The tripartite efflux system chiefly responsible for intrinsic multidrug resistance to tetracyclines, chloramphenicol and fluoroquinolones in Escherichia coli is:
- A MexAB-OprM
- B AcrAB-TolC ✓
- C AdeABC
- D NorA
Explanation
AcrAB-TolC is the constitutively expressed resistance-nodulation-division (RND) pump of Enterobacteriaceae: AcrB is the inner-membrane transporter, AcrA the periplasmic adapter and TolC the outer-membrane channel. It exports a broad range of agents and is upregulated through global regulators such as MarA, SoxS and Rob. MexAB-OprM performs the equivalent role in Pseudomonas aeruginosa, AdeABC in Acinetobacter baumannii and NorA is a single-component major facilitator pump handling fluoroquinolones in Staphylococcus aureus, so each distractor belongs to a different organism.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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