Final answer:
It is important to diagnose infections with Nocardia spp. because they are resistant to penicillin and antifungal agents do not kill them. However, they are susceptible to sulfonamides.
Step-by-step explanation:
It is extremely important to diagnose infections with Nocardia spp. because these organisms are resistant to penicillin and antifungal agents do not kill them. However, these organisms are susceptible to sulfonamides, which can be used for effective treatment. Therefore, the correct answer is option C: these organisms are susceptible to sulfonamides.
Nocardia spp. are susceptible to sulfonamides, making these drugs an effective treatment option. It's important to diagnose infections with Nocardia spp. promptly because if left untreated or if the wrong antimicrobial therapy is chosen, the infections can become chronic and severe. While antifungal agents are not effective against Nocardia spp., and some strains may be resistant to penicillin, sulfonamides, such as trimethoprim-sulfamethoxazole (TMP-SMX), are commonly used in the treatment of Nocardia infections.