Biology Reference
In-Depth Information
Antibiotics Should Not Be Used Prophylactically for Nonnecrotic Snakebites
Several observational studies/reviews have reported a low incidence of wound infec-
tion after most snakebites (e.g., several
Crotalus
spp. and others; Clark et al., 1993;
LoVecchio et al., 2002; White and Dart, 2008). In a prospective controlled trial with
114 patients, there were no statistically significant differences in outcome in terms of
the number of abscesses that occurred between antibiotic-treated and untreated patients.
On the basis of these results, the authors declined recommending routine use of prophy-
lactic antibiotics for prevention of infectious complications of crotaline envenomation
(Kerrigan et al., 1997). Similarly, a retrospective review of snakebites (number unclear)
that presented during 2003-2008 to the Jawaharlal Institute of Postgraduate Medical
Education and Research Hospital in Pondicherry, India, identified 43 cases that included
infections. The snakes involved were not specifically identified, but the bacteria isolated
included
Staphylococcus aureus
,
Enterococcus faecalis
,
Streptococcus
spp.,
Escherichia
coli
,
Klebsiella pneumonia
,
Pseudomonas aeruginosa
, and others (Garg et al., 2009).
The authors indicated that broad-spectrum antibiotics should be used only in the event
of clinical evidence of infection after snakebites (Garg et al., 2009).
The only double-blinded randomized study addressing this question enrolled 251
patients with proven envenoming by
Bothrops
spp. that were admitted to two hospi-
tals in Brazil between 1990 and 1996 (Jorge et al., 2004). The potential role of pro-
phylactic antibiotics in preventing local infections or abscesses among these patients
was studied by providing chloramphenicol to 122 patients (“group 1”), while 129
were given placebo (“group 2”). There were no significant differences in the occur-
rence of abscesses (six patients in each group, or a combined incidence of 4.8%) or
necrosis (seven in group 1, and five in group 2, or a combined incidence of 4.8%).
It was concluded that the use of orally administered chloramphenicol for victims of
Bothrops
envenomation with signs of local envenoming on admission was not effec-
tive for the prevention of local infections (Jorge et al., 2004).
However, several authors have cautioned that snakebite wounds should be care-
fully scrutinized (especially in Third World clinical facilities) because secondary
infection may be a complication of some snakebites, particularly those that develop
necrosis (Lam et al., 2010; Theakston et al., 1990). In a study of 310 snakebite vic-
tims who presented at Eshowe Hospital in Kwazulu-Natal, South Africa,
10% had
necrotic wounds, and the author suggested that antibiotics be reserved for use only
in these cases (Blaylock, 1999). Although relatively uncommon, cases of serious
secondary infection have been documented; all from recognizably severe envenom-
ing by front-fanged species (e.g.,
A. hydrophila
infection that resulted in necrotizing
fasciitis postenvenoming by
A. piscivorus
, Angel et al., 2002; mixed local infec-
tion 2 weeks postenvenoming by
B. jararaca
, Bucaretchi et al., 2010). Review of
the available evidence (much of it from observational studies) emphasizes that anti-
biotics should only be used prophylactically in snakebites that feature, or have a
known tendency for, necrosis. Otherwise, antibiotics should only be used when there
is clinical evidence of infection, and in such a case should be started after speci-
mens for culture (anaerobic and aerobic) and sensitivity testing have been obtained.
Specific sensitivities of cultured organisms and regional antibiotic resistance patterns
should guide the choice of antibiotics when these are deemed necessary. Antibiotics
