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UWORLD
Microbiology
Question | Answer |
---|---|
What is the most common bacterial cause of Febrile gastroenteritis? | Listeria monocytogenes infection |
What is the structure of Listeria monocytogenes? | Facultative intracellular, gram positive rod |
What mediates most oth pathogenesis of Listeria monocytogenes febrile gastroenteritis? | Listeriolysin O |
What is Listeriolysin O? | Enzyme that creates pore in phagosomes, which allows bacteria (Listeria) to escape lysosomal destruction |
What is "escaped" by Listeria with the action of Listeriolysin O? | Lysosomal destruction, by creating pores in the phagosomes |
Which population is at increased risk of febrile gastroenteritis by L. monocytogenes? | Pregnant women in the third trimester |
Which trimester of pregnancy is the most dangerous for female? | 3rd |
What are the possible complications due to L. monocytogenes febrile gastroenteritis in pregnant women? | Fetal demise, early labor, and neonatal infection |
What is the leading cause of foodborne gastroenteritis? | Non-typhoidal salmonella |
How is clinically presented and unique non-typhoidal salmonella-gastroenteritis? | Marked by 3-4 days of self-limited fever, nausea, vomiting and watery diarrhea |
What type of diarrhea is seen in non-typhoidal salmonella gastroenteritis? | Watery diarrhea |
What are the major organs to which non-typhoidal salmonella infection may spread into? | 1. Long bones (osteomyelitis) 2. Vasculature (mycotic aneurysm) 3. Heart (endocarditis) |
Which type of patients are at greatest risk of developing complication by non-typhoidal salmonella infection? | Sickle cell anemia, immunocompromised, and those in extreme end ages |
What pathogen infection causes syphilis? | Treponema pallidum |
What are the Non-treponemal tests? | Rapid plasma reagin and, VDRL |
What is measured or tested in non-treponemal diagnostic tests? | Anticardiolipin antibodies (nonspecific) |
What is evaluated by treponemal diagnostic tests? | Antibodies against T. pallidum |
If a test evaluates for anticardiolipin antibodies, is it non-treponemal or treponemal test? | Non-treponemal diagnostic test |
VDRL. Treponemal or non-treponemal test? | Non-treponemal diagnostic test |
What is the description of the genital ulcers caused by H. ducreyi? | Deep, painful ulcer with ragged bodes |
What are some clinical asscotatein sith H. ducreyi genital ulcers? | Grey exudate and inguinal lymphadenopathy |
How is the exudate seen in genital ulcers caused by H. ducreyi? | Gray exudate |
Which causative pathogen is suspected if the patient has a painful ulcer, and the diagnosis is made by scraping off the base of the ulcer to gram stain it? | H. ducreyi |
What is the result from HIV pol gene mutations? | Responsible for acquired resistance to reverse transcriptase inhibitors, protease inhibitors, and integrase strand transfer inhibitors |
What do HIV env gene mutations cause? | Enable escape from host-neutralizing antibodies |
Which HIV gene mutation causes NRTi, PI, and Integrase inhibitors to develop resistance? | HIV pol gene mutation |
Which HIV gene mutation allows the virus to escape the host-neutralizing antibodies? | HIV env gene mutation |
Which antibiotics have a similar structure to D-alanine-D-alanine? | Penicillins |
What enzyme is inhibited by D-ala-D-ala and by penicillins? | Transpeptidase |
How does the inhibition of Transpeptidase occurs in penicillins? | Binding covalently to its active site |
What is a common endemic illness of Latin (South) America? | Chagas disease |
What type of household create a higher risk for Trypanosoma cruzi infection? | Houses with adobe walls and thatcher roofs |
What are some characteristics of Chagas cardiomyopathy? | Heart failure, ventricular arrhythmias, and ventricular aneurysms |
Does vertical tansmission of HBV to unborn child, needs to be from a mother with an active infection or inactive infection? | Active Hepatitis B infection |
Which serum marker positivity greatly increases the risk of vertical transmission of Hepatitis B virus? | HBeAg |
How is prevented/treated possible vertical transmission of HBV to all newborns with actively infected mothers? | Passive immunization at birth with HBIG, followed by active immunization with recombinant HBV vaccine |
What type of food characteristic is known to transmit toxoplasmosis? | Consumption of undercooked meat |
What population is at greatest risk to a Toxoplasmosis infection due to consuming undercooked meat? | Pregnant women |
What is the structure of Toxoplasma gondii? | Intracellular, crescent-shaped parasite that can cross the placenta to the fetus |
What are most typical features of congenital toxoplasmosis? | Chorioretinitis, hydrocephalus, and diffuse intracranial calcifications |
What is Chorioretinitis? | Inflammation of the choroid (thin pigmented vascular coat of the eye) and retina of the eye |
Form of posterior uveitis | Chorioretinitis |
Why is active TB never treated with drug monotherapy? | Fast emergence of mycobacterial antibiotic resistance for rapid, selective gene mutations |
Which cases is TB can be treated with Isoniazid monotherapy? | Patients with a (+) PPD and a negative CXR |
What are Arboviruses? | Small RNA viruses, transmitted by biting arthropods |
What type of virus infection is the MCC of encephalitis in the USA? | Arbovirus infection (mosquito bite) |
What is the prevention strategy for arboviruses? | Since no vaccine is available, the elimination of the vector arthropod is the best method of eradication |
What nosocomial-associated activity is often causative of skin commensal bacteria, to enter the bloodstream? | Intravascular catheters |
What are the most common bacteria introduce to the bloodstream by intravascular catheters? | Staph aureus and coagulase-negative staphylococci |
What is the definition of herpangina? | Oral ulcers without rash |
What are the most common manifestations (clinically) of enteroviral infection? | Hand, Footh, Mouth disease and Herpangina |
What is a rare but significant complication of Hand, Foot, Mouth disease? | Myocarditis |
Which viral infection causes a lifelong latent infection of the sensory ganglion? | Herpes simplex virus |
What is the result of periodic viral replication of HSV in a host? | Reemergence of symptoms that flare and resolve over time |
After a hookworm is introduced to the bloodstream by breaking the skin of the foot, most likely, it follow what path? | Travels to the LUNGS, then is coughed up, and finally it is swallowed and reaches the digestive tract |
In which organ do adult hookworms reside? | Small intestine |
What is the most severe complication of adult hookworms residing in the small intestine? | Chronic Iron deficiency anemia (microcytic anemia) |
Why is long-term hookworm infection associated with microcytic anemia? | Adult hookworms reside in small intestine and feed off human blood, leading to anemia. |
What is Phenotypic Mixing? | Coinfection of host cell by 2 viral strains, resulting progeny virions that from nucleocapsid protein from one strain and the unchanged parental genome of the other strain |
Are the changes caused by Phenotypic mixing carried by progeny of the first mutated virions? | No, the progeny of the mutated virions reverts back to original unmixed phenotypes |
What is the major virulence factor of Pharyngitis? | M protein |
What organism is highly associated with the M-protein as a virulence factor? | Strep pyogenes |
What is the M-protein structure? | Alpha-helical coiled-coil protein |
What does the M-protein share structural similarities? | Tropomyosin and Myosin |
How does the M-protein promote Strep pyogenes infection? | Extends from the cell wall wall and prevents phagocytosis, inhibits complement binding, and mediates bacterial adherence |
Does the M-protein prevent phagocytosis or inhibits complement binding, none, or both? | Both |
How does the M-protein leads to Rheumatic carditis? | Antibodies against the M-protein are formed shortly after acute infection, and these CROSS-REACT with epitopes on myosin |
What condition is due to M-protein antibodies cross reacting with epitopes of Myosin? | Rheumatic carditis |
What does HSV-1 infection in children often causes? | Gingivostomatitis ( vesicular lesions on the lips and hard palate) |
What is the genomic structure of HSV? | ds-DNA, enveloped virus |
Is HSV a, DNA or RNA, virus? | DNA |
IS HSV, enveloped or naked? | Enveloped |
Common enveloped, ds-DNA virus, causative of vesicular lesions in the hard palate and lips? | HSV-1 infection |