Question

Part III – The Physician

June 5th

ree weeks had passed. e swelling was still present and it had become even more di cult for Margo to move

her nger. In addition, the amount of uid oozing from the wound had increased, suggesting that the medication hadn’t worked. It was now time to visit a local physician. Following the advice of a neighbor, Margo set up an o ce appointment with Dr. Chan, an internist. After the usual battery of questions, Dr. Chan sent in the nurse to collect a specimen from Margo’s nger. Dr. Chan mentioned to Margo that the specimen would be sent o to the regional hospital laboratory for analysis and that he would provide her with another prescription for Ke ex, which she should continue to take until test results came back.

June 15th

e test results arrived in Dr. Chan’s o ce on June 15th and were as follows: • No yeast or fungal elements were noted

• Gram-stain reaction: no organisms seen

• Culture of anaerobes and aerobes @48 hours yielded no growth

• Enrichment culture results: moderate growth on day 5 of an acid-fast bacterium (AFB). o Growth identi ed as Mycobacterium fortuitum by the Florida State Laboratory.

Armed with a microbial identi cation, Dr. Chan prescribed Doxycycline and Bactrim to be taken for four months. Dr. Chan also mentioned that the isolated organism was known to be found in tap water. Consequently, Margo planned to ask her condo community why an organism that could cause so much pain would be living in the water that was coming out of her faucets. And although she was annoyed to learn of the source of the organism, at least she could take some comfort in the fact that she nally had an accurate diagnosis and that by taking her medicine she could fully recover from her injury and start to enjoy her new home.

Questions

1. Compare and contrast aerobes and anaerobes. Why were no microbes noted upon aerobic and anaerobic culture?

2. Investigate the properties and characteristics of M. fortuitum. Where is this organism typically found (reservoirs)?

3. Why must the acid fast stain be performed to identify organisms of the genus Mycobacterium?

4. Why did Dr. Chan prescribe two antibiotics rather than only one?

5. How does doxycycline kill bacteria (cellular target)?

6. Why were the antibiotics prescribed for an extended period (4 months)?

7. No organisms were noted upon Gram staining, yet the enrichment culture yielded M. fortuitum after several days. Provide an explanation.