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4/27/2015 Infectious Diseases Board Review Session One • James Myers MD • Program Director Infectious Diseases • Quillen College of Medicine • 18 year old woman seen at JCIM with complaint of tender periauricular lymph node • Occasional fever • Very tender lymph node approximately 6 cm in diameter • Small, healed excoriations over right wrist 1 4/27/2015 KNOW THE DIFFERENTIAL DIAGNOSIS OF CERVICAL LYMPHADENOPATHY -malignancy -TB, non-TB mycobacteria -actinomycosis -viral (EBV, CMV) -bacterial/suppurative -Bartonella infection • Bartonella henselae • 25,000 cases annually • B. henselae recovered from the blood of healthy cats and from cat fleas • 90% of cases are typical: papule, ipsilateral lymphadenopathy (>90%), fever (up to 60%), mild leukocytosis • nodes may be multiple, persist for 2-4 months • Biopsies reveal nonspecific inflammation including granulomata and stellate necrosis • bacilli are seen by Warthin-Starry staining • serologic testing is more sensitive than skin testing • treatment controversial: • Bass et al. (Pediatr Infect Dis J 1998;17:447) demonstrated a more rapid resolution of LAD when treated with azithromycin • however, outcome is almost always benign (Margileth et al.: Pediatr Infect Dis J 1992;11:474) • other drugs reported to be successful 2 4/27/2015 • 45 yo woman with RA presents with 12 hours of fever, nausea, and abdominal pain • Meds include prednisone 15 mg QD and methrotrexate • Exam: temp 102.6, BP 90/62, RR 16, P 110; no rash, abdomen mildly tender in mid-epigastrium; no HSM; joint deformities c/w RA • Urine culture negative, U/S RUQ negative • Develops loose stools 12 h later • Blood culture, stool culture: Campylobacter jejuni KNOW THE DIFFERENTIAL DIAGNOSIS OF DYSENTERY • • • • Fever, tenesmus, bloody stools most common symptoms Check fecal lactoferrin or WBC count and stool culture Salmonella, Shigella, Campylobacter, Yersinia E. coli 0157:H7 Treatment: • Shigella:bactrim DS or a fluoroquinolone X 3 d • Campylobacter: erythromycin X 5 d • E. coli 0157: DON’T treat, avoid antimotility agents • Salmonella: only treat typhoidal disease or if severely ill or immunocompromised; use a fluoroquinolone or ceftriaxone 3 4/27/2015 • 56 yo man underwent CABG two weeks ago • Complicated by post-operative aspiration pneumonia treated with ceftriaxone and clindamycin with improvement • HD#7 develops onset of fever, profuse loose stools, leukocytosis to 28,000 • Exam with hypoactive bowel sounds, marked distention • Abdominal flat plate reveals… 4 4/27/2015 • Onset after 3 d in hospital; associated fever, abdominal pain, leukocytosis common • Associated especially with cephalosporins, penicillins, and clindamycin; can occur with chemotherapy • New Tcd mutant/NAP1 strain: hypersecretor • Diagnosis by stool PCR • Could send stool for fecal lactoferrin (up to 75% will be +) or fecal WBC (up to 40% +) or for C. diff toxin assay • Treatment: • metronidazole 250 mg Q6 or 500 mg Q8 X 10 d • Stop the offending agent • Oral vancomycin (NOT IV) MORE effective now and should be used in all severe cases • little data on combining the two • 22 yo college student c/o watery diarrhea for 6 weeks • Previously traveled to Belize KNOW THE DIFFERENTIAL OF CHRONIC DIARRHEA • Persistent diarrhea for > 7 days • Send inflammatory screen and O&P • Consider parasites: • • • • • Giardia Cryptosporidium Cyclospora Isospora belli If HIV positive, add Microsporidia, Mycobacterium avium, and communityacquired pathogens • Treatment based on findings 5 4/27/2015 Rice/Chinese food: Bacillus cereus Poorly cooked beef: E. coli 0157:H7 Pork (especially Mexico): neurocystercercosis (Taenia solium) Raw/unpasteurized dairy/cheese (esp. goat): Brucella, Listeria, Mycobacteria bovis • Strawberries/raspberries/sprouts: Isospora, cyclospora • Mountain stream water: Giardia lamblia • Seafood: • Vibrio sp. (cirrhotics) • Hepatitis A • If freshwater….Aeromonas • • • • • 34 yo female with a benign PMH presents in August of 2000 with 3 days of worsening HA without decrease in mental status • exam reveals temp of 39.1 C, nuchal rigidity, and photophobia; no papilledema • LP reveals 300 WBC, 95% lymphocytes; CSF protein 54, CSF glucose 82 • gram stain negative generally no decreased MS fever 76-100%, nuchal rigidity 50% HA uniform, often frontal CSF pleocytosis is present, characteristically lymphocytes or monocytes (100-1000 cells/mm3) • CSF protein is usually minimally elevated and CSF glucose minimally decreased • etiology... • • • • 6 4/27/2015 • Enteroviral most common: • echovirus • coxsackievirus • • • • • seasonal: late summer and fall family outbreaks may be associated with rash; LP ? therapeutic diagnosis: immunoassays; PCR treatment: supportive • HIV!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! • Look for rash over upper chest • Diagnose with HIV RNA by RT PCR • • • • • • • Lyme disease/Borrelia burgdorferii Ehrlichia/Anaplasma sp. Cat-scratch disease rabies TB syphilis fungal • Drugs • NSAIDS • sulfa agents • autoimmune diseases • RA, lupus • Behcet’s • sarcoidosis 7 4/27/2015 • 48 yo school teacher brought to ER by family after being found sitting on the floor in her bedroom • Further questioning: headache all day, “just can’t get my words out” • Exam: temp 99.4; no focal motor abnormalities; MMSE 18/30, poor short-term memory • LP: 12 WBC, 700 RBC, prot 56, glu 65 • MRI... KNOW THE DIFFERENTIAL DX OF ENCEPHALITIS • =inflammation of the brain • Viruses most common: HSV, WNV, arboviruses, rabies, herpesviruses in general (EBV/CMV) • Other causes • • • • • Rickettsia Syphilis Lyme Fungi parasites • Only HSV and Enteroviral encephalitis can be treated 8 4/27/2015 • Diagnosis: • HSV PCR on CSF • HSV culture from CSF VERY poor • HSV serologies not useful • Treatment: • IV Acyclovir 10 mg/kg Q8 h • Empiric treatment in all cases of encephalitis of unknown etiology • Only major side effect: reversible renal failure due • 56 yo renal transplant on CSA/prednisone • C/o 1 d of SOB, fever 9 4/27/2015 • ? Clinical clues: • • • • • • • Severe clinical illness Hyponatremia Diarrhea Multilobar involvement Sputum with leukocytosis but gram stain, culture negative Immunocompromised Outbreaks: associated with air conditioning units, cooling towers, whirlpools • Diagnosis: • Legionella urinary antigen (only L. pneumophila serotype 1) • sputum DFA • Treatment • Fluoroquinolone • azithromycin • Birds • Chlamydia psittaci=psittacosis (parrots, parakeets) • Cryptococcus (bird feces) • Dirt (often lung-skin and occasionally brain diseases) • Histoplasmosis (Ohio River Valley) • Cryptococcosis • Blastomycosis • Coccidiomycosis (San Juaquin Valley) • 32 yo man with history of Hodgkin’s disease, cured X 10 years • Presents with acute onset fever and prostration • Denies fever, cough, nausea/vomiting, diarrhea • Had “flu” 10 days ago, improved until this A.M. • Exam: temp 103.2, BP 80/50, P 130, RR 24; lungs with minimally decreased LLL breath sounds • No sputum could be obtained 10 4/27/2015 KNOW WHAT INFECTIONS YOU GET WITH IMPAIRED SPLENIC OR HUMORAL FUNCTION • Defects in antibody production=impaired opsonization • Mortality high in this setting • diseases with impaired antibody production • Splenectomized patients • CLL • Sickle cell anemia • Lymphomas • Cirrhotics • Hemodialysis patients • Congenital and acquired immunoglobulin deficiencies • Organisms • Strep. Pneumoniae************** • H. flu • N. meningitidis • Capnocytophagia=DF2 • babesiosis 11 4/27/2015 • 24 yo WF s/p heart transplant 5 weeks ago • Meds include CSA, prednisone, mycophenolate • C/o fatigue, nausea, fever, abdominal discomfort, dysphagia • Exam reveals temp 100.5; no rash • Labs reveal AST 82, ALT 69, WBC 2.9 • Chest film WNL s/p transplant KNOW WHAT INFECTIONS ARE SEEN IN THE SETTING OF T CELL IMPAIRMENT • At risk: AIDS pts, transplant recipients, patients on immunosuppressants (including RA, lupus, COPD, GN) • Defective T cell immunity= INTRACELLULAR PATHOGENS • Viruses (esp. CMV, HSV, EBV, VZV) • Fungi (esp. Candida sp., cryptococcus, pneumocystis) • Bacteria (esp. mycobacteria species, listeria,toxoplasma) A 35-year-old male office worker from Baltimore was feeling fatigued and had low grade fevers. He went to his family physician, and is referred to you because his liver function tests are abnormal. He has been previously healthy, but he has had multiple male and female sexual partners without condom use. On physical examination, he is icteric, and has mild RUQ tenderness, but no other abnormality. He denies any recent illness or travel, and drinks a “few” beers per week. He had an insurance physical exam with blood tests one year ago and donated blood at a hospital two months ago. He was not informed of any abnormality although he failed to reveal that he had many sexual partners. Lab profile: • ALT =1600 IU/L; AST = 1200 IU/L; Bili 4.2 mg/dl; Prothrombin time 12.0 seconds • CBC: normal • Hepatitis A antibody: positive (history of hep A immunization) • Hepatitis C antibody: negative • Hepatitis B: IgM antibody to HBc positive; IgG to HBc positive, HBs-antigen positive, HBs antibody negative, e antigen negative. • Hepatitis D antibody negative Which if the following tests would be most useful? A. Hepatitis E antibody B. RPR C. Hepatitis B viral load D. Hepatitis D viral load E. Hepatitis C viral load 12 4/27/2015 A 27-year-old man is brought by ambulance to the emergency room. His mother came home at the end of her work day and found him delirious on the living room couch. When she touched him he was “burning up,” and she called for emergency service. In the emergency room his temperature is 103.4° F, his heart rate is 132, and his blood pressure is 88/56mmHg. He is not responsive to commands and mumbles incoherently. He has an abdominal scar that his mother reports is due to a splenectomy, the result of trauma from a motorcycle accident when he was 19 years old. There is a deep abrasion on his right lateral calf that was erythematous, but not purulent. His mother reports that he scraped his leg 5 days ago when he slipped and fell off a stone wall while helping her plant spring flowers. She says the family dog likes to lick the wound. She thinks her son had “all his shots” as a child but is unclear about his tetanus immunization history. His white blood cell count is 24,700 with 19% band forms. The lab calls to say that they think they see little rod-shaped bacteria on the Wright-stained blood smear. His illness is most likely due to which one of the following? A. Streptococcus pneumoniae B. Haemophilus influenzae C. Vibrio vulnificus D. Capnocytophaga canimorsus E. Pasteurella canis Correct Answer: D Rationale: “Dog bite septicemia” is a rare but highly lethal infection caused by Capnocytophaga canimorsus or Capnocytophaga cynodegmi producing overwhelming sepsis or meningitis. It occurs most often in asplenic or alcoholic persons who are bitten by a dog or who have a wound licked by a dog. There is high grade bacteremia and the gram-negative rod bacteria may be seen on peripheral blood smears. S. pneumoniae and H. influenzae may cause overwhelming sepsis postsplenectomy,but the rods seen on peripheral smear are not consistent with pneumococci. H. influenzae bacteremia is quite rare in adults. Neither pneumococcus nor Haemophilus is associated with wounds or dog contact. The epidemiology here is not consistent with Vibrio infection (no water contact; no shellfish ingestion). Pasteurella canis is much less virulent than P. multocida and is often found as part of complex flora in infected dog bite wounds, but rarely causes bacteremia. 13 4/27/2015 • Which of the following would be the mostly likely pathogen in this rapidly expanding skin lesion in a febrile neutropenic patient with acute leukemia? The skin biopsy with sutures is seen in the lesion. • A. Fusarium solani B. Streptococcus pyogenes C. Borrelia burgdoferi D. Pseudomonas aeruginosa • This lesion is typical of early ecthyma gangrenosum, typically presenting in neutropenic patients and usually due to Pseudomonas aeruginosa.. • The sharp border and pale center comes from invasion of blood vessels in the dermis. • Lyme lesions (Borrelia burgdorferi) or streptococcal cellulitis are sharply circumscribed but don’t have pale centers. • Fusariosis causes nodular, erythematous lesions which often ulcerate with time. • This 25 year old woman from Guatemala had been given antithymocyte globulin and cyclosporine for her aplastic anemia but had as yet not responded and remained profoundly aplastic when she was observed to have over 24 hr to develop this swelling underneath her chin. There no lesions visible in the front of her mouth but she couldn’t open very wide because that caused pain She took sips of fluid without discomfort but was very nauseated and drinking very little. The swelling was firm and not apparently red or painful. She could speak softly without obvious hoarseness. • The most likely source of this infection is which of the following: A. Herpetic stomatitis B. Dental abscess C. Oropharyngeal candidiasis D. Vincent’s angina E. Lemierre’s syndrome • 14 4/27/2015 • This is Ludwig’s angina in a patient with poor dental hygiene. Ludwig’s is an infection of the submandibular and sublingual space from streptococci or other oral bacteria and originates from a dental abscess in the first molar or adjacent tooth. Infection spreads below the mylohyoid line into the soft tissue below the mandible. • The tongue protrudes upward and posteriorly, potentially obstructing the airway. Tracheostomy may be necessary. • The patient is febrile, toxic and has difficulty opening the mouth if infection has spread into the pterygoid space Therapy with piperacillin-tazobactam, ampicillinsulbactam or any regimen that is active against both aerobic and anaerobic flora is indicated. • Surgical drainage of the dental abscess can wait until the patient has responded to antibiotic therapy. • Septic thrombosis of the internal jugular vein to cause Lemierre’s syndrome does not cause symmetrical submandibular swelling and there is no indication of septic emboli to the lung or positive blood culture in this patient. Vincent’s angina is severe gingivitis, and like herpetic stomatitis and oropharyngeal candidiasis, does not extend into the neck. • This man was referred from Puerto Rico for management of his chronic myelogenous leukemia, currently responding to imatinib (Gleevec). He brought summaries from recent hospitalizations which mentioned courses of amphotericin B which were apparently given empirically during periods of neutropenia. He had indwelling vascular catheters at the time but they had been removed. He was currently feeling relatively well and had a normal physical examination and liver function tests. Because he had a low grade persistent fever he had a CT scan done. • The most likely source of the lesions is which of the following: A. Aspergillus B. Hemangioma C. Chronic myelogenous leukemia D. Bartonella species E. Candida species • • These multiple small rim-enhancing lesions are consistent with chronic disseminated candidiasis, an infection which begins during neutropenia but is only appreciated in the survivors, usually after recovery of neutrophils and treatment with antifungal agents. • These necrotic lesions may be seen in the liver or spleen as well. Aspergillus, Fusarium and agents of mucormycosis rarely result in this imaging result. • An erroneous diagnosis of aspergillosis is often made because pseudohyphae of Candida may resemble a mold on liver biopsy and cultures may be negative because of prior treatment. • Metastatic cancer can give a similar image but not CML and usually without fever. Bacillary peliosis hepatis, due to Bartonella henselae, is accompanied by fever and can cause similar lesions on imaging (Abdom Imaging 2005;30:738-40) but this infection is rarely noted in patients recovering from neutropenia, such as the one above. • Perhaps the antibacterial antibiotics given to febrile neutropenics account in part for the rarity of Bartonella infections in this population. Hemangiomas in the liver are common but have contrast enhancement located within the lesion, if at all, rather than in the margin, and would not explain the fever. 15 4/27/2015 • This 34 year old female with AIDS was brought to a Washington DC emergency room by her husband because of fever and somnolence. There is no history of travel outside the locality. Her only medications had been naturopathic. • Which of the following would most likely be effective: • A. azithromycin B. metronidazole C. quinine+clindamycin D. pyrimethamine+clindamycin • The location in the basal ganglia and the HIV-infected host would be consistent with toxoplasmosis or lymphoma. • Only one of the drug choices would treat toxoplasmosis and, of course, none would treat lymphoma. • The usual treatment of cerebral toxoplasmosis would be sulfadiazine plus pyrimethamine but pyrimethamine plus clindamycin gave comparable therapeutic results in one randomized trial. • Trimethoprim-sulfamethoxazole has been reported useful in a few case reports. • This 9 year old girl from a dairy farm near Frederick, Maryland had the sudden onset in July of fever, severe headache, nausea, vomiting and muscle aches. On the fourth day she developed the rash shown here on her palms and soles. The drug of choice would be: • A. cefotaxime B. penicillin G C. levofloxacin D. doxycycline 16 4/27/2015 • Development of a petecchial rash on the fourth day is very consistent with Rocky Mountain Spotted fever, as is a severe headache, fever and myalgias. • Treatment of this rickettsiosis is doxycycline despite her age. Meningococcal sepsis can cause a similar rash and severe headache but rash would have appeared earlier after the onset of severe headache. • This 32 year old male from a rural area on the Eastern shore of Maryland had a low grade fever and expanding rash on his abdomen, shown here. • Which of the following would be the most likely later complication of this infection? • A. transverse myelitis B. sexual transmission C. uveitis D. arthritis • The lesion is typical of erythema migrans due to Lyme disease, Borrelia burgdorferi infection acquired from a deer tick bite in an endemic area. • Days to weeks after the skin lesion appears, cardiac or neurologic complications occur. Arthritis begins in weeks or months, with intermittent attacks of acute arthritis, usually large joints, with each episode lasting from days to months. • A few patients with acute arthritis develop chronic arthritis, usually in the knee. Uveitis and transverse myelitis are not associated with Lyme, though neuroretinitis and encephalitis can occur. 17 4/27/2015 • This EKG from a 35 yr old female Nantucket shop owner was most likely acquired by a bite of a: • A. mosquito B. fly C. tick D. flea • The EKG shows second degree heart block with a 3:1 capture ratio. Heart block is one of the most common cardiac complications of Lyme disease, starting from days to weeks after a bite by an infected Ixodid (deer) tick. • Heart block also occurs in acute rheumatic fever and chronic Chagas’ disease. Chagas’ cardiomyopathy can be occur years after the bite of a Triatome (reduviid) bug in South America but is very rare in US residents. • Heart failure usually accompanies cardiac conduction abnormalities in Chagas’ cardiomyopathy. The other insect vectors listed are not associated with diseases that cause AV block. • This is the modified acid fast smear of sputum from a 34 year old woman with pneumonia. She had systemic lupus erythematosus and was receiving prednisone 60 mg daily. When she had been given sulfamethoxale trimethoprim last year, she had developed severe Stevens Johnson syndrome. • Of the following antimicrobial agents, which would be select for treatment of her pneumonia: • A. imipenem plus amikacin B. intravenous azithromycin C. clarithromycin and ethambutol D. ceftriaxone 18 4/27/2015 • Presence of branching acid fast bacilli indicates nocardiosis, one of the causes of pneumonia in immunosuppressed patients. • Trimethoprim-sulfamethoxazole is the preferred drug but reports of imipenem, with or without amikacin, have indicated efficacy. • Azithromycin does not appear to be effective. There are a few reports of success with ceftriaxone but this may depend on the Nocardia species. • Susceptibility testing is not clearly reliable and speciation is often not available at time of diagnosis, making ceftriaxone not recommended. • The following tongue lesion was scraped: Wet mount with Calcofluor stain for fungus and Gram Stain for bacteria were negative. • The patient is asymptomatic and has no notable symptoms related to his tongue or mouth. • Which of the following is linked etiologically to this lesion: • A. HSV B. VZV C. CMV D. EBV E. HHV-6 • The structures involved are: - Usually lateral tongue, but buccal mucosa floor of mouth, palate may also be involved. • OHL is EBV associated. • No treatment is necessary although the lesions often regress with acylcovir. • These lesions often disappear on antiretroviral therapy 19 4/27/2015 • A 34 year old male with HIV (CD4 = 12 cells, VL = 800k) has not been in care. • He presents with visual blurring. • His fundoscopic examination is shown. • The most likely cause of this lesion is: • A. Toxoplasmosis B. Syphilis C. CMV D. HSV E. VZV • There is a long list of causes of retinitis in a highly immune deficient patient with HIV. • CMV is by far the most common, especially in a patient with little anterior or posterior chamber inflammation (the fundus can be clearly visualized here) and with the combination of hemorrhages and exudates. • Infectious disease specialists should know the differential diagnosis, and the basic findings of the common syndromes of CMV, HSV, VZV, Toxoplasma, and syphilis. • A previously healthy young female had the onset of pain in her calf and a red, tender rash on her calf. She was unaware of preceding trauma. In the photo, the bleeding was from an unsuccessful needle aspirate. She was given cephalexin 250 mg po qid but the progressively excruciating pain increased and came to the emergency room about 48 hours after onset. Her vital signs were normal except for a temperature of 102. There was no rash outside the calf, which was red, tensely swollen and tender. A soft tissue film showed no gas. WBC was 15,000 with 80% PMN and 5% bands. • The clinical picture is most consistent with infection by which of the following organisms: • A. Streptococcus pyogenes B. Clostridum perfrigens C. Staphylococcus aureus D. Mixed infection with anaerobes and aerobes 20 4/27/2015 • This patient should be considered to have streptococcal necrotizing fasciitis and emergency surgical consultation obtained. • The location, normal host, severe pain and rapid progression make Meleney’s gangrene with mixed anaerobes and aerobes less likely. Clostridum perfringens, gas gangrene, usually follows major trauma or occurs in poorly vascularized tissue and has gas in the tissue. • Staphylococcal pyomyositis is a rare cause of this clinical picture in the calf and is most often mistaken for deep venous thrombosis. • But patients in the USA with Staphylococcal pyomyositis often have comorbid conditions, pain is less intense or progression slower. Imaging is often helpful in distinguishing causes in patients like this. • This lesion in the ocular fundus is most consistent with which of the following: • A. Miliary tuberculosis B. Candidemia C. Endocarditis D. Systemic lupus erythematosus • A retinal hemorrhage with a pale center is called a Roth spot, as occurs in endocarditis. • Retinal lesions due to candidemia, miliary tb and SLE (cytoid bodies) are pale with no surrounding hemorrhage. 21 4/27/2015 A 56 year-old man is admitted with 3 days of fever, rash, confusion, and leg weakness in August. He lives in Alabama. He is febrile to 104°F and is confused. He has a faint maculopapular rash in the trunk. His neurologic exam reveals mild tremors, a strength of 5/5 in the arms, 3/5 in the lower extremities, normal deep tendon reflexes, and normal sensory exam. CBC, chemistry tests, urinalysis, chest-X-ray and head CT without contrast are normal. HIV is negative. A lumbar puncture reveals 1351 WBC, 70% polys, 30% lympho/monos, protein 81 mg/dL, glucose 92 mg/dL. Gram stains and Cryptococcal antigen are negative. He is treated with vancomycin and ceftriaxone. Over the next three days the weakness progresses to the point that he is paraplegic. Which of the following is the most likely diagnosis? A) Poliovirus B) West Nile virus C) Saint Louis encephalitis virus D) Acute HIV infection E) Guillain-Barre syndrome West Nile virus has an extensive distribution, it is seen in Africa, the Middle East, parts of Europe and Asia, Australia, and in recent years has become endemic in the continental United States. It has a seasonal incidence, with a peak in late summer or early fall. The virus is transmitted by the Culex mosquitoes, other less common mechanisms of transmission are blood transfusion, organ transplantation, transplacental transmission or breastfeeding, and occupational transmission in healthcare workers. It is estimated that 80% of the infections are asymptomatic. West Nile fever is seen in 20%, and is characterized by nonspecific symptoms such as fever, headache, malaise, back pain, myalgias, anorexia, or rash. Neuroinvasive disease is seen in 1 out of 150 individuals who are infected. The neurological manifestations include encephalitis, meningoencephalitis, meningitis, poliomyelitis (acute flaccid paralysis). In endemic areas, flaccid paralysis or weakness with or without encephalitis is very suggestive of West Nile virus. Lumbar puncture usually reveals meningitis, with elevated WBCs with either lymphocytes or neutrophils. The diagnosis of neuroinvasive diseaseis based on detection of IgM antibody in CSF. Viral cultures become negative too early to be useful in previously normal patients; initial results can be negative so it is important to check convalescent titers. Risk factors for severe disease are older age, diabetes, alcohol abuse, and being immunocompromised. Poliovirus has been eradicated from the United States. Acute HIV infection can occasionally present with a Guillain-Barre-like syndrome (GBS). GBS is an acute immune mediated polyneuropathy, with progressive ascending weakness and albuminocytologic dissociation where the CSF protein is very high and the cell count is not. St. Louis encephalitis virus is one of etiologic agents of viral encephalitis in the United States, and presents as encephalitis, not as poliomyelitis. Which one of the following is true about progressive multifocal leukoencephalopathy? A) Anti-TNF-alpha therapy may predispose to infection B) Seizures are rare C) Serodiagnosis is useful D) Transmission is by sexual intercourse E) Infection with this agent usually leads to disease 22 4/27/2015 A number of cases of PML have been described in patients receiving anti TNF alpha therapy and in patients receiving other immunosuppressive monoclonal antibodies, including rituximab. PML is rare in immunologically intact persons. Exposure to JC is common and by the respiratory route. Approximately 80% of the population has antibody to JC virus and thus serum antibody testing is not useful. Which of the following antibiotics is active against Mycoplasma pneumoniae? A) Ampicillin-sulbactam B) Azithromycin C) Imipenem D) Penicillin E) Vancomycin Mycoplasma species are unique among bacteria because they do not have a cell wall and their cell membrane contains sterols. The absence of the cell wall renders the mycoplasmas resistant to antibiotics that interfere with synthesis of the cell wall, such as penicillins (ampicillin-sulbactam, penicillin), cephalosporins, carbapenems (imipenem), and vancomycin. Azithromycin is a macrolide antibiotic that inhibits bacterial growth by disrupting protein synthesis 23 4/27/2015 A 22-year-old male, previously in good health, develops a low-grade fever and a cough. On the third day of his illness, he developed the skin rash (shown below) on his trunk, extremities, palms, and soles, and has mucosal erosions in his mouth and genitals. He comes to your office for evaluation. Chest x-ray shows a patchy bilateral bronchopneumonia. CT is shown below. Oxygen saturation on room air: 98% WBC = 6000 with a normal differential The most likely cause of his skin lesions A) Treponema pallidum B) Streptococcus pneumoniae C) Mycoplasma pneumoniae D) Legionella bozemanii E) Chlamydia pneumoniae While many infectious agents can be associated with erythema multiforme, which is the skin and mucous membrane lesion shown here. Up to 7% of patients with M. pneumoniae infection have been reported to develop erythema multiforme or Stevens Johnson syndrome. Other types of skin lesions also have been reported. While this skin rash could be due to syphilis, the presence of a respiratory infection makes M. pneumoniae a much more likely cause. HSV is a common cause of erythema multiforme, but many respiratory viruses and live attenuated vaccines can also be associated. Since no respiratory viruses were listed as possible answers, M. pneumoniae is the best answer. Which one of the following procedures would provide the most sensitive and specific test for the diagnosis of Clostridium difficile diarrhea? A) Submit 1 stool specimen for cytotoxicity testingB B) Submit 1 stool specimen for enzyme immunoassay tests C) Submit 1 stool specimen for PCR test D) Submit 3 daily stool specimens for enzyme immunoassay tests E) Submit 1 stool for latex agglutination test 24 4/27/2015 The FDA approved PCR test for the C. difficile toxin B gene is the most sensitive and specific test available. Cytotoxicity testing was formerly the gold standard for detection of toxins but is associated with some false-negative and false-positive reactions. The EIA tests have been found to be both insensitive and nonspecific. There is no evidence that more than one test is required (in contrast to detection of enteric parasites). The latex test for C. diffiicile LDH is sensitive but not specific. 25