Study of the Effect of Bacterial Resistance Monitoring in Clinical Microbiology Testing

Objective:To observe and analyze the effect of bacterial resistance monitoring in clinical microbiology testing.Methods:600 microbial specimens collected in our hospital in the past year(April 2021 to April 2022)were used as the test subjects of this study.The specimens were divided into Group A(control group)and Group B(research group),with 300 cases in each group.Group A consisted of blood culture specimens,while Group B consisted of sputum specimens.After the tests were completed,the rates of unfavorable and favorable results,bacterial species distribution,and bacterial drug resistance of the specimens in both groups were compared.Results:Among group A specimens,29 cases were positive(9.67%)and 271 cases were negative(90.33%);among group B specimens,99 cases were positive(33.00%)and 201 cases were negative(66.00%);the difference between the two groups of data was statistically significant(P<0.05).As for the distribution of the types of bacteria,there were 472 cases of Gram-negative bacteria and 128 cases of Gram-positive bacteria.Conclusion:Bacterial resistance monitoring is helpful in clinical microbiology testing.Through proper monitoring,bacterial resistance can be well understood.In this way,patients get to receive appropriate treatment measures and suitable antibacterial prescriptions,thereby improving the patient outcome.

Insecticide resistance monitoring for the invasive populations of fall armyworm,Spodoptera frugiperda in China

Fall armyworm has invaded China and colonized its populations in tropical and sub-tropical regions of South China since December 2018.Chemical spray has been widely used to control the pest,which shall lead to resistance evolution.In this research,we collected five populations of the pest from Yunnan,Hainan,Tibet,and Fujian of China,and tested their susceptibilities to pyrethroid,organophosphorus,oxadiazine,diamide,antibiotics and other types of insecticides(14 insecticides totally)in the laboratory.Based on the susceptible baseline published from the previous studies,the resistance ratio was 615-1068-fold to chlorpyrifos,60-388-fold to spinosad,26-317-fold to lambda-cyhalothrin,13-29-fold to malathion,9-33-fold to fenvalerate,8-20-fold to deltamethrin,3-8-fold to emamectin benzoate and 1-2-fold to chlorantraniliprole,respectively.The median lethal concentration(LC_(50))of other six insecticides without the susceptible baselines was 148.27-220.96μgmL^(-1) for beta-cypermethrin,87.03-128.43μgmL^(-1) for chlorfenapyr,16.35-99.67μgmL^(-1) for indoxacarb,10.55-51.01μgmL^(-1) for phoxim,7.08-8.78μgmL^(-1) for M-EBI(the mixed insecticide of emamectin benzoate and indoxcarb)and 1.49-4.64μg mL^(-1) for cyantraniliprole.This study can be helpful for chemical control as well as for resistance monitoring and management of the pest in China.

Six-year analysis of key monitoring for bacterial strain distribution and antibiotic sensitivity in a hospital

BACKGROUND With the widespread use of antimicrobial drugs,bacterial resistance has become a significant problem,posing a serious threat to public health.The prevalence of clinical infection strains in hospitals and their drug sensitivities are key to the appropriate use of antibiotics in clinical practice.AIM To identify prevalent bacteria and their antibiotic resistance profiles in a hospital setting,thereby guiding effective antibiotic usage by clinicians.METHODS Specimens from across the institution were collected by the microbiology laboratory.The VITEK 2 compact fully automatic analyzer was used for bacterial identification and antibiotic sensitivity testing,and the WHONET5.6 software was utilized for statistical analysis.RESULTS A total of 12062 bacterial strains of key monitoring significance were detected.Staphylococcus aureus demonstrated widespread resistance to penicillin,but none of the strains were resistant to vancomycin or linezolid.Moreover,219 strains of methicillin-resistant coagulase-negative staphylococci and 110 strains of methicillin-resistant Staphylococcus aureus were detected.Enterococcus faecalis showed moderate resistance to the third-generation quinolones ciprofloxacin and levofloxacin,but its resistance to nitrofurantoin and tetracycline was low.Enterococcus faecium displayed significantly lower resistance to third-and fourthgeneration quinolones than Enterococcus faecalis.The resistance of two key monitoring strains,Escherichia coli and Klebsiella pneumoniae,to piperacillin/tazobactam was 5%-8%.However,none of the Escherichia coli and Klebsiella pneumoniae strains were resistant to meropenem.The resistance of Acinetobacter baumannii to piperacillin/sulbactam was nearly 90%.Nonetheless,the resistance to tigecycline was low,and Pseudomonas aeruginosa demonstrated minimal resistance in the antibiotic sensitivity test,maintaining a resistance of<10%to the cephalosporin antibiotics cefotetan and cefoperazone over the last 6 years.The resistance to amikacin remained at 0.2%over the past 3 years.CONCLUSION Our hospital’s overall antibiotic resistance rate was relatively stable from 2017 to 2022.The detection rates of key monitoring strains are reported quarterly and their resistance dynamics are monitored and communicated to the entire hospital,which can guide clinical antibiotic selection.

Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method:A review

Detecting, real-time monitoring and early warning of underground water-bearing structures are critically important issues in prevention and mitigation of water inrush hazards in underground engineering. Direct current （DC） resistivity method is a widely used method for routine detection, advanced detection and real-time monitoring of water-bearing structures, due to its high sensitivity to groundwater. In this study, the DC resistivity method applied to underground engineering is reviewed and discussed, including the observation mode, multiple inversions, and real-time monitoring. It is shown that a priori information constrained inversion is desirable to reduce the non-uniqueness of inversion, with which the accuracy of detection can be significantly improved. The focused resistivity method is prospective for advanced detection;with this method, the flanking interference can be reduced and the detection dis-tance is increased subsequently. The time-lapse resistivity inversion method is suitable for the regions with continuous conductivity changes, and it can be used to monitor water inrush in those regions. Based on above-mentioned features of various methods in terms of benefits and limitations, we propose a three-dimensional （3D） induced polarization method characterized with multi-electrode array, and introduce it into tunnels and mines combining with real-time monitoring with time-lapse inversion and cross-hole resistivity method. At last, the prospective applications of DC resistivity method are discussed as follows： （1） available advanced detection technology and instrument in tunnel excavated by tunnel boring machine （TBM）, （2） high-resolution detection method in holes, （3） four-dimensional （4D） monitoring technology for water inrush sources, and （4） estimation of water volume in water-bearing structures.

Detection and monitoring of insect resistance to transgenic Bt crops

Transgenic crops expressing Bacillus thuringiensis （Bt） endotoxins havebecome one of the most important tools for managing corn and cotton insect pests in the US and other countries. The widespread adoption of transgenic Bt crops could place a high degree of selection pressure on the target insect populations and accelerate development of resistance, raising concerns about the long-term durability of Bt plants as an effective pest management tool. Conservation of Bt susceptibility in insects has become one of the most active research areas in modern agriculture. One of the key factors for a successful Bt resistance management plan is to have a cost-effective monitoring system that can provide information on. （i） the initial Bt resistance allele frequencies at low levels in field insect populations; and （ii） early shifts in Bt resistance allele frequencies so that proactive measures for managing resistance can be deployed well before field control failures. Developing such a monitoring program has been difficult because： （i） resistance traits that occur at very low frequencies are hard to detect; （ii） many factors affect the sensitivity and accuracy of a Bt resistance monitoring program; and （iii） monitoring resistance is costly. Several novel methods for detecting Bt resistance alleles developed during the last decade have made a cost-effective monitoring system possible. Future studies should focus on how to improve and standardize the methodologies for insect sampling and Bt resistance detection.

Baseline susceptibility of Helicoverpa armigera,Plutella xylostella,and Spodoptera frugiperda to the meta-diamide insecticide broflanilide

Broflanilide is a novel meta-diamide insecticide that acts as a y-aminobutyric acid-gated chloride channel allosteric modulator.With its unique mode of action,broflanilide has no known cross-resistance with existing insecticides and is expected to be an effective tool for the management of insecticide resistance.Establishing the base-line susceptibility to this insecticide is an essential step for developing and implementing effective resistance management strategies.Here we evaluated the baseline susceptibil-ity to broflanilide for 3 cosmopolitan lepidopteran pest species,Helicoverpa armigera,Plutella xylostella,and Spodoptera frugiperda.Broflanilide exhibited high activity against populations sampled in the major distribution range of these pests in China,with median lethal concentrations(LCso)ranging between 0.209 and 0.684,0.076 and 0.336,and 0.075 and 0.219 mg/L for H.armigera,P xylostella,and S.frugiperda,respectively.Among-population variability in susceptibility to broflanilide was moderate for H.armigera(3.3-fold),P xylostella(4.4-fold),and S.frugiperda(2.9-fold).The recommended diagnostic concentrations for H.armigera,P xylostella,and S.frugiperda were 8,4,and 2 mg/L,re-spectively.Little or no cross-resistance to broflanilide was detected in 3 diamide-resistant strains of P xylostella and 1 spinosyns-resistant strain of S.frugiperda.Our results provide critical information for the development of effective resistance management programs to sustain efficacy of broflanilide against these key lepidopteran pests.

Antimicrobial susceptibility of Gram-negative bacteria causing intra-abdominal infections in China： SMART China 2011

Background The Study for Monitoring Antimicrobial Resistance Trends program monitors the activity of antibiotics against aerobic and facultative Gram-negative bacilli （GNBs） from intra-abdominal infections （IAIs） in patients worldwide.Methods In 2011,1 929 aerobic and facultative GNBs from 21 hospitals in 16 cities in China were collected.All isolates were tested using a panel of 12 antimicrobial agents,and susceptibility was determined following the Clinical Laboratory Standards Institute guidelines.Results Among the Gram-negative pathogens causing IAIs,Escherichia coli （47.3％） was the most commonly isolated,followed by Klebsiella pneumoniae （17.2％）,Pseudomonas aeruginosa （10.1％）,and Acinetobacter baumannii （8.3％）.Enterobacteriaceae comprised 78.8％ （1521/1929） of the total isolates.Among the antimicrobial agents tested,ertapenem and imipenem were the most active agents against Enterobacteriaceae,with susceptibility rates of 95.1％ and 94.4％,followed by amikacin （93.9％） and piperacillin/tazobactam （87.7％）.Susceptibility rates of ceftriaxone,cefotaxime,ceftazidime,and cefepime against Enterobacteriaceae were 38.3％,38.3％,61.1％,and 50.8％,respectively.The leastactive agent against Enterobacteriaceae was ampicillin/sulbactam （25.9％）.The extended-spectrum β-lactamase （ESBL） rates among E.coli,K.pneumoniae,Klebsiella oxytoca,and Proteus mirabilis were 68.8％,38.1％,41.2％,and 57.7％,respectively.Conclusions Enterobacteriaceae were the major pathogens causing IAIs,and the most active agents against the study isolates （including those producing ESBLs） were ertapenem,imipenem,and amikacin.Including the carbapenems,most agents exhibited reduced susceptibility against ESBL-positive and multidrug-resistant isolates.