Infectious disease Flashcards
RIPE therapy for TB the most common indication to discontinue therapy?
Rifampin, Isoniazid, Pyrazinamide, and Ethambutol.
The most common indication to alter or discontinue therapy is an elevation of liver enzymes 5 times greater than baseline.
Patient with HIV and a CD4+ count less than 50 along with painless vision loss
Is most likely suffering from cytomegalovirus (CMV) retinitis. He should be treated with valgancyclovir.
Positive tuberculin test
Low-risk patients: greater than or equal to 15mm in diameter read at 48-72 hours.
Persons with diabetes, malignancy, silicosis, immigrants from high prevalence countries who arrived within five years, and persons who use illicit drugs: > or equal to 10mm.
HIV, fibrotic changes from previous TB, and recent contact with persons with active TB: > or equal to 5mm.
Necrotizing fasciitis is most commonly caused by?
Streptococcus pyogenes (Group A strep).
Common causes of epiglottitis in vaccinated patients?
Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus.
Bordatella pertussis choice of treatment?
Macrolides
Rocky Mountain Spotted Fever
Is a tick-borne infection caused by Ricketsia rickettsii.
Southeastern and south-central United States (e.g Tennessee, North Carolina).
Fevers, headaches, myalgia, and malaise, starting less than one week after exposure. The associated, “spotted” rash starts as a maculopapular rash on the ankles and wrist, and eventually develops into a petechial rash that moves to the trunk.
It appears within 2-6 days of exposure due to a small vessel vasculitic process, although some patients with RMSF will not have the classical rash.
Doxycycline is the therapy of choice.
Any patient with a contaminated penetrating injury and unclear tetanus vaccination history should be treated with?
A tetanus vaccine and tetanus immune globulin.
Leprosy
Caused by a mycobacterial infection. Leprosy can occur in a diffuse or lepromatous form, which occurs when a weak immune response is mounted.
Tuberculoid form, which has limited involvement of skin. The tuberculoid form often presents with a raised skin lesion, loss of sensation over the affected area, and loss of any overlying hair.
Leprosy can be confirmed via biopsy.
Antibiotic coverage for intraabdominal infections
Should target gram-negative and anaerobic pathogens.
Regimens that are commonly used: ceftriaxone/metronidazole, ciprofloxacin/metronidazole, piperacillin-tazobactam, or ampicillin-sulbactam.
The most common cause of acute bacterial rhinosinusitis?
Moraxella catarrhalis
A facultative anaerobic, gram-positive cocci in clusters that cause toxic shock syndrome?
S. aureus
the prozone phenomenon
The negative RPR/VDRL test is a result of the prozone phenomenon, which is caused by excess antibodies leading to an imbalance of the antibody to antigen ratio.
Gram-positive cocci in clusters and in chains
Clusters: S. aureus
Chains: Streptococcus or Enterococcus
Reiter’s syndrome
Uveitis, urethritis and arthritis.
Chlamydia trachomatis
For patients undergoing emergency splenectomy, vaccine series should be started?
14 days after splenectomy
Hib vaccine 1 dose
Meningococcal serotype ACWY B 2 doses, 8 weeks apart. booster every five years.
Meningococcal serotype B 2 doses at leat 1 month apart, booster 1 year and 2-3 years after that.
Recombinant zoster vaccine 2 doses 2-6 months apart if 50 years or older.
Seasonal influenza.
20 valent pneumococcal conjugate no booster.
PCV15 is used, one dose of the 23 calent pneumococcal polysaccharide should be given at least 8 weeks later.
The first line treatment for shigella in ambulatory patients?
Azithromycin
Nocardia
Gram-positive filamentous rod
Can cause pneumonia and central nervous system disease or skin lesions in immunocompromised patients.
treatment: Trimetropim sulfamethoxazole.
Primary prophylaxis HIV CD4 counts
For pneumocystis jirovecii pneumonia is needed in HIV+ positive patients as their CD4+ goes below 200 cells/mm3 with TMP-SMX.
<100 cells/mm3, TMP-SMX also covers for toxoplasma gondii encephalitis.
<50 cells/mm3, prophylaxis against disseminated MAC disease is needed with azithromycin.
Combined therapy to treat chronic hepatitis C
Interferon and ribavirin is warranted in patients with hepatitis C (HCV) who have elevated liver enzymes, detectable HCV RNA, and evidence of chronic hepatitis.
A newer alternative therapy is sofosbuvir which can eliminate the need for interferon.
The most accurate test for osteomyelitis is?
A biopsy which can confirm the diagnosis and organism thus guiding antibiotic therapy.
The prozone phenomenon
Is a false-negative result in serological tests (like those for syphilis) caused by an excess of antibodies that interfere with the formation of the antigen-antibody lattice network needed for a positive result.
HIV positive patients, there is hyperactivity of B-cell behavior that leads to excess production of anti-cardiolipin antibodies
