Biology Reference
In-Depth Information
4.6.2.13 Imaging Studies
There are no general indications for imaging of patients with medically significant col-
ubroid envenoming. However, some patients envenomated by hazard level 1 colubrids
may require imaging, as brain hemorrhage has been reported in several cases [e.g., from
R. tigrinus
and
T. kirtlandii
envenomations; Ogawa and Sawai, 1986 (see Plate 4.46D),
and Mebs et al., 1978, respectively; see
Table 4.1
and Section 4.3]. Therefore, CT
(computerized axial tomography) of the head without contrast should be performed on
patients that exhibit consumptive coagulopathy with altered sensorium
other neuro-
logical signs or at the discretion of the attending physician. There are no data supporting
the need for other imaging aside from the assessment of secondary effects from exac-
erbations of preexisting comorbidities or specific complications (e.g., chest films for
suspected pulmonary edema or congestive heart failure, venous and/or arterial Doppler
ultrasound imaging of an bitten extremity with history of vascular insufficiency).
4.6.2.14 Additional Investigations
Other investigations that may be considered could include fecal occult blood
(guaiac) serial assays; 24-h creatinine; renal sonogram; continuous cardiac monitor-
ing/echocardiogram (as indicated); and esophageal gastroduodenoscopy (in the set-
ting of posttreatment unexplained bleeding). However, any invasive investigation,
including those listed above, should be carefully considered from a risk-benefit per-
spective, if there is active coagulopathy still present.
4.6.2.15 Microbiology of the Ophidian Oropharynx and the Use of Antibiotics
for Medically Significant Colubrid Bites
Overview of Microbial Flora
The buccal cavity of snakes contains a wide array of microorganisms, some of recog-
nized medical importance (Goldstein et al., 1979, 1981; Lam et al., 2010; Parrish et al.,
1956; Theakston et al., 1990; Williams et al., 1954). Clinically important species of
crotaline viperids and elapids studied to date harbor numerous strains (in some cases
400) of up to 72 bacterial taxa (including Gram-negative, Gram-positive, facultative
and anaerobic flora; Lam et al., 2010; Shek et al., 2009; Theakston et al., 1990). Some
bacterial species present in the ophidian oropharynx (e.g.,
Stenotrophomonas malto-
philia
) are also relevant to the veterinary care of captive snakes, as well as human med-
icine (e.g.,
Aeromonas hydrophila
; Angel et al., 2002; Hejnar et al., 2007; Jacobson,
2007).
The oropharynx of non-front-fanged colubroid snakes contains a similarly broad
variety of bacterial species. A study of 50 specimens of four
Thamnophis
spp. [
T.
s. sirtalis
,
T. couchi
(Western aquatic, or Sierra garter snake),
T. radix
, and
T. sau-
ritus
] found 126 strains of aerobic and facultative bacteria. The potential patho-
gens included
Pseudomonas aeruginosa
,
Klebsiella oxytoca
,
Arizona hinshawii
,
Acinetobacter calcoaceticus
(var.
anitratus
), and
Shigella
spp. (Goldstein et al.,
1981). A similar spectrum of bacterial species have been cultured from the oropha-
rynx, venom glands, and venom of several species of crotaline viperids and captive
