Ífarandi sýkingar af völdum Bacillus-tegunda á Íslandi árin 2006-2018

Abstract

INNGANGUR Bakteríur af ættkvíslinni Bacillus finnast víða í umhverfinu og eru almennt taldar hafa litla meinvirkni, að miltisbrandsbakteríunni B. anthracis undanskilinni. Oft er álitið að um mengun sé að ræða ef Bacillus-tegundir finnast með ræktun. Tegundin B. cereus getur valdið ífarandi sýkingum í mönnum en hún getur framleitt vefjaskemmandi eitur. Faraldsfræði þessara sýkinga hefur lítið verið rannsökuð. EFNIVIÐUR OG AÐFERÐIR Allar mögulegar ífarandi sýkingar af völdum Bacillus á Landspítala árabilið 2006-2018 voru fundnar með leit í ræktunarniðurstöðum. Farið var yfir klínískar upplýsingar þeirra sem taldir voru með mögulegar eða staðfestar sýkingar. Mat á því hvort bakterían taldist vera mengunarvaldur, mögulegur sýkingarvaldur eða staðfestur sýkingarvaldur byggðist á skilmerkjum sem höfundar settu saman. Nýgengi mögulegra eða staðfestra ífarandi sýkinga var reiknað. NIÐURSTÖÐUR Á tímabilinu 2006-2018 ræktaðist Bacillus frá 126 einstaklingum; í blóði (116), liðvökva (8) eða heila- og mænuvökva (2). Alls voru 26 tilvik talin staðfest sýking (20,6%), 10 möguleg sýking (7,9%) og 90 mengun (71,4%). Nýgengi mögulegra eða staðfestra sýkinga var 1,4/100.000 íbúa/ár. Notkun vímuefna í æð var áhættuþáttur meðal 11/26 með staðfesta sýkingu. Algengasta birtingarmynd sýkingar var blóðsýking/sýklasótt. Bakterían var ónæm fyrir beta-laktam sýklalyfjum í 92% staðfestra sýkingartilvika en í 66% mengunartilvika (p=0,02). ÁLYKTANIR Mikilvægt er að taka jákvæðar ræktanir af Bacillus alvarlega, sérstaklega þegar um ræðir sjúklinga sem nota vímuefni í æð, hafa illkynja sjúkdóm eða eru ónæmisbældir. Mikilvægt er að taka ávallt tvö sett af blóðræktu INTRODUCTION: The bacterial genus Bacillus is widely distributed environmentally and is usually considered a low-virulence organism, except for B. anthracis. A blood culture positive for Bacillus is often looked at as contamination. Nevertheless, B. cereus can cause invasive infections in humans and produces harmful toxins. The epidemiology of these infections remains poorly studied. MATERIAL AND METHODS: All possible invasive infections caused by Bacillus during 2006-2018 at Landspitali University Hospital were identified from culture results. Clinical information was used to evaluate if there was a possible infection or confirmed infection. Here, the authors propose and use clinical criteria to categorize each case as contamination, possible infection or confirmed infection. The incidence of possible or confirmed infections was calculated using hospital catchment population data. RESULTS: Positive cultures of Bacillus sp. from sterile sites during 2006-2018 were identified from 126 patients; blood (116), synovial fluid (8) and cerebrospinal fluid (2). In total, 26 cases were confirmed infection (20.6%), 10 possible infection (7.9%) and 90 contamination (71.4%). The incidence was 1.4 cases/100.000 inhabitants/year. Injection drug use was a risk factor among 11/26 patients with confirmed infection. The most common clinical presentation was sepsis. In this study, Bacillus was resistant to beta-lactam antibiotics in 92% of confirmed infections and 66% of the cases considered contamination (p=0.02). CONCLUSION: Positive blood cultures of Bacillus sp. should be taken seriously, especially among patients with injection drug use, malignancy or immunocompromised state. It is important to draw two sets of blood cultures if there is a real suspicion of an infection to establish diagnosis and avoid unnecessary antibiotic therapy.