Download MICROBIOLOGY LEGEND CYCLE 40 ORGANISM 6

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MICROBIOLOGY LEGEND
CYCLE 40 ORGANISM 6
Erysipelothrix rhusiopathiae
Erysipelothrix rhusiopathiae was first isolated by Koch in 1876 and E. rhusiopathiae –
which literally means “erysipelas thread of red disease” – is the only named species in the
genus Erysipelothrix.
E. rhusiopathiae is a slender gram positive nonsporulating rod that is a facultative
anaerobe whose growth is improved by 5-10% CO2. It can be found in a variety of
configurations such as in short chains, pairs, in a "V" configuration or even grouped
randomly. These gram positive organisms can appear gram negative because of their
tendency to decolorize rapidly. The colonies have two distinct forms, rough and smooth.
Erysipelothrix rhusiopathiae is a pathogen that causes infections in the hosts it infects.
This organism infects a large variety of animals from a house fly to a wild bear. Infections
have been reported worldwide in as many as 50 different types of animals with the
highest occurrence found in domestic swine. Erysipelothrix rhusiopathiae is unable to
survive for an indefinite amount of time within the external environment but can survive
for a long time in the faeces of pigs.
E. rhusiopathiae has been found in the faeces of healthy swine, showing that it does not
always induce a disease. It can cause infections within humans as well. There are three
clinical categories for the human disease caused by this organism. A localized cutaneous
form (most common), a generalized cutaneous form, and a septicaemic form (associated
with the heart disease endocarditis). Human infections are primarily found as a result of
occupational hazards such as those who handle fish, or among butchers. Other animals
that can transmit the infection are sheep, rabbits, chickens, turkeys, ducks, emus, scorpion
fish and lobsters. Erysipeloid is an occupational disease, mainly found in animal breeders,
veterinarians, slaughterhouse workers, furriers, butchers, fishermen, fishmongers,
housewives, cooks and grocers. One epidemic of erysipeloid was described in workers
involved in manufacturing buttons from animal bone. Erysipelothrix rhusiopathiae
primarily enters its host via scratches or puncture wounds on the surface of the skin. A
patient infected by this organism with the localized cutaneous form commonly exhibit
symptoms of a throbbing itching pain and swelling on the finger or part of hand infected.
Infections can be easily treated by antibiotic therapy.
This organism has several very interesting characteristics such as its ability to infect such a
large variety of vertebrate and invertebrate animals. The extreme diversity found within
this single species is also of interest because further studies are still required to determine
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48 Monte Carlo Crescent
Kyalami Business Park, Kyalami
Johannesburg, 1684
South Africa
www.thistle.co.za
Tel: +27 (011) 463 3260
Fax to Email: + 27 (0) 86-557-2232
e-mail : [email protected]
if one species is really a sufficient means to catagorize this organism.
Traditionally, culture methods for the isolation of E. rhusiopathiae involve the use of
selective and enrichment media. Commercially available blood culture media are
satisfactory for primary isolation from blood since E. rhusiopathiae is not particularly
fastidious. A number of selective media for the isolation of Erysipelothrix have been
described also. A commonly used medium is Erysipelothrix selective broth (ESB), a
nutrient broth containing serum, tryptose, kanamycin, neomycin, and vancomycin.
Modified blood azide medium (MBA) is a selective agar containing sodium azide and horse
blood or serum. Packer’s medium is a selective medium for grossly contaminated
specimens, which contains sodium azide and crystal violet. Bohm’s medium utilises
sodium azide, kanamycin, phenol and water blue. Shimoji’s selective enrichment broth
contains tryptic soy broth, Tween 80, Tris-aminomethane, crystal violet and sodium azide.
Laboratory smears show Gram-positive rods (though Gram stain has low sensitivity for this
microbe). It is non-motile, catalase-negative, microaerophilic, capnophilic, and non-sporeforming. It can also produce H2S (gas), which is a unique characteristic for a Gram-positive
bacillus.
Penicillin is the treatment of choice. It is resistant to vancomycin. E. rhusiopathiae is
sensitive in vitro and in vivo mainly to penicillins but also to cephalosporins (cefotaxime,
ceftriaxone), tetracyclines (chlortetracycline, oxytetracycline), quinolones (ciprofloxacin,
pefloxacin), clindamycin, erythromycin, imipenem and piperacillin. It is resistant to
vancomycin, chloramphenicol, daptomycin, gentamicin, netilmicin, polymyxin B,
streptomycin, teicoplanin, tetracycline and trimethoprim ⁄ sulfamethoxazole. Penicillins
and cephalosporins are the first-line choice for treatment. A 7-day course is appropriate,
and clinical improvement is usually observed 2–3 days after the beginning of the
treatment.
References:
1. Dawson, S. (1981). Prokaryotes volume II Chapter 73 pps 1629-1638. Springer, New
York.
1. Q. Wang; B.J. Chang; Th.V. Riley (2010). "Erysipelothrix rhusiopathiae". Journal of
Veterinary Microbiology. 140: 405–417.
3. S. Veraldi; V. Girgenti; F. Dassoni; R. Gianotti (2009). "Erysipeloid: a review". Journal of
Clinical and Experimental Dermatology. 34: 859–862.
Questions:
Why do you think E. rhusiopathiae is translated as “erysipelas thread of red disease”?
1. Discuss the various options for culturing this bacterium.
2. Consider what preventive measures could be taken by the population most at risk
of infection by E. rhusiopathiae.
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