Escherichia coli is one of the most common bacteria which producing extended-spectrum β-lactamase (ESBL) and is also one of the most common pathogens in clinical infections. In the past ten years, the prevalence of ESBL-PE colonization and infection has continued to increase dramatically worldwide [10], and these pathogens generally associated with delayed initiation of appropriate antimicrobial therapy and extra medical costs, hence leading to worse clinical outcomes [4]. Patients with malignancy are predisposed to developing infections caused by these resistant pathogens since cancer patients are easily immunocompromised due to frequently exposed to cytotoxic agents, surgery, radiation, malnutrition, and malignancy itself [3]. Therefore, timely and appropriate antibiotic therapy plays an essential role in cancer patients developed nosocomial infections caused by these pathogens. Thus, we conducted this seven years period retrospective study to investigate the clinical characteristics, antibiotic-resistant patterns, and prognostic factors associated with nosocomial infections caused by ESBL-PE in cancer patients.
In the present study, the prevalence of ESBL-PE infection is 15.4% (155/1008) among cancer patients. This finding was comparable with the studies conducted in Germany (17.5%) [11] and the Czech Republic (11.3%) [12] among patients with malignancy. Previous studies reported high colonization rates of ESBL-PE among cancer patients in Asia [13–15]. This could be explained by the fact that the prevalence of nosocomial infections among cancer patients varies widely from region to region. Our study demonstrated that ESBL-PE was primarily derived from urinary tract infections, followed by the bloodstream and abdominal cavity infections, which is consistent with the findings of many previous studies [16–19].
The results of this study suggested that the length of antibiotics treatment more than 6.93 days was independent risk factor for nosocomial infections in cancer patients caused by ESBL-PE. Biehl LM et al. [4] reported that nosocomial acquisition, recent antimicrobial use, ICU care, and prolonged hospitalizations were associated with increased ESBL-PE BSI risk in patients with malignancy. Besides, cancer patients constitute a population that is intrinsically vulnerable to developing FN since they frequently underwent radiation and chemotherapy. Therefore, beta-lactams with beta-lactamase inhibitors and carbapenems are widely considered the first-choice treatment option for infections caused by ESBL-PE in our hospital, and generally, the length of antibiotics treatment at least more than one week.
Nosocomial infections in cancer patients have been associated with increased mortality in this patient population [4]. Several studies [14, 15, 20] reported that the overall case-fatality was significantly higher in the ESBL-positive group compared with ESBL-negative group. Conversely, there was no significant difference in the 30-day mortality between patients with nosocomial infections caused by ESBL-PE and those infected with non-ESBL-PE in this study, similar to the findings of some previous studies [19, 21, 22]. This may be attributed to the use of many broad-spectrum antibiotics in the clinic due to the current high prevalence of ESBL-PE. In multivariate analysis, we found that ECOG performance status score more than 2 is an independent risk factor for 30-day mortality in cancer patients with nosocomial infections caused by ESBL-PE, which is consistent with the previous study [19]. An interesting finding of our study is that the presence of respiratory tract infection is an independent risk factor for 30-day mortality in these patients as well despite its small proportion in our cohort. This may have been due to respiratory tract infection is a strong independent predictor of chemotherapy interruption, which in turn impacts disease control [23]. Our analysis demonstrated that septic shock is also an independent risk factor for 30-day mortality in patients with ESBL-PE caused nosocomial infections, which is also similar to previous studies [14–16]. We also found that low lymphocytes count and serum albumin are independent risk factors for 30-day mortality in cancer patients with nosocomial infections caused by ESBL-PE. Lymphocytes count level is a standard indicator for assessing a patient’s immune status. Lymphocytopenia has been identified as a prognostic factor in several solid tumors since it was associated with a condition of cancer-induced immunodeficiency, which can limit tumor control following radiation and chemotherapy [24]. Several studies have shown that patients with hypoproteinemia were correlated with worse prognosis in hospitalized patients, and serum albumin level is generally used to evaluating patients’ nutritional status, organ function, and comorbidity [19, 25].
In this retrospective study, we observed that E. coli was highly sensitive to carbapenems, beta-lactams with beta-lactamase inhibitors, amikacin, and tigecycline, regardless of ESBL status. Compared with non-ESBL-PE, the isolated ESBL-PE were highly resistant to aztreonam and third-generation cephalosporins. We also observed that both ESBL-PE and non-ESBL-PE were associated with slightly increased resistance to fluoroquinolones. These observations are consistent with previous studies [26]. Thus, piperacillin/tazobactam or carbapenem should be used for the initial empirical treatment of cancer patients with nosocomial infections caused by ESBL-PE [4]. To our knowledge, this is the first study evaluated clinical characteristics, antibiotic-resistant patterns, and prognostic factors associated with nosocomial infections caused by ESBL-PE among cancer patients in China. However, our study has several limitations. First, there might be hidden biases in the analyses of the relationship in this retrospective study. Besides, this study was conducted from data at a single center. Therefore, it needs to be further validated in a prospective multicenter study. Moreover, we should perform more precise drug resistance gene detection to better understand the drug resistance patterns and the appropriate treatment options.