Infectious disease Flashcards
1) What is not covered by Cephalosporins?
a) Enterococcus
b) Group A Strep
c) Group B Strep
A. Enterococcus. Cephalosporins do not cover Enterococcus – in fact, cephalosporins given prior to cesarean actually increase Enterococcus colonization, thereby increasing the prevalence of this species in post-cesarean endometritis (although overall decreasing the incidence of endometritis). Cephalosporins can be divided into “generations,” 1-5. First generation cephalosporins (cefazolin) are active against most gram-positive cocci but not against enterococci, Listeria, ORSA, penicillin-resisant pneumococci. First generation cephalosporins are not generally active against gram-negative organisms (gonococcus, meningococcus, H. flu). Second generation cephalosporins (cefoxitin) have decreasing activity against gram-positive organisms and increasing activity against gram negative organisums. Third generation cephalosporins (ceftriaxone) are again less active against gram-positive organisms & are still inactive against enterococci, Listeria, ORSA. Usually active against pneumocci with intermediate sensitivity to PCN. Fourth generation cephalosporins (cefepime) has increased activity against gram negatives and is active against Pseudomonas.
2) What causes Toxic Shock Syndrome?
a) Group A Strep
b) Group B Strep
c) Clostridium
d) Anaerobic Strep
A. Group A Strep. Causes of toxic shock syndrome include staphylococcus, group A strep, and Clostridium sordelii (which is known for having caused septic abortions in women receiving vaginal misoprostol).
3) What decreases oral contraceptive efficacy? What types of drugs and which ones in each class?
Several agents decrease the efficacy (steroid levels) of oral contraceptives. The only antibiotic is rifampin. The other major class of drugs that do this are anti-epileptics; notably phenytoin, carbamazepine, and topiramate decrease steroid levels.
4) What is given for MAI prophylaxis with a CD4 count of 80?
a)
MAC prophylaxis is indicated in HIV+ patients when their CD4 count falls below 50 (although older literature states 75-80). The appropriate choices for prophylaxis are azithromycin (1200 mg weekly), clarithromycin (500 mg BID), or rifabutin (300 mg Qday).
5) PVL is associated with which maternal infection?
a) Chorioamnionitis
b) Pyelonephritis
c) Pneumonia
A. Chorioamnionitis. Evidence suggests that intra-amniotic infection is associated with increased risks of periventricular leukomalacia & cerebral palsy, likely due to a fetal inflammatory response syndrome.
6) What is the most common side effect with Combivir and Lamivudane?
a) Anemia
b) Hepatotoxicity
?Anemia. The most common side effects are nausea/vomiting and bone marrow suppression (anemia). Hepatotoxicity, lactic acidosis, hypersensitivity reaction, and Stephens-Johnson syndrome are all rare side effect.
7) What is the most predictive of transmission of HIV?
a) Ruptured membranes
b) CD4 count
c) Viral load/HIV RNA
C. Viral load. The most important factor in determining perinatal transmission of HIV is maternal viral load. Decreased CD4 count has been associated with vertical transmission, but this is likely reflective of overall disease control (co-linear with viral load). Increased duration of membranes is also associated with increased risk of transmission, but this is 2% over baseline risk for every hour increment of rupture of membranes. So if somebody had a baseline risk of 1% (due to low viral load & HAART), risk of transmission after 1 hour of SROM is 1.02% and after 8 hours is 1.16%.
8) What is most resistant to GBS?
a) Erythromycin
b) Clindamycin
c) Penicillin
d) Azythromycin
A. Erythromycin. GBS is most resistant to erythromycin – incidence of erythromycin resistance is 25-32%. GBS is also frequently resistant to clindamycin (13-20%), but its use is acceptable if documented sensitivity to both erythromycin & clindamycin. Erythromycin is never an acceptable option for GBS prophylaxis. The majority of GBS is remains sensitive to PCN, ampicillin, and cephalosporins. (See 2010 CDC guidelines.)
12) What is not associated with placental thickening?
a) Syphilis
b) Rh Issoimmunization
c) Non-immune hydrops
d) Listeriosis
D. Listeriosis. Listeriosis is associated with stillbirth, miscarriage, and neonatal sepsis. Listeria causes placental abscesses but not necessarily an enlarged placenta. Hydrops (immune or non-immune) is associated with placentomegaly. Syphilis is associated with an enlarged edematous placenta, and can also cause non-immune hydrops.
13) What is used in the treatment of Lyme?
a) Penn
b) Doxy
c) Vancomycin
d) Clindamycin
e) Cephalosporin
E. Cephalosporin. The treatment of uncomplicated Lyme disease is a 14-day course of ampicillin, cefuroxime, or doxycycline. Doxycycline is contraindicated in pregnancy due to concerns regarding deposition in bones. Therefore, the correct answer will be either ampicillin or a cephalosporin. Complicated Lyme disease (carditis, encephalitis) is treated with IV penicillin or cephalosporins.
14) A mother who is HIV positive who took no meds during the pregnancy what is given in labor to decrease transmission?
a) Acyclovir
b) Lamiduvane
c) Navaripine
C. Nevirapine. In the US, we use zidovudine (AZT) during labor to decrease the risk of vertical transmission. However, nevirapine has been demonstrated to decrease the risk of transmission when AZT is unavailable. Concerns regarding side effect profile and resistance have resulted in the US discouraging the use of nevirapine intrapartum.
15) A patient presents with pneumonia that has a LLL infiltrate and a fever, what is the most likely cause?
a) Strep pnuemonae
b) Mycoplasma
c) H. influenza
A. Streptococcus pneumoniae. Streptococcus pneumoniae is the most common bacterial pathogen to cause pneumonia in pregnancy. It produces a “rusty” sputum and asymmetric consolidation with air bronchograms on chest x-ray. H. influenzae is the second most common. It produces consoldiation with air bronchograms, often in the upper lobes. Less frequent are Klebsiella pneumoniae, which causes air bronchograms, pleural effusion & cavitation, and Staph aureus, which presents with pleuriits, chest pain & consolidation without air bronchograms. The atypical pneumonia pathogens are Mycoplasma, Legionella, and Chlamydia, which present with lower fever, mucoid sputum, and patchy or interstitial infiltrates on CXR.
18) What is the mechanism of fetal anemia caused by parvovirus?
Parvovirus infects erythropoietic precursors and is cytotoxic. As a result, the fetus becomes anemic.
21) Least likely associated with mental retardation?
a) Varicella 1st trimester
b) Rubella 1st trimester
c) CMV
?? A. Varicella in first trimester. All three are associated with developmental delay/microcephaly/cerebral cortical atrophy, etc. So this is really a question about transmission rates. 80% of women infected with rubella develop congenital rubella. 40% of women with primary CMV have affected children; 32% of children infected in 1st trimester have CNS manifestations. Only 0.4% of women with varicella in first trimester have affected children.
28) Which doesn’t cause NIH? non immune hydros
a) toxo
b) syphilis
c) parvo
d) listeria
D. Listeria. The main manifestation of Listeria is stillbirth. Toxoplasmosis, syphilis, and parvo can all cause non-immune hydrops.
