Discussion

In our study, a substantial number of patients in the adult ICU, Hematology clinic, and Oncology clinic displayed CRKP and CREC positivity in perianal swabs. These results emphasize the vulnerability of critically ill and immunocompromised patients to colonization with multidrug-resistant pathogens.

In a systematic review assessing infection risk following CRE colonization, the analysis of 1806 initially colonized patients revealed 299 clinical infections, yielding a cumulative infection rate of 16.5%. Furthermore, among the 223 previously colonized patients for whom the site of infection was reported, primary bloodstream infections were identified in 30 patients (13.4%). ^{Reference Tischendorf, de Avila and Safdar5} Similarly, in a study assessing the risk of CRKP-related BSI in colonized patients, it was observed that 37 out of 353 patients (11%) developed CRKP-related BSI. ^{Reference Giacobbe, Del Bono and Bruzzi6} Kontopoulou et al. investigated 498 patients, of which 226 exhibited rectal colonization by CRKP. Among these, 48 patients (21%) developed a CRKP-related BSI. Their findings indicated a median time of 8 days from hospital admission to the detection of CRKP rectal colonization, with a subsequent median time of 4 days from colonization to the development of BSI. ^{Reference Kontopoulou, Iosifidis and Antoniadou7} In our study, BSI rates among patients exhibiting CRKP growth in PAS samples demonstrated variation ranging from 3.7% to 9.58%. Among the patients with PAS (+), 17 had CRKP growth in blood culture whereas only 1 had CREC growth in blood culture. Across departments, our study found a median time of 19 to 57 days from hospital admission to CRKP BSI identification and 13 to 92 days from CRKP rectal colonization to BSI onset. We believe that the disparities in bloodstream infection rates among colonized patients in the literature, as well as the variations in median times of infection development following hospitalization and PAS positivity, could stem from differences in patient cohorts and hospital wards, as well as the colonization status of patients prior to admission.

Chu et al. conducted an investigation involving a total of 1203 patients, among whom 85 were found to be colonized by CRE. Out of these, 21 patients developed CRE infections, with 13 of them progressing to CRE-related BSI. The study highlighted a heightened prevalence of intestinal CRE colonization, especially among hospitalized patients and those in ICU, indicating potential rapid horizontal transmission and strongly suggesting a correlation between intestinal colonization and the occurrence of CRE-related BSI in hospitalized patients, underlining the possibility that the infecting strains might be linked to their colonized counterparts. ^{Reference Chu, Hang and Li8} In our study, CVC-BSIs were identified as a notable source in both the adult ICU and Hematology clinic, highlighting the importance of catheter care and infection control measures in preventing such infections. We believe that the heightened incidence of invasive procedures might be a contributing factor to this elevated (9.58%) BSI rate in adult ICU.

Xu et al. investigated 2914 patients with hematological diseases via analyzing perianal swabs. Seventy-four patients were identified with CRE, and among them, 13 (17.5%) experienced CRE-related bloodstream infections. CRKP rectal colonization was identified as an independent risk factor for CRE-related BSI and suggested that rectal swab screening could serve as an early warning for subsequent CRE-related BSI. ^{Reference Xu, Su and Lyu9} In our study, out of 288 Hematology clinic patients, 33.6% tested positive for PAS CRKP (+) and 31.2% for PAS CREC (+), with 7 patients in the CRKP group and 1 patient in the CREC group having corresponding pathogens in blood cultures. Moreover, this study highlighted the significance of monitoring intestinal CRE colonization, not just in ICU or oncologic patients, but also in individuals with hematologic diseases.

Alon et al.’s research demonstrates the effectiveness of implementing infection control measures, including maintaining a case registry, strict contact isolation, and dedicated nursing staff, in significantly reducing acquisition rates of carbapenem-resistant Acinetobacter baumannii (CRAB) during a hospital-wide outbreak (p < 0.001). ^{Reference Alon, Mudrik, Chowers and Shitrit10} Although the study primarily examines CRAB, we contend that the principles of surveillance and isolation can be applicable to CRE prevention as well.

Our study has several limitations, such as its retrospective nature, the absence of an assessment regarding compliance with infection control measures, and the lack of admission samples with molecular analysis of carbapenemase types preventing determination of whether patients were colonized on admission or acquired CRE in the hospital. Additionally, the study’s design primarily emphasizes epidemiological data rather than delving into the clinical aspects of the patients.

In conclusion, our findings highlight the increased susceptibility of critically ill and immunocompromised patients to multidrug-resistant pathogens, reinforcing the need for vigilant surveillance and infection control strategies. The high yield of PAS in this study supports the practice of targeted screening in high-risk units that can aid in earlier detection, providing the opportunity to apply infection control precautions to prevent transmission and potentially reduce adverse clinical outcomes.