MDR infection as a global public health event brings great challenges to clinicians, and they often face the situation that no sensitive antibiotics are available. The colonization of MDR is the basis for infection, which is widespread. Infection occurs when the body's resistance and immunity decline, so MDR infections are more common in elderly patients and pediatric patients. As we have shown, patients with MDR infection were mostly distributed in departments dominated by elderly patients and pediatrics, with an average age of 61.3 years. ICU contributed the most to MDR, which is consistent with the previous report [12]. Compared with general patients, patients in ICU have more chronic coexisting diseases and more severe acute physiological disorders, so they are in a state of relative immunosuppression [13]; the frequency of indwelling catheter is very high in ICU patients, which provides a path for microorganisms to invade; patients in ICU are faced with higher pressure of bacterial selection and colonization; these are the main reasons. Geriatrics, respiratory department, and rehabilitation department are mainly based on elderly patients who have been hospitalized for a long time, often accompanied by lung infections, so MDR frequently appears in these departments. The high incidence of MDR in cardiac and macrovascular surgery is unexpected, which may be related to the large surgical trauma, long operation time, and high proportion of patients admitted to ICU for a brief transition after operation. Many patients in the dermatology and burns department are chronic wounds of skin and soft tissues, contributing most of the multidrug-resistant MRSA [14]. MDR derived from sputum specimens accounted for three quarters, which was the main source of Acinetobacter baumannii and Klebsiella pneumoniae. Therefore, the lung is the most vulnerable organ to MDR, and long-term bed rest and ventilator application are the susceptible factors [15]. Urinary tract infection account for a large part of all nosocomial infections [16], urine becomes the second largest source of MDR, which mainly is Escherichia coli. As a regional central hospital, patients with various acute and chronic wounds are often treated, which has become a wide source of secretions isolated for MDR [14]. In addition, MDR can originate from almost all systems, such as blood, chest, abdomen, and biliary tract.
The MDR acquired from the community was significantly higher than that in hospital, indicating that the prevalence of MDR in the community should also be paid attention to [17]. Nonstandard use of antibiotics in community or primary medical institutions is an important reason for the prevalence of MDR [18]. Comparing the mortality of patients infected with MDR in hospital and patients infected with common bacteria in hospital, the mortality of the former was significantly higher than that of the latter, which further confirmed that the infection of MDR is an independent risk factor for death [19], so reducing the infection of MDR is to reduce the mortality.
Gram-negative bacilli accounted for nearly 90% of all MDR, of which the main bacterial species were Acinetobacter baumannii, Klebsiella, Pseudomonas aeruginosa, and Escherichia coli. In recent years, the prevalence of ESBL producing organisms and carbapenemase producing organisms are increasing rapidly [20, 21]. ESBL is a class of enzymes that make bacteria resistant to most of the β - lactam antibiotics. Carbapenems are the most effective against infections caused by ESBL producing organisms [22]. Therefore, carbapenems play an important role in the field of anti-infectives. However, β - lactamases that can hydrolyze carbapenems have emerged, which seriously threatens the clinical utility of these antibiotics and “Extreme drug resistance” in Gram-negative bacilli leaves us helpless [23]. In this research, Acinetobacter baumannii were resistant to almost all carbapenems, and only had a high sensitivity to tigecycline, but 10% were resistant to all kinds of antibiotics. It is reported that this part of the bacteria is still sensitive to polymyxin [24], but not available in mainland China. ESBL-producing E. coli and ESBL-producing K.pneumoniae were highly sensitive to carboxycycline, penicillin, cefoxitin and piperacillin tazobactam, but carbapenemase producing enterobacteriaceae were only sensitive to tigecycline. Pseudomonas aeruginosa were highly sensitive to amikacin, and the sensitivity rate to other antibiotics was not more than 50%. Therefore, besides amikacin, quinolones, piperacillin, ceftazidime, and meropenem can still be selected to anti-Pseudomonas aeruginosa based on antibiotic sensitivity tests. In general, multidrug-resistant Gram-negative bacilli infections often leave us rare antibiotics to choose. MRSA as the most common multidrug-resistant Gram-positive bacteria were highly sensitive to vancomycin, linezolid, and quinoprptin / daptoptin, 70% of MRSA were sensitive to quinolones and were resistant to all other antibiotics. The emergence of MRSA resistant to vancomycin and linezolid needs to be vigilant, which makes clinicians helpless.
Prevention of the emergence and spread of MDR is an urgent international task. Measures are mainly divided into two types of strategies, one is to control the use of antibiotics, the other is to take a variety of infection control measures [25]. In China, the standardized use of antibiotics has only been emphasized in recent years, but the situation in primary and community hospitals is still worrying. Strictly maintaining good hand hygiene is the simplest and effective infection control measure. At the same time, strengthening the active monitoring of MDR and decolonizing when necessary are also effective measures.
In conclusion, MDR are mainly Gram-negative bacteria, which are distributed in almost all departments of the hospital. ICU contributes most of MDR and other departments dominated by elderly patients also have a large number of MDR. Pulmonary infection is the main origin of MDR. The five most common MDRS are Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and MRSA. MDR infection is an independent risk factor for death. Carbapenems are the most effective antibiotics for ESBL-producing Enterobacteriaceae, but tigecycline is the only effective one for carbapenemase producing Enterobacteriaceae. Vancomycin, linezolid, and quinoprptin / daptoptin are very effective against MRSA, but we need to be alert to the emergence of vancomycin-resistant MRSA. This study is helpful to understand the distribution of MDR in hospital and the extent of antibiotic resistance. The lack of susceptibility factors, underlying diseases, antibiotic application, and follow-up after discharge are the limitations of this article and need to be further studied.