Micro Flashcards
Protein A
Virulence factor in peptidoglycan cell wall of Staph aureus that binds the Fc portion of IgG, leading to impaired complement activation, opsonization, and phagocytosis.
How to visualize Cryptococcus neoformans
India ink staining - stains background black and allows thick polysaccharide capsule of yeast to be visualized
Cryptococcal meningitis presentation
Slowly worsening headache, fever, lethargy in immunocompromised individual
Treatment for cryptococcal meningitis
Amphotericin B and flucytosine for initial treatment. Long term maintenance with fluconazole
CSF findings in cryptococcus meningitis
low glucose, increased protein, mild pleocytosis with predominance of lymphocytes
Which drug is used to treat trichomonas vaginitis and bacterial vaginosis?
Metronidazole
What is the major virulence factor among E. coli strains that cause neonatal meningitis?
K1 capsular antigen
Describe the identifying qualities of Strep pneumo
Gram +, alpha hemolytic, optochin-sensitive, bile soluble, lancet shaped diplococci
What is the mechanism of vancomycin resistance in organisms such as VRE?
Substitution of D-lactate in the place of D-alanine during the process of peptidoglycan cell wall synthesis. This prevents vancomycin from binding to its usual D-alanyl-D-alanine binding site
What are CMV related complications observed in infants exposed in utero?
Chorioretinitis, sensorineural deafness, seizures, jaundice, hepatomegaly, splenomegaly, and microcephaly
Acute rheumatic fever presentation
Migratory arthritis, new onset murmur, fever, and positive antistreptolysin O titer
Primary cause of morbidity in acute rheumatic fever?
Heart failure from severe pancarditis
Adenovirus
Self limiting, year round infection that causes acute onset of fever, cough, congestion, pharyngitis, and conjunctivitis. Outbreaks among those living in close quarters
Name the viruses with segmented genomes
Orthomyxoviruses, reoviruses, bunyaviruses, arenaviruses
Describe parvovirus B19
Nonenveloped single-tranded DNA virus
What infections are transmitted by the Ixodes tick?
Babesiosis and Lyme disease
What is found in tissue samples of patients infected with Coccidioides immitis
Spherules containing endospores
Coccidioides immitis infection
Asymptomatic or can cause pulmonary disease ranging from flu-like illness to chronic pneumonia. Disseminated disease in immunocompromised
What diseases are transmitted by Ixodes ticks?
Babesiosis and Lyme disease
What is the presentation of babesiosis?
Acute febrile illness, thrombocytopenia, hemolytic anemia, abnormal liver fxn tests, and intraerythrocytic inclusions
Describe severe babesiosis. Who is at increased risk?
Acute respiratory distress syndrome - dyspnea, coarse crackles, bilateral infiltrates. Increased risk in splenectomy patients
What microbes primarily account for central venous catheter infections?
Gram positive cocci, primarily coagulase-negative staphylococci and staphylococcus aureus
Blastomyces dermatitidis presentation
In immunocompetent individials - lung infection or flu like illness. In immunocompromised - causes disseminated disease with fever, weight loss, night sweats, cough, dyspnea, skin lesions, and bone pain
Large yeast with a single, broad based bud
Blastomyces dermatitidis
Where is Blastomyces dermatitidis found?
In the southeastern United States in soil and rotten organic matter
Which organism causing gastroenteritis has a low number of organisms required to cause disease?
Shigella. As few as 10-500 cells can cause infection
Most common cause of aseptic meningitis
Enteroviruses
What do viridans streptococci produce?
Dextrans - aid in colonizing host surfaces, such as dental enamel and heart valves
The only pathogenic fungus with a polysaccharide capsule
Cryptococcus neoformans
Describe appearance of Cryptococcus neoformans with staining
Appears red on mucicarmine stain and as a clear unstained zone with Indian ink
Replication of Hepatitis B genome
Occurs within a newly synthesized capsid through the action of reverse transcriptase on an RNA template. Mature capsid contains partially double-stranded circular DNA and reverse transcriptase
Tumbling motility, gram + rod
Listeria
Bartonella henselae
Causes cat-scratch disease, bacillary angiomatosis, and culture negative endocarditis
What does Haemophilus influenzae require to grow
X factor (hematin) and V factor (NAD+)
Describe H influnzae
Gram negative coccobacillus. Type b has an antiphagocytic polysaccharide capsule, which allows it to spread hematogenously and cause invasive disease such as septic arthritis and meningitis
Treatment for Enterobius vermicularis (Enterobiasis)
Albendazole
Major pathogen in burn patients
Pseudomonas aeruginosa
Antibiotics for Pseudomonas
Ticarcillin, piperacillin, ceftazidime, cefepime
What are the atypical lymphocytes observed in peripheral blood smears of pts with mono?
Activated CD8+ cytotoxic T-lymphocytes. They fxn to destroy virally infected B lymphocytes
Schistosomiasis
Acquired via contact with freshwater sources that contain snails infected with Schistosoma larvae
Which bacteria produce IgA protease?
Neisseria meningitidis, N gonorrhoeae, Streptococcus pneumoniae, and Haemophilus influenzae.
What is the function of IgA protease?
Cleaves secretory IgA at its hinge region, rendering it ineffective and facilitating mucosal adherence of bacteria
West Nile virus
Single-strand flavivirus. Asymptomatic or flu-like illness often with a maculopapular or morbilliform rash
Describe manifestation of neuroinvasive West Nile virus
Meningitis, encephalitis, or asymmetric flaccid paralysis. Pts may have parkinsonian features
Secondary dengue virus infection
Due to infection with a different viral serotype and usually causes a more severe illness
Dengue viruses
Single-stranded RNA viruses with 4 different serotypes
Parvovirus B19
nonenveloped single stranded DNA virus
Pseudomonal exotoxin A and diphtheria toxin mechanism
Ribosylating and inactivating EF-2, inhibiting host cell protein synthesis and causing cell death
CMV
Enveloped double stranded DNA virus
Treatment for enterobiasis
Albendazole
