Case #1: This 65 year old woman was bitten by her cat on the dorsal aspect of the right middle finger at 8:00 a.m. she rinsed the bite with water and at 4:30 p.m she noted pain and swelling in the finger and the dorsum of the right hand. She then noted pain in the axilla, red streaking up the fore arm, and chills. On examination, she had a temperature of 38 degree celsius and her upper right extremity was notable fo swelling, erythema, warmth and tenderness on the dorsum of the hand. Two small puncture wounds were seen on the proximal phalanx of the long finger, also noted. Laboratory sutdies demontrated an eleveted white blood cell count of 12000/micro liter with a left shift (the presence of immature neutraphils in peripheral blood). Aspiration of an abscess on her finger was sent for culture, and the patient was taken to the operating room for incision and drainage of the abscess. Gram stain of the organism causing this woman's infection is seen in Fig.1, and Fig 2 shows cultures on sheep blood and chocolate agars.
1. Which organism was isolated on culture of the abscess?
2. What is the reservoir of this organism? How do humans most commonly become infected by this organism?
3. How can infection with this organism be prevented?
4. Which other clinical syndromes can be caused by this organism?
Case #2: The patient was a 34-year old male with a history of tobacco and alcohol abuse .(12 cans of beer per day). Two months prior to admission he was seen at an outside hospital, where he was found to have a necrotic lesion in his right upper lobe on chest X-ray. He was PPD (purified protein derivative) negative, and 3 sputum cultures done for Mycobacterium spp. were negative. he had no risk factors for HIV infection. Four weeks prior to admission, he presented with fever, productive cough, night sweats, chills, and a 10-lb (4.5 kg) weight loss. He was treated for amoxicillin-clavulanic acid for 14 days. Fevers, chills, night sweats decreased. On admission, he presented with a firm right chest wall mass (4 by 4 cm), which was aspirated for diagnostic purposes. The aspirated material was dark green and extremely viscous. Two days later, for the nurses found him urinating on the wall of his room. Because this was unusual behavior for this patient, it was decided to perform a CT scan of the head, the scan revealed multiple ring-enhancing lesions. The patient was taken to surgery and the brain lesions were aspirated. A Gram stain of the organisms recovered from the brain lesion aspirate showed a branching, beaded gram-positive rod. The colonial morphology of the organism recovered from the brain lesion aspirate after 4 days of incubation.
1. What do the lesions in the patient's head probably indicate? What therapy does this patient need?
2. Explain the relationship between his chest wall lesion and his brain lesions.
3. Which lifestyle factors predisposed this patient to the chest wall lesion?
4. What is the origin of the organism causing this patient's infection?
5. Two genera of organisms are likely on the basis of the gram stain. Which test could be performed on the brain aspirate to determine the genus to which this organism belonged?