National Surveillance for Clostridioides difficile Infection, Sweden, 2009-2016

Abstract

We report results from a national surveillance program for Clostridioides difficile infection (CDI) in Sweden, where CDI incidence decreased by 22% and the proportion of multidrug-resistant isolates decreased by 80% during 2012-2016. Variation in incidence between counties also diminished during this period, which might be attributable to implementation of nucleic acid amplification testing as the primary diagnostic tool for most laboratories. In contrast to other studies, our study did not indicate increased CDI incidence attributable the introduction of nucleic acid amplification testing. Our results also suggest that successful implementation of hygiene measures is the major cause of the observed incidence decrease. Despite substantial reductions in CDI incidence and prevalence of multidrug-resistant isolates, Sweden still has one of the highest CDI incidence levels in Europe. This finding is unexpected and warrants further investigation, given that Sweden has among the lowest levels of antimicrobial drug use.

Keywords: CDI; Clostridioides difficile; Clostridium difficile; Sweden; antibiotic resistance; antimicrobial resistance; bacteria; bacterial infection; epidemiology; outbreaks; surveillance; typing.

Figure 1

National incidence of Clostridioides difficile infection (CDI), Sweden, 2012–2016. A) CDI cases/10,000 patient-days. B) CDI cases/100,000 inhabitants. Error bars indicate SD of the mean county incidence for each year.

Figure 2

National incidence of new Clostridioides difficile infection (CDI) cases, Sweden, 2012–2016. A) Incidence by age group and year; B) incidence by age group and sex. Error bars indicate SD. *p<0.05; **p<0.01 (both by t-test).

Figure 3

Variation in PCR ribotype distribution in 4 counties with large changes in Clostridioides difficile infection incidence rates, Sweden, 2012–2016. A) Östergötland; B) Uppsala; C) Västernorrland; D) Jämtland. 1/D, Simpson’s reciprocal index 1/D.

Figure 4

Correlation between Clostridioides difficile infection (CDI) cases and sampling rates, Sweden, 2009–2016. A) Correlation between number of positive CDI cases/100,000 inhabitants per county and sampling rates. B) Correlation between percentage of CDI cases and sampling rates. Dots indicate values per county; lines indicate regression analyses (R values as indicated). C) Mean positivity rate (bars) and mean sampling frequency (line), by year. Error bars show interlaboratory SD in positivity rates.

Figure 5

Resistance of Clostridioides difficile to indicator antimicrobial drugs, Sweden, 2009–2016. A) Percentage of isolates resistant and sensitive to indicator antimicrobial drugs erythromycin, clindamycin, and moxifloxacin. B) PCR ribotype distribution of MDR isolates. MDR, multidrug-resistant (i.e., resistant to erythromycin, clindamycin, and moxifloxacin); S, sensitive to erythromycin, clindamycin, and moxifloxacin.