Abstract:Objective To study the bacterial resistance in different levels of hospitals in China from 2014 to 2019. Methods Data related to different levels of hospitals were extracted from reports of China Antimicrobial Resistance Surveillance System (CARSS) in 2014-2019, change in data of tertiary and secondary hospitals were analyzed and compared. Results From 2014 to 2019, the top 5 Gram-positive bacteria isolated from all hospitals were Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pneumoniae and Enterococcus faecium. Compared with tertiary hospitals, proportion of Streptococcus pneumoniae in secondary hospitals was higher. The top 5 Gram-negative bacteria from all hospitals were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacter cloacae. During 6 years, isolation rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase negative Staphylococcus (MRCNS) in tertiary hospitals decreased from 36.2% to 30.6% and 79.9% to 76.1% respectively, isolation rates of MRSA and MRCNS in secondary hospitals also decreased. Isolation rate of vancomycin-resistant Enterococcus faecalis in tertiary hospitals was lower than that in secondary hospitals, isolation rates of vancomycin-resistant Enterococcus faecium in tertiary and secondary hospitals all showed a downward trend. Isolation rate of imipenem-resistant Pseudomonas aeruginosa in different levels of hospitals didn't change much, but isolation rates in tertiary hospitals (18.8%-21.4%) were all higher than those in secondary hospitals (12.3%-16.3%) during the same period. Isolation rates of imipenem-resistant Acinetobacter baumannii in different levels of hospitals increased year by year, tertiary hospitals (55.5%-60.2%) were all higher than those in secondary hospitals (38.2%-42.8%) during the same period. Isolation rate of cefotaxime-resistant Escherichia coli in tertiary and secondary hospitals decreased gradually, but tertiary hospitals (51.9%-60.9%) were all higher than those in secondary hospitals (46.7%-56.0%) during the same period. In different levels of hospitals, isolation rate of imipenem-resistant Escherichia coli changed little, all were lower than 2%. In tertiary hospitals, isolation rate of imipenem-resistant Klebsiella pneumoniae increased significantly in different levels of hospitals (from 4.9% to 11.1%), while in secondary hospitals, it increased from 3.6% to 5.3%. Conclusion The proportion of special antimicrobial-resistant bacteria in Gram-positive bacteria in tertiary hospitals has decreased, but change is not obvious in secondary hospitals. Among Gram-negative bacteria, isolation rates of imipenem-resistant Klebsiella pneumoniae and imipenem-resistant Acinetobacter baumannii present a significant upward trend, antimicrobial resistance in tertiary hospitals is more serious than that in secondary hospitals. Management on rational use of antimicrobial agents as well as prevention and control of healthcare-associated infection should be continued to strengthen.

Abstract:Objective To analyze the distribution and antimicrobial susceptibility of bacterial strains isolated from elderly patients in China, and provide reference for empirical treatment of infection in elderly patients. Methods In 2014-2019,according to technical program of China Antimicrobial Resistance Surveillance System(CARSS), antimicrobial susceptibility testing was performed by Kirby-Bauer method, automatic instrument method or E-test method, data of pathogenic bacteria from elderly patients (≥ 65 years old) were analyzed by WHONET 5.6 software. Results From 2014 to 2019, the ratio of Gram-positive bacteria to Gram-negative bacteria remained at about 1:4 yearly. Among Gram-positive bacteria, Staphylococcus aureus accounted for 5.9%-6.3%, Enterococcus faecium and Enterococcus faecalis accounted for 3.1%-4.0% and 2.8%-2.9% respectively. Isolation rate of methicillin-resistant Staphylococcus aureus (MRSA) decreased year by year, from 48.8% to 35.2%, isolation rate of methicillin-resistant coagulase negative Staphylococcus (MRCNS) accounted for about 80.0% of coagulase negative Staphy-lococcus, vancomycin- and teicoplanin-resistant strains was not found. Resistance rates of Enterococcus faecalis and Enterococcus faecium to vancomycin decreased from 1.1% to 0.3% and 3.7% to 1.4% respectively. Resistance rate of Streptococcus pneumoniae isolated from non-cerebrospinal fluid specimens to cefotaxime decreased year by year, from 10.0% to 6.1%. The top 4 isolated Gram-negative bacteria were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. Resistance rates of Escherichia coli to ceftriaxone and cefotaxime were still higher than 54%, to carbapenems was about 1.3%. Resistance rates of Klebsiella pneumoniae to imipenem and meropenem continued to rise, from 5.6% to 11.7% and 5.2% to 12.1% respectively. Resistance rates of Pseudomonas aeruginosa and Acinetobacter baumannii to carbapenems were about 20% and >56% respectively. Except for ceftazidime, resistance rates of Stenotrophomonas maltophilia to other antimicrobial agents decreased significantly in 2015, and then fluctuated slightly, ranging from 0.9% to 1.4%. Resistance rate of Haemophilus influenzae to ampicillin increased continuously, reaching 63.8% in 2019. Conclusion Gram-negative bacteria are the main pathogens causing infection in the elderly, isolation rates of clinically important antimicrobial-resistant bacteria MRSA and vancomycin-resistant Enterococcus continue to decline, while isolation rate of carbapenem-resistant Klebsiella pneumoniae increased persistently, which needs special attention.

Abstract:Objective To investigate the distribution and antimicrobial resistance of common clinical pathogens from blood specimens in China. Methods Antimicrobial resistance of bacterial isolates from all blood culture reported on China Antimicrobial Resistance Surveillance System (CARSS) from 2014 to 2019 was analyzed. Results A total of 1 599 273 strains of bacteria were isolated from blood specimens, including 828 846 strains (51.8%) of Gram-negative bacteria. The top 5 pathogens didn't change from 2014 to 2019, the first was Escherichia coli (402 818 strains, 25.2%), followed by Staphylococcus epidermidis (193 968 strains, 12.1%), Klebsiella pneumoniae (162 613 strains, 10.2%), Staphylococcus hominis (136 396 strains, 8.5%) and Staphylococcus aureus (106 915 strains, 6.7%). Among non-fermentative bacteria, Pseudomonas aeruginosa (43 565 strains, 2.7%) and Acinetobacter baumannii (37 244 strains, 2.3%) had the highest isolation rates, but showed a downward trend year by year. Resistance rates of Escherichia coli to carbapenems ranged from 0.8% to 1.6%, and to meropenem increased from 0.8% to 1.3%. Resistance rates of Klebsiella pneumoniae to imipenem and meropenem increased, which were 6.6%-11.7%. Resistance rate of Pseudomonas aeruginosa to imipenem decreased, resistance rate to amikacin decreased from 7.1% to 2.6%. Resistance rate of Acinetobacter baumannii to carbapenems decreased. Vancomycin-, linezolid- and teicoplanin-resistant Staphylococcus spp. was not found. Resistance of Enterococcus to vancomycin, teicoplanin and linezolid were all low. Conclusion Gram-negative bacilli are the most common clinical pathogens from blood specimens in China, there is no significant change in the constituent of species of pathogens. Isolation rate of carbapenem-resistant Klebsiella pneumoniae increased, isolation rates of carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii decreased, it is necessary to strengthen surveillance on antimicrobial resistance of pathogens causing bloodstream infection and use antimicrobial agents rationally.

Abstract:Objective To understand the distribution characteristics and antimicrobial resistance of pathogenic bacteria from peritoneal effusion specimens in China, and provide evidence for clinical rational selection of antimicrobial agents. Methods All the surveilled data were from strains isolated from peritoneal effusion specimens reported by member hospitals of China Antimicrobial Resistance Surveillance System (CARSS) from January 2014 to September 2019, the first strain of the identical bacteria from the same patient was adopted to be analyzed finally, and repetitive strains were excluded. Results A total of 244 744 strains of non-repetitive bacteria from peritoneal effusion were isolated in 2014-2019, and the number of isolated strains showed an upward trend each year. The top 4 isolated strains were Escherichia coli (32.2%), Klebsiella pneumoniae (9.2%), Enterococcus faecium (7.3%) and Staphylococcus epidermidis (5.8%). Enterobacteriales had higher resistance rates to ceftazidime, cefotaxime and levofloxacin, and lower resistance rates to imipenem and amikacin, but Klebsiella pneumoniae had higher resistance rates to imipenem and amikacin than other Enterobacteriales. Among non-fermentative bacteria, Pseudomonas aeruginosa had low resistance to amikacin (2.3%-5.2%), Acinetobacter baumannii had high resistance to cephalosporins, carbapenems and quinolones (most were >50%), resistance rates to minocycline were 14.4%-28.4%. Isolation rate of methicillin-resistant Staphylococcus aureus (MRSA) decreased year by year, linezolid vancomycin and teicoplanin resistant strain was not found. Resistance rates of MRSA to all antimicrobial agents were all higher than those of methicillin-susceptible Staphylococcus aureus (MSSA). Enterococcus faecalis and Enterococcus faecium were the most common Enterococcus species. Except linezolid and minocycline, the overall resistances rates of Enterococcus faecalis to other antimicrobial agents were all lower than that of Enterococcus faecium. Conclusion Bacteria from peritoneal effusion are widely distributed in China, mainly Gram-negative bacilli such as Escherichia coli and Klebsiella pneumoniae, isolation rate is increasing year by year; antimicrobial resistance strains is common, the growth trend of bacterial resistance in recent 6 years is relatively stable, resistance rate of individual strains to specific antimicrobial agents present a downward trend year by year. Surveillance on some strains such as Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii still need to be strengthened. Rational selection of antimicrobial agents should be based on antimicrobial susceptibility testing results.

Abstract:Objective To analyze the distribution as well as antimicrobial susceptibility and resistance of bacteria isolated from wound and pus specimens from member hospitals of China Antimicrobial Resistance Surveillance System(CARSS). Methods Antimicrobial susceptibility testing data of bacteria from wound and pus specimens from member hospitals of CARSS in 2014-2019 were analyzed, antimicrobial susceptibility testing results were interpreted according to Clinical and Laboratory Standards Institute (CLSI) and analyzed by WHONET 5.6 software. Results A total of 1 182 888 bacterial strains from wound and pus were isolated in 2014-2019, the top 5 bacteria were Escherichia coli (27.8%), Staphylococcus aureus (21.0%), Klebsiella pneumoniae (9.0%), Pseudomonas aeruginosa (6.7%), and Staphylococcus epidermidis (3.8%). In 2014-2019, isolate rates of methicillin-resistant Staphylococcus aureus (MRSA) were 30.8%, 30.0%, 29.9%, 29.4%, 27.4% and 26.9% respectively, isolate rates of methicillin-resistant coagulase negative Staphylococcus (MRCNS) were 75.2%, 76.1%, 73.0%, 72.1%, 71.3% and 71.0% respectively, linezolid- and vancomycin-resistant Staphylococcus were not found. Resistance rates of Enterococcus faecium to common antimicrobial agents were significantly higher than those of Enterococcus faecalis, resistance rates of Enterococcus faecalis and Enterococcus faecium to vancomycin were 0.2%-0.7% and 0.7%-2.0% respectively, to linezolid were 1.4%-2.3% and 0.4%-1.5% respectively, and to teicoplanin were 0.3%-0.7% and 0.9%-1.9% respectively. Resistance rate of Streptococcus pneumoniae to penicillin decreased from 8.1% in 2015 to 1.4% in 2019, vancomycin- and linezolid-resistant Streptococcus pneumoniae was not found. Resistance rates of Escherichia coli to cefotaxime and ceftriaxone were both above 50% in 2014-2016, slightly lower than 50% in 2017-2019, resistance rate to quinolones was>38%, to trimethoprim-sulfamethoxazole was above 58%, and susceptibility rates to imipenem and meropenem were the highest, both were higher than 98%, followed by cefoperazone/sulbactam (>83%). Resistance rates of Klebsiella pneumoniae to ceftriaxone, cefotaxime, quinolones, and trimethoprim-sulfamethoxazole were all lower than those of Escherichia coli, but resistance rate to carbapenems was higher than that of Escherichia coli, resistance rate to cefoperazone/sulbactam was <10%. Resistance rates of Pseudomonas aeruginosa to cefoperazone/sulbactam, ceftazidime, cefepime, imipenem, meropenem, and ciprofloxacin were all <15%, to amikacin were all <10%, the overall resistance rate of Acinetobacter baumannii was higher than that of Pseudomonas aeruginosa, resistance rates to cefepime, imipenem, meropenem and ciprofloxacin were all >47%, while resistance rates to minocycline was <25%. Conclusion Pathogens isolated from wound and pus are mainly Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa, antimicrobial resistance rate of bacteria is high, change of antimicrobial resistance of bacteria from wound and pus should be surveilled regularly to provide basis for rational use of antimicrobial agents and clinical treatment experience.

Abstract:Objective To investigate the distribution characteristics and antimicrobial resistance of pathogens isolated from pleural effusion specimens in China. Methods According to China Antimicrobial Resistance Surveillance System (CARSS) technical program, data of bacteria isolated from pleural effusion specimens and antimicrobial susceptibility testing results reported by CARSS member hospitals in 2014-2019 were analyzed with WHONET 5.6 software. Results A total of 75 375 strains of bacteria were isolated from pleural effusion specimens in 2014-2019, Gram-positive bacteria were mainly Staphylococcus aureus; Gram-negative bacteria were mainly Escherichia coli and Klebsiella pneumoniae. Isolation rates of methicillin-resistant Staphylococcus aureus (MRSA) in 6 years were between 33.7%-43.4%. Resistance rates of MRSA to all antimicrobial agents were all significantly higher than those of methicillin-susceptible Staphylococcus aureus (MSSA). Vancomycin-, teicoplanin- and linezolid-resistant Staphylococcus aureus were not found; resistance rates of Streptococcus pneumoniae to penicillin were 1.1%-7.6%; most Enterobacteriales had good activity on carbapenems, resistance rates of Escherichia coli to the third generation cephalosporins showed a slightly downward trend. Conclusion Isolation rate and distribution of bacteria from pleural effusion in China changed little, proportion of Gram-positive bacteria and Gram-negative bacteria is similar. Resistance rates of some strains to partial antimicrobial agents decreased in varying degrees. Surveillance on Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae should be strengthened to guide clinical rational antimicrobial use.

Abstract:Objective To investigate the distribution and antimicrobial resistance of pathogens isolated from fecal specimens in China. Methods Relevant data of fecal specimens (excluding intestinal normal colonized bacteria) were extracted from surveillance report of China Antimicrobial Resistance Surveillance System (CARSS) in 2014-2019, changes of intestinal pathogenic bacteria and antimicrobial resistance rates in the past 6 years were analyzed. Results A total of 61 809 strains were isolated, the top 3 were Salmonella spp. (82.12%), Shigella spp. (8.08%) and Vibrio spp. (4.03%), Salmonella spp. accounted for more than 70% of pathogenic bacteria in fecal specimens each year, with the highest proportion of 87.16% in 2018. In the past 6 years, there was no change in the top 6 pathogenic bacteria strains, only constituent ratios of bacterial species changed slightly each year, Salmonella spp. showed an upward trend, while Shigella spp. showed a downward trend. The major bacteria were unclassified species of Salmonella (49.39%), Shigella flexneri (46.64%), Vibrio parahaemolyticus (91.20%), Aeromonas hydrophila (55.80%) and enteropathogenic Escherichia coli (85.02%). Resistance rate of enteropathogenic bacteria to ampicillin was high, Shigella spp. and diarrheagenic Escherichia coli (>90%) were higher than Salmonella spp. and Vibrio spp. Resistance rate of Salmonella to levofloxacin was low, but show a rising trend, which increased from less than 3% to about 10%; resistance rate of Shigella spp. to ciprofloxacin was low (29.9%) in 2016; resistance rates of Vibrio spp. to antimicrobial agents (except ampicillin) were low (<6%); carbapenem-resistant Aeromonas spp. strains emerged, resistance rates of Aeromonas spp. and diarrheagenic Escherichia coli to amikacin were both low. Conclusion There are multiple species of pathogenic bacteria causing bacterial diarrhea, mainly Salmonella spp. and Shigella spp., antimicrobial resistance is serious, different bacterial species and strains vary significantly, it is necessary to continue to strengthen the management of rational application of antimicrobial agents as well as prevention and control of healthcare -associated infection, and do a good job in the surveillance of antimicrobial-resistant bacteria.

Abstract:Objective To investigate the change in antimicrobial resistance of carbapenem-resistant Klebsiella pneumoniae (CRKP) in China. Methods Data of CRKP in report of China Antimicrobial Resistance Surveillance System(CARSS) from 2014 to 2019 were analyzed, change in antimicrobial resistance of CRKP in different areas, different levels of hospitals, different specimen sources, different age groups, and different departments were compared. Results Isolation rate of CRKP in China rose from 6.4% in 2014 to 10.9% in 2019. In 2019, the highest isolation rates of CRKP were in Henan Province and Shanghai City, which were 32.8% and 28.7% respectively, and the lowest rate was 0.6% in Xizang; in 2019, isolation rates of CRKP in children's hospitals, tertiary hospitals and secondary hospitals were 14.0%, 11.6% and 5.5% respectively; isolation rate of CRKP from patients in intensive care unit was the highest (23.0%), which was higher than those of other hospitalized patients, patients in outpatient department and emergency department. Conclusion Isolation rate of CRKP in China is on the rise, there are differences among different area and departments.

Abstract:Objective To analyze the risk factors for multidrug-resistant Escherichia coli (MDR-EC) infection in children aged 0-14 years, and explore the application value of bundle management in the prevention and control of infection. Methods Patients with infection in a hospital from June 1, 2016 to September 30, 2019 were selected as the research objects. The observation group was from June 1, 2016 to December 31, 2017, bundle management group was from January 1, 2018 to September 30, 2019. Clinical data of patients in observation group were analyzed, risk factors for MDR-EC infection were explored, bundle management scheme was adjusted according to the results, MDR-EC infection between two groups of patients was compared. Results A total of 343 patients in observation group and 328 patients in bundle management group were investigated. In observation group, 70 patients were with MDR-EC infection, the independent risk factors for MDR-EC infection in patients in observation group were non-ICU hospitalization time ≥ 14 days, ICU hospitalization time ≥ 7 days, respiratory tract infection, mecha-nical ventilation, mechanical ventilation ≥ 7 days, combined use of antimicrobial agents, and antimicrobial use time ≥ 14 days (all P<0.05). Compliance rate of hand hygiene in patients in bundle management group was higher than that in observation group (95.99% vs 94.39%). The proportion of MDR-EC infection in infection cases was lower than that in observation group (14.02% vs 20.41%), differences were both significant (both P<0.05). The mechanical ventilation time, central venous catheterization time, antimicrobial use time, hospitalization time and hospitalization expenses of bundle management group were all lower than those of observation group, differences were all statistically significant (all P<0.05). Conclusion MDR-EC infection in children is affected by many factors, bundle management can reduce the occurrence of infection.

Abstract:Phages are viruses that can infect bacteria specifically and have been used to treat bacterial infections since their discovery. However, with the discovery of antibiotics and their characteristics of high efficiency, conve-nience and low cost, antibiotics are widely used all over the world, so the research on phages have been slowed down gradually. In recent years, due to the increasingly serious problem of bacterial resistance and the emergence of multidrug-resistant organisms, the search for new antimicrobial agents has become the focus and trend of anti-infection treatment. As a result, phage therapy, which has been on the verge of oblivion, attracts the attention of clinical researchers again. Based on the current research on phages at home and abroad, this paper summarizes the application of phages in the treatment of bacterial infection, and analyzes the advantages and limitations of phage therapy.