Abstract
Introduction:
Catheter-associated urinary tract infections (CAUTIs) are one of the most common infections encountered in healthcare settings. Candida spp. were excluded as the causative agents of CAUTIs as per Centres for Disease Control and Prevention (CDC) and National Healthcare Safety Network (NHSN) definitions in 2015.
Aim:
To determine the impact of the 2015 definition change on the CAUTI rate of patients admitted to medical and surgical intensive care units (ICUs) of a tertiary care and teaching hospital in India.
Method:
CAUTI rates were compared in both the ICUs over a period of two years with inclusion and exclusion of Candida spp.
Results:
Out of the total 116 CAUTI episodes during the study period, a mean of 9.08 CAUTIs per 1000 catheter days were observed in both the ICUs when Candida spp. were included, but the mean CAUTI rate was reduced to 4.78/1000 catheter days when Candida spp. were excluded.
Discussion/Conclusion:
The mean CAUTI rate decreased by 46.03% solely by excluding Candida spp. This significant reduction in CAUTI rates may be applicable to institutions having high rates of candiduria in catheterised patients, but may not be applicable in centres where the incidence of candiduria is already low. Disregarding Candida as a causative agent of CAUTI did not impact rates of central line-associated bloodstream infections during the study period.
Keywords: Catheter-associated urinary tract infection, healthcare-associated infections, urinary catheter
Introduction
Urinary tract infections (UTIs) are considered to be one of the most common healthcare-associated infections (HCAIs), accounting for over 30% of all HCAIs reported by hospital settings (Weiner et al., 2016). Yeast, particularly Candida spp., contribute to a significant number of CAUTI events in intensive care units (ICUs) (Padawaer et al., 2015). Candiduria in catheterised individuals mostly represent colonisation events and the incidence of colonisation increases with duration of indwelling catheterisation (Padawaer et al., 2015). Given the subjectivity of clinical features such as fever and laboratory features such as leucocytosis to distinguish Candida urinary tract colonisation from true infection events and the rarity of true urinary tract infection due to Candida spp., the Centers for Disease Control and Prevention (CDC) and the National Healthcare Safety Network (NHSN) has eliminated Candida spp. from the CAUTI surveillance definition (Allen-Bridson et al., 2015). Moreover, 15% of secondary bloodstream infections (BSI) may be erroneously classified as central line-associated bloodstream infections (CLABSI) if funguria is not classified as a CAUTI (Kieffer et al., 2015), thus leading to falsely inflated rates of CLABSIs. Even if Candida funguria is excluded from the CDC-NHSN surveillance definition of CAUTI, laboratories should still continue with speciation of non-albicans Candida spp., with particular attention to Candida auris, for purposes of infection control. The aim of the present study was to see the impact of the modified CDC-NHSN definition on the rate of CAUTIs over a period of two years in medical and surgical ICUs of a tertiary care and teaching hospital of India.
Method
The present study was conducted in the medical and surgical ICUs of a tertiary care and teaching hospital in India from 1 August 2017 to 31 July 2019. During these two years, the rates of CAUTI per 1000 catheter days were calculated using CDC-NHSN 2013 criteria as well as revised CDC-NHSN 2015 criteria. A combination of device criteria (indwelling catheter for a duration > 2 days), any one clinical criteria (fever, dysuria, urgency, frequency, suprapubic tenderness) and laboratory criteria (growth of up to two organisms with colony count of at least one organism being >105 colony-forming unit [CFU]/mL) was taken as the surveillance definition of CAUTI. As per the revised criteria, Candida spp. were not regarded as a cause of symptomatic UTIs if isolated as the sole pathogen. However, Candida spp. were regarded as a cause of CAUTI if it was isolated with any other bacterial pathogen with a colony count ⩾105 CFU/mL. In addition, the CAUTI events in which Candida spp. were isolated, were also analysed for average duration of catheterisation, bacterial co-infections, usage of broad spectrum antibiotics and secondary bloodstream infection.
Results
During the study period, a total of 74 CAUTI events were recorded from medical ICUs and 42 from surgical ICUs. Of the CAUTI events attributed to Candida spp., 43 (43/74, 58.1%) were in the medical ICUs and 15 (15/42, 35.7%) were in the surgical ICUs (Figures 1 and 2). The corresponding catheter utilisation ratios in the medical and surgical ICUs were 0.72 and 0.9, respectively. The average duration of catheterisation before the occurrence of CAUTI in the medical and surgical ICU rates was 9.5 and 4.1 days, respectively. Mean CAUTI rates in the medical and surgical ICUs including Candida spp. were 9 and 9.15 per 1000 catheter days, respectively. The mean CAUTI rates were reduced to 3.71 and 5.8 per 1000 catheter days in the medical and surgical ICUs when Candida spp. were excluded. During this period, out of a total of 116 CAUTI episodes in both the ICUs, a total of 125 microorganisms were isolated. Candida spp. were the predominant isolated microorganism (69/125, 55.2%) followed by E. coli and Enterococcus spp., in 14 cases each (14/125, 11.2%). Nearly all the bacterial isolates associated with CAUTIs were found to be multidrug-resistant. The overall mean rate of CAUTIs was reduced from 8.9 to 4.65 per 1000 urinary catheter days in both the ICUs when Candida spp. were included. The overall mean reduction rate was decreased by 46.03% (95% confidence interval [CI] = 0.67–1.34) solely on excluding candiduria. In the present study, we have included only symptomatic candiduria. Asymptomatic candiduria cases were not included in the analysis. Among the various Candida spp. contributing to symptomatic UTIs, 66.7% were attributed to various non-albicans Candida spp. Candida auris was isolated from one case of CAUTI during the study period, for which immediate infection control measures were initiated such as changing of the indwelling catheter, isolation of the patient and environmental sampling of areas surrounding colonised patients (Rhodes and Fisher, 2019). On follow-up, that patient did not develop invasive infections due to Candida auris.
Figure 1.
CAUTI rate per 1000 catheter days including and excluding Candida in the medical ICU. CAUTI, catheter-associated urinary tract infection; ICU, intensive care unit.
Figure 2.
CAUTI rate per 1000 catheter days including and excluding Candida in the surgical ICU. CAUTI, catheter-associated urinary tract infection; ICU, intensive care unit.
Discussion
From the current study, we found that the CAUTI rate was 9.08 per 1000 urinary catheter days in a period of 24 months, but the mean CAUTI rate was reduced to 4.78/1000 catheter days when Candida spp. were excluded. Exclusion of Candida spp. as the causative agent of CAUTI could achieve a reduction of 46.03% in the CAUTI rate. A similar finding was reported by Fakih et al. (2017) in which a reduction of more than 40% in the CAUTI rate was achieved after implementing the revised definition of NHSN (Fakih et al., 2017). This effect was more pronounced in large hospitals. Significantly higher rates of CAUTI have been observed from large teaching hospitals as compared to smaller hospitals (Dudeck et al., 2015). The proportion of Candida spp. as an aetiology of CAUTI varies depending on hospital size where almost 50% of the CAUTI events could be attributed to yeast; thus, its exclusion mostly benefits tertiary care centres (Tedja et al., 2015). In a multicentric study, the rate of CAUTI was found to be reduced to 25% by excluding funguria in the surveillance (Dicks et al., 2015). Bardossy et al. (2016), in a single-centre study, reported a reduction of approximately 50% in the rates of CAUTI, primarily due to the exclusion of candiduria (Bardossy et al., 2016). As per CDC-NHSN guidelines, a secondary bloodstream infection (BSI) may be erroneously classified as CLABSI if the fungal aetiology is excluded from CAUTI (Kieffer et al., 2015). There are few studies that evaluate the impact of change of the definitions of funguria and low levels of bacteriuria on the incidence of CAUTI rates (e.g. Fakih et al., 2017; Kieffer et al., 2015). In those studies, CLABSI rates increased by 27.1% and 15%, respectively. In the analysis by Fakih et al. (2017), Candida-associated CLABSI increased by 91.1%, from 0.104 to 0.198 per 1000 device days. In the analysis by Kieffer et al. (2015), 7.6% of fungal CAUTI were reclassified as primary CLABSI resulting in a non-significant 15% increase in the overall ICU CLABSI rate. In our analysis of BSI data (central line-associated as well as secondary BSI), there was no BSI event attributed to Candida during the two-year period. To conclude, the significant reduction in the rates of CAUTIs by adopting 2015 definitions is applicable to hospitals having high rates of candiduria in catheterised patients. We advocate that the urine culture results at colony counts for any bacteria as well as Candida spp. should be taken into account as matching cultures during the calculation of BSI events, to avoid unnecessary overestimation of CLABSI. All laboratories should speciate non-albicans Candida isolated from urine culture for continuous surveillance of Candida auris.
Limitation of the study
Hospitals previously having low levels of fungal CAUTI may not benefit from these definitions. The impact of the CDC definition could be better analysed with a large sample size.
Acknowledgments
Abstract published in ICPIC, 2019.
Footnotes
Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
Peer review statement: Not commissioned; blind peer-reviewed.
ORCID iD: Ashoka Mahapatra 
https://orcid.org/0000-0002-4046-7305
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