Acinetobacter baumannii is a non-fermenting gram-negative bacterium, which is one of the important opportunistic pathogens causing hospital infection. In recent years, hospital infection caused by Acinetobacter baumannii has increased year by year, especially in intensive care unit ( ICU ).

Currently, there is a growing number of reports on the isolation, infection, and drug resistance of Acinetobacter baumannii.

Isolated from human infections and hospital outbreaks [1]. According to the latest CHINET data in China, the clinical isolation rate of Acinetobacter in 2012 was 10.1 %, of which Acinetobacter baumannii accounted for 91.5 %[2]. Respiratory tract marker

The isolation rate of Acinetobacter baumannii in this study was 17.3 % . Multidrug-resistant strains of A.baumannii have been found in hospitals in Europe, North America, Argentina, Brazil, China, Japan and South Korea, as well as in the South Pacific island of Tahiti. [3,4] In recent years, Acinetobacter baumannii has shown increasing resistance to commonly used antibiotics worldwide.

Medicinal properties [5]. According to the latest drug resistance survey published on CHINET ( 2023 ), the resistance rate of Acinetobacter baumannii to imipenem was 66.7 %, and the resistance rate to meropenem was 69.3 %. The resistance rates to cefoperazone-sulbactam and minocycline were 43. 5 % and 44. 4 %, respectively. The resistance rates to polymyxin B and tigecycline were low ( 0. 1 % and 6. 0 % ).

The drug resistance rate of the test drugs was more than 40 % [6].

Acinetobacter baumannii is the most important opportunistic pathogen of nosocomial infection in the world. Due to the failure of clinical anti-infection treatment caused by bacterial resistance and the outbreak of nosocomial infection, Acinetobacter baumannii poses a great threat to human health. In particular, patients with weak immune resistance are more likely to be infected by this opportunistic pathogen. Therefore, the study of Acinetobacter baumannii has extremely important clinical significance.

This study aims to clarify the distribution of multidrug-resistant Acinetobacter baumannii strains detected in ICUs of major hospitals in Xinjiang Uygur Autonomous Region through homology analysis,the results can be used to monitor the hospital infection management and monitoring departments of hospitals at all levels in Xinjiang. Provide important theoretical basis.

Acinetobacter baumannii is one of the major pathogens causing nosocomial infections worldwide in recent years [7], especially carbapenem resistant strains, which bring great difficulties to clinical treatment. Some literatures have reported that Acinetobacter baumannii has strong biofilm forming ability. When the bacteria exist in the form of biofilm, the drug resistance and pathogenicity are significantly enhanced [8,9]. According to the data analysis of the expert committee of the bacterial drug resistance monitoring network of Xinjiang Autonomous Region, the resistance rate of Acinetobacter baumannii to carbapenems was 56.4% in 2023, which was 75.5% in our hospital, which was also higher than the report of nearly 70% in Chinet bacterial drug resistance monitoring in 2023 [10]. In addition, prolonged hospitalization and the use of expensive antibiotics have significantly increased the incidence, mortality and medical costs of iatrogenic infections caused by multidrug-resistant bacteria.

In this study, we collected 72 multidrug-resistant Acinetobacter baumannii strains that met our criteria from the ICUs of nine hospitals across Xinjiang.The purpose was to understand the distribution of drug-resistant clones in hospitals in various regions. The results of this study can provide important theoretical basis for the monitoring of nosocomial infection management and monitoring departments in hospitals at all levels in Xinjiang. Many scholars have successively reported the advantages and disadvantages of various genotyping methods [11,12]. The diversilab system was used in this study. According to the analysis reported by quyanyan et al. [13], this method has the advantages of simple operation, high throughput and strong typing ability. Repeat based PCR primers are paired with many repeats that are specific to the entire genome; After PCR amplification, multiple fragments with different lengths were formed. According to their quality differences, these amplified fragments were electrophoretically analyzed to obtain repetitive sequence PCR DNA fingerprints composed of multiple bands with different strengths and specificities. This method was used to study the homology of multidrug-resistant Acinetobacter baumannii in Xinjiang, and the results were divided into four different clonal types: 43 strains of multidrug-resistant Acinetobacter baumannii from the same source were detected in 9 regions (prefectures) of Xinjiang with genotype 1, which were distributed in all regions. The experimental results showed that 20 strains were distributed in Urumqi, 5 strains in Aksu, 4 strains in Turpan, 3 strains in Kashgar, 4 strains in Korla, 2 strains in Shihezi, 3 strains in Ili, 1 strain in Hetian and 1 strain in Changji, indicating the spread of multidrug-resistant Acinetobacter baumannii in different regions, hospitals, wards or the same region, hospitals, wards in Xinjiang. Whether it is due to the clonal transmission of carbapenem resistant Acinetobacter baumannii remains to be further studied. Type 3 is a unique clone strain in Urumqi. Clinical data showed that five strains of multidrug-resistant Acinetobacter baumannii were simultaneously cultured from blood, secretions, and sputum samples of different burn patients in SICU in August 2017; At the same time, another multidrug-resistant Acinetobacter baumannii was isolated from the drainage fluid sample of another patient in SICU. The patient was clinically diagnosed with spinal stenosis; At the end of August and the beginning of September, all burn patients were transferred to the burn wound repair department, and the same drug-resistant bacteria as SICU were cultured from the venous catheter tip, secretion, and sputum samples; At the same time, the same drug-resistant bacteria as SICU were also cultured from the secretion samples of patients with electrical injury in this department. According to the polymorphism of amplified fragments, the similarity coefficient between strains was 95% - 100%, suggesting that multidrug-resistant Acinetobacter baumannii from the same source was detected; It showed that the clone had cross transmission in SICU, and there was cross transmission between SICU and burn wound repair ward. One of the cloned strains originated from the ICU of Hotan District Hospital, which may be related to the transfer of patients. The genotype of type 2 appeared in Urumqi and Hetian area. The characteristics of this group were that six strains of the same genotype were isolated from different ICU (RICU, SICU, nsicu) patient specimens, and the three ICUs were distributed in different areas and floors of the hospital. Secondly, ICU did not accompany, and medical staff did well in personal protection when entering and leaving the ward. However, the patients were transferred. The main factors leading to the spread were closely related to environmental pollution and hand hygiene, which was consistent with the report of liuyanyuan et al. [14]. At the same time, it was found that there were different strains in SICU, suggesting that different clonal strains may cross infect in the hospital. There are two strains of bacteria isolated from the respiratory ward in Hotan, belonging to the same genotype, suggesting that Urumqi and Hotan also have homology. The genotype of type 4 was distributed in Changji and Hotan regions, showing a unique significant band; Through the analysis of clinical data: isolated from the respiratory ward on August 10, 2022, the specimen was sputum, which was clinically diagnosed as pulmonary infection; Isolated from ICU on August 23 of the same year, the specimen was sputum, which was clinically diagnosed as acute attack of chronic bronchitis; On September 6 of the same year, it was isolated from the respiratory ward. The specimen was sputum. The clinical diagnosis of emphysema was made. The above three strains of drug-resistant Acinetobacter baumannii were from Hotan hospital, and the similarity coefficient was 99%. It showed that the same clonal strain existed in the patient standard of ICU 20 days after discharge of the former infected patient and 1 month after discharge, and the multi drug-resistant Acinetobacter baumannii with homology was still detected in the patient specimens of the same department. It is suggested that the environmental sanitation disinfection of the ward is not complete, and the multi drug resistant Acinetobacter baumannii cannot be completely killed: this clone strain is an epidemic strain in Hotan area, and there are 6 strains in Changji area. It belongs to type 4 clonal strain, and all strains are from ICU. The difference between hospital and discharged patients is 45 months. The specimen is sputum. The clinical diagnosis of severe pneumonia and lung infection: it indicates that there is cross infection between ICU patients, indicating that Changji and Hotan regions have homology, and it is also the main epidemic strain in Changji region. At the same time, the drug resistance rate of type 1 and type 3 clones was compared, and type 3 was slightly higher than type 1.

In this experiment, 8 biofilm related genes and several significant resistance efflux pump genes of Acinetobacter baumannii isolated from clinical samples were amplified by PCR to explore the potential correlation between tigecycline resistance and biofilm formation ability. This study indicates that the multidrug resistance group increased the transcription level of BFS genes and the corresponding biofilm formation ability. BFS is closely related to the formation of biofilms. The drug resistance rate of the BFS gene positive group was higher than that of the relative gene negative group (chi square test, P<0.05). Consistent with this, the expression level of the efflux pump gene AdeB in the multidrug-resistant Acinetobacter baumannii group was significantly higher than that in the non resistant group. Therefore, it can be considered that the multidrug-resistant Acinetobacter baumannii isolated clinically in our hospital is significantly correlated with BFS. Drug resistance is mainly caused by the efflux pump genes adeB and bfs. However, the potential regulatory mechanisms of these two genes at the transcriptional level need further explanation.

In conclusion, analyzing the epidemic characteristics of clonal strains in Xinjiang, local (state) hospitals should attach great importance to monitoring Acinetobacter baumannii in the ward environment, especially when it is necessary to transfer hospitals and departments: cut off the spread and scattered transmission of multidrug-resistant Acinetobacter baumannii in Xinjiang, hospitals, departments and wards, and prevent cross infection.