Characterization of a Clostridioides difficile outbreak caused by PCR ribotype 046, associated with increased mortality

Figures & data

Figure 1. Flowchart of isolates included in the study from Högland Hospital catchment area, 2010–2011.

Figure 2. Timeline for CDI outbreak and interventions at Högland Hospital. Epidemiological curve showing CDI cases caused by RT046 at different wards at Högland Hospital during the outbreak (2010–2011) and CDI cases/10,000 bed days (July 2011–2013).

Table 1. Clinical characteristics of patients with primary Clostridioides difficile infection caused by PCR ribotype 046 compared to the six next most common ribotypes (comparison group).

Characteristic	Median (interquartile range), mean (SD) or no. (%) for patients infected with C. difficile of:
	Ribotype 046 (n = 104)	Comparison group (n = 102)	p-value
Age in years	81.0 (74.5–86.0)	79.0 (71.0–86.0)	0.41
Female	51 (49.0)	64 (62.7)	0.05
CDI high-risk antimicrobials	93 (89.4)	85 (83.3)	0.20
Hospital associated C. difficile infection^a	96 (92.3)	78 (78.0)	<0.01
Recurrence (≥1)	35 (33.7)	34 (33.3)	0.96
Multiple recurrence (≥2)	14 (13.5)	17 (16.6)	0.52
30-day mortality	21 (20.2)	8 (7.8)	0.01
One-year mortality	56 (53.8)	36 (35.3)	<0.01
Charlson comorbidity index	2.9 (±2.0)	2.7 (±1.9)	0.53
Intensive care unit	3 (2.9)	1 (1.0)	0.32

^a Two patients in the comparison group had primary infections that were defined as indeterminate.

Figure 3. One-year survival rate after CDI among patients infected with C. difficile of RT046 (dashed line) compared to the comparison group (continuous line).

Table 2. Risk factors for 30-day mortality among patients with Clostridioides difficile infection.

		Odds ratio (95% CI)		Odds ratio (95% CI)
Characteristics	Number of patients who died within 30 days/total no. (%) of patients	Unadjusted	p-value	Adjusted	p-value
Ribotype
Comparison group	8/102 (7.8)	ref		ref
Ribotype 046	21/104 (20.2)	3.0 (1.3–7.1)	0.01	3.1 (1.3–7.5)	0.01
Age
18–69	3/39 (7.7)	ref		ref
70–79	6/57 (10.5)	1.4 (0.3–6.0)	0.79	not significant
≥80	20/110 (18.2)	2.7 (0.7–9.5)	0.07	not significant
Sex
Female	15/115 (13.0)	ref
Male	14/91 (15.3)	1.2 (0.6–2.7)	0.63
Antibiotic prior to C. difficile infection
Narrow	4/28 (14.3)	ref
Broad	25/178 (14.0)	0.98 (0.3–3.1)	0.97
Antibiotic treatment
Metronidazole	19/153 (12.4)	ref
Vancomycin (in combination or not with metronidazole)	5/32 (15.6)	1.3 (0.4–3.8)	0.89
None	4/18 (22.2)	2.0 (0.6–6.8)	0.37
Acquisition
Community associated	3/30 (10.0)	ref
Hospital associated	26/174 (14.9)	1.6 (0.4–5.6)	0.48
Charlson comorbidity index
0–3	16/145 (11.0)	ref		ref
4–6	8/51 (15.7)	1.5 (0.6–3.7)	0.22	1.6 (0.6–4.2)	0.30
7–9	5/10 (50.0)	8.1 (2.1–30.9)	<0.01	8.2 (2.0–33.1)	<0.01

Table 3. Antibiotic treatment for primary Clostridioides difficile infection caused by ribotype 046 compared to the six next most common ribotypes (comparison group).

Antibiotic treatment	No. (%) of patients infected with C. difficile of:
	Ribotype 046 (n = 100)^a	Comparison group (n = 85)^a	p-value
Metronidazole	80 (80)	73 (85.9)	0.29
Vancomycin	5 (5)	6 (7)	0.56
Vancomycin and Metronidazole	15 (15)	6 (7)	0.09

^a Three patients with ribotype 046 and 15 in the comparison group did not receive any treatment. Data is missing for one patient in the ribotype 046 group and 2 in the comparison group.

Figure 4. Ridom SeqSphere+ minimum spanning tree (MST) for 222 samples based on 2583 targets, pairwise ignoring missing values. Each colour of the circles represents a different ribotype. The size of the circles is not proportional to the number of isolates. The number on the lines shows the number of allelic differences. The length of the lines is not proportional to the allelic differences. Each number in the circles represents a single isolate and is according to the sampling date.