Detection of Erysipelothrix rhusiopathiae in clinical and environmental samples.

Erysipelothrix rhusiopathiae is pathogenic for both animals and humans, causing erysipelas in swine and erysipeloid in humans. In swine, disease may be either acute or chronic, resulting in the development of arthritis and endocarditis. In Japan, erysipelas remains an animal hygiene problem causing great economic loss as infected swine are disused. Human infection closely resembles that seen in swine, with both acute and chronic forms also. The most common presentation is erysipeloid, a localized cutaneous infection. In Western Australia, an erysipeloid-like infection referred to as "crayfish poisoning" occurs in lobster fishermen and handlers. A second type of presentation is a generalized cutaneous form involving lesions that progress from the initial site of infection or appear in remote areas. The third and most serious form of disease is a septicemia that is almost always linked to endocarditis. The mortality rate in Erysipelothrix endocarditis is still high (38%) and can be explained by the use of vancomycin (to which Erysipelothrix spp. are inherently resistant) as empirical therapy. Therefore, it is critical to have an early diagnosis of E. rhusiopathiae infection.Unfortunately, several problems exist with the diagnosis of E. rhusiopathiae infections by conventional cultural procedures, and these infections are often incorrectly diagnosed. First, because of their very small colony size and slow growth rates, it is difficult to isolate E. rhusiopathiae from heavily contaminated specimens. Various selective media have been described to improve the isolation of E. rhusiopathiae from contaminated specimens; however, not all contaminants are inhibited. The development of two polymerase chain reaction (PCR) methods has created an opportunity to greatly improve the efficiency with which these organisms are detected and identified. Makino et al. designed a PCR method that amplifies a 407-bp DNA fragment derived from the 16S rRNA coding sequence. The primers in this method are specific for the genus Erysipelothrix and do not differentiate between the species. A second set of primers designed by Shimoji et al. amplifies a 937-bp DNA fragment which is derived from a sequence associated with virulence of E. rhusiopathiae. These primers are specific for E. rhusiopathiae only. Shimoji et al. also utilized a selective enrichment medium based on tryptic soy broth containing ethidium bromide and sodium azide.

Susceptibility of Erysipelothrix rhusiopathiae to antimicrobial agents and home disinfectants.

AIM: Erysipelothrix rhusiopathiae causes the occupationally-related infection erysipeloid in humans, and may be responsible for infections in lobster fishermen in Western Australia. There are little recent data pertaining to antimicrobial susceptibility, or susceptibility to disinfectants that might be used in the environment. The aim of this study was to determine the susceptibility of E. rhusiopathiae from human, animal and environmental sources to various antimicrobial agents and disinfectants. METHODS: The susceptibility of 60 E rhusiopathiae isolates was determined using a recommended agar dilution procedure. Susceptibility to disinfectants was achieved using a broth microdilution method. RESULTS: Penicillin and ceftriaxone, with low minimum inhibitory concentrations (MICs) (MIC90 0.03 mg/l and 0.125 mg/l, respectively), remained active against E. rhusiopathiae and should continue to be recommended for treatment. Ciprofloxacin MICs were particularly low (MIC90 0.06 mg/l), offering an alternative agent for the penicillin allergic patient. Erysipelothrix rhusiopathiae is still resistant to vancomycin (MIC90 64 mg/l), highlighting the importance of early diagnosis of E. rhusiopathiae infection in cases of endocarditis. In addition, 31 E. rhusiopathiae isolates were tested against several commercially available home disinfectants. Most were effective in killing E. rhusiopathiae with minimum bactericidal concentrations of 0.001% for Pine O Cleen, and 0.03% for Domestos, Linely and the Wheelie Bin Phenyl Cleanser. CONCLUSIONS: There appeared to be no new emergence of antibiotic resistance in E. rhusiopathiae. Various disinfectants could be used following mechanical cleaning of work environments, such as fishing boats, and equipment, to reduce the risk of infection with E. rhusiopathiae.