sublineages were distinguished by differences in the position, addition, or deletion of one or two restriction sites. In general, as the number of isolates examined increased, the amount of clonal variation observed increased. Most of the mastitis isolates could be grouped into two major lineages, and these demonstrated some clonal variation due to one or two genetic events affecting restriction-fragment size. The number of new isolates examined this year was approximately equal to that examined in the previous year.
Impacts
Staphylococci are one of the most prevalent bacteria causing infections in humans and animals resulting in morbidity and mortality. Their infections can result in high economic losses to agriculture. Once strains or lineages causing the most damage to health can be identified, it should be possible to monitor them using molecular fingerprinting methods to identify their sources and limit their proliferation. Several years of typing such lineages have supported the hypothesis that relatively few lineages are responsible for most infections.
Publications
- Smith, P., C. Spooner, R. Lyman, C. George, W. Kloos, and K. Anderson. 2002. Distribution of strains of Staphylococcus aureus isolated from milk of cows in North Carolina. Proc. 41st Annu. Meet. National Mastitis Council, p. 233-234.
- Liebl, W., W. E. Kloos, and W. Ludwig. 2002. Plasmid-borne macrolide resistance in Micrococcus luteus. Microbiol. 148: 2479-2487.
|
Progress 01/01/01 to 12/31/01
Outputs
The continuation of macrorestriction analyses of the chromosome of Staphylococcus aureus using pulsed field gel electrophoresis has identified specific lineages and strains responsible for human septicemia and bovine mastitis. Two lineages accounted for most of the S. aureus isolates taken from North Carolina institutional herds suffering from mastitis. These and numerous others were detected among private herds of this state. Major lineages could be subdivided into strains or clones differing from one another on the basis one or two genetic events affecting restriction fragment size (e.g., by small deletions, insertions and/or the addition or subtraction of restriction sites).
Impacts
Staphylococci are one of the most prevalent bacteria causing infections in humans and animals resulting in morbidity and mortality. Their infections can result in high economic losses to agriculture. Once strains causing the most damage to health can be identified, it should be possible to monitor them using molecular fingerprinting methods to identify their sources and limit their proliferation.
Publications
- Kloos, W. E., and J. M. Hardie. 2001. International committee on systematic bacteriology subcommittee on the taxonomy of staphylococci and streptococci. Minutes of the meeting, 4 July 1994, Prague, Czech Republic. Int. J. Syst. Evol. Microbiol. 51:715-716.
- Kloos, W. E., J. M. Hardie, and R. A. Whiley. 2001. International committee on systematic bacteriology subcommittee on the taxonomy of staphylococci and streptococci. Minutes of the meeting, 17 September 1996, Institut Pasteur, Paris, France. Int. J. Syst. Evol. Microbiol. 51:717-718.
|
Progress 10/01/99 to 09/30/00
Outputs
n/a
Impacts
(N/A)
Publications
- No publications reported this period
|
|