Infectious Disease Flashcards
11 mo old with resp distress, AOM, nl CXR, and lymphocyte predominance - most likely what virus?
hMPV. Could also be RSV.
BOTH cause bronchiolitis - indistinguishable
Options for immunoprophylaxis after exposure to varicella
- passive varicella zoster immune globulin
- immunocompromised, neonates, and pregnant women
- up to 10 days after exposure - varicella vaccine
- not immune to varicella but does not meet criteria for IG
- only if 12 months of age or older
- up to 5 days after exposure
What is perichondritis?
Infection of the connective tissue of the ear that covers the cartilage. Inflammation and pus can separate the cartilage from the connective tissue (that carries o2 and nutrients) leading to necrosis. Often occurs from a piercing.
Either from:
Pseudomonas (gram neg rods).
Staph aureus
Tx:
Ciprofloxacin for pseudomonas
Salmonella Typhi
Fever + invasive infections (hepatitis, bacteremia, osteo, meningitis)
Hx:
Travel to resource limited country
Typhoid vaccine should be offered prior to travel.
Dx: BLOOD CULTURE. As stool cultures are often negative.
Non-typhi forms of salmonella usually just cause enteritis. And hosts include birds, reptiles, mammals whereas typhi is just humans.
Toxic Shock Syndrome
Due to S. aureus releasing TSST-1 toxin.
Can occur: surgical and postpartum wound infections, burns, and as a complication of infections such as influenza, sinusitis, osteomyelitis, and enterocolitis
Dx is clinically! BCx may be negative for S. aureus
Fever> 102 Rash (diffuse erythroderma) Desquamation (usually palms/soles) Hypotension MULTISYSTEM involvement (3 or more)
Tx for UTI for a patient with neurogenic bladder with UCx showing GPC in pairs/chains
Enterococcus!
Resistant to cephalosporins.
Tx: Ampicillin
Rubella infection
Only TORCH infection that causes cardiac defects (PDA) and cataracts (complete absence of red reflex).
+ sensorineural hearing loss
VS:
- intracranial calcifications (toxo, CMV)
- microcephaly (CMV, Zika)
- chorioretintiis (white spots on retina vs. complete absence of red reflex - toxo)
Peritonsillar abscess - org and treatment
Strep pyogenes
Tx: penicillin
Trichomonas on wet mount and tx
Mobile Trichomonas
Sx: vag discharge (green, foamy) vulvovaginal pruritus and irritation, abdominal pain, dysuria and dyspareunia.
Tx: Metronidazole 2g. Abstinence from alcohol is recommended during treatment with nitroimidazoles.
How to test for HIV in children
<18 months: nucleic acid: HIV DNA polymerase chain reaction or HIV RNA assays. Immunoglobulin assays are not useful bc they may have maternal antibodies
> 18 months: HIV-1 Ab/HIV-2 Ab/p24 Ag immunoassay.HIV p24 structural capsid protein antigen helps identify early infection during the 20- to 30-day window after infection has occurred until HIV antibody is present.
Most common viruses causing the common cold
Rhinovirus is most common - also associated with 2/3 of all asthma exacerbations
Coronavirus is 2nd most common. Indistinguishable.
Yersenia
- fever and diarrhea (often bloody in children), abdominal pain, nausea, and vomiting (frequently indistinguishable from other acute diarrheal illnesses)
- principally found in pigs
- slow subclinical onset and protracted duration of up to 3 weeks
- Pharyngitis may provide an important diagnostic clue for Yersinia as the causative pathogen because pharyngitis is not associated with other acute bacterial diarrheas.
Tx: Antibiotics are not beneficial in the treatment of acute uncomplicated yersiniosis.
Vs: C diff - usually doesn’t occur in those younger than 12-24 months bc lack the ability to bind and process the clostridial toxin, creating asymptomatic carriage and preventing colitis from occurring.
Hepatitis A post-exposure prophylaxis
> 12 months: give Hep A vaccine (as effective as IG and is long-term protection)
Hep A IG - give to those < 12 months, or immunocompromised.
NOT indicated if exposure occurred > 2 weeks ago!
70% of children younger than 6 years of age with HAV infection are asymptomatic.
Persistent hypothermia is a sign of?
Hypothalamic Dysfunction - need to get MRI head.
Ex: tumors and granulomas of the hypothalamus
Other sx: polyphagia, obesity, precocious puberty, adrenal insufficiency, short stature, polydipsia, polyuria.
Parvovirus B19 infection
- fifth’s disease - intense red appearance of the cheeks
- petechial papulopurpuric gloves and socks syndrome - petechiae on the hands/feet/legs
- aplastic anemia from hemolysis
- spontaneous abortion and hydrop fetalis
Corynebacterium Diphtheriae
Sx due to the exotoxin.
Cutaneous - ulcers covered with gray membrane
Resp - forms pseudomembrane attached to the underlying resp mucosa
Cards - ST-T wave changes, QTc prolongation, 1st degree heart block, myocarditis
Neuritis - paralysis of soft palate/pharyngeal wall
After exposure and sx suspicious for pertussis, when can a healthcare worker go back to work?
AFTER Treatment!
Clearance occurs after 5 days of antibiotic therapy such as Azithromycin (macrolide)
Despite immunization, you are still at risk.
Masking is not sufficient protection for someone who is symptomatic to avoid transmission.
What abx regime to treat dog bite?
Empiric coverage for likely pathogens from the animal’s mouth (Pasteurella) and from the patient’s skin (Staphylococcus aureus, Streptococcus pyogenes).
Pasteurella is the most common pathogen isolated from animal bite wounds. Infection is characterized by an intense inflammatory response occurring within 24 hours of the initial exposure.
Options:
- Amoxicillin-clavulanate
- third-generation cephalosporin (cefixime or cefpodoxime)
- trimethoprim-sulfamethoxazole (Pasturella) + clindamycin (MRSA)
Candidemia evaluation
Immunocompetent - thrush, dermatitis, onychia
Immunocompromised, premature/very low birth weight - invasive candidiasis
- Needs LP and Opthalmologic eval**
- If multiple positive cultures, consider Abd US and ECHO
Hepatitis B post-exposure prophylaxis
If confirmed HBsAg positive source:
Nonimmune individuals
- hepatitis B vaccination series AND
- hepatitis B immune globulin as soon as possible
Immunized individuals
- one booster dose of hepatitis B vaccine.
If HBsAg status is unknown:
Nonimmune individuals: hepatitis B vaccination series
Immunized individuals: no further treatment.
Recreational Water Illnesses
Most common is gastroenteritis - from Cryptosporidium
- can survive in chlorinated pool. Has watery brown diarrhea that can last for 2 weeks, but otherwise relatively well-appearing.
VS: norovirus (most common cause of AGE < 5: abd pain, n, v, fever - but most resolve in 3 days)
VS: salmonella - bloody diarrhea
Chlorine effective against noro and salmonella
Other RWI diseases:
Hot tub folliculitis - Pseudomonas
Pneumonia - steam or mist containing Legionella
Otitis externa (swimmer’s ear) - P aeruginosa and Staphylococcus aureus.
Testing for TB
If you’re immigrant from endemic area:
2-14 yrs: PPD (TST) or Quantiferon (interferon gamma release assay)
15 or older: CXR
No routine testing for children < 2 unless suspecting it, known contact with active TB, or has HIV
TST = preferred for those < 5 (even if they got BCG!)
Once older than 5 and hx of BCG, then use Quant.
Hepatitis B test interpretations
The presence of hepatitis B surface antigen and total antibody to hepatitis B core antigen without IgM hepatitis B core antibody is indicative of chronic hepatitis B virus infection.
The presence of hepatitis B e antigen suggests high viral replication and increased risk of hepatitis B virus transmission.
What would be an indication to start abx in a burn patient?
Discoloration/change in appearance of the burn.
NOT
SIRS because burns naturally cause SIRS due to hypovolemia from cap leak and hypermetabolic state.
Extent of burn - this only dictates if they need to be treated at burn center.
What characterizes aseptic meningitis and what test to diagnose?
Relatively low wbc count
Mildly elevated protein
Low-normal glucose
No orgs on gram staining!
Dx through CSF PCR
Enterovirus types and clinical manifestations
Summer-Fall
Fecal-Oral contact
Febrile, nonspecific resp/GI: any
Aseptic meningitis: coxsackie B, echo, numbered entero
Herangina, hand foot mouth: coxsackie A
Carditis: coxsackie B
Neonatal: coxsackie B, echo (sepsis, meningoencephalitis, hepatitis, myocarditis)
What does HPV vaccine protect against?
4-valent (types 6, 11, 16, 18)
9-valent (types 6, 11, 16, 18, 31, 33, 45, 52, 58).
Anogenital warts
Precancerous lesions - intraepithelial neoplasia
Cervical, Anal, Vulvar, Vaginal cancers
How do you diagnose HUS?
Hemolytic anemia, thrombocytopenia, renal abnl
in a patient with hx of fever, bloody diarrhea.
NOT a blood culture because the E.coli is producing Shiga toxin!
Coccidioides
Inhalation of FUNGAL spores. Southwestern US, Mexico, Central/South America.
Asymptomatic or self-limited
Pulmonary infection, pleural, mediastinal
Cutaneous: erythema nodosum or multiforme
Disseminated is rare
Diagnosis: Complement fixation of IgG!
Not urine antigen, eosinophilia, or tree in bud which are supportive of diagnosis but not definitive.
Campylobacter
Spiral/Helical shaped Gram negative bacilli
Leading bacterial cause of foodborne gastroenteritis: fever, diarrhea, crampy abd pain, or bloody diarrhea in infants
Exposures in unpasteurized milk, undercooked poultry, contaminated water, animal contact. + Daycares!
Tx: azithromycin or erythromycin decreases the duration of diarrheal illness by hastening eradication of Campylobacter organisms in the feces by 2 to 3 days.
Meningococcemia
Neiserria Meningitidis
Sepsis (Fever, tachy, hypotension) + Rash (purpuric, blotchy, non-blanching). Vomiting, Stiff Neck for meningitis.
Why? Endotoxin from the bacterial capsule causes a severe host inflammatory response that can lead to cardiovascular collapse because of myocardial depression and vasodilation, disseminated intravascular coagulation, lethargy, respiratory failure, and death.
Tx: Ceftriaxone
How are pinworm infections spread?
Pinworms (Enterobius vermicularis) may be transmitted by the fecal-oral route indirectly from contact with toys, bedding, clothing, and toilet seats that are contaminated with eggs.
Autoinfection from scratching the perianal area and transferring eggs back to one’s own mouth is common.
Sx: pruritus, restless sleep, and occasionally vulvitis associated with dysuria
Pinworm infestation is often clinically diagnosed, and medical providers may choose to treat pinworm infestation empirically if the clinical scenario is consistent.
Vertical transmission of Hep C results in?
Slowly progressive fibrosis in childhood.
Only 5% of infants born to mothers with hepatitis C virus infection acquire the virus. Although the likelihood of vertical transmission of hepatitis C virus is low, a large portion of infected infants will develop chronic infection.
The possible long-term outcomes of patients who have chronic hepatitis C virus infection include slowly progressive fibrosis -> cirrhosis -> liver failure, and hepatocellular carcinoma.
Individuals with chronic hepatitis C virus infection should have annual evaluation of hepatic enzymes and function, and children with significant liver disease should undergo at least annual hepatocellular carcinoma screening through ultrasonography and α-fetoprotein measurement.
Listeria infection in neonate
Gram positive rods: purple (Listeria)
Gram negative rods: pink (E.coli)
Acquired when mom ingested contaminated food.
Neonate will either have early disease = sepsis or late disease = meningitis.
Tx: ampicillin and gent
How to definitely diagnose syphilis?
Painless genital ulcer with indurated border
Dark field microscopy to look for spirochetes.
- but most ppl use non-treponemal test (RPR, VDRL) but an have false positives, so if positive, have to use a treponemal test to verify (FTA-ABS, TP-PA)
Influenza Diagnosis
Molecular assays (RT-PCR, NAAT) are best 86-100% sensitivity. Rapid tests such as antigen detection are not as reliable.
If child is < 2 or has comorbidities predisposing to severe disease (asthma, cards, sickle cell, diabetes) = then give oseltamivir WITHOUT waiting for test results.
Flu season peaks Jan-March
Head Lice
Should NOT be sent home from school!
Head lice have low contagion within classrooms, and children with active infestations are likely to have been infested for some time. Therefore, a child with head lice should not be restricted from attending school, and no-nit policies should be abandoned.
Household members should be checked for head lice and treated when live lice or nits are found within 1 cm of the scalp. Empiric treatment is recommended for all family members who share a bed with the affected child. Items that have been in contact with the head of the infested person within 48 hours prior to treatment should be considered contaminated and washed, vacuumed, or dried at a temperature greater than 54.4°C. Alternatively, placing items in a closed plastic bag for 2 weeks is an effective decontamination technique.
Infectious Mononucelosis
EBV = human herpesvirus4
Primary Epstein-Barr = infectious mononucleosis
- fever, malaise or fatigue, pharyngitis, and cervical lymphadenopathy, splenomegaly, palatal petechiae
- those treated with antibiotics, especially amoxicillin or ampicillin, can develop a distinct morbilliform rash (more severe than that associated with IM itself which is usually just trunk and spares extremities)
Dx:
- 10% atypical lymphocytes on a peripheral blood smear + positive heterophile antibody test (but may not have if less 4 years old)
- IgM antibody against viral capsid antigen in the absence of antibodies against Epstein-Barr nuclear antigen
Infant who presents with constipation, difficulty feeding, muscle weakness (unable to sit up), ptosis, weak cough and gag reflexes, diminished head control, and mild weakness of all extremities. Over the course of 2 weeks
Infant Botulism!
- usually 2-6 month age group
- inhalation of C. Botulinum spores (or honey or corn syrup)
- Botulinum neurotoxin binds to Ach-R irreversibly!
Sx:
- constipation
- weakness rostrocaudally: bulbar weakness, ptosis, decreased gag/cough reflex -> large muscles (poor head control, truncal instability
- also with parasympathetic involvement: dry MM, constipation
Tx: IV botulinum IG
VS:
- Duchenne’s: preschool, large muscles NOT bulbar
- Myasthenia: waxing/waning (not in infants)
- GBS: ascending weakness (not in infants)
- SMA: can be in infants, BUT SLOW progression over MONTHS not days-weeks. And does not involve the face.
Ring-enhancing lesion on Brain MRI
T solium
Dx: Antibody assays to T solium serum (better than CSF). Serum antibody test results are often negative with minimal disease (a solitary cyst) but positive in patients with multiple lesions.
- Neurocysticercosis is a neglected tropical parasitic disease caused by 1 or more cysticerci (larvae) of the pork tapeworm Taenia solium. In the United States, most patients with neurocysticercosis are immigrants from Latin America or Asia.
- Seizures are the most common clinical manifestation of intracranial neurocysticercosis and often result from acute or chronic host inflammation of degenerating Taenia solium brain cysts. Also ocular.
EBV Titer interpretations
Acute/Recent infection: + IgM-VA and IgG-VA (persists for life). - IgG against nuclear antigen (EBNA). IgM lasts for about 2 months
Previous infection: - IgM and + EBNA
Reactivation: previous infection + early antigen
Lyme disease - treatment
Serologies are NOT detectable 1-2 weeks after the tick bite. So, if has erythema migrans, just Treat!
Doxy or Amox or Cefuroxime
Epi
- spirochete Borrelia burgdorferi and transmitted to humans by the bite of the infected Ixodes (deer) tick
- New England, the Eastern mid-Atlantic, and the upper Midwest.
Sx:
Early localized Lyme disease = erythema migrans (1-4 wks after tick bite)
Early disseminated = multiple erythema migrans lesions, facial nerve palsy, carditis (heart block), aseptic meningitis
Late = arthritis (usually knee)
Bacterial Meningitis Empiric Treatment
Vanco + CTX for anyone older than 1 month
Streptococcus pneumoniae and Neisseria meningitidis are the 2 most common bacteria causing pyogenic meningitis in previously healthy children older than 1 month. In unimmunized children younger than 4 years, Haemophilus influenzae type b must also be considered.
Vanco covers resistant strains of s.pneumo
What infectious etiology causes malabsorptive diarrhea?
Giardia!
Dx’ed with ova and parasite exam: direct microscopic evaluation and/or Giardia-specific enzyme immunoassay of stool samples.
TX: metronidazole
