Overview of Carbapenem-Resistant Enterobacteriaceae

Overview of Carbapenem-Resistant Enterobacteriaceae. This article provides a comprehensive review of carbapenem-resistant Enterobacteriaceae (CRE). Carbapenem-resistant Enterobacteriaceae have emerged, which confer broad resistance to most ß-lactam antibiotics including last-line carbapenems. Infection with Carbapenem-resistant Enterobacteriaceae is emerging as an emerging and serious global public health threat. Carbapenem-resistant Enterobacteriaceae is widely spread and is now a major factor in morbidity and mortality in health-care settings. Continued research is desperately needed to determine the most appropriate treatment for serious Carbapenem-resistant Enterobacteriaceae infections.


Introduction
Respiratory infection is one of the most common diseases in the world, with high incidence and mortality. Enterobacteriaceae is the most clinically important gram-negative pathogenic bacteria, which are increasingly being reported worldwide. Antimicrobial resistance is globally recognized as one of the greatest threats to public health. For years, carbapenems have been used successfully to treat infections due to resistant Enterobacteriaceae, such as Escherichia coli and Klebsiella pneumoniae. However, recently Carbapenem-resistant Enterobacteriaceae have emerged, which confer broad resistance to most ß-lactam antibiotics including lastline carbapenems. Carbapenem-resistant Enterobacteriaceae refers to Enterobacteriaceae that are resistant to any drug of ertapenem, Doripenem, imipenem, meropenem, or enterobacteriaceae that produce carbapenemase. Infection with Carbapenem-resistant Enterobacteriaceae is emerging as an important challenge in healthcare settings and a growing concern worldwide, it is very easy to spread in patients with long-term hospitalization or low immunity, leading to nosocomial infection, and may even cause a small-or large-scale outbreak [1][2][3] or asymptomatic colonization, among which Ventilator-associated pneumonia (VAP) was the most common [5]. Severe pneumonia has always been a common respiratory disease, which can endanger life. Statistics [6] show that infectious diseases account for 30% of all deaths worldwide, with severe pneumonia leading the way.
Carbapenem-resistant Enterobacteriaceae infection was reported in 68.8% of patients with hospital acquired bacterial pneumonia [7]. Consistent mortality rates of 40-50% are observed among inpatients with infections caused by CRE in hospitals worldwide, while the mortality rate from CRE infection in pneumonia patients is as high as 60% [8]. Carbapenem-resistant Enterobacteriaceae infection is a very difficult problem in clinical practice.

Risk Factors of Acquisition of CRE Infection
There are a number of factors that predispose persons to infections by CRE. Exposure to these resistant organisms can cause

Treatment Options for CRE Infections
There are numerous different types of carbapenemase enzymes, each conferring varying spectrums of resistance. In general, the presence of a carbapenemase confers broad resistance to most ß-lactam antibiotics including penicillins, cephalosporins, and the monobactam aztreonam (excluding metallo-β-lactamases [MBLs] and oxacillinases [OXAs]) [13]. At present, the main drugs for the treatment of CRE in the world are polymyxins, Tigecycline, fosfomycin, Ceftazidime-Avibatam and aminoglycoside antibiotics.
Polymyxins and tigecycline were highly sensitive to CRE in vitro vomiting, nausea, constipation, and anxiety [14].
Combination therapy for CRE infections may decrease mortality compared with monotherapy. Benefits of combination therapy include reduction of initial inappropriate antimicrobial therapy, potential synergistic effects, and suppression of emerging resistance [15]. For patients who are critically ill or with deep-seated infections, consider empiric and antibiogram-directed combination therapy with 3 drugs, basing on antimicrobial sensitivity results.
Polymyxins may be most effective as part of a combination for serious CRE infections [15,16].

Conclusion
In summary, the burden of carbapenem-resistant Enterobacteriaceae is increasing rapidly worldwide. CRE is widely spread and is now a major factor in morbidity and mortality in health-care settings. The results at present are still not good, especially in elderly patients with a history of CRE infection. The extremely high mortality rates of patients with CRE infections have driven efforts to prevent the acquisition and spread of these bacteria in hospitals. Although the above measures are simple, they can prevent the spread of CRE to some extent. However, continued research is desperately needed to determine the most appropriate treatment for serious CRE infections.