Objective To develop a new method for the determination of trace manganese in water by flame atomic absorption after cloud point extraction. Methods The effect of experimental conditions such as pH value and concentration of reagents and equilibration temperature on cloud point extraction and determination sensitivity was discussed. The chemical variables affecting the separation phase and extraction recovery were optimized. Results Under the optimum conditions, pre-concentration of only 50 ml of sample in the presence of 0.05% Triton X-114 presented a detection limit of 0.28 ?g/L(3?) for manganese. The enhancement factor was 65 for manganese. The relative standard deviation was 2.17%. The calibration graph using the pre-concentration system for manganese was linear with a correlation coefficient of 0.999 at levels near the detection limits up to at least 120 ?g/L. The recovery rates were 98.0%-101.5%. Conclusion The method is rapid, accurate, simple and is suitable for determination of trace manganese in water samples.

Objective: To retrospectively analyze distribution characteristics of pathogenic bacteria and their antimicrobial susceptibility in patients with diabetic foot osteomyelitis(DFO). Methods: Sixty cases of suspected DFO were collected from the Endocrinology Department of Henan Provincial People′s Hospital. After admission, bone biopsy was carried out to confirm the pathological diagnosis, and the pathogenic bacteria and drug sensitivity were determined by bone culture. In addition, bacterial culture was carried out in the basal tissue of the wound, and the results of bacterial culture were compared with those of bone culture. Results: Sixty patients were diagnosed as DFO after bone biopsy. Among the 60 patients, 45 patients underwent bone culture and basal tissue culture. There are 24 patients of whom the results were consistent, accounting for 53.3%. The positive rate of bone culture was 55.0%, there were 16 strains of gram-positive bacteria and 22 strains of gram-negative bacteria. Staphylococcus aureus(9 strains) occurrence was the most, common finding, followed by Escherichia coli(6 strains). The course of diabetic foot, albumin(ALB), and antibiotic usage rate before admission were lower in bone culture positive group than those in bone culture negative group, while white blood cell(WBC) and C-reactive protein(CRP) were higher in bone culture negative group(P<0.05). There was no significant difference in gender, age, course of diabetes, HbA_1C, and creatinine(CREA) levels between the two groups(P>0.05). The results of bone culture showed that Staphylococcus aureus was the main Gram-positive bacteria, which was more sensitive to vancomycin, tigecyclin, linezolid, etc. Escherichia coli was the main Gram-negative bacteria, which was more sensitive to tigecyclin, carbapenems, amikacin, etc. Conclusion Bone biopsy and bone culture should be carried out in cases for suspected DFO patients to identify the pathogenic bacteria, and the bone tissue should be preserved and obtained according to the operation specification before the application of antibiotics, and the appropriate antibiotics should be selected according to the drug sensitivity results.

Objective To investigate the changing distribution and antibiotic resistance profiles of clinical isolates of Staphylococcus in hospitals across China from 2015 to 2021.Methods Antimicrobial susceptibility testing was conducted for the clinical isolates of Staphylococcus according to the unified protocol of CHINET(China Antimicrobial Surveillance Network)using disk diffusion method and commercial automated systems.The CHINET antimicrobial resistance surveillance data from 2015 to 2021 were interpreted according to the 2021 CLSI breakpoints and analyzed using WHONET 5.6.Results During the period from 2015 to 2021,a total of 204,771 nonduplicate strains of Staphylococcus were isolated,including 136,731(66.8％)strains of Staphylococcus aureus and 68,040(33.2％)strains of coagulase-negative Staphylococcus(CNS).The proportions of S.aureus isolates and CNS isolates did not show significant change.S.aureus strains were mainly isolated from respiratory specimens(38.9±5.1)％,wound,pus and secretions(33.6±4.2)％,and blood(11.9±1.5)％.The CNS strains were predominantly isolated from blood(73.6±4.2)％,cerebrospinal fluid(12.1±2.5)％,and pleural effusion and ascites(8.4±2.1)％.S.aureus strains were mainly isolated from the patients in ICU(17.0±7.3)％,outpatient and emergency(11.6±1.7)％,and department of surgery(11.2±0.9)％,whereas CNS strains were primarily isolated from the patients in ICU(32.2±9.7)％,outpatient and emergency(12.8±4.7)％,and department of internal medicine(11.2±1.9)％.The prevalence of methicillin-resistant strains was 32.9％in S.aureus(MRSA)and 74.1％in CNS(MRCNS).Over the 7-year period,the prevalence of MRSA decreased from 42.1％to 29.2％,and the prevalence of MRCNS decreased from 82.1％to 68.2％.MRSA showed higher resistance rates to all the antimicrobial agents tested except trimethoprim-sulfamethoxazole than methicillin-susceptible S.aureus(MSSA).Over the 7-year period,MRSA strains showed decreasing resistance rates to gentamicin,rifampicin,and levofloxacin,MRCNS showed decreasing resistance rates to gentamicin,erythromycin,rifampicin,and trimethoprim-sulfamethoxazole,but increasing resistance rate to levofloxacin.No vancomycin-resistant strains were detected.The prevalence of linezolid-resistant MRCNS increased from 0.2％to 2.3％over the 7-year period.Conclusions Staphylococcus remains the major pathogen among gram-positive bacteria.MRSA and MRCNS were still the principal antibiotic-resistant gram-positive bacteria.No S.aureus isolates were found resistant to vancomycin or linezolid,but linezolid-resistant strains have been detected in MRCNS isolates,which is an issue of concern.

Objective To monitor the susceptibility of clinical isolates to antimicrobial agents in tertiary hospitals in major regions of China in 2022.Methods Clinical isolates from 58 hospitals in China were tested for antimicrobial susceptibility using a unified protocol based on disc diffusion method or automated testing systems.Results were interpreted using the 2022 Clinical &Laboratory Standards Institute(CLSI)breakpoints.Results A total of 318 013 clinical isolates were collected from January 1,2022 to December 31,2022,of which 29.5％were gram-positive and 70.5％were gram-negative.The prevalence of methicillin-resistant strains in Staphylococcus aureus,Staphylococcus epidermidis and other coagulase-negative Staphylococcus species(excluding Staphylococcus pseudintermedius and Staphylococcus schleiferi)was 28.3％,76.7％and 77.9％,respectively.Overall,94.0％of MRSA strains were susceptible to trimethoprim-sulfamethoxazole and 90.8％of MRSE strains were susceptible to rifampicin.No vancomycin-resistant strains were found.Enterococcus faecalis showed significantly lower resistance rates to most antimicrobial agents tested than Enterococcus faecium.A few vancomycin-resistant strains were identified in both E.faecalis and E.faecium.The prevalence of penicillin-susceptible Streptococcus pneumoniae was 94.2％in the isolates from children and 95.7％in the isolates from adults.The resistance rate to carbapenems was lower than 13.1％in most Enterobacterales species except for Klebsiella,21.7％-23.1％of which were resistant to carbapenems.Most Enterobacterales isolates were highly susceptible to tigecycline,colistin and polymyxin B,with resistance rates ranging from 0.1％to 13.3％.The prevalence of meropenem-resistant strains decreased from 23.5％in 2019 to 18.0％in 2022 in Pseudomonas aeruginosa,and decreased from 79.0％in 2019 to 72.5％in 2022 in Acinetobacter baumannii.Conclusions The resistance of clinical isolates to the commonly used antimicrobial agents is still increasing in tertiary hospitals.However,the prevalence of important carbapenem-resistant organisms such as carbapenem-resistant K.pneumoniae,P.aeruginosa,and A.baumannii showed a downward trend in recent years.This finding suggests that the strategy of combining antimicrobial resistance surveillance with multidisciplinary concerted action works well in curbing the spread of resistant bacteria.