Læknablaðið - 01.03.2022, Blaðsíða 24
136 L ÆKNABL AÐIÐ 2022/108
E N G L I S H S U M M A R Y
Anna Kristín Gunnarsdóttir1
Helga Erlendsdóttir2,3
Magnús Gottfreðsson3,4,5
1Department of psychiatry, 2Department of clinical microbiology,
3Department of infectious diseases, 4Faculty of Medicine, School of
Health Sciences, University of Iceland, 5Department of science
Landspitali University Hospital.
Correspondence: Anna Kristín Gunnarsdóttir, annakg@landspitali.is
Key words: Bacillus species, Bacillus cereus, penicillin resistance, invasive
infections. sepsis, epidemiology, diagnostic criteria.
Invasive infections of Bacillus species in Iceland, 2006-2018
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.
doi 10.17992/lbl.2022.03.681
Heimildir
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