A 19 year old college student presents to the student health clinic complaining of weakness, malaise, and a chronic cough. He has a fever of 100 degrees F and a dry cough; no sputum can be obtained for laboratory analysis, so a bronchial lavage is performed and the washings are submitted to the laboratory. The laboratory repos that the organism is "slow-growing."Serodiagnosis reveals Strep MG agglutinins in the patient's serum. Which of the following organisms is the most likely cause of this student's illness?