ID Flashcards
S. Aureus- toxin mediated syndromes
toxic shock, staph scalded skil, staph food poisoning
methicillin resistance in S. Aureus is classified as:
Oxacillin MIC of >/= 4 mcg/ml
CA- MRSA is generally susceptible to:
TMP/SMX, Gentamicin, Doxy, Clinda (varying resistance)
Gene that confirms methicillin resistance
mecA gene, encodes for a low affinity binding protein (penicillin binding protein 2a) that permits organisms to grow in the presence of beta-lactam antibiotics
Abs for serious infections with MRSA
Vancomycin. Other alternatives: linezolid ($$$), daptomycin (no lung activity), Ceftaroline, Tigecycline
Empiric therapy of life-threatening infections where MRSA is a likely cause
Vanc AND Nafcillin (more effective against MSSA)
Impetigo
Typically S. Aureus, sometimes strep progenies
- Honey crusted lesions
- Can cause post strep glomerulonephritis, NOT rheumatic fever
Treatment:
- Topial: Mupirocin
- Systemic: Cephalexin, or Clindamycin if concern for MRSA. Linezolid if severe
the d-test
determines if there is clindamycin resistance
most common cause of osteomyelitis
S. Aureus (except in sickle-cell patients: Salmonella)
S. Aureus is the most common cause of:
Impetigo, boils, furuncles, bacterial parotitis, bacterial tracheitis, suppurative lymphadenitis
CA_MRSA pneumonia has increased risk of:
empyema
Influenza and Measles can predispose children to:
superimposed S. Aureus pneumonia
Staph Toxic Shock Syndrome
- 50% associated with tampons
- Rash with desquamation
- Invovlement of >3 organ systems
- Nafcillin or Vancomycin PLUS clindamycin (to decrease toxin production) +/- IVIG
SSSS
- Caused by S. Aureus
- exfoliative toxins A and B
- Nikolsky sign
- Watch out for dehydration and superinfection
- Oder children may not have the skin sloughing (just red, tender skin.
Food poisoning- most commonly caused by:
- S. Aureus
- ingestion of preformed enterotoxin
- incubation period: <4-6 hours
- Supportive care
Coagulase negative Staph
Staph epidermidis and staph saprophyticus
Catheter related bacteremia and foreign body (prosthetic) related bacteremia: bacteria and treatment
- Typically S. Epidermidis
- treat with Vanc +/- Gent (for serious infections) +/- Rifampin (prosthetic device infections)
Most common cause of late onset bacteremia in preterm infants
Staph Epidermidis (think catheter association)
Encapsulated organisms
Strep pneumo, N. Meningitidis, H. Flu
Encapsulated infection more common in:
Splenic patients (anatomically or functionally), very young or very old, hypogammaglobulinemia (Burtons, Nephrotic Syndrome), or dysfunctional immunoglobulins (HIV)
Children at higher risk for invasive pneumococcal disease include:
- HIV
- Cochlear implants
- Alaska natives or Native americans < age 2
AOM: pathogen, antibiotic, treatment protocol based on age
- Most commonly S. Pneuma
- High dose Amox. If no response in 2 days > Augmentin or 2nd/3rd generation Cephalosporin
- For children 6 months-2 years with UNILATERAL AOM w/o otorrhea AND for children > 2 years with unilateral or bilateral without otorrhea you can observe for 48-72 hours
Empiric treatment of meningitis
Vanc and Cefotaxime or Ceftriaxone
Group A Strep
Strep Pyogenes Causes: -Pharyngitis -Scarlet fever -Impetigo, erysipelas, perianal cellulitis -Strep TSS -Rheumatic fever -Acute post streptococcal glomerulonephritis
Toddlers with Group A Strep infection
thick, purulent nasal discharge
Suppurative complications of Strep throat
AOM, Sinusitis, cervical lymphadenitis, peritonsillar abscess
Non-suppurative complications of strep pyogenes
Rheumatic fever and acute glomerulonephritis
- Acute GN cannot be prevented
- RF can be prevented with therapy
- Skin strains can cause GN but not RF
Scarlet fever
- sandpaper rash
- Can see Pastia lines (confluent petechia)
- Circumoral pallor
- Fades after about 1 week > desquamation of hands and feet
Erysipelas
Acute strep infection of the upper dermis and superficial lymphatics
- tender skin
- Often see well demarcated line (“leading edge”)
Treatment of choice for Strep Pyogenes infection
Penicillin
- Amoxicillin for better palatability
- PCN allergic: Cephalexin > Erythromycin or Azithromycin
Carriers of Group A Strep, pharyngitis
Typically doesn’t need to be treated unless:
- Local outbreak of acute rheumatic fever or post-strep GN
- Outbreak of GAS
- Family history of rheumatic fever
- Excessive anxiety
- Multiple episodes of pharyngitis
Treatment: Clindamycin 20 mg/kg/day divided TID x10 days
Treatment of rheumatic fever
PCN IM q3-4 weeks, or oral PCN daily for at least 5 years or until 21 years (whichever is longer)
-Some rec treating all household contacts, though most say those >65 or with risk factors
Group B Strep
Strep Agalactiae
-major cause of neonatal infection
Early onset GBS sepsis
- occurs within first 7 days
- Bacteremia most common, then pneumonia, then meningitis
Late onset GBS sepsis
- Range of onset day 7- 3 months
- Bacteremia most common, then meningitis, then osteomyelitis/septic arthritis
- Maternal prophylaxis has no effect on late-onset disease
Treatment of sick newborn
Initially with ampicillin and gentamicin
-If confirmed GBS, narrow to Penicillin or Ampicillin
Most common cause of endocarditis in children
Viridian’s streptococci
- often normal oral flora
- frequently present in transient bacteremia
- Strep anginosus, mitis, salivarius, mutans
Enterococcus infection
Most common infections: UTI, polymicrobial abdominal infection, bacteremia
- Resistance is increasing
- Ampicillin or Vancomycin used in combination with Gentamicin causes synergistic killing of organisms
Listeria infection
- Most common in neonates and elderly
- Exposure to contaminated milk products or meats
- Resistant to cephalosporins
- This is one reason why neonates get Amp and Gentamicin
Diptheria
- Caused by corynebacterium
- see grey-white membrane on tonsils, LOW fever, sore throat
- Often see conjunctivitis and “bull neck” (unilateral swelling)
- Can result in respiratory compromise
- Treatment: antitoxin and erythromycin
- Prophylax close contacts
Anthrax
- Caused by bacillus anthracis
- encapsulated, spore-forming gram positive rod
- Three types: cutaneous, gastrointestinal, inhalation
- Inoculation from handling contaminated hides or wool
Cutaneous anthrax
-Painless ulcer with subsequent eschar development
Treatment of anthrax
- Cutaneous: amoxicillin or ciprofloxacin
- GI or inhalation: 2 drugs, i.e cipro and clinda +/- antitoxin
- Mortality of GI and lung disease is high
Bacillus cereus
2 forms of gastro:
- short emetic type due to consuming preformed heat stable toxin (typically in fried rice)
- longer incubation diarrheal type due to heat-labile enterotoxin production in-vivo
- Typically self-limiting
C. Diff
- GI disease or asymptomatic carriage (5% of patients are carriers)
- often antibiotic associated
- often prolonged bloody diarrhea
- diagnosis based on evidence of c. diff toxin (not stool culture)
- Treatment: stop other antibiotics, 14 days metronidazole (oral drug of choice), addition of oral Vancomycin for severe disease
- Treat first recurrence with Metronidazole, second with prolonged course with oral Vanc, +/- fecal transplant
Tetanus: bug, 4 forms, clinical presentation
- clostridium tetani
- 4 forms: generalized, local, cephalic, neonatal
- Portal of entry is often a small wound
- often starts with generalized stiffness of muscles of neck, jaw and back. By 24 hours there is marked stiffness, followed by spasms of tetanus
Tetanus: treatment
- Low stimuli environment
- mechanical ventilation & neurologic blocking agents
- Human tetanus immune globulin is required and Flagyl for 2 weeks
Tetanus prophylaxis
- If the wound is dirty AND the immunization history is unknown or child has had < 3 tetanus shots: give TIG and immunize. If clean just immunize
- If the wound is clean and immunizations are up to date (most recent < 10 years) > no treatment
- Wound is dirty and immunizations are up to date (most recent < 5 years) > no treatment
- If wound is dirty and last immunization > 5 years > give TDap (or DTap if < 7)
Highest incidence of meningococcal infection
children < 2 (when maternal IgG antibodies wane) and teenagers 15-19 years
Meningococcemia: presents with…
fever, hypotension, diffuse purpuric lesions, DIC
Meningococcal prophylaxis
- for close intimate contacts and passengers seated directly next to index case on plane for more than 8 hours
- Close intimate contacts: household contacts, daycare/preschool mates, direct exposure to oral secretions.
- Ppx with Rifampin x2 days or Ceftriaxone
Meningococcal immunization
- Meningococcal conjugate vaccine (Menactra or Menveo) to all 11-12 year olds with booster at 16 years of age
- Anatomic of functional asplenia: get additional series starting as young as 2 months of age
- Serogroup B (Trumemba or Bexsero): 2 doses based on clinical discretion, stating at age 16, or to those with functional or anatomic asplenia
Ophthalmia in newborn
- If < 48 hours after delivery almost always chemical conjunctivitis 2/2 prophylaxis
- If 7-14 days post-birth and p/w bloody or serosanguinous discharge think chlamydia.
- If concern for gonococcal conjunctivitis: blood culture and LP often indicated
- Ceftriaxone is sufficient for treating ophthalmia neonatorum, however may need additional antibiotics for 2-3 days pending culture results
Bordatella pertussis: 3 stages of infection
- Catarrhal stage: mild respiratory infection
- Paroxysmal stage: persistent cough
- Convalescent stage: gradual improvement (6-10 weeks)
Pertussis: treatment
- Azithromycin (or erythromycin)
- Chemoprophylaxis for all household and day care contacts (same medication)
- Give booster dosages of pertussis vaccine if they are due
Moraxella catarrhalis
3rd most common cause of AOM (behind S. Pneumo and non-typeable H. Flu)
-Often does not require ABx
Salmonella
- Non-typoidal salmonella: common cause of diarrheal illness, rarely causes bacteremia, meningitis or bone infection (think sickle cell)
- Salmonella Typhi: common source of food borne outbreaks. Exotic pets can be carriers
- Do not treat with antibiotics (for uncomplicated gastro) unless <3 months or immunocompromised
- For invasive disease: given Ceftriaxone
Typhoid fever
- Leukopenia, fever, splenic enlargement, rose spots
- Complications: intestinal perforation or metastatic abscesses or encephalitis
- Treatment: based on susceptibilites
Shigella
- Diarrheal illness (can progress to dysentery)
- person-to person transmission is very high
- complications: rectal prolapse, new-onset seizures, HUS, reactive arthritis
- Treatment for severe cases, does decrease spread
- Must culture any symptomatic close contacts, no return to school until diarrhea stopped >24 horus
E. Coli
EHEC produces shiga toxin which can cause bloody diarrhea, HUS and can stimulate TTP
-Do not treat with antibiotics
Cat scratch disease
Bartonella henselae
- Chronic, tender regional lymphadenopathy and h/o cat scratch (often kitten)
- Avoid I&D of nodule (can cause persistent sinus tract)
- Can treat with 5 days of azithromycin, but usually is self-limiting
Cat or dog bites
pasturella multicida
- Usually treat with Augmenting (penicillin drug of choice)
- PCN allergy: Bactrim plus clindamycin
- Given ABx for ALL cat bites and only for those dog bites that appear infected, involve a critical area or are deep wounds
TB testing
- Tuberculin skin test is preferred fro children < 5
- Interferon-gamma is preferred if >5 and have previously received BCG vaccine or in children with limited follow-up
- Also OK to use IGRA in children 2-5
TST cutoffs
5 mm- for those with HIV, abnormal CXR, close contacts or severely immunocompromised
15 mm- No risk factors and >4 years
10 mm- all the rest
Evaluation/Treatment of latent TB
- CXR
- If latent: Isoniazid for 9 months
- If isoniazid resistant: rifampin for 6 months
Treatment of active tuberculosis
4 drug regimen: (RIPE)
- Rifampin
- Isoniazid
- Pyrazinamide
- Ethambutol
3 drug regimen: (RIP) only if sure that there is no drug resistance
-All except Ethambutol
TB treatment of pyridoxine
Pyridoxine = B6
- Use to prevent peripheral neuropathy
- Give to exclusively breast fed infants, or to kids with milk or meat deficient diets, pregnant adolescents and HIV patients
Monitoring during TB treatment
- RIP meds are hepatotoxic!
- Must monitor LFTs
- Stop treatment when AST/ALT > 3x upper limit with symptoms, or > 5x upper limit without symptoms
Testing for lyme disease
2 step approach
- Follow a positive EIA or IFA with a western blot
- Treat only if positive on both tests
Treatment of localized lyme disease (and isolated Bells Palsy)
Doxycycline
- or amoxicillin if < 8 years of age
- for 14-21 days
Lyme disease prophylaxis
Treat with single dose of Doxycycline if tick attached > 36 hours, within 72 hours of tick bite, in an area hyper endemic for Lyme disease
Coccidioides
US southwest and northern mexico
-Flu-like illness> arthralgias > erythema multiforme/erythema nodosum
Histoplasma
Mississippi, Missouri and Ohio river valley
-Present in bat and bird droppings
Blastomyces
Arkansas and Wisconsin
- Hunters and loggers
- Beaver dam!
Malaysia furfur
- Superficial dermatitis: tinea versicolor
- Line infection in NICU babies getting TPN and lipids (requires olive oil overlay to grow)
Roseola
HHV-6
- Typically see fever 3-5 days then abrupt cessation of fever followed by red rash
- Seizures can occur during febrile stage
Rubella
German Measles
- Adenopathy is usually first (post auricular lymphadenopathy)
- Viral symptoms for 1-5 days
- Rash: typically starts on face, then to turn and extremities
Rubeola
Measles
- Symptoms start with 3Cs: cough, coryza, conjunctivitis
- Koplik spots (white spots on mucosa)
- Rash: starts at hairline and spreads down and out
Mumps
- If symptomatic: see uni or bilateral parotitis, aseptic meningitis and/or encephalitis
- in post-pubertal males with mumps: may see a epididymoorchitis that is often unilateral
Parvovirus B19
5th disease
- Slapped check rash
- and may see a lattice-like rash
- Can cause aplastic anemia in patients with chronic hemolytic anemias
