Study On Distribation And Resistance Of 589 Bacterial Isolates From Community-Associated Skin And Soft Tissue Infections

Objective: To investigate pathogenic species and antimicrobial resistance of bacteria in community-acquired skin and soft tissue infection in order to provide the theoretical basis for rational use of antibiotics in clinic.Methods: Wounded secretions or pus specimens were collected from 557 patients with community-acquired skin and soft tissue infection who were hospitalized in the dermatology department of our hospital during the period of January 2013 to December2017.Bacterial culture and identification were performed.The major pathogens susceptibili ty to antimicrobial agents was tested.The clinical data,pathogen distribution and drug susceptibility results of the patients were collected for retrospective analysis.Results: 1.There were 557 patients in this series: 308 males,249 females.Their ages ranged from January to 95.The average age was 27.83±27.70 years old.2.A total of 589(43 species)pathogens were isolated.The mixed infection rate was 5.7%.The isolating rate of gram-positive bacteria(516 strains,87.6%)was the highest.Gram-negative bacteria(69 strains,11.7%)ranked second.Fungi(4 strains,0.7%)ranked the third.Among the gram-positive bacteria,staphylococcus aureus,staphylococcus epidermidis,and staphylococcus haemolyticus accounted for 64.9%,7.5%,and 5.1% respectively.The susceptibility testing results showed the isolating rate of methicillin-resistant staphylococcus Aureus(MRSA)was up to 35.3%,methicillin-resistant coagulase-negative staphylococci(MRCNS)up to 59.5%.Pseudomonas aeruginosa,Klebsiella pneumoniae,Escherichia coli,and Enterobacter cloacae were the main gram-negative pathogenic bacterium.3.The resistance of major gram-positive cocci to common antibiotics: the resistance rate of staphylococcus aureus to penicillin,erythromycin and lincomycin were98.2%,76.7% and 74.7% respectively.The resistance rate to rifampicin,ciprofloxacin,levofloxacin,moxifloxacin and gentamicin were 1.6%,2.9%,1.6%,1.6% and 4.6%respectively.The resistance rate of staphylococcus epidermidis to penicillin,erythromycin,sulfamethoxazole,oxacillin,lincomycin and tetracycline were 97.7%,77.3%,75%,75%,56.8% and 56.8% respectively.The resistance rate of staphylococcus haemolyticus to penicillin,erythromycin and lincomycin was as high as 100%,and the resistance rate to oxacillin,ciprofloxacin,levofloxacin,tetracycline and cotrimoxazole were 90%,83.3%,70%,63.3%,and 63.3% respectively.Both were sensitive to rifampicin,moxifloxacin,and gentamicin.Three major gram-positive cocci are sensitive to tigecycline,nitrofurantoin,linezolid,and quinupristin/dafoprefen.No vancomycin-resistant staphylococci were found.4.Compared with methicillin-sensitive staphylococcus aureus(MSSA),the resistant rate of MRSA to penicillin,oxacillin,ciprofloxacin,levofloxacin,tetracycline,erythromycin,gentamicin and lincomycin were all significantly higher(P<0.05).Compared with methicillin-sensitive coagulase-negative staphylococci(MSCNS),the resistant rate of MRCNS to oxacillin,rifampicin,tetracycline and compound sulfamethoxazole were all significantly higher(P<0.05).5.Main Gram-negative bacilli drug susceptibility results:The sensitivity of pseudomonas aeruginosa to ceftazidime,cefepime,meropenem,imipenem,piperacillin/tazobactam,amikacin,gentamicin,tobramycin,ciprofloxacin and levofloxacin were higher than 93.3%.The resistance rate of enterobacteriaceae bacteria to ampicillin and cefazolin were 91.7% and 70.4% respectively.The resistance rate to ampicillin/sulbactam was 53.3%.The resistance rate of enterobacteriaceae bacteria to ceftazidime,ceftriaxone,cefepime,ceftitan,amitracin,gentamicin,ciprofloxacin,levofloxacin and compound xinnomin ranged from 21.9% to 37.5%.The sensitivity to imipenem,ertapenem,amikacin,piperacillin/tazobactam was higher than 96.8%.Conclusion: 1.Staphylococcus aureus was the major pathogenic bacterium for community-acquired skin and soft tissue infection in this region.2.The detection rate of MRSA in this region was 35.3%,indicating that there was a high proportion of community-acquired methicillin-resistant Staphylococcus aureus(CA-MRSA)infection in the region,which needed to be highly regarded clinically.3.In order to alleviate the production of drug-resistant bacteria,the clinician should strengthen the etiological examination and choose the antibiotics reasonably to treat skin and soft tissue infection according to bacterial culture and susceptibility testing results.