Identification of risk factors for Clostridium difficile infection in older adult hospitalized patients with pressure ulcers

Abstract

BACKGROUND

Clostridium difficile (C. difficile) infection (CDI) is a common healthcare-associated infection. Older adult hospitalized patients with pressure ulcers are more susceptible because of low immunity and disordered flora, but their specific risk factors are unknown. This study hypothesizes that the use of antibiotics for more than 2 weeks, the use of proton pump inhibitors (PPIs), and the use of β-lactam antibiotics are independent risk factors for CDI in this population.

AIM

To determine the risk factors for CDI in hospitalized older adults with pressure ulcers.

METHODS

A total of 120 older adults hospitalized with pressure ulcers from 2020 to 2023 were enrolled in the wound repair ward of the hospital. Stool samples were collected for anaerobic culture, C. difficile glutamate dehydrogenase (GDH) antigen and toxin detection, and multivariate logistic regression was used to analyze risk factors.

RESULTS

Among 120 older adults hospitalized patients with pressure ulcers, 39 tested positive for C. difficile, with an incidence rate of 32.5%. Thirty-nine patients (32.5%) were positive for GDH antigen. Twelve patients (10.0%) were positive for toxin A/B. Multivariate analysis shows that the use of antibiotics for more than 2 weeks, the use of proton pump inhibitors, and the use of β-lactam antibiotics are independent risk factors for CDI (all P values < 0.05).

CONCLUSION

From 2020 to 2023, the incidence of CDI in 120 hospitalized older adult patients with pressure ulcers was 32.5%, and three independent risk factors were identified.

Key Words: Older adult patients; Pressure ulcers; Wound repair ward; Clostridium difficile; Infection; Risk factors; Detection

Core Tip: This study shows that the incidence of Clostridium difficile infection inolder adult hospitalized patients with pressure ulcers is 32.5%. The use of antibiotics for more than 2 weeks, the use of proton pump inhibitors, and the use of β-lactam antibiotics are independent risk factors, providing important evidence for targeted clinical prevention and control.

INTRODUCTION

Clostridium difficile (C. difficile) is a gram-positive, spore-forming anaerobic bacterium transmitted through the fecal-oral route[1]. After colonization of the intestine, C. difficile releases two exotoxins, namely, TcdA and TcdB. These toxins are the main causative factors driving the development of C. difficile infection (CDI)[2]. The severity of CDI ranges from asymptomatic colonization and self-limiting diarrhea to potentially life-threatening fulminant colitis, a major cause of antibiotic-associated diarrhea[3]. Recent studies have indicated that C. difficile colonization is more likely in patients with a history of recent hospitalization or those receiving proton pump inhibitors (PPIs) or corticosteroids[4].

Older adult patients face a greater risk of CDI because of frequent hospital admission and age-related changes, including weakened immunity and disrupted gut microbiota[5]. Consequently, both antibiotic exposure and an age over 65 years are recognized as independent risk factors for CDI[5]. The incidence of CDI has steadily increased in recent years, with older adult patients experiencing higher recurrence rates, greater severity, and increased mortality[6]. Identifying risk factors in this population is therefore critical for improving outcomes.

Pressure ulcers are injuries to the skin and underlying tissue caused by prolonged pressure and commonly affect areas over bony prominences such as the sacrum, heels, and occiput[7]. They frequently develop in bedridden patients who remain in one position for extended periods[7]. As the population ages, the incidence of pressure ulcers increases accordingly, with the prevalence among hospitalized patients reaching 8.4%[7]. Moreover, pressure ulcers may further increase the risk of CDI, as affected patients often have poor nutritional status and compromised immune function[8]. Despite this clear association, few studies have investigated the risk factors for CDI in hospitalized older adult patients with pressure ulcers. This study identifies the risk factors for CDI by analyzing the clinical and laboratory data of older adult hospitalized patients with pressure ulcers, thus providing support for the formulation of effective treatment and prevention strategies.

MATERIALS AND METHODS

Study population

From January 2020 to December 2023, fresh stool samples were collected from 120 older adult patients with pressure ulcers in the wound repair ward of Hangzhou Geriatric Hospital. The diarrhea patients were divided into a CDI group and a non-CDI group according to whether C. difficile was detected in the stool. During the research period, the stages of pressure sores in hospitalized older adult patients were relatively evenly distributed, with no noticeable aggregation observed. During the same period, fresh stool samples were collected from 216 older adult hospitalized patients without pressure ulcers in the medical ward for C. difficile and toxin detection. Both groups of patients were long-term bedridden patients.

All older adult hospitalized patients with pressure ulcers included in the study met the diagnostic criteria for pressure ulcers, and their pressure ulcer staging was determined according to the “Clinical Practice Guidelines for the Prevention and Treatment of Pressure Injuries” jointly developed by the National Pressure Ulcer Advisory Panel, the European Pressure Ulcer Advisory Panel and the Pan-Pacific Pressure Injury Association.

Instruments and reagents

The following instruments and reagents were used in this study: A CO₂ incubator (Thermo Fisher Scientific), a C. difficile Quik Chek Complete Assay (TechLab) for the detection of C. difficile glutamate dehydrogenase (GDH) antigen and toxin, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), a biosafety cabinet (Health Force), C. difficile selective medium (cycloserine-cefoxitin-fructose-agar, Oxoid), and an anaerobic gas-generating bag (bioMérieux).

Isolation, cultivation, and identification of strains

After being treated with absolute ethanol, the fecal samples were vortexed and left to stand at room temperature for 60 minutes. Following centrifugation at 3000 rpm for 10 minutes, the pellet was inoculated onto cycloserine-cefoxitin-fructose-agar (CCFA) plates and incubated anaerobically at 37 °C for 48 hours. Large yellow colonies with rough surfaces and irregular edges were selected. Under ultraviolet irradiation, these colonies exhibited yellow–green fluorescence and were identified as C. difficile by MALDI-TOF MS.

Detection of GDH antigens and toxins

To detect C. difficile GDH antigens and toxins, 750 μL of diluent, one drop of conjugate, and 25 μL of stool sample were thoroughly mixed in a test tube. Aspirate 500 μL of in-tube solution and add it to the sample well of the assay kit. After 15 minutes of incubation at room temperature, 300 μL of wash buffer was added to the reaction window so that it was fully absorbed, after which two drops of substrate were added to the reaction window. The samples were incubated at room temperature for 10 minutes, after which the results were read.

Data collection

Clinical variables, such as sex, age, hospital stay duration, wound healing time, the duration of nasogastric feeding, the presence of diabetes, and the duration of antibiotic treatment, were obtained from electronic medical records to identify the factors associated with CDI in older adult hospitalized patients with pressure ulcers.

Statistical analysis

The data were analyzed via SPSS 24.0 (IBM SPSS). Categorical variables are expressed as percentages and were compared via χ² tests. Continuous variables are presented as the mean ± SD if normally distributed and were compared via Student’s t test; nonnormally distributed data are reported as the median and interquartile range (IQR) and were analyzed via the Wilcoxon rank-sum test. Variables with statistical significance in the univariate analysis were included in a multivariate logistic regression analysis to identify independent risk factors. A P value < 0.05 was considered to indicate statistical significance.

RESULTS

C. difficile detection

From January 2020 to December 2023, 120 fecal samples collected from older adult hospitalized patients with pressure ulcers were analyzed. C. difficile was isolated from 39 samples (32.5%). Among these patients, 69.2% had hospital stays exceeding two months, and 66.7% had received antibiotics for more than two weeks. All 39 positive cultures were also GDH positive, indicating a GDH positivity rate of 32.5%. Toxins A and B were detected in 12 patients, resulting in a toxigenic C. difficile infection rate of 10.0%.

Comparative analysis of the CDI and non-CDI groups

This study included 120 older adult inpatients with pressure ulcers divided into CDI and non-CDI groups on the basis of their C. difficile culture results. Significant differences in the length of hospital stay (P value = 0.030), duration of antibiotic use (P value = 0.001), and use of PPIs (P value < 0.001) and β-lactam antibiotics (P value = 0.001) were detected (Table 1). Similarly, laboratory parameters, including white and red blood cell counts; hemoglobin, platelet, C-reactive protein, and procalcitonin levels; and liver and kidney function markers, did not significantly differ between the groups (all P values > 0.05; Table 2).

Table 1 Univariate analysis of Clostridium difficile infection in older adult hospitalized patients with pressure ulcers, n (%).

Factor	CDI group (n = 39)	Non-CDI group (n = 81)	P value
Sex			0.169
Male	24 (61.5)	39 (48.1)
Female	15 (38.5)	42 (51.9)
Age, years			0.101
> 80	33 (84.6)	39 (48.1)
≤ 80	6 (15.4)	42 (51.9)
Length of hospital stay, month			0.030
> 2	27 (69.2)	39 (48.1)
≤ 2	12 (30.8)	42 (51.9)
Wound healing time, month			0.578
> 2	27 (69.2)	60 (74.1)
≤ 2	12 (30.8)	21 (25.9)
Duration of nasogastric feeding, month			0.535
> 1	24 (61.5)	45 (55.6)
≤ 1	15 (38.5)	36 (44.4)
Diabetes	12 (30.8)	18 (22.2)	0.311
Duration of antibiotic use, week			0.001
> 2	26 (66.7)	27 (33.3)
≤ 2	13 (33.3)	54 (66.7)
PPI use	25 (64.1)	27 (33.3)	< 0.001
Type of medication
Quinolones	6 (15.4)	9 (11.1)	0.507
Carbapenems	6 (15.4)	5 (6.2)	0.101
Aminoglycosides	2 (5.1)	3 (3.7)	0.751
β-lactams	18 (46.2)	15 (18.5)	0.001

CDI: Clostridium difficile infection; PPI: Proton pump inhibitor.

Table 2 Laboratory indicators of Clostridium difficile infection in older adult hospitalized patients with pressure ulcers.

Indicator	CDI group (n = 39)	Non-CDI group (n = 81)	P value
WBC (× 109/L)	7.8 (4.2, 12.6)	8.3 (4.0, 12.0)	0.394
RBC (× 1012/L)	3.29 (2.67, 4.06)	3.33 (2.79, 4.18)	0.631
HGB (g/L)	87 (69, 117)	88 (60, 124)	0.779
PLT (× 109/L)	126 (73, 204)	137 (89, 163)	0.051
CRP (mg/L)	27.5 (2.7, 140.2)	22.5 (2.5, 94.6)	0.285
PCT (ng/mL)	0.46 (0.10, 1.72)	0.43 (0.03, 1.09)	0.669
TB (μmol/L)	13.9 (6.9, 18.9)	15.6 (2.3, 53.4)	0.125
ALT (U/L)	24 (13, 59)	23 (7, 75)	0.745
AST (U/L)	20 (10, 67)	19 (5, 60)	0.451
ALB (g/L)	32.7 (29.8, 46.8)	34.1 (30.7, 55.0)	0.134
BUN (mmol/L)	5.54 (2.70, 9.80)	6.47 (2.38, 18.70)	0.069
Cr (μmol/L)	82 (50, 177)	82 (59, 120)	0.948

CDI: Clostridium difficile infection; WBC: White blood cell; RBC: Red blood cell; HGB: Hemoglobin; PLT: Platelets; CRP: C-reactive protein; PCT: Procalcitonin; TB: Total bilirubin; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; ALB: Albumin; BUN: Urea nitrogen; Cr: Creatinine.

Multivariate logistic regression analysis

Multivariate logistic regression revealed three independent risk factors for CDI in older adult inpatients with pressure ulcers: The use of PPIs [odds ratio (OR) = 6.952, 95% confidence interval (CI): 2.489–19.415, P value < 0.001], the use of antibiotics for longer than two weeks (OR = 5.469, 95%CI: 2.058–14.528, P value < 0.001), and the use of β-lactam antibiotics (OR = 5.791, 95%CI: 2.071–16.191, P value < 0.001) (Table 3).

Comparative analysis with older adult inpatients without pressure ulcers

From January 2020 to December 2023, stool samples from 216 older adult inpatients without pressure ulcers in our internal medicine ward were tested. Thirty-four patients tested positive for C. difficile (CDI incidence, 15.7%). Thirty-four patients tested positive for GDH antigen (15.7%). Fourteen tested positive for toxin A/B (6.5%). These results were significantly lower than the CDI incidence (32.5%) and toxigenic C. difficile infection rates (10.0%) in older adult inpatients with pressure ulcers.

Table 3 Multifactorial analysis of Clostridium difficile infection in older adult patients with pressure ulcers in the hospital.

Factor	OR (95%CI)	P value
Length of hospital stay > 2 month	2.032 (0.776-5.317)	0.148
PPI use	6.952 (2.489-19.415)	< 0.001
Antibiotic use exceeding 2 weeks	5.469 (2.058-14.528)	< 0.001
β-lactam antibiotic use	5.791 (2.071-16.191)	< 0.001

OR: Odds ratio; CI: Confidence interval; PPI: Proton pump inhibitor.

DISCUSSION

The global incidence of CDI has increased in recent years, largely driven by widespread antibiotic use[9,10]. Older adults are especially at risk because of weakened immunity, chronic health conditions, and extended or repeated hospital stays, all of which disrupt the gut microbiota and increase susceptibility to infection[11]. Age over 65 years is recognized as an independent risk factor for CDI[6,12]. CDI is associated with prolonged hospitalization, increased mortality, increased healthcare costs, and reduced quality of life[6,13].

Older adult patients with chronic conditions often experience prolonged hospital stays and immobility, increasing their risk of pressure ulcers[14,15]. These ulcers, compounded by age-related immune decline, increase the risk of infection, prolong recovery, and worsen outcomes[14,15]. Identifying risk factors for CDI in this population is essential for guiding effective prevention and treatment.

In this study, anaerobic culture alongside GDH antigen and toxin testing was employed to screen for CDI. GDH, a metabolic enzyme abundantly expressed by C. difficile, is highly sensitive for initial detection[16,17], whereas toxin immunoassays can be used to identify toxigenic strains by detecting toxins A and B. These test kits are efficient, easy to use, and well suited for routine laboratory application owing to their high sensitivity and specificity. The infection rate of toxigenic C. difficile was 10.0% in this series of cases, suggesting a low prevalence among older adult inpatients with pressure ulcers in our hospital. Positive PCR detection of residual gene fragments from asymptomatic carriers or cured patients is not a CDI that requires clinical intervention. The main focus in clinical practice is on toxin-positive CDI, not colonizers. The combined approach of “anaerobic culture + GDH antigen + toxin A/B detection" has a diagnostic accuracy (especially specificity) that is no less than that of PCR in clinically suspected CDI patients (especially the older adult inpatients with pressure ulcers in this study) through multilayer verification of “live bacteria confirmation + antigen screening + toxin confirmation”, is more in line with the core definition of clinical toxigenic CDI and is in line with the standardized diagnostic process recommended by domestic and international guidelines.

This study identified key risk factors for CDI among older adults who were inpatients with pressure ulcers. Multivariate analysis shows that the use of antibiotics for more than 2 weeks, the use of proton pump inhibitors, and the use of β-lactam antibiotics are independent risk factors for CDI. These associations may be explained by the age-related decline in immune function and immune dysregulation often observed in patients with prolonged hospital stays and pressure ulcers, which increase susceptibility to infection[5,18]. Long-term antibiotic use, particularly β-lactam use, disrupts the intestinal microbiota, facilitating C. difficile colonization[19,20]. PPI use may further increase the risk of CDI by damaging the colonic mucosa through acid suppression[21]. These findings underscore the importance of minimizing unnecessary antibiotic exposure and the cautious use of PPIs to reduce the risk of CDI in this high-risk population. Combined with the data of 216 older adult inpatients without pressure ulcers, this study further confirms that the incidence of CDI among older adult inpatients with pressure ulcers is significantly greater than that among older adult inpatients without pressure ulcers and that pressure ulcers are a potential risk factor for CDI among older adult inpatients.

In this study, the annual incidence of CDI among older adult inpatients with pressure ulcers from 2020 to 2023 was statistically analyzed: There were 7 cases in 2020, 10 cases in 2021, 12 cases in 2022, and 10 cases in 2023. The data is evenly distributed, with no obvious clustering phenomenon.

This study provides important insight into the CDI among older adult hospitalized patients with pressure ulcers. This study reveals that the use of antibiotics for more than 2 weeks, the use of proton pump inhibitors, and the use of β-lactam antibiotics are independent risk factors for CDI, emphasizing the need to develop targeted prevention strategies. Although the findings are valuable, they are limited by small sample sizes, a single-center design, and a lack of exclusion of other potential risk factors such as laxatives. These limitations have resulted in limited statistical power, which may restrict the generalizability of the results. Multiple meta-analyses and clinical studies have shown that the combined use of probiotics during antibiotic treatment can reduce the incidence of CDI in high-risk patients, such as those taking long-term broad-spectrum antibiotics and older adult hospitalized patients. However, this recommendation should be based on individual risk assessment and is not universally recommended. Owing to the constraints of retrospective data, this study did not systematically evaluate the relationship between probiotic use and CDI risk. Future studies should expand the sample size, conduct multicenter research, and further explore the impact of data on other potential risk factors, such as laxatives, to increase representativeness and statistical reliability. The introduction of more sensitive diagnostic tools, such as PCR, can further improve the accuracy of the results. In-depth investigations into the underlying mechanisms of CDI in this population are also needed. On the basis of the identified risk factors, targeted interventions should be developed, and their effectiveness and safety should be evaluated. Such interventions include early diagnostic screening for infectious diarrhea of unknown etiology, the cautious use of antibiotics and PPIs, and the maintenance of gut microbiota health. Long-term follow-up is recommended to assess the impact of CDI on survival rates and quality of life, thereby providing a basis for personalized prevention and treatment strategies.

CONCLUSION

In conclusion, this study identified high-risk factors for Clostridium difficile infection in older adult hospitalized patients with pressure ulcers and provided practical guidance for clinical management. Ongoing research is crucial for improving outcomes.

ACKNOWLEDGEMENTS

We sincerely thank the laboratory department and medical staff of Hangzhou Geriatric Hospital.