A person with prolonged usage of contact lenses presented with irritation of left eye. A diagnosis of keratitis was made and corneal scrapings revealed growth of multidrug resistant pseudomonas aeroginosa. Which of the following, best explains the mechanism of antimicrobial resistance in these isolated pseudomonas aeroginosa strains?
**Core Concept**
Pseudomonas aeruginosa is a gram-negative bacterium known for its ability to develop antimicrobial resistance, particularly in immunocompromised individuals or those with prolonged exposure to antibiotics or other environmental factors. The development of resistance in P. aeruginosa is often linked to the production of specific enzymes or efflux pumps that confer resistance to commonly used antibiotics.
**Why the Correct Answer is Right**
The correct answer is related to the production of efflux pumps, specifically the MexXY-OprM efflux pump, which is known to confer resistance to multiple antibiotics, including fluoroquinolones and aminoglycosides. This efflux pump is composed of two proteins, MexX and MexY, which are integral membrane proteins, and OprM, a lipoprotein that forms a pore in the outer membrane of P. aeruginosa. The MexXY-OprM efflux pump works by recognizing and binding to antibiotics, and then pumping them out of the cell, thereby reducing their intracellular concentration and conferring resistance.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the production of beta-lactamases, such as TEM or SHV, is more commonly associated with resistance in gram-negative bacteria like E. coli and Klebsiella pneumoniae, rather than P. aeruginosa.
**Option B:** This option is incorrect because the production of acetyltransferases is more commonly associated with resistance to aminoglycosides in gram-negative bacteria like E. coli and Pseudomonas aeruginosa, but through a different mechanism involving the modification of the antibiotic rather than efflux.
**Option C:** This option is incorrect because the production of metallo-beta-lactamases is more commonly associated with resistance in gram-negative bacteria like P. aeruginosa, but through a different mechanism involving the hydrolysis of beta-lactam antibiotics rather than efflux.
**Option D:** This option is incorrect because the production of beta-lactamase inhibitors, such as clavulanic acid, is actually used to inhibit the activity of beta-lactamases, rather than conferring resistance.
**Clinical Pearl / High-Yield Fact**
Pseudomonas aeruginosa is known for its ability to develop resistance to multiple antibiotics, and the production of efflux pumps like MexXY-OprM is a key mechanism of resistance. This highlights the importance of using combination therapy and monitoring antibiotic susceptibility patterns to stay ahead of resistance.
**Correct Answer:** C.