Page 996 - Clinical Small Animal Internal Medicine

934 Section 9 Infectious Disease

Abscesses and Cellulitis in Cats Caused by been developed. Alternatively, PCR‐denaturing gradient
VetBooks.ir Mycoplasmas and L‐Form Bacteria gel electrophoresis (DGGE) may be applied, enabling pri­
mary detection and differentiation of mycoplasmas in
Abscess formations caused by mycoplasmas presumably
introduced by bite wounds have been reported in cats. clinical material even if mixed infections occur. Recently,
matrix‐assisted laser desorption/ionization time of flight
Nonodorous, nondegenerate, neutrophilic, gram stain‐ (MALDI TOF) mass spectrometry has become an excel­
negative exudates are characteristic for Mycoplasma lent method for the identification and differentiation of
abscesses. L‐form bacteria have been isolated from cats animal mycoplasmas, representing a promising alterna­
with persistently draining cellulitis and synovitis. Usual tive to the currently practiced cumbersome diagnostics.
sources of infection with L‐form bacteria have been pen­ No serologic assays for the detection of immune responses
etrating bite wounds or surgical incisions. Spread of to canine or feline mycoplasmas have been standardized
infection can occur manifested by polyarthritis or dis­ and made commercially available so far.
tant abscess formation.

Diagnosis Therapy

The fragile nature of mycoplasmas mandates careful In most diagnostic laboratories, susceptibility testing of
attention to specimen collection, inoculation of trans­ mycoplasmas to antimicrobials is not available. As is
port medium, and proper transportation and shipping known, mycoplasmas are inherently resistant to beta‐
conditions. Laboratory diagnosis of canine and feline lactam antibiotics. Treatment with nonbeta‐lactams
mycoplasmas is commonly achieved by cultivation such as macrolides, tetracycline, chloramphenicol, clin­
(Figure 98.1) which also allows quantification or by poly­ damycin or fluoroquinolones should be effective against
merase chain reaction (PCR) if a particular Mycoplasma most canine and feline mycoplasmas providing that ani­
species is sought. mals are treated for an extended period. For example, in
Cultivation is, however, expensive and requires special­ cats with URTD, M. felis was eliminated with either pra­
ized media and expertise not commonly available at all dofloxacin or doxycycline treatment for 42 days. No vac­
laboratories. Culture results are usually available within cines are currently available to prevent Mycoplasma
2–4 days for most canine and feline mycoplasmas, but infections in dogs and cats although they are successfully
definitive species identification requires additional tests used in other animals.
which traditionally include serologic methods depending
on specific antisera to each individual Mycoplasma spe­
cies. Such specific antisera are not readily available in Public Health Implications
most diagnostic laboratories and multiple cross‐reactions
may occur. Due to their rather strict host specificity, mycoplasmas
To circumvent the limitations of serologic differentia­ of the dog and cat are not considered a major public
tion methods, more accurate and rapid identification health risk. Zoonotic infections have only been occa­
schemes employing PCR‐restriction fragment length pol­ sionally documented, predominantly involving immuno­
ymorphism (RFLP) of the 16S‐23S intergenic region have suppressed individuals.

Figure 98.1 Cultivation.