Clinical Comparison Of Pertussis Infected With Macrolides-resistant Or Macrolides-sensitive Bordetella Pertussis

Objective: To analyze the clinical characteristics between patients infected by macrolide-sensitive Bordetella pertussis or those infected by macrolide-resistant Bordetella pertussis.Methods: The clinical data of hospitalized children with pertussis diagnosed by positive nasopharyngeal swab culture in Shenzhen Children’s Hospital infectious Department from December 2015 to December 2017 were collected,including age,sex,vaccination,onset time,clinical manifestations,laboratory examination,treatment and outcome.Based on the results of antimicrobial susceptibility testing,patients were divided into 2 groups:macrolide-sensitive(MS)group and macrolide-resistant(MR)group.The clinical characteristics of the two groups were analyzed and compared retrospectively.Results:(1)154 pertussis patients who were diagnosed by positive nasopharyngeal swab culture were analyzed.Of these patients,117(75.97%)were younger than 6 months,95(61.69%)were unvaccinated against pertussis,and 80(51.95%)had contact history with coughing family members or nannies.(2)The MIC values of erythromycin,SMZ-TMP,amoxicillin,azithromycin,clarithromycin and levofloxacin in 154 strains of Bordetella pertussis were detected by E-Test method.MIC value ranges of erythromycin,azithromycin and clarithromycin were <0.016ug/ml~>256ug/ml,<0.016ug/ml~>256ug/ml and 0.094ug/ml~>256ug/ml,respectively.The susceptibility rates of these three antibiotics were 49.35%.The MIC value ranges of SMZ-TMP,amoxicillin and levofloxacin were0.006ug/ml~0.75ug/ml,0.125ug/ml~1ug/ml and 0.064ug/ml~1.5ug/ml,respectively.The susceptibility rates of these three antibiotics were 100%.(3)The median age of patients in MR group was significantly older than that in MS group(4 months vs 3 months,Z=-(18)(13)(23)(20),P<0.05).More patients had been vaccinated against pertussis in MR group(48.71% vs27.63%,c2=7.24,P<0.05).Wheezing was more common in MR group(32.05% vs 15.79%,c2=5.58,P<0.05).More intravenous immunoglobulin(30.77% vs 15.79%,c2=4.82,P<0.05)and SMZ-TMP(16.67% vs 0%,c2=13.8,P<0.05)were used in MR group.The logarithmic value of PCR copy number of pertussis was higher in MR group(Z=-5.01,P<0.05).Except for one patient who was discharged automatically,all the children in the two groups were discharged after improvement.Conclusion: Macrolides resistance was common in pertussis.Wheezing was more common in children infected with macrolides-resistant Bordetella pertussis,and there was no significant difference in other clinical manifestations of children infected with macrolides-resistant or macrolides-sensitive Bordetella pertussis.The infection of macrolides-resistant strains was more common in children who had been vaccinated,and as to the patients infected with macrolides-resistant strains,most of them could be cured effectively with the treatment of erythromycin.Only a small fraction of them need to be treated with SMZ-TMP.