Indukce životaschopného, ale nekultivovatelného stavu u stafylokoků a jeho dopad na citlivost k fágové terapii
| Title in English | Induction of a viable but non-culturable state in staphylococci and its impact on susceptibility to phage therapy |
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| Authors | |
| Year of publication | 2024 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Staphylococci are important agents of infections in humans and animals. Environmental stress factors, such as antibiotic treatment, can cause staphylococci to enter a dormancy state where cells remain viable but non-culturable (the so-called VBNC state). VBNC populations pose a risk to patients because they cannot be detected using conventionally used laboratory media, thus contributing to false negatives laboratory tests. After treatment, the VBNC population may then return to normal metabolic state, thereby inducing recurrent infection in the patient. Staphylococci are characterized by biofilm production, occurring in a culturable state, which subsequently helps induce and maintain the VBNC state by internal adverse conditions such as low oxygen and nutrient concentrations. The biofilm also provides the cells with increased resistance to antimicrobial agents. In addition to antibiotics, phage therapy can be used to eradicate it, or a combination of both approaches. The main objective of the present work was to induce a VBNC state in Staphylococcus aureus using the antibiotics ciprofloxacin, gentamicin, and amoxicillin and to test the susceptibility of VBNC cultures to therapeutic phage 812h1. Two clinical S. aureus strains of sequence types ST8 (MRSA) and ST121 and two laboratory prophage-less S. aureus strains of sequence types ST8 and ST4618 were used. All S. aureus strains were able to induce the VBNC state. The viability of the cultures was confirmed by LIVE/DEAD staining, followed by evaluation by fluorescence microscopy and flow cytometry. Induction of VBNC was the fastest in the laboratory strain SH1000 (ST8) by amoxicillin treatment after only three weeks. Bacteriophage 812h1 multiplied on cultures with a predominance of VBNC cells, but its titer decreased with increasing culture time. Similarly, adsorption of phage to biofilm cells showed a slower rate compared to the planktonic S. aureus population. |
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