Final answer:
Concomitant use of opiates and vancomycin may increase the risk of superinfection, a secondary infection occurring due to disturbed body flora from long-term broad-spectrum antimicrobials.
Step-by-step explanation:
The concomitant use of opiates and vancomycin may increase the frequency of superinfection. Superinfection is a secondary infection that may arise when the flora of the body is disturbed by long-term use of broad-spectrum antimicrobials like vancomycin. Opioid use, while providing effective pain relief and utility in treating coughs, nausea, and diarrhea, can also lead to side effects that resemble severe flu symptoms upon withdrawal. Both medications have their respective serious risks and side effects, which, when used together, can potentially compound or lead to an increased risk of complications like superinfections.