Exam 7 (CNS, Circulatory, RES, Lymphatic Infections) Flashcards
Prior to immunization, what was the leading cause of pediatric meningitis?
- H. influenzae type B
In what locations of the heart do most infective endocarditis infections occur?
- Cardiac valves (natural or prosthetic) on the mitral or aortic valves
Leading cause of fungal meningitis
- Cryptococcus neoformans
Define septic shock
- Severe sepsis (microbial etiology + at least two of four conditions + one ore more signs of organ failure) with hypotension (systolic less 90 mmHg)
Pathogen of African trypanosomiasis? Vector? Location in intracellular stage?
- Trypanosoma brucei (gambiense or rhodesiense) = protozoa - Vector = Tsetse fly - No intracellular stage
Protozoa responsible for infections of CNS
- Entamoeba histolytica - Trypanosoma brucei - Plasmodium falciparum - Opportunistic = acanthamoeba, naegleria, balamuthia - Toxoplasma gondii
Diseases caused/associated by/with EBV?
- Infectious mononucleosis - Oral hairy leukoplakia - Burkitt’s lymphoma - Hodgkin’s disease/lymphoma - Nasopharyngeal carcinoma - Post-transplantation lymphoproliferative disorder
What is visceral larva migrans? Diseases caused? Symptoms? Diagnosis? Treatment?
- Zoonotic disease. Infection of humans by ascarid-type nematode (roundworm), which normally infect dogs (Toxocara canis) and cats (Toxocara cati) through accidental ingestion of eggs. - Eggs hatch in intestines releasing larvae that enter bloodstream and migrate to numerous body sites. Development is arrested as humans aren’t host. Lesion develop commonly in liver, spleen, lung and eye (most common). Symptoms include fever and depend on location of larval dissemination. Lesions in brain result in epilepsy or encephalopathy. - Diagnosis: eosinophilia, serology, history, clinical presentation, no eggs - Treatment: steroids
Categories of CNS infections
1.) Affecting meninges = meningitis 2.) Affecting brain parenchyma = encephalitis
Patterns of bacteremia
1.) Transient 2.) Intermittent 3.) Continuous: infective endocarditis and catheter bacteremia
More likely microbial agents to cause sepsis
- Bacteria - Fungi and other agents can, but less frequently
Pts at risk for infective endocarditis
- Prosthetic valve pts - IV drug users - Immunosuppressed - HIV pts esp if IV drug user
Genes involved in EBV carcinogenesis
1.) LMP1 (latent membrane protein): CD40 homologue, which is constitutively active increasing cell growth and suppressing apoptosis 2.) LMP2: increases growth in B cells 3.) EBNA1 (Epstein Barr Virus Nuclear Antigen 1): inhibits apoptosis
Staph aureus. Characteristics, how does it cause sepsis/toxic shock?
- G pos cocci clusters, catalase pos, coagulase pos - Sepsis/toxic shock caused by TSST-1, which is a superantigen that links APCs and T-cells leading to cytokine storm
LaCrosse (CA) Encephalitis Virus. Characteristics, transmission, disease caused/symptoms, endemic areas/epidemiology
- Characteristics: Bunyavirus - Transmission: chipmunks/tree squirrels (reservoir) with transmission = via mosquito to humans - Disease caused: initially as non-specific summer illness with symptoms = fever, HA, nausea, vomiting and lethargy. Severe disease (50% of cases) = seizures, coma, paralysis. Less than 1% are fatal. - Endemic areas/epidemiology: primary in Midwest and Mid-Atlantic states
Which of the following diseases are arthropod borne? West Nile, Rabies, Eastern/Western/Venezuelan Equine encephalitis, Lymphocytic Choriomeningitis, St. Louis encephalitis, LaCrosse (California) Encephalitis and Japanese Encephalitis.
- Rabies and Lymphocytic Choriomeningitis are directly transmitted from mammals to humans - The rest are arthropod borne
Most common cause of bacterial meningitis in infants and young children
- Strep pneumoniae
Zygomycoses. Species, characteristics, diseases caused, pathogenesis, diagnosis, treatment, source, risk factors
- Species = rhizopus, absidia, mucor - Characteristics = non-septated hyphal fungi with sporangia with spores - Diseases: a.) Rhinocerebral mucormycosis: infection in sinuses via inhalation of spores, infection extens to neighbouring tissue including brain. Symptoms: nasal congestion, blood-tinged rhinorrhea, tender sinuses, HA, fever. Progresses to facial / periorbital edema, visual disturbances, AMS, coma and death - Diagnosis: a.) hyphal elements in clinical material (broad-aseptated hyphae branching at 90 degrees) b.) culture - Treatment: amphotericin B - Source: ubiquitous in environment (soil, vegetation, food) - Risks: immunosuppression, diabetes (esp rhinocerebral mucormycosis) and burn patients. Infection rare in normal healthy individuals
What is the most common cause of vaccine-preventable death in US?
- Pneumococcal disease (strep pneumoniae)
What is refractory septic shock?
- Septic shock lasting more than 1 hour and not responding to fluid/pharmacologic treatment
Pathogen of Chagas’ disease? Vector? Location in intracellular stage?
- Trypanosoma cruzi = protozoa - Vector = Reduvid bugs - Skeletal, cardiac and others
Naegleria. Characteristics, disease caused / symptoms, pathogenesis, diagnosis, treatment, source
- Characteristics: opportunistic free living amoebal protozoa - Disease caused = primary amebic meningoencephalitis (PAM). Symptoms = fever, HA, vomiting, confusion, rapidly progress to coma and death. Typically fatal in 1 week. - Pathogenesis: intranasal inoculation - Diagnosis: observation of protozoa in biopsy/CSF - Treatment: amphotericin B may be helpful, usually cases are fatal in 1 week - Source: acquired typically by swimming in warm water (hot springs, heated pools, hot tubs). Recent outbreak associated with use of Neti pot. Most outbreaks in Southern USA
Granulomatous amoebic encephalitis. Caused by, symptoms, pathogenesis, diagnosis, treatment, source, risk
- Caused by: Acanthamoeba, Balamuthia - Symptoms: slow onset of fever, HA, vomiting, confusion, coma and death - Pathogenesis: amoeba invade brain resulting in slow developing granuloma/ulcerative lesion - Source: fresh water - Risk: infection in AIDS pts may disseminate
Cardinal symptom of adult T-cell lymphoma?
- Hypercalcemia
CMV caused/associated illnesses/diseases
- Infectious mononucleosis-like illness - Cytomegalic inclusion body disease - Immunosuppressed: CMV pneumonitis, GI tract illness, GVHD, CMV retinitis
Babesiosis. Pathogen, characteristics, pathogenesis/life cycle, symptoms, risk factors, diagnosis, treatment, epidemiology
- Pathogen: Babesia spp (microti and divergens) - Characteristics: sporozoan flagella - Pathogenesis/life cycle: tick bite transmits protozoa from reservoir = rodents and cattle - Symptoms: many asymptomatic infections a.) symptomatic = fever, chills, myalgia, hemolytic anemia - Risk factors: elderly, asplenic, immunosuppressed at high risk for symptomatic infection - Diagnosis: blood smear = Maltese cross in RBC - Treatment: atovaquone and azithromycine (or qunine and clindamycin) - Epidemiology: US (upper Midwest, New England, CA)
Pathophysiology underlying sepsis/septic shock
1.) LPS/Endotoxin (lipid A) from gram negs: binds CD14 and TLR4 on phagocytes and APCs leading to inflammation via IL-1, IL-6 and TNF 2.) Peptidoglycan or exotoxins from gram pos (eg. TSST-1 from Staph) 3.) Polysaccharides (eg. C. albicans) 4.) Teichoic acid (eg. Staph) 5.) Capsules (eg. Strep pneumo)
Protozoal cause of brain abscess
- Entamoeba histolytic
Hemorrhagic skin lesions in a septic person who recently ate raw oysters is suggestive of infection by what organism?
- Vibrio vulnificus
80 year old male with prosthatic heart valve goes to dentist for tooth extraction. You are concerned about what type of infection?
- Concerned about SBE (subacute bacterial endocarditis) caused by Viridans strep group of bacteria that are normal flora of the oropharynx entering the blood stream
Malaria. Pathogen, characteristics, pathogenesis/life cycle, symptoms, complication, diagnosis, treatment, epidemiology
- Pathogen: Plasmodium falciparum/vivax = most cases, others from ovale and malariae - Characteristics: sporozoan protozoa - Pathogenesis/life cycle: female mosquitos (Anopheles) transmit the protozoa during blood meal feeding, hepatocytic stage of life cycle and erythrocytic stages where they lyse respective cells, vivax and ovale can enter a hypnozoite stage in the hepatocytic cycle and lay dormant for years/decades becoming reactivated during immune status/physiological/stress event - Symptoms: characteristic feature = malarial paroxysm = synchronous lysis and release of merozoites from RBCs where pt presents with flu-like symptoms including fever, chills, HA and myalgias. Paroxysms dependent on species. Cold stage, hot stage, sweat stage. - Complications: anemia (most severe in falciparum infection), splenomegaly, hypoglycemia, lactic acidosis, cerebral malaria d/t microvascular occlusion by “sticky” RBCs - Diagnosis: clinical syndrome, history of travel a.) Blood smear: ring and banana/crescent-shape = P. falciparum - Treatment: no vaccines yet, antimalarial (chloroquine) for active infection and prophylactically, resistance to drug is an issue - Epidemiology: worldwide distribution: Central/S. America, Africa, Asia, transmission in US eradicated in 70s, outbreaks in US are from airports or via competent mosquito vectors feeding on human exposed elsewhere, cases in US mostly around travelled
Leishmaniasis (visceral). Pathogen, characteristics, pathogenesis/life cycle, symptoms, diagnosis, treatment, epidemiology
- Pathogen: visceral by Leishmania donovani/infantum/chagasi - Characteristics: flagellated protozoa - Pathogenesis/life cycle: reservoirs = canines and rodents, bite of infected female sand flies transmit protozoa after blood meal, protozoa enter macrophages in human and disseminate throughout reticuloendothelial system and are found in liver, spleen, bone marrow, no antibody response as intracellular only - Symptoms: +/- lesion where bite occurred, presentation is irregular low grade fever, most infections asymptomatic and resolve. Full blown disease = fever, weight loss, hepatosplenomegaly, wasting/cachexia, immunosuppression and secondary infections leading to death in very old and young or malnourished. - Diagnosis: blood smear - Treatment: heavy metal compounds with high toxicity - Epidemiology: widespread (big issue in S. America), rare to have cases acquired in US possibly in Southern, opportunistic in HIV+ individuals of Mediterranean descent
Organisms responsible for toxic shock
- Staph aureus via TSST-1 - Strep pyogenes via pyrogenic toxins (SpeA/B/C)
Pathogen of Leishmaniasis? Vector? Location in intracellular stage?
- Leishmania spp. - Vector = sandflies - Macrophages
Pathogen of Babesiosis? Vector? Location in intracellular stage?
- Babesia spp. - Vector = ticks - RBCs
Mechanisms underlying anemia in malaria
1.) RBCs lysed by mature intracellular protozoa 2.) Suppression of erythropoiesis by cytokines TNFalpha and IL-1 3.) Destruction of RBCs by spleen
CMV. Characteristics, pathogenesis, transmission, diagnosis, treatment
- Characteristics: herpesviridae virus, enveloped, dsDNA - Pathogenesis: Binds and enter mucosal epithelium, viremia occurs, latency in monocytes - Transmission: saliva, breast milk, urine, fomites, sexual contact - Diagnosis: viral DNA from disease tissue, seroconversion - Treatment: a.) 1st line = gancyclovir (IV or oral: drug converted to DNA pol inhibitor by CMV enzymes), valganciclovir (oral: converted to gancyclovir in body has increased bioavailability, same action) – these have bone marrow toxicity and cause drug-related neutropenia b.) 2nd line (if virus resistant to 1st line drugs) = cidofivir (IV: converted to DNA pol inhibitor by enzymes) or foscarnet (IV: direct inhibitor of DNA pol) – both are more toxic than 1st line, foscarnet has renal toxicity
Common virulence factor(s) in bacterial causes of meningitis
- Capsule - Fimbriae, pili, outer membrane proteins
In what cell types does EBV virus reside? What does this virus use to gain entry?
- Epithelial and B-cells - Used 3d component of complement
In the year 2030, you develop an effective CMV vaccine. In 2040, you expect to see a dramatic reduction in disease d/t CMV infection in immunocompromised invidiuals and immunocompetent ___________. A. neonates B. school-aged children C. adults
- Answer = A. neonates. Awaiting email from Nguyen with why only neonates and not all groups?
Viral myocarditis. Symptoms, most common causes, diagnosis, treatment, prognosis, risk, epidemiology
- Symptoms: SOB, exercise intolerance, fatigue = typical presentation, also chest pain, abdominal pain, palpitations and syncope – could mimic infarction - Causes: adenovirus (types 2 and 5), enterovirus (esp coxsackievirus type B), B19 parvovirus and HHV-6. Less frequently = influenza, echovirus, mumps virus - Diagnosis: CXR, ECG and endomyocardial biopsy - Tx: manage symptoms and arrhythmias, rest and observation - Prognosis: 50% have full cardiac function restored, 25% will have ECG/CXR abnormalities w/o symptoms - Risk: CHF with unknown etiology - Epidemiology: more commonly in men
Are antivirals of use in HHV-8 (Kaposi’s sarcoma) infections?
- No. Virus is in latent phase
Children (2-18 years) bacterial meningitis causes
- N. meningitidis - S. pneumoniae
Japanese Encephalitis Virus. Characteristics, transmission, disease caused, epidemiology
- Characteristics: flavivirus - Transmission: birds/livestock = reservoir and transmitted to humans via mosquito - Disease caused: encephalitis similar to WNV and St. Louis Encephalitis - Epidemiology: leading cause of viral encephalitis in Asia
Symptomatology associated with bacterial CNS infections
- Fever, headache, stiff neck (nuchal rigidity), altered mental status - 50% of pts present with first three - Nearly 100% present with combination of two of 4
African Trypanosomiasis (Sleeping Sickness). Pathogen, characteristics, pathogenesis/life cycle, symptoms, diagnosis, treatment, epidemiology
- Pathogen: Trypanosoma brucei (gambiense in W. Africa and rhodesiense in E. Africa) - Characteristics: flagellated protozoa - Pathogenesis/life cycle: Tsetse fly ingests them during blood meal, part life cycle within salivary gland of fly, enters human through bite site when fly refeeds, maturation in blood / lymph of human, later invasion into CNS. Protozoa expresses variable surface glycoproteins and undergoes antigenic variation, which is rapid switching of the glycoproteins to avoid absolute clearance of all organism by hosts immune system - Symptoms: more acute with E. African form a.) Early (when organism in blood and peripheral LNs): painless chancre at site of entry, fever, myalgia, chills, lymphadenopathy b.) Late (when organism in CNS): HA, seizures, tremors, encephalitis, sleeplessness, lethargy, coma and death - Diagnosis: parasite in blood smear, lymph node aspirates or CSF - Treatment: melarsoprol (highly toxic), difluoromethylornithine (DFMO) - Epidemiology: W. and E. Africa
A patient’s sepsis was initiated by a gram-neg bacterium. If abx were not given to the patient and three blood cultures were taken over an 8 hour period, there is a 99% chance that the gram-neg bacterium will be detected in the blood. True/False.
- False. Only about 50% of pts with sepsis will have bacteremia to begin with. Idea about taking multiple cultures over time is that if the pt is bacteremic, first culture will only be about 80-90% positive, second culture 90-95% positive and third culture 99% positive.
An unexplained encephalitis or meningitis in summer/early fall in adults over 50 years of age should lead to suspicious of what disease(s)?
- West Nile and other arboviral diseases
Multiorgan failure definition
- Dysfunction of >1 organ AND - DIC
Treatment of sepsis/septic shock
1.) If shock, ie. With hypotension: IV fluids 2.) Hypoxia: ventilator 3.) DIC: transfuse with FFP and platelets OR heparin to stop bleeding 4.) Antibiotics: broad spectrum such as vancomycin and gentamicin to cover G+ and G-
What is cytomegalic inclusion body disease? Cause? Symptoms? Population affected? Risk factors? Epidemiology? Prevention? Treatment?
- Congenital infection of newborn by CM - Symptoms: commonly = hepatosplenomegaly, jaundice, petechial rash. Less commonly = microcephaly, growth retardation, inguinal hernias, chorioretinitis - Population affected: commonly newborn to seronegative mother (infected with CMV for first time) - Risk factors: seronegative pregnant women infected with CMV during pregnancy – risk of transmission = 33% - Epidemiology: most common congenital viral infection - Prevention: interrupt CMV transmission - Tx: none – CMV immunoglobulin under investigation
Filariasis (aka elephantiasis). Pathogen, characteristics, pathogenesis/life cycle, symptoms, diagnosis, treatment, epidemiology
- Pathogen: Wuchereria bancrofti an Brugia malayi - Characteristics: nematodes (roundworms) - Pathogenesis/life cycle: mosquito (including Anopheles) take up microfilariae, development in mosquito, bite human, larvae migrate into lymphatics where they develop into adults and mate releasing microfilariae, these enter bloodstream at night in hopes of mosquito feeding - Symptoms: a.) Acute = fevers, chills and lymphadenitis lasting for weeks and recur frequently b.) Elphantiasis = chronic debiliting swelling/clogging of lymphatics of upper/lower extremities and male genitalia c.) Tropical pulmonary eosinophilia = asthma attacks during to high IgE/eosinophilia - Diagnosis: eosinophilia with pulmonary involvement, clinical, microfilariae in blood (collected at night) - Treatment: DEC, steroids to counteract allergic response to dying worms, surgery if disease severe - Epidemiology: Bancrofti in Africa, Mediterranean coast, Asia, Caribbean and S/Central America. Malayi in Asia
True / False. Bacteremia is typically present with infective endocarditis.
- True, more than 95% of cases of infective endocarditis yield positive blood cultures
Rabies virus (aka Lyssavirus). Characteristics, transmission, disease caused/symptoms/pathogenesis, diagnosis, treatment, endemic areas/epidemiology
- Characteristics: rhabdoviridae - Transmission: reservoirs = humans and other mammals (dogs, cats, raccoons, bats) with transmission via infected saliva (bites, mucous membrane, aerosolized), most infections via infected dogs, bats, skunks and foxes; rare cases via corneal transplant - Disease/pathogenesis: virus proliferates locally, enters peripheral nerves and transported to CNS, non-specific flu-like signs (few days to more than month after incubation) = fever, malaise or headache, virus disseminates within CNS and spreads to peripheral nerves, behavioral changes (anxiety, confusion, agitation, delirium, abnormal behavior, hallucinations, insomnia) including hydrophobia (fear of water) in 50% of cases, end result is coma and death. Once clinical signs appear, disease is nearly always fatal in ~ 2 weeks. - Diagnosis: serology, confirmation of Negri bodies in animals thought to have infected human - Treatment: pooled immune globulin and 5 doses of vaccine (over 28 day period) - Endemic areas: Worldwide (except Australia, Gr. Britain and Hawaii)
Post-transplantation lymphoproliferative disorder (PTLD). What is it? Symptoms? Risk factors? Diagnosis? Treatment?
- Abnormal proliferation of lymphoid cells in a transplant patient, benign or malignant - Symptoms = fever, fatigue, weight loss, progressive encephalopathy - Risk factors = EBV infection at time of transplant - Diagnosis: detect of EBV genome in specimen via in situ hybridization - Tx: reduce immunosuppression, rituximab anti-CD20, conventional chemo
Streptococcus. Characteristics, how does it cause toxic shock?
- G pos cocci in pairs or chains, catalase neg - Strep pyogenes produces pyrogenic exotoxins (SpeA and SpeC), which are superantigens that bind APCs and T-cells lead to cytokine storm
EBV. Characteristics of virus, general pathogenesis/virology
1.) Characteristics: herpesviridae, enveloped, dsDNA 2.) Pathogenesis/virology - Uses 3d component of complement to gain entry into epithelial and B-cells where replication occurs - Induces proliferation of B cells, induces production of heterophile antibodies (to non-specific antigens) - Becomes latent - In carcinogenesis
50% of N. meningitidis invasive disease in children less than 2 years of age are due to which serotype? Why?
- B. No effective vaccine