The threat of multidrug-resistant staphylococci poses a significant threat. Much attention has been given to well-known pathogens in companion animals, but rare species are gaining significance. One example is Staphylococcus pettenkoferi is a rare bacterium not commonly found in healthy humans or animals but important due to its multidrug resistance and the ability to form biofilms. New research from the Wrocław University of Environmental and Life Sciences in Poland found all isolates originally derived from a cat cage in a veterinary hospital were resistant to penicillin and almost all were methicillin resistant. Antibiotic susceptibility testing (AST) revealed a high prevalence of multidrug resistance (MDR) in all human strains they tested when compared with the feline strains. Comparatively, there were shared resistance genes like blaZ, mecA and ermA that were shared between the human and feline isolates.
Horizontal al gene transfer (HGT) and recombination are genetic drivers in these coagulase-negative staphyloccci (CNS). Similar to other CNS, S. pettenkoferi could be a reservoir of antibiotic resistance and virulence genes. However, the mechanism of its pathology, antimicrobial resistance (AMR) patterns, and its ability to firm biofilms remain poorly understood.
For identification, authors used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and a sequence analysis of the 156S rRNA gene and partial rpoB gene sequencing. Surprisingly, they found that the feline strains were genetically similar to the human strains. Antimicrobial profiles were determined using MIC, disk diffusion and PCR. Prior to this study, the ability of humans as potential carriers of S. pettenkoferi has not been studied. Results showed a high degree of similarity between regional strains of both human and feline origin via rpoB sequencing. The pathogenicity of the organism remains unclear.
Biofilm production was tested in vitro using a microtiter plate test (MPT). Biofilm production was shown to increase a higher temperatures and after prolonged incubation. Biofilm-encoding genes like bap and icaA were not detected but biofilm-forming properties were demonstrated. Several antibiotics from TOKU-E EU were used for the in vitro biofilm production and MPT test including Clindamycin, Erythromycin, Teicoplanin, Tetraycline. and Vancomycin. Additionally, Oxacillin and Teicoplanin were used for antibiotic susceptibility testing methods using broth microdilution.
The insect larva (Galleria mellonella) is used as a model system since its immune system shows many similarities to mammals. This moth can be used to monitor sRNA and mRNA in S. aureus pathogenesis, for example, and be applied to other pathogens. This was the first time this model was used with S. pettenkoferi. and it revealed low pathogenicity. The team found that the pathogen has the potential, however, to develop resistance to many classes of antibiotics. Since zoonotic transmission could be possible, more investigation is needed to understand this feline microbe and its role in managing multidrug-resistant infections.
Reference:
Bierowiec K et al (2025) Comparison of Staphylococcus pettenkoferi Isolated from Human Clinical Cases and Cat Carriers Regarding Antibiotic Susceptibility and Biofilm Production. Int. J. Molec. Sci. 26(5):1948 Link.