Capnocytophaga canimorsus Capsular Serovar and Disease Severity, Helsinki Hospital District, Finland, 2000-2017

Abstract

We assembled a collection of 73 Capnocytophaga canimorsus isolates obtained from blood cultures taken from patients treated at Helsinki University Hospital (Helsinki, Finland) during 2000-2017. We serotyped these isolates by PCR and Western blot and attempted to correlate pathogen serovar with patient characteristics. Our analyses showed, in agreement with previous research, that 3 C. canimorsus serovars (A-C) caused most (91.8%) human infections, despite constituting only 7.6% of isolates found in dogs. The 3 fatalities that occurred in our cohort were equally represented by these serovars. We found 2 untypeable isolates, which we designated serovars J and K. We did not detect an association between serovar and disease severity, immune status, alcohol abuse, or smoking status, but dog bites occurred more frequently among patients infected with non-A-C serovars. Future research is needed to confirm serovar virulence and develop strategies to reduce risk for these infections in humans.

Keywords: 16S rDNA sequencing; Capnocytophaga canimorsus; Finland; Helsinki; Helsinki Hospital District; bacteria; capsular serovar; capsular typing; coagulopathy; disease severity; dog commensal; dogs; human infection; sepsis; septic shock; serovar J; serovar K; typing; virulence; zoonoses.

Figure 1

Prevalence of capsular serovars among Capnocytophaga canimorsus isolates from patients and dogs. A) Prevalence among 73 isolates from patients in Helsinki, Finland, 2000–2017. B) Prevalence among 25 isolates acquired from patients worldwide. C) Prevalence among pooled samples (n = 98). D) Prevalence among 52 isolates from dog mouths, Switzerland and Belgium. Percentages do not add up to 100% because of rounding. A portion of the data presented in panels B and D were previously published (7).

Figure 2

Association between Capnocytophaga canimorsus capsular serovar and various patient factors, Helsinki, Finland, 2000–2017. A) Disease severity (n = 70); B) immune compromised (n = 73); C) alcohol abuse (n = 49); D) smoking status (n = 48); and E) contact with dogs (n = 73). Fisher exact test was used for statistical analysis.