Opredelitev kliničnih izolatov Staphylococcus argenteus pri bolnikih iz Osrednjeslovenske regije

Petek, Lara (author), Ružić Sabljić, Eva (mentor), Cvitković Špik, Vesna (comentor)

Staphylococcus argenteus je nova bakterijska vrsta, opisana leta 2015, ki je bila pred tem poznana kot klonalni kompleks CC75 vrste Staphylococcus aureus, danes pa poleg štirih drugih bakterijskih vrst tvori kompleks S. aureus. S. argenteus je v patogenosti zelo podobna vrsti S. aureus in je globalno razširjena, zato je pomembno, da jo v rutinski diagnostiki prepoznamo, da imamo na voljo metode, ki jo zanesljivo identificirajo in da jo pravilno poročamo na izvidu preiskav. V Osrednjeslovenski regiji je bil dosedaj rutinsko identificiran samo en klinični izolat S. argenteus iz brisa nosu s preiskavo kultura patogenih bakterij. Klinični izolat smo fenotipsko opredelili in z določanjem občutljivosti za antibiotike ugotovili, da je bil občutljiv za vse testirane antibiotike razen za penicilin. Preverili smo zmožnost metod za prepoznavo S. argenteus v rutinskih preiskavah. Ugotovili smo, da vrsto lahko identificiramo z MALDI-TOF MS, z določanjem nukleotidnega zaporedja gena nucA in z novo opisanim vrstnospecifičnim tarčnim PCR Sa-Sarg. Vrste ne moremo prepoznati po izgledu kolonij na osnovnih trdnih gojiščih ali kromogenih gojiščih za S. aureus ali jo identificirati do nivoja vrste s hitrim aglutinacijskim testom Pastorex (Bio-Rad) in bakterijskim širokospektralnim PCR, pač pa zgolj do nivoja kompleks S. aureus. Med 325 izolati MRSA iz nadzornih kužnin bolnikov iz Osrednjeslovenske regije v času med 1. 1. 2019 in 30. 6. 2019 nismo z MALDI-TOF MS našli nobenega izolata, ki bi pripadal vrsti S. argenteus. Med 42 izolati DNK iz primarno sterilnih kužnin iz obdobja med 1. 1. 2022 in 15. 10. 2023, v katerih smo z bakterijskim širokospektralnim PCR dokazali S. aureus, nismo s vrstno specifičnim tarčnim PCR Sa-Sarg v nobenem izolatu identificirali S. argenteus. V Osrednjeslovenski regiji je za meticilin občutljiv S. argenteus prisoten, vendar je incidenca okužb izredno nizka, o proti meticilinu odpornem S. argenteus pa zaenkrat ni dokazov, zato zelo verjetno ni prisoten.

• Language: Slovenian
• Keywords: Staphylococcus argenteus, kompleks Staphylococcus aureus, identifikacijske metode, fenotipska opredelitev, incidenca
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [L. Petek]
• Year: 2024
• PID: 20.500.12556/RUL-158720
• UDC: 579.61:616-078
• COBISS.SI-ID: 199461379
• Publication date in RUL: 20.06.2024

Secondary language

• Language: English
• Title: Characterisation of clinical isolates of Staphylococcus argenteus in patients from the Central Slovenian region

Abstract

Staphylococcus argenteus is a new bacterial species described in 2015, which was previously known as clonal complex CC75 of the species Staphylococcus aureus, but now forms the S. aureus complex together with four other bacterial species. S. argenteus is very similar to S. aureus in its pathogenicity and is distributed worldwide. It is therefore important to recognize it in routine diagnostics, to have methods that reliably identify it and to accurately report it in the test results. One clinical isolate of S. argenteus from the Central Slovenia region was identified from a nasal swab in routine laboratory diagnostics by culture. We phenotypically characterized the clinical isolate and determined by antibiotic susceptibility testing that it was sensitive to all antibiotics tested except penicillin. We tested the ability of the methods to identify S. argenteus in routine tests. We found that the species can be identified by MALDI-TOF MS, by sequencing of the nucA gene and by the newly described target species-specific PCR Sa-Sarg. The species cannot be recognized or identified to the species level by the appearance of colonies on commonly used solid media and chromogenic media for S. aureus, by the rapid agglutination test Pastorex (Bio-Rad) or by bacterial broad-spectrum PCR. These methods can only identify it to the level of S. aureus complex. Among the 325 MRSA isolates from the surveillance samples of patients from the Central Slovenia region between 1. 1. 2019 and 30. 6. 2019, we did not find any isolate belonging to the species S. argenteus using MALDI-TOF MS. Among the 42 clinical DNA isolates from primarily sterile sites from the period between 1. 1. 2022 and 15. 10. 2023, in which we identified S. aureus with bacterial broad-spectrum PCR, we found with the use of PCR Sa-Sarg that no isolate belonged to the species S. argenteus. Although methicillin-susceptible S. argenteus is present in the Central Slovenia region, the frequency of infections is very low. There is no evidence of methicillin-resistant S. argenteus, therefore it is most probably not present in the region.

• Keywords: Staphylococcus argenteus, Staphylococcus aureus complex, identification methods, phenotypic characterization, incidence