The Evaluation Of The Curative Effect Of Gentamycin-Lincomycin Injection In Treatment Of Bacterial Respiratory Disease

Porcine respiratory disease is a general term of respiratory diseases caused by multiple factors-a mixture of primary and secondary pathogens.The infectionrate is the highest in the case of a complex infection of PRRSV,PCV,Haemophilus parasuis and Streptococcus suis,while mortality rate is the highest and damage is serious in the case of secondary infections caused by Streptococcus suis,Haemophilus parasuis.Our team finally chose gentamicin sulphate and lincomycin hydrochloride as the final drugs from the perspectives of formulation screening,economic cost,anti-drug resistance,and aqueous solution stability.However,the therapeutic effect of the combination of two drugs on respiratory disease complex caused by mixed bacterial infectionis unclear.For this reason,the antibacterial effect of gentamycin sulfate-lincomycin hydrochloride injection on Streptococcus suisand Haemophilus parasuis andtherapeutic effect on respiratory disease caused by mixed infection were studies in this article.The effect of combined antibacterial test and pharmacodynamic experimentusing the gentamycin sulfate-lincomycin hydrochloride injection to sterilize Haemophilus parasuis and Streptococcus suis was determined by micro-broth dilution method,checker-board method and Time-kill curves.Results showed that these two drugsmanifested additive or synergistic effects on 95% of Streptococcus suis and 92.3% of Haemophilus parasuis,respectively.In clinical trials,naturally pathogeneticnursery pigs with porcine respiratory diseases were selected.Clinical symptoms,clinical therapeutic effect,bacterial isolation and counting in vivo,histopathological observations,and feed weight ratio before and after drug administering,were used to determine the therapeutic effect of gentamicin sulfate-lincomycin hydrochloride injection on respiratory diseases.Results show that:(1)After drug administration,there was a significant difference in clinical symptom scores of the group of gentamicin sulphate-hydrochloride lincomycin injection comparing with other control groups(p<0.05),indicating that the drug can effectively improve the clinical symptoms of the pathogenetic pigs..(2)After drug administration,the effective rate and cure rate of the group of gentamicin sulphate-hydrochloride lincomycin injection were significantly higher than those of other drug control groups(p<0.05),indicating that therapeutic effect of gentamicin sulphate-hydrochloride lincomycin injection was significantly better than that of other drug control groups.In addition,the pigs injected with gentamicin sulphate-hydrochloride lincomycin injection were alive after 21 days of drug administration,indicating that the therapeutic effect was significantly better than that of other drug control groups.(3)Compared with the control groups,the number of bacteria in the nasal cavity of the gentamicin sulphate-hydrochloride lincomycin injection group was significantly reduced(p<0.05)on the 3rd day and on the 5th day of drug administration,indicating that the drug can effectively kill the bacteria in the nasal cavity of the pathogenetic pigs.(4)Specific PCR identification of the suspected isolated strains showed that the pathogenetic pigs were infectedwith Streptococcus suisand Haemophilus parasuis.(5)Histopathological observations showed that gentamycin sulfate-hydrochloride lincomycin injection can effectively improve the pathological changes of various organs,indicating that therapeutic effect of the combined drugs is good.(6)After drug administration,the feed weight ratio of the group of gentamycin sulfate-hydrochloride lincomycin injection was significantly lower than that of the control group(p<0.05),indicating that the combined drugs can effectively increase the feed utilization rate.This study confirmed that the treatment of gentamycin sulfate-hydrochloride lincomycin injection on the bacterial porcine respiratory disease is good,providing a clinical evidence for the development of new veterinary drugs.