Isolation and Identification of Staphylococcus Species Obtained from Healthy Companion Animals and Humans

Abstract

The close contact between people and their pets has generated the exchange of skin microbiota, accompanied by bacteria that present resistance to antibiotics. Staphylococcus spp., opportunistic pathogens present in the skin and mucosa of mammals, have had their importance recognized in human and veterinary medicine. The objectives of this study were to identify Staphylococcus spp. present in isolates from the nostrils of healthy humans, dogs and cats as well as to determine their phenotype of resistance to methicillin. Strain identification was performed by MALDI-TOF mass spectrometry and antimicrobial susceptibility was determined using a disk diffusion assay for 12 antibiotics. Sixty humans (veterinary and technicians), sixty dogs and sixty cats were sampled; of them, 61.6%, 56.6% and 46.6%, respectively, carried Staphylococcus spp. in their nostrils, and only two people carried two different species of Staphylococcus in the only anatomical site sampled. A methicillin-resistant phenotype was present in 48.7% of the humans, 26.5% of the dogs and 57.1% of the cats, and sampled. These results demonstrate the presence of Staphylococcus spp. strains resistant to methicillin in personnel who work in contact with animals, as well as in dogs and cats that entered the same hospital or veterinary clinic, which alerts us to the potential transfer of these strains to or between people, dogs and/or cats.

Keywords: Staphylococcus spp.; antimicrobial susceptibility testing; cats; dogs; human; resistance.

Figure 1

Number of Staphylococcus isolates per group. In total, 15 different species from the Staphylococcus genus were isolated from the studied subjects. Considering the frequency, 28 Staphylococcus spp. were isolated from the 60 healthy adult cats, 34 Staphylococcus spp. were isolated from the 60 healthy adult dogs and 39 Staphylococcus spp. were isolated from the 60 healthy adult human participants of the study.

Figure 2

Number of methicillin-resistant isolates per group (cats, dogs and humans).

Figure 3

Number of resistant isolates obtained from dogs, cats and humans. All isolates were tested for antimicrobial susceptibility employing the disk diffusion method following CLSI guidelines. Colors represent the total number of Staphylococcus isolates that showed resistance to cefoxitin (FOX, 30 µg), oxacillin (OX, 1 µg), imipenem (IPM, 10 μg), ciprofloxacin (CIP, 5 μg), vancomycin (VA, 30 μg), doxycycline (DO, 30 μg), erythromycin (E, 15 μg), amikacin (AMK, 30 μg), gentamicin (GEN, 10 μg), trimethoprim/sulfamethoxazole (SXT, 1.25/23.75 μg), amoxicillin/clavulanic acid (AMC, 30 μg) and clindamycin (DA, 2 μg).

Figure 4

Cumulative resistance of the number of isolates obtained from dogs, cats and humans against the antibiotics used. In total, 11 isolates from cats, 22 from dogs and 2 from human participants showed resistance to zero antimicrobials. Two isolates showed resistance to nine, and one isolate showed resistance to 10, 11 and 12 antimicrobials.

Figure 5

Specific multidrug resistance of isolates. In total, seven isolates from cats, four isolates from dogs, and fifteen isolates from human participants showed resistance to three or more antibiotics. All isolates from cats showed resistance to OX, E and DA. Isolates from dogs showed elevated multidrug resistance, with all isolates being resistant to E as well as DA and three of them also showing resistance to GEN, SXT, DO, CIP and OX. Finally, most of the isolates from human participants showed resistance to FOX and DA.