Study population
A total of 3274 patients fulfilling the CDI case definition criteria diagnosed between January 1, 2016, and December 31, 2020 were included. The median age of patients in the cohort was 66 years (interquartile range (IQR) 52–78). 1760 (54%) were men and 335(11%) were of Hispanic/Latino ethnicity. Whites (39.7%) and Asians (38.2%) were the predominant races in the cohort, with Blacks and other races accounting for 8.5% and 15.6% of the cohort, respectively. CDI cases were classified as healthcare facility associated (HCFA) in 1177 (36.2%), community-onset healthcare facility associated (CO-HCFA) in 768 (23.6%), and community-associated (CA) in 1310 (40.2%). Table 1 presents a summary of the distribution of socio-demographic factors in the CDI cases, broken out by case definition categories. CDI cases were diagnosed using EIA (31.5%), GDH (26.6%), and NAAT (41.8%).
Table 1
Demographic characteristics of patients with clostridioides difficile infection in San Francisco County, California from 2016 to 2020
| | Overall | CO | HCFO | CO-HCFA |
n | | 3274 | 1322 | 1180 | 772 |
Age (%) | < 45 years | 593 (18.2) | 361 (27.4) | 126 (10.7) | 106 (13.8) |
| 45–65 years | 1017 (31.2) | 401 (30.5) | 338 (28.7) | 278 (36.2) |
| 65–85 years | 1222 (37.5) | 429 (32.6) | 508 (43.1) | 285 (37.1) |
| > 85 years | 431 (13.2) | 125 (9.5) | 206 (17.5) | 100 (13.0) |
Ethnicity (%) | Hispanic | 356 (10.9) | 137 (10.4) | 133 (11.3) | 86 (11.1) |
| Non-Hispanic | 2211 (67.5) | 788 (59.6) | 887 (75.2) | 536 (69.4) |
| Unknown | 707 (21.6) | 397 (30.0) | 160 (13.6) | 150 (19.4) |
Race (%) | White | 1298 (39.6) | 538 (40.7) | 442 (37.5) | 318 (41.2) |
| Black | 421 (12.9) | 118 (8.9) | 177 (15.0) | 126 (16.3) |
| Asian | 859 (26.2) | 316 (23.9) | 357 (30.3) | 186 (24.1) |
| American Indian | 8 (0.2) | 5 (0.4) | 1 (0.1) | 2 (0.3) |
| Pacific Islander | 28 (0.9) | 12 (0.9) | 5 (0.4) | 11 (1.4) |
| Unknown | 660 (20.2) | 333 (25.2) | 198 (16.8) | 129 (16.7) |
Sex (%) | Female | 1508 (46.1) | 673 (50.9) | 482 (40.8) | 353 (45.7) |
| Male | 1766 (53.9) | 649 (49.1) | 698 (59.2) | 419 (54.3) |
HCFO = Healthcare Facility Onset, CO-HCFA = Community-Onset Healthcare Facility Associated, CA = Community Associated |
Medical conditions, clinical features, and previous medication exposures
Diabetes mellitus, chronic kidney disease, and chronic obstructive pulmonary disease were the three most prevalent conditions, present in 15.6%, 14.7%, and 9.6% of patients in the cohort, respectively. Table 2 summarizes the frequency distribution of selected medical conditions.
Table 2
Frequency distribution of medical comorbidities across the epidemiologic CDI case definition categories in San Francisco County, California, 2016–2020
| Overall | CA | HCFO | CO-HCFA |
n | 3274 | 1322 | 1180 | 772 |
Liver Disease (%) | 174 (5.3) | 71 (5.4) | 10 (0.8) | 93 (12.0) |
AIDS (%) | 45 (1.4) | 24 (1.8) | 1 (0.1) | 20 (2.6) |
HIV (%) | 104 (3.2) | 52 (3.9) | 4 (0.3) | 48 (6.2) |
Heart Failure (%) | 228 (7.0) | 72 (5.4) | 22 (1.9) | 134 (17.4) |
Hematologic malignancy (%) | 62 (1.9) | 26 (2.0) | 4 (0.3) | 32 (4.1) |
Non metastatic solid organ tumor (%) | 179 (5.5) | 94 (7.1) | 13 (1.1) | 72 (9.3) |
Metastatic Solid Organ Tumor (%) | 112 (3.4) | 45 (3.4) | 8 (0.7) | 59 (7.6) |
Organ transplant recipient (%) | 46 (1.4) | 21 (1.6) | 3 (0.3) | 22 (2.8) |
Stem cell transplant recipient (%) | 12 (0.4) | 6 (0.5) | 0 (0.0) | 6 (0.8) |
Diverticulosis (%) | 150 (4.6) | 89 (6.7) | 2 (0.2) | 59 (7.6) |
Inflammatory bowel disease (%) | 134 (4.1) | 103 (7.8) | 2 (0.2) | 29 (3.8) |
CKD (%) | 473 (14.4) | 221 (16.7) | 28 (2.4) | 224 (29.0) |
COPD (%) | 303 (9.3) | 162 (12.3) | 13 (1.1) | 128 (16.6) |
Diabetes (%) | 505 (15.4) | 233 (17.6) | 39 (3.3) | 233 (30.2) |
Total | 3274 | 1322 (40.4) | 1180 (36) | 772 (23.5) |
HCFO = Healthcare Facility Onset, CO-HCFA = Community-Onset Healthcare Facility Associated, CA = Community Associated, HIV = Human Immunodeficiency Virus, AIDS = Acquired Immunodeficiency Syndrome, COPD = Chronic Obstructive Pulmonary Disease, CKD = chronic kidney disease |
Watery diarrhea, nausea, and vomiting, observed in 29.5%, 7.,7%, and 5.7% of the cases, were the most frequent clinical presentations. In our assessment of exposure to medications within 12 weeks before the incident CDI, proton pump inhibitors (21%) were the medications most often identified. Vancomycin (10.6%) and ceftriaxone (10.1%) were the two most frequent antibiotic exposures.
The five-year mean cumulative incidence of CDI cases per 100,000 population was 78.2. The five-year mean case definition category-specific cumulative incidences per 100,000 for HCFO, CO-HCFA, and CA CDI were 27.6, 17.1, and 32, respectively. Figure 1 shows the trends in annual overall and CDI case definition category-specific cumulative incidence throughout the study period. There were 150 deaths within 30 days of admission, yielding a total all-cause 30-day mortality of 4.6%. Of the 150 deaths HCFO, CO-HCFA, and CA cases account for 60.7%, 24.7%, and 14.6% respectively. The rate of recurrent CDI cases was 11.1%. HCFO, CO-HCFA, and CA cases account for 4.9%, 46.9%, and 48.2% of recurrent cases, respectively.
Results of bivariate analysis for independent associations with unadjusted odds ratios
All-cause 30-day Mortality
In the bivariate analysis, we found several variables to be independently associated with increased odds of mortality. Compared to CA CDI, HCFO (OR = 7.4; 95% CI [4.7–12]) and CO-HCFA (OR = 3.6; 95% CI [2.2–6.2]) CDIs were both significantly associated with a higher odds of mortality. Compared to those 18 to 44 years of age, the odds of mortality were higher in those 45 to 64 (OR = 4.8; 95% CI [2.3–11.7]), 65–84 (OR = 6.4; 95% CI [3.2–15.3]), and ≥
85 (OR = 10.3; 95% CI [4.9–25.2]) years of age. A white blood cell count > 15,000 cells/mm3 and a serum albumin concentration < 2.5 mg/dl were also each associated with a higher odds of mortality with odds ratios of 2.2 (95%CI [1.4–3.6]) and 3.5 (95%CI [2–7]), respectively. Male sex was associated with a higher odds of mortality with an OR of 1.34 (95% CI [1.002-1.8]. Compared to Whites, Asians had higher odds of mortality, with an OR of 1.58 (95% CI [1.13–2.2]. Exposure to clindamycin (OR = 3.4; 95% CI 1.3–13.7) and to metronidazole (OR = 3.4; 95% CI [1.4–11.2]) in the 12 weeks before the incident CDI episode were each independently associated with an increase in the odds of mortality, as was ICU admission (OR = 4; 95% CI [2.6–6]). The presence of a hematologic malignancy was the only medical condition that was significantly associated with a higher odds of mortality (OR = 2.4 (95% CI [1.03–4.8]).
Recurrence of CDI
In the bivariate analysis, we found no statistically significant difference in the relative risk of CDI recurrence between the CA and HCFO cases categories. However, compared to CA cases, CO-HCFA cases had a higher risk of CDI recurrence with an RR of 1.78 (95% CI [1.3–2.5]). Compared to those 18 to 44 years of age, only those ≥ 85 years of age had a higher risk of CDI recurrence (RR = 2.2; 95% CI [1.25–4]).
Results of the multivariate logistic regression models with adjusted OR
All-cause 30-day mortality
In the multivariate logistic regression model, we found that HCFO (AOR = 3.1; 95% CI [1.3–7]) and CO-HCFA (AOR = 2.4; 95% CI [1.4–4.3]) CDI cases had a significantly increased odds of mortality, compared to CA CDI cases. Male sex and recent exposure to clindamycin and metronidazole were not significantly associated with increased odds of mortality in the adjusted model. (Table 3)
Recurrence of CDI
In the adjusted multivariate log-binomial regression model, we found that CO-HCFA and age ≥ 85 years were each significantly associated with an increased risk of recurrence, with adjusted relative risks of 1.7 (95% CI [1.2–2.4]) and 2 (95% CI [1.1–3.7]), respectively. None of the medical conditions, laboratory parameters, or ICU admission status were significantly associated with an increased risk of recurrence of CDI.