Page 110 - Journal of Special Operations Medicine - Spring 2015

An Ongoing Series

Staphylococcus sciuri:
An Entomological Case Study and a Brief Review of the Literature

Michael A. Washington, PhD; Lauren Kajiura, MS;
Mark K. H. Leong, MS; Willie Agee, PhD; Jason Barnhill, PhD

ABSTRACT

Staphylococcus sciuri is an emerging gram­positive bac­ (an antibiotic compound similar to coumarin and often
terial pathogen that is infrequently isolated from cases of used in the clinical laboratory for the species­level iden­
human disease. This organism is capable of rapid con­ tification of individual members of the staphylococci),
version from a state of methicillin sensitivity to a state they are metabolically diverse in that they are able to use
of methicillin resistance and has been shown to express inorganic salts as nitrogen sources, and they are capable
a set of highly effective virulence factors. The antibiotic­ of fermenting or metabolizing a compound known as
resistance breakpoints of S. sciuri differ significantly cellobiose (a complex carbohydrate that can only be fer­
from the more common Staphylococcus species. There­ mented by a subset of the staphylococci). In addition,
4,8
fore, the rapid identification of S. sciuri in clinical mate­ all known strains of S. sciuri tend to produce a structur­
rial is a prerequisite for the proper determination of the ally unique cell wall by incorporating an unusual type
anti biotic­resistance profile and the rapid initiation of of peptidoglycan (cross­linking structure). Many of the
10
antimicrobial therapy. Here, we present a brief literature original strains of the S. sciuri group were isolated from
review of S. sciuri and an entomological case study in flying squirrels and, consequently, the word sciuri is de­
which we describe the colonization of an American cock­ rived from a Latin phrase that roughly translates into
roach with this agent. In addition, we discuss potential “of the squirrel.” 8
implications for the distribution and evolution of antibi­
otic­resistant members of the genus Staphylococcus. Although members of the S. sciuri group are not tra­
ditionally recognized as pathogens, there have been
Keywords: bacteriology, entomology, operating environ- numerous consistent, albeit sporadic, reports of these
ment, preventive medicine organisms being isolated from cases of human disease
and wounding. 1,2,9,11–13,15–17 Arguably, the most significant
member of the group is the eponymous S. sciuri, which
is the most frequently isolated member. S. sciuri has been
Introduction
isolated from cases of wound infection, urinary tract in­
Bacteria in the S. sciuri group are emerging pathogens fection, endocarditis, and sepsis. Significantly, S. sciuri
and colonizers that have been implicated in both the was the causative agent behind an outbreak at a tertiary
development of human disease and in the evolution of care center in Benin and isolates of multidrug­resistant
multidrug­resistant organisms. This group consists of S. sciuri have been cultured from cases of wound and
1–7
S. sciuri, S. lentus, S. vitulinus, and S. pulvereri. These bloodstream infection. 2,5,12,16 A recent report from Greece
organisms and their respective characteristics were first described the isolation of an S. sciuri strain from a
described in 1976 by Kloos and others. 1,4,8,9 The initial case of sepsis in an intravenous drug user; the strain was
recognition and subsequent differentiation of the S. sci- resistant to aminoglycosides, macrolides, rifampicin,
uri group from other members of the genus were pri­ oxa cillin, and tetracycline. This case was particularly
18
marily based on the analysis of specific biochemical and concerning given the fact that the isolate in question was
metabolic characteristics. For example, members of found to carry an antibiotic­resistance gene known as
4,8
the S. sciuri group tend to be resistant to novobiocin mecA (the term mecA is a gene designation and not an

100