University of the Witwatersrand, Johannesburg, South Africa.
Biol Res. 2010;43(2):141-8. Epub 2010 Sep 24.
Salmonellosis and shigellosis are significant and persistent causes of diarrheal diseases among humans in developing countries. With that in mind, the current study investigates the occurrence of plasmid-encoded multidrug resistances in Salmonella and Shigella from diarrheal cases among humans. The isolates were characterized by serotyping, antimicrobial-susceptibility testing, transfer experiments and curing. The extended spectrum β-lactamase (ESBL) was detected by the double disc diffusion synergy test (DDST). A significant number of the plasmid-encoded multidrug resistant (PEMDR) Salmonella and Shigella isolates were found to harbour transferable plasmid genes resistant to antibiotics like ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, ceftriaxone, cefuroxime and to a lesser extent to ciprofloxacin and ofloxacin. The conjugative R-plasmids-encoded extended-spectrum β-lactamase also showed resistances to cephalosporins (ceftriaxone and cefuroxime) and ampicillin. Curing experiments showed chromosomal resistances to varied antibiotics. The findings confirmed the presence of PEMDR in Salmonella and Shigella strains as a suitable adaptation to a changing antibiotic environment. The results therefore suggest the limited use of the commonly prescribed/or third generation cephalosporins as an empirical treatment of multidrug resistant Salmonella and Shigella because this may affect therapeutic outcomes.
在发展中国家，沙门氏菌病和志贺氏菌病是导致人类腹泻病的重要且持续存在的原因。有鉴于此，本研究调查了人类腹泻病例中沙门氏菌和志贺氏菌中质粒编码的多重耐药性的发生情况。通过血清分型、抗菌药物敏感性试验、转移实验和消除实验对分离株进行了特征描述。采用双纸片协同扩散试验（DDST）检测扩展谱β-内酰胺酶（ESBL）。研究发现，相当数量的质粒编码的多重耐药（PEMDR）沙门氏菌和志贺氏菌分离株携带可转移的质粒基因，对氨苄西林、氯霉素、甲氧苄啶-磺胺甲恶唑、头孢曲松、头孢呋辛和环丙沙星和氧氟沙星有一定程度的耐药性。可转移的 R 质粒编码的扩展谱β-内酰胺酶也对头孢菌素（头孢曲松和头孢呋辛）和氨苄西林具有耐药性。消除实验显示对多种抗生素存在染色体耐药性。研究结果证实了 PEMDR 在沙门氏菌和志贺氏菌菌株中的存在，这是对不断变化的抗生素环境的一种合适的适应。因此，建议谨慎使用常用的/第三代头孢菌素作为多药耐药性沙门氏菌和志贺氏菌的经验性治疗，因为这可能会影响治疗效果。
