Objectives—To characterize protein composition of
shell scute of desert tortoises and to determine
whether detectable differences could be used to
identify healthy tortoises from tortoises with certain
Animals—20 desert tortoises.
Procedures—Complete postmortem examinations
were performed on all tortoises. Plastron scute proteins
were solubilized, scute proteins were separated
by use of sodium dodecyl sulfate-polyacrylamide gel
electrophoresis (SDS-PAGE), and proteins were analyzed,
using densitometry. Two-dimensional immobilized
pH gradient-PAGE (2D IPG-PAGE) and
immunoblot analysis, using polyclonal antisera to
chicken-feather β keratin and to alligator-scale β keratin,
were conducted on representative samples. The
14-kd proteins were analyzed for amino acid composition.
Results—The SDS-PAGE and densitometry revealed
7 distinct bands, each with a mean relative protein
concentration of > 1%, ranging from 8 to 47 kd, and
a major protein component of approximately 14 kd
that constituted up to 75% of the scute protein. The
2D IPG-PAGE revealed additional distinct 62- and 68-
kd protein bands. On immunoblot analysis, the 14-,
32-, and 45-kd proteins reacted with both antisera.
The 14-kd proteins had an amino acid composition
similar to that of chicken β keratins. There was a substantial
difference in the percentage of the major 14-
kd proteins from scute of ill tortoises with normal
appearing shells, compared with 14-kd proteins of
Conclusions and Clinical Relevance—The major
protein components of shell scute of desert tortoises
have amino acid composition and antigenic features
of β keratins. Scute protein composition may be
altered in tortoises with certain systemic illnesses.
( Am J Vet Res 2001;62:104–110)
Objective—To determine the prevalence of antimicrobial resistance to macrolide antimicrobials or rifampin in Rhodococcus equi isolates and to describe treatment outcome in foals infected with antimicrobial-resistant isolates of R equi.
Sample Population—38 isolates classified as resistant to macrolide antimicrobials or rifampin received from 9 veterinary diagnostic laboratories between January 1997 and December 2008.
Procedures—For each isolate, the minimum inhibitory concentration of macrolide antimicrobials (ie, azithromycin, erythromycin, and clarithromycin) and rifampin was determined by use of a concentration-gradient test. Prevalence of R equi isolates from Florida and Texas resistant to macrolide antimicrobials or rifampin was determined. Outcome of antimicrobial treatment in foals infected with antimicrobial-resistant isolates of R equi was determined.
Results—Only 24 of 38 (63.2%) isolates were resistant to > 1 antimicrobial. Two isolates were resistant only to rifampin, whereas 22 isolates were resistant to azithromycin, erythromycin, clarithromycin, and rifampin. The overall prevalence of antimicrobial-resistant isolates in submissions received from Florida and Texas was 3.7% (12/328). The survival proportion of foals infected with resistant R equi isolates (2/8 [25.0%]) was significantly less, compared with the survival proportion in foals that received the same antimicrobial treatment from which antimicrobial-susceptible isolates were cultured (55/79 [69.6%]). Odds of nonsurvival for foals infected with resistant R equi isolates were 6.9 (95% confidence interval, 1.3 to 37) times the odds for foals infected with susceptible isolates.
Conclusions and Clinical Relevance—Interpretation of the results emphasized the importance of microbiological culture and antimicrobial susceptibility testing in foals with pneumonia caused by R equi.