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Objective Toinvestigateantimicrobialresistanceamonggram-positivecocciinChinain 2013.Methods Retrospectivestudy.FromJune2013toDecember2013,1663consecutiveandnon-repetitive gram-positive cocci were collected from 15 teaching hospitals. The minimal inhibitory concentration ( MIC) of antibacterial agents was determined by agar dilution method. A retrospective study was conducted on rates of resistance to antimicrobial agents. The prevalence of penicillin-resistant Streptococcus pneumoniae ( PRSP) between children and adult patients and the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) between elder group and younger adult patients were compared using chi-square test. Results The prevalence of PRSP in children below 3 years old ( 72. 9%, 51/70 ) was higher than adult patients (55. 2%, 106/192) (χ2 =6. 653,P<0. 05). About 94. 9%(261/275) and (92. 7%,255/275) of S. pneumonia were resistant to erythromycin and clindamycin. All S. pneumoniae strains were susceptible to teicoplanin, vancomycin, linezolid, tigecycline and daptomycin. Penicillin still showed very high activity against Streptococcus spp. β-Hemolytic group. More than 60% of Streptococcus spp.β-Hemolytic group were resistant to erythromycin, clindamycin and tetracyclines. The prevalence of MRSA and methicillin-resistant coagulase-negative Staphylococci(MRCoNS) was 39. 7%(229/576) and 80. 6%(224/278), respectively. The MRSA prevalence ranged from 24. 2% to 70. 0% in different regions. About 52. 6%( 100/190 ) of Staphylococcus aureus from respiratory tract specimens, 38. 5%(40/104)of Staphylococcus aureus from blood samples, and 29. 7%(58/195) of Staphylococcus aureus from wound and pus were resistant to methicillin. The prevalence of MRSA in elder group ( 48. 6%, 84/173 ) was higher than that in younger adult patients (35. 7%, 144/403)(χ2 =8. 322,P <0. 05). The susceptibility rates of MRSA to chloramphenicol and trimethoprim/sulfamethoxazole were 86. 4% ( 244/228 ) and 94. 7% ( 237/228 ) , respectively. Susceptibility rates to gentamycin, erythromycin, clindamycin, tetracyclines, rifampicin and quinolones were ranged from 15. 8% to 59. 6%. All Staphylococci isolates were susceptible to teicoplanin, vancomycin, linezolid, daptomycin and tigecycline. All Enterococcus isolates were susceptible to daptomycin and tigecycline. All E. faecalis ( 158/158 ) and 96. 4% ( 133/138 ) of E. faecium were susceptible to teicoplanin. About 98. 0% ( 150/153 ) of E. faecalis and 97. 1% ( 145/138 ) of E. faecium were susceptible to linezoild. About 45. 8% (70/153) of E. faecalis and 60. 9% (84/138) of E. faecium were resistant to gentamycin with a high concentration. The susceptibility of E. faecalis to all the antibiotics tested exceptchloramphenicolandtetracyclinewashigherthanthatofE.faecium.Conclusions Basedon different age groups and regions, the resistance rates of Gram-positive cocci are different. Teicoplanin, vancomycin, tigecycline, daptomycin, linezolid and tedizolid showed very high activity against Gram-positive cocci. (Chin J Lab Med,2015,38:373-381)
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ObjectiveTo learn the rpoB mutation difference in rifampicin/rifabutin cross-resistant (RIF/Rfb-R)clinical isolates and in rifampicin-resistant/rifabutin-susceptible (RIF-R/Rbo-S)clinical isolates of Mycobacterium tuberculosis.Methods To sequence the full-length genome of rpoB gene,and analyze the rpoB full-length gene mutation differences in 278 RIF/Rfb-R clinical isolates,40 RIF-R/Rfb-S clinical isolates,30 rifampicin-susceptible/rifabutin-susceptible (RIF-S/Rfb-S) and in 1 reference strain ofH37Rv.ResultsNo mutations of rpoB full-length gene were found in H37Rv reference strain and RIF-S/Rfb-S clinical isolates.In RIF/Rfb-R clinical isolates,531 (70.5％ ) and 526 (20.9％ ) were the most frequent mutation codons.223 (80.2％ ) isolates possesed single mutations as S531L,S531W,H526D,H526Y,H526R,Q513K,Q513P,Q510H,V176F,P287R,Y395C and H404Y.55 (19.8％) isolates had multiple mutations,and among these the S531L,H526 R,H526Y,H526D,D516G and Q513K were the main substitutions which were in combination with other points.In RIF-R/Rfb-S clinical isolates,516 (65.0％),526 ( 17.5％ ) and 533 ( 10.0％ ) were the most frequent mutation codons.21 (52.5％ ) isolates possesed single mutations as L533P,H526L,H526S,S522L,D516V,D516Y and D516F.19 (47.5％)isolates had multiple mutations and among these the D516V and L533P were the main substitutions which were in combination with other points.CondusionsIn our study,100％ rifamycin-resistant clinical isolates of Mycobacterium tuberculosis had rpoB mutations,but the mutations in RIF/Rfb-R clinical isolates were sharply different from RIF-R/Rfb-S clinical isolates in mutation positions or amino acids substitutions of single mutations strains,mutation positions or combination types and the most frequently mutation codons or amino acids substitutions of multiple mutations strains.Thus,DNA sequencing is instructive and meaningful to choose rifampicin or rifabutin for tuberculosis treatment.