Spirillum Minus
المؤلف:
Patricia M. Tille, PhD, MLS(ASCP)
المصدر:
Bailey & Scotts Diagnostic Microbiology
الجزء والصفحة:
13th Edition , p447-448
2025-08-21
472
GENERAL CHARACTERISTICS
Spirillum minus is a gram-negative, helical, strictly aerobic organism.
EPIDEMIOLOGY AND PATHOGENESIS
Little information is available regarding the epidemiology or pathogenesis of S. minus, but it is supposed to be similar in some regards to that of S. moniliformis. The mode of transmission of infection is by a rat bite.
SPECTRUM OF DISEASE
S. minus also causes rat-bite fever in humans and is referred to as sodoku. The clinical signs and symptoms are similar to those caused by S. moniliformis, except that arthritis is rarely seen in patients with sodoku and swollen lymph nodes are prominent; febrile episodes are also more predictable in sodoku. The bite wound heals spontaneously, but 1 to 4 weeks later, it reulcerates to form a granulomatous lesion; at the same time, the patient develops constitutional symptoms of fever, headache, and a generalized, blotchy, purplish, maculopapular rash. Differentiation between rat-bite fever caused by S. minus and that caused by S. moniliformis is usually accomplished based on the clinical presentation of the two infections and isolation of the latter organism in culture. The incubation period for S. minus is much longer than that for streptobacillary rat-bite fever, which has occurred within 12 hours of the initial bite.
LABORATORY DIAGNOSIS
Specimen Collection, Transport, and Processing
Specimens commonly submitted for diagnosis of sodoku include blood, exudate, or lymph node tissues. There are no requirements for specimen collection, transport, or processing of the organisms discussed in this chapter.
Direction Detection Methods
Because S. minus cannot be grown on synthetic media, diagnosis relies on direct visualization of characteristic spirochetes in clinical specimens using Giemsa or Wright stains, or dark-field microscopy. S. minus appears as a thick, spiral, gram-negative organism with two or three coils and polytrichous polar flagella. Diagnosis is definitively made by injection of lesion material or blood into experimental white mice or guinea pigs and subsequent recovery 1 to 3 weeks after inoculation.
Serodiagnosis
There is no specific serologic test available for S. minus infection.
ANTIMICROBIAL SUSCEPTIBILITY TESTING AND THERAPY
Because this spirochete is nonculturable, routine antimicrobial susceptibility testing is not performed.
PREVENTION
No vaccines are available to prevent rat-bite fever. Disease is best prevented by avoiding contact with animals known to harbor the organism.
الاكثر قراءة في البكتيريا
اخر الاخبار
اخبار العتبة العباسية المقدسة
