Staphylococcus intermedius in canine gingiva and canine-inflicted human wound infections: laboratory characterization of a newly recognized zoonotic pathogen

Abstract

Staphylococcal gingival flora was characterized in cultures from 135 dogs. Staphylococcus intermedius was isolated in 39% of the cultures, S. aureus was isolated in 10%, and both were isolated in 2.0%. S. aureus was isolated more often from dogs of working breeds with weights of >40 lb (ca. 18 kg) and with outdoor habitats than was S. intermedius, which was associated with dogs of nonworking breeds with weights of <40 lb and indoor habitats. S. intermedius was distinguished from S. aureus by the following characteristics: coagulation of rabbit plasma at 4 h (26 versus 100%, respectively), hemolysis of sheep blood at 24 h (30 versus 79%, respectively), and mannitol fermentation at 24 h (4 versus 93%, respectively). A clear separation of the two species was apparent only with the acetoin (modified Voges-Proskauer) reaction (100% of the S. aureus isolates versus 0% of the S. intermedius isolates) and P-galactosidase activity on the API Staph-Ident strip (0% of the S. aureus isolates and 100% of the S. intermedius isolates). Susceptibilities of S. intermedius and S. aureus were 72 and 7%, respectively, to penicillin G, and 100% of both species to oxacillin. Fourteen previously collected strains of coagulase-positive staphylococci from infected canine-inflicted human wounds were reanalyzed; 3 of 14 (21 %) isolates were S. intermedius. We conclude that S. intermedius is a common canine gingival flora and is responsible for some canine-inflicted human wound infections, thus representing a newly recognized zoonotic pathogen.

Prevalence and antimicrobial susceptibility of staphylococci isolated from saliva of clinically normal cats

“…intermedius was obtained from 30 cats, which represents 28·8% of the isolates. This species is the major pathogenic staphylococcal species in dogs (Devriese 1990) and causes skin, urinary tract, bone and central nervous system infections in several animal species (Talan et al 1989). Their presence has already been reported in canine gingiva and canine-inflicted human wound infections (Talan et al 1989), on the skin (Cox et al 1985;Lilenbaum et al 1998) and in the mouth of clinically healthy cats (Cox et al 1985).…”

“…Although synthetic penicillinase-resistant penicillins such as oxacillin and methicillin are considered to be effective against the majority of staphylococcal strains (Talan et al 1989), 23 strains (22·1%) were identified as resistant to methicillin; these strains were distributed among all the Staphylococcus species except Staph. epidermidis.…”

“…Several bacterial genera, such as Corynebacterium, Bacillus, Escherichia, Pasteurella and Neisseria, have already been reported from the gingival flora of dogs (Saphir and Carter 1976). Nevertheless, a series of canine-inflicted bite wounds in humans indicates that staphylococci represent one of the predominant pathogens in such wounds, accounting for 10-50% of bacterial isolates (Talan et al 1989). Staphylococci were also isolated from the mouths of dogs (Cox et al 1988) and cats (Cox et al 1985).…”

“…intermedius may be a relatively common and potentially invasive pathogen of canine-infected human wounds. It was suggested that clinical laboratories should consider differentiating coagulase-positive staphylococci isolated from canine-infected wounds (Talan et al 1989). Also Cox et al (1988) found this species to be the most common isolate from the mouths of healthy dogs.…”

Antibiotic resistance in staphylococci associated with cats and dogs

“…Resistance genes are easily acquired in such a polymicrobial environment. Their habitat on mammals makes staphylococci very amenable to spread from one animal to another and in some situations to humans by cat and dog bites (Talan et al 1989). Staphylococci are largely species specific and most of the times strains from one species do not cause infections in another species and there are few reports in the literature of spread of staphylococci between species.…”