This study described a pertussis outbreak caused by macrolide-resistant B. pertussis in a primary school and indicated that close contact of index case causes the bacterial transmission.
Objective To analyse macrolide resistance and molecular characteristics of Bordetella pertussis clinical isolates from western China, and to explore the relationship between macrolide-resistance and genotypes. Methods Susceptibilities of B. pertussis clinical isolates to erythromycin, azithromycin and clarithromycin were determined by epsilometer test (E-test). Isolated strains were sequenced to ascertain the presence of the 23S rRNA gene A2047G mutation. Strains were typed using multilocus antigen sequence typing, multilocus variable-number tandem-repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). Results Of 58 B. pertussis strains isolated in this study, 46 were macrolide-resistant and 12 were macrolide sensitive. All macrolide-resistant strains carried the A2047G mutation and were the prn1/ ptxP1/ ptxA1/ fim3-1/ fim2-1 genotype; the MLVA types were MT195 (19/58), MT55 (13/58) and MT104 (14/58), and the PFGE profiles were classified into BpSR23 (17/58) and BpFINR9 (29/58) types. None of the macrolide-sensitive strains carried the A2047G mutation; genotypes were ( prn9 or prn2)/ ptxP3/ ptxA1/ fim3-1/ fim2-1, and all were MT27. PFGE profiles differed from the macrolide-resistant strains. Conclusions B. pertussis clinical isolates from western China were severely resistant to macrolides. Genotypes differed between macrolide-resistant and macrolide-sensitive strains, and there may be a correlation between acquisition of macrolide resistance and changes in specific molecular types.
This study aimed to assess the prevalence of anti-hepatitis E virus (HEV) immunoglobulin (Ig) M and elevated serum alanine aminotransferase (ALT) levels among employees in catering and public place industries. Blood samples were collected between January and December 2020 from 26,790 employees working in the Qinhuai district of Nanjing, China. Anti-HEV IgM in the serum samples was tested by the capture ELISA method and ALT was tested by the IFCC method. Samples positive for anti-HEV IgM or with ALT levels over 200 U/L were subjected to PCR screening of HEV RNA. The overall seroprevalence of anti-HEV IgM was 0.41%, and the seroprevalence was slightly higher in males (0.47%) than in females (0.37%); however, the difference was not substantial (p = 0.177). Seroprevalence of anti-HEV IgM increased with age, reaching its peak level after 48 years of age. The prevalence of elevated ALT levels was 4.24%, and males exhibited a higher prevalence than females (6.78% vs 2.65%, p < 0.001). Prevalence of elevated ALT levels differed in age groups and the 26-36-year-old group had the highest rate of elevated ALT levels. Employees with elevated ALT levels had a higher prevalence of positive anti-HEV IgM than those with normal ALT (0.57% vs 0.31%, p < 0.001). Positive HEV RNA was detected in one anti-HEV IgM-negative employee with ALT higher than 200 U/L. In our study, all the HEV RNA-positive and IgM-positive individuals are asymptomatic, and a combination of ALT tests, serological methods, and molecular methods is recommended to screen asymptomatic HEV carriers and reduce the risk of transmission.
ObjectiveTo compare the macrolide resistance and molecular characteristics of clinical isolated Bordetella pertussis, and explore the relationship between the macrolide-resistance and genotypes. MethodsErythromycin、azithromycin and clarithromycin susceptibility of clinical isolates during 2018-2020 was determined by E-test. The A2047G of the 23S rRNA genes was sequenced for drug-resistance mutation. Multilocus antigen sequence typing (MAST)、Multiple Locus Variable-number tandem repeat Analysis (MLVA) and Pulsed field gel electrophoresis (PFGE) methods were employed to do molecular typing for the strains. Results58 strains were isolated in this study, 46 of them were macrolide-resistant and 12 sensitive. All macrolide-resistant strains carried a genetic mutation at the A2047G site, genotype was prn1/ptxP1/ptxA1/fim3-1/fim2-1, the MLVA types were identified as MT195、MT55 and MT104, PFGE profiles were classified into BPSR23 and BpFINR9 types. However, no mutations were found in all macrolide-sensitive strains whose genotypes were (prn9 or prn2)/ptxP1/ptxA1/fim3-1/fim2-1 and MT27, and PFGE classified other profiles. ConclusionsThe clinical isolated Bordetella pertussis has serious resistance to erythromycin and began to spread to other macrolides. There were differences between macrolide-resistant and -sensitive Bordetella pertussis in genotypes. The acquisition of macrolide resistance may be associated with change of specific molecular types.
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