Distribution And Drug Resistance Of Pathogenic Bacteria In Respiratory Tract Specimens

Objective:To explore the species distribution of bacteria isolated from respiratory tract specimens and their resistance to antibiotics in this area,so as to provide scientific basis for clinical empirical anti-infective treatment and formulation of reasonable antibacterial drug program,so as to avoid the abuse of antibiotics and slow down the occurrence of drug-resistant bacteria.Methods:Sputum and alveolar lavage samples from 1965 patients in our hospital from September 2020 to September 2021 were collected,and a total of 2,021 strains of bacteria were isolated(only the first strain of the same bacteria isolated in the same patient was retained).Bacteria were identified using stroma-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS).The antimicrobial susceptibility test was conducted using VITEK 2-Compact automatic bacterial identification drug sensitivity instrument combined with K-B disk diffusion method.Drug sensitivity results were determined according to the 2020 edition of the CLSI(American Institute of Clinical and Laboratory Standards)standards.Results:1.Distribution of pathogenic bacteria in lower respiratory tract specimensIn the sputum and alveolar lavage samples collected from 1965 patients in our hospital from September 2020 to September 2021,a total of 2021 strains of bacteria were isolated,including 1988 strains from sputum,33 strains from alveolar lavage,1909 cases of single bacterial infection,and 56 cases of mixed infection with two kinds of bacteria.There were 1,912 strains(94.6%)of Gram-negative bacteria and 109strains(5.4%)of Gram-positive bacteria.The main isolates of gram-negative bacteria were 663 strains of Klebsiella pneumoniae(33%),340 strains of Pseudomonas aeruginosa(17%),236 strains of Acinetobacter baumannii(12%),133 strains of stenotrophomonas maltophilia(7%),109 strains of Escherichia coli(5%)and 97 strains of Enterobacter cloacae(5%).The gram-positive bacteria accounted for a small proportion,mainly Staphylococcus aureus 92 strains(5%)and Streptococcus pneumoniae 15 strains(1%).The patients were divided into groups according to the age of the patients.The children group was 0-17 years old.The young and middle-aged patients were 18-59 years old;The elderly group included patients over 60 years old.In the children group,there were 3gram-positive bacteria(25%)and 9 Gram-negative bacteria(75%).In the young and middle-aged group,there were 47 gram-positive bacteria(6.6%)and 675 Gram-negative bacteria(93.4%).In the elderly group,59(4.5%)strains of gram-positive bacteria and 1228(95.5%)strains of Gram-negative bacteria were found.2.Analysis of bacterial resistance in respiratory specimensThe resistance rate of Klebsiella pneumoniae to the first and second generation of cephalosporae was about 20%.The drug resistance rate of ceftazidime and cefepime was slightly lower,less than 15%;The resistance rate to amicacin,colistin,penicillin combined with enzyme inhibitors(piperacillin/tazobactam),cephalosporin + enzyme inhibitors(cefoperazone/sulbactam)and carbapenems(imipenem,meropenem)was the lowest,less than 5%.The resistance rates of Klebsiella pneumoniae to ceftriaxone,levofloxacin and ciprofloxacin were 17.8%,11.8% and23.7%,respectively.The resistance rate of Escherichia coli to carbapenems,Amikacin and colistin was the lowest,less than 4%.The resistance rates of Escherichia coli to ceftriaxone,levofloxacin and ciprofloxacin were67.6%,67.9% and 71.6%,respectively.The resistance rate of Pseudomonas aeruginosa to piperacillin/tazobactam,cefepime,colistin,tobramycin and amicacin was the lowest(less than 3.3%).The resistance rate to ceftazidme and cefoperazone/sulbactam was low,about 10%,and the resistance rate of Pseudomonas aeruginosa to carbapenems was 16%.In addition to colistin,minocycline,and tegacycline,Acinetobacter baumannii had high resistance to most commonly used clinical antibiotics(more than 50%)and resistance to carbapenems was 69.1%.The resistance rates of stenotrophomonas maltophilia to levofloxacin and minocycline were 2.3% and 3.7%,respectively.The highest resistance rate of Staphylococcus aureus to erythromycin was 68.8%,and the resistance rate of Staphylococcus aureus to other antibiotics was less than 37.6%.The resistance rate of Streptococcus pneumoniae to erythromycin,clindamycin and tetracycline was up to 100%.The resistance rate to cotrimoxazole was higher than64.3%;It is more sensitive to other antibiotics.No vancomycin,tegacycline and linezolidin-resistant strains were found in the two positive strains.1.Distribution and drug resistance analysis of bacteria isolated from respiratory specimens in different departmentsThere were 316 isolates(19.4%)from neurosurgery department,199isolates(12.2%)from respiratory department and 145 isolates(5.8%)from ICU department.The common bacteria isolated from respiratory tract specimens in neurosurgery were gram-negative bacteria,among which Klebsiella pneumoniae(36.4%)accounted for the highest proportion,followed by Acinetobacter baumannii(12.8%)and Pseudomonas aeruginosa(8.6%).The most common bacteria isolated from respiratory specimens were Gram-negative bacteria,among which Pseudomonas aeruginosa accounted for the highest proportion(28.4%),followed by Klebsiella pneumoniae(27.1%)and stenotrophomonas maltophilia(10.2%).The most common bacteria isolated from ICU respiratory tract were Acinetobacter baumannii(25.5%),Pseudomonas aeruginosa(19.3%)and Klebsiella pneumoniae(17.2%).The resistance rate of Acinetobacter baumannii to carbapenems in ICU was higher than that in other departments,up to 83.3%.Except for colistin,the resistance rate of common clinical antibiotics was higher.The resistance rate to minocycline and cotrimoxazole was less than 50%.Pseudomonas aeruginosa was the most isolated bacteria in the department of respiratory medicine,and the resistance rates to quinolones(ciprofloxacin and levofloxacin)were 27.3% and 30.2%,respectively.The rates of drug resistance to carbapenems(imipenem and meropenem)were 22.4% and 20.6%,respectively,higher than those in other clinical departments.conclusion1.Gram-negative bacilli were the most commonly isolated bacteria in respiratory tract specimens,with Klebsiella pneumoniae,Pseudomonas aeruginosa and Acinetobacter baumannii being the most common.2.Gram-negative bacilli isolated from respiratory tract specimens were highly sensitive to p-colistin,tegacycline and amikacin,Klebsiella pneumoniae and Escherichia coli were highly sensitive to carbapenems,and Acinetobacter baumannii was highly resistant to carbapenems.No vancomycin and linezolidin-resistant Staphylococcus aureus was found.3.There were differences in the distribution of bacteria isolated from different departments,among which Pseudomonas aeruginosa was the most common in respiratory department,Klebsiella pneumoniae was the most common in neurosurgery department,and Acinetobacter baumannii was the most common bacteria isolated from ICU.4.The detection rate of carbapenem-resistant Acinetobacter baumannii in ICU was higher than that in other departments.