ID Bacterial Infections

timing of perioperative antibiotics

• pre-operative: infuse cefazolin or cefuroxime within 60 min before first incision

  • if quinolone or vanc: 120 min before

• intra-operative: additional doses may be used >4hr long surgeries

• post-operative: abx not usally needed

what 2 abx are indicated for perioperative ppx

• cefazolin (1st gen)

• cefuroxime (2nd gen)

for perioperative ppx, if pt has beta-lactam allergy, what 2 meds can be used?

• clindamycin

• vancomycin

in GI surgeries, what must the ppx regimen contain?

• gram negative and anaerobic coverage

what drugs can be added to cefazolin for perioperative GI ppx (4)

• metronidazole

• cefotetan (2nd gen)

• cefoxitin (2nd gen)

• Unasyn (aminopenicillin)

how is meningitis diagnosed?

Lumbar puncture of CSF

• gram stain to guide abx tx

• high CSF pressure = infection

most common bacterial causes of meningitis (3) (NSH)

• Neissereia meningitidis

• streptococcus pneumoniae

• haemophilus influenzae

who is at risk for Listeria monocytogenes for meningitis? (3)

• neonates

• age >50

• immunocompromised

empiric abx regimen for meningitis in neonates (<1 month)

• ampicillin (Listeria)

• + ceftazidime or cefepime

• ± gentamicin

empiric abx regimen for age >1 month - 50 yrs

vancomycin + ceftriaxone

empiric abx regimen for age >50 yrs or immunocompromised

ampicillin (Listeria) + ceftriaxone + vancomycin

why should dexamethasone be added prior to abx for bacterial meningitis?

• IV dexamethasone admin 15-20 min PRIOR to first abx dose can prevent neurological conditions (hearing loss)

• d/c if s. pneumoniae is not identified

common bacteria in AOM (3) (SHM)

• s. pneumoniae

• h. influenzae

• moraxella catarrhalis

when can observation be used in AOM?

• 48-72 hrs for ages ≥6 months with non-severe AOM

• no otorrhea, otalgia < 48 hrs

• temp <102 F (39C)

• ages 6-23 months: 1 ear only

• ages ≥2 yrs: 1 or both ears

what is first line for AOM?

high dose amoxicillin 90mg/kg/d in 2 divided doses or Augmentin to cover most strains of s.pnuemoniae

why is Augmentin Es-600 preferred?

contains target 14:1 ratio (600mg/42.9mg) which decreases risk of diarrhea

what is treatment duration of AOM in ages <2 yrs

10 days

• 7 days for 2-5 yrs

• 5-7 days for ≥6 yrs

if a children have a non-severe penicillin allergy in AOM, what is preferred?

2nd or 3rd gen cephalosporin

what can be given if treatment failure (not improved after 2-3 days) for AOM?

• ceftriaxone 50mg/kg IM for 3 days

pharyngitis bug, sx, and treament

• bug: s. pneumoniae (GAS)

• sx: sore throat, fever, swollen lymph nodes, white patches on tonsils

• dx: rapid antigen test

• drug: penicillin or amoxicillin

acute sinusitis bug, sx, drug

• bug: SHM (s. pneumoniae, h. influenza, m. catarrhalis)

• sx: nasal congestion, purulent nasal discharge, facial/ear/dental pain, headache

  • sx > 10 days or >3 days of severe sx (fever >102)

• drug: Augmentin

are abx recommended in acute bronchitis?

NO

• cough lasting 1-3 weeks

• preceded by upper respiratory tract virus

• chest x-ray is NORMAL

• supportive care only

Bordetlla pertussis (whooping cough) first-line

macrolides (azithromycin, clarithromycin)

• highly contagious

acute bacterial exacerbation of COPD bugs (3) HSM

• s. pneumoniae

• h. influenzae

• m. catarrhalis

3 cardinal sx of COPD exacerbation

1. increased dyspnea

2. increased sputum volume

3. increased sputum purulence

what supportive treatment should be given in COPD exacerbation?

• oxygen

• short-acting inhaled corticosteroids

• IV or PO steroids

who qualifies to receive abx in COPD exacerbation?

• any one of the following are met

  • all 3 cardinal sx

  • inc sputum purulence + 1 additional sx

  • mechanically ventilated

what is the preferred abx for COPD exacerbation?

Augmentin 5-7 days

• azithromycin

• doxycycliine

• respiratory quinolone

common bugs of CAP (3) HSM

• s. pneumoniae

• h. influenzae

• Mycoplasma pneumoniae

what is the gold standard for CAP dx?

chest x-ray

• infiltrates, opacities, consolidations

duration of tx for CAP

5-7 days

Outpatient CAP treatment relies on?

comorbidities

• increase risk of abx resistance (s. pneumoniae)

CAP drugs in healthy patients (3)

amoxicillin 1g TID OR doxycycline OR macrolide (azithro or clarithro if resistance <25%)

CAP regimen for high risk outpatient

beta lactam + macrolide OR doxycycline

• augmentin or cephalosporin (cefpodoxime/cefuroxime)

• PLUS

  • macrolide or doxycycline

• OR

  • respiratory quinolone monotherapy

    • levo/moxi

CAP regimen for non-severe inpatient

beta-lactam + macrolide or doxycycline

• ceftriaxone or Unasyn

respiratory quinolone monotherapy

CAP regimen for severe inpatient

beta-lactam + macrolide (no doxy)

beta-lactam + resp quinolone (don’t use monotx!)

when does HAP and VAP occur?

HAP: > 48 hrs after hospital admission

VAP: >48 hrs after mechanical ventilation

• raise head >30 degrees

• wean off ventilator

• remove NG tubes

• d/c unnecessary SUPs

what are common pathogens in HAP/VAP

• nosocomial pathogens

• MRSA

• MDR gram-negative rods

  • pseudomonas, acinetobacter, enterobacter, e.coli, klebsiella

treatment duration for HAP/VAP

7 days

what should ALL patients with HAP/VAP receive coverage for? (2)

pseudomonas and MSSA

• cefepime

• pip/tazo

• levofloxacin

when should MRSA coverage be added in HAP/VAP?

• vancomycin or linezolid if mrsa risk factors

• cefepime + vanc

• meropenem + linezolid

• aztreonam + vanc

abx for pseudomonas in HAP/VAP

• beta-lactams: pip/tazo, cefepime, ceftazidime, imipenem/cilastin, meropenem

• levofloxacin or ciprofloxacin

• aztreonam

• aminoglycosides

what patients should receive and IGRA test for latent tb?

patients who received the bacille Calmette-Guerin (BCG vaccination)

• this vaccine can cause false-positive TST skin test

dx of latent tb skin test for >5mm induration (2)

• HIV infection

• immunosuppression

dx of latent tb skin test for >10mm induration (1)

residents/employees of high-risk congregate settings

dx of latent tb skin test for >15mm induration (1)

patients with NO risk factors

what duration is preferred in latent tb?

• shorter regimens of 3-4 months

• less risk of hepatotoxicity and higher completion rates

what is the biggest barrier in rifampin-containing and rifapentine-based regimens?

drug interactions

treatment regimens for latent tb (4)

1. INH and rifapentine once weekly for 12 weeks with directly observed therapy or self-admin

2. INH with rifampin daily for 3 months

3. rifampin 600mg daily for 4 months

4. INH 300mg daily for 6-9 months

   1. preferred in HIV-positive pts taking anti-retroviral meds (9 months rec)

how is active TB diagnosed?

chest x-ray: consolidation or cavitation

AFB smear (acid-fast bacilli) - not specific to MTB

sputum culture or PCR: slow growing organism, can take 6 weeks for C and S ***

active TB treatment regimen

• intensive phase 2 months

  • Rifampin

  • Isoniazid

  • Pyrazinamide

  • ethambutol

• continuation phase 4 months

  • rifampin

  • isoniazid

• daily treatment or DOT 5x/week is recommended for ALL pts to increase medication adherence

rifampin side effects/notes

side effects

• inc LFTs

• hemolytic anemia (positive coombs test)

• flu-like syndrome

• orange-red discoloration of body fluids!

notes

• many drug interactions

  • rifabutin can replace

isoniazid (INH) side effects/warnings

• boxed warning: hepatitis

• warnings

  • peripheral neuropathy

• side effects

  • incr LFTs

  • hemolytic anemia (+ coombs test)

  • DILE

what med should be taken with INH to reduce INH-induced peripheral neuropathy?

vitamin B6 pyridoxine 25-50mg PO daily

pyrazinamide SEs/contraindications

• contraindication: acute gout

• side effects

  • incr LFTs

  • hyperuricemia/gout

ethambutol side effects

• inc LFTs

• optic neuritis (dose-related)

• confusion

• hallucinations

what metabolite is rifampin?

potent inducer of CYP1A2, 2C8, 2C9, 2C19, 3A4, p-gp

decreases concentrations of other drugs

what drugs does rifampin reduce? (3)

• protease inhibitors (substitute rifabutin)

• warfarin (large dec in INR)

• oral contraceptives (dec efficacy)

what 2 drugs should NOT be used with rifampin?

apixaban

rivaroxaban

common bugs of IE (3)

1. staphylococci

2. streptococci

3. enterococci

duration of IE with IV abx

4-6 weeks

gentamicin for IE is used for synergy. what are the target peaks and trough levels

peak: 3-4 mcg/mL

trough: <1 mcg/mL

what medication regimen is used mainly in IE?

vancomycin + ceftriaxone

why is rifampin used in IE?

treat organisms in a biofilm

• prosthetic valves with staph

what is the preferred regimen for IE dental ppx

• amoxicillin 2g PO once 30-60 min before procedure

• azithromycin or clarithromycin 500mg

• or doxycycline 100mg

how is SBP diagnosed?

≥250 cells/mm3 PMNs via paracentesis

empiric treatment for SBP

ceftriaxone for 5-7 days

(streptococci, proteus, e. coli, klebsiella)

what 2 drugs can be given for secondary ppx for SBP

SMX/TMP or ciprofloxacin

what bugs should be covered in intra-abdominal infections? (3)

• streptococci

• entergic gram-negatives

• anaerobes (B. fragilis)

treatment duration for intra-abdominal infections?

4-5 days

CA-intra abdominal infection drugs

1. ertapenem

2. moxifloxacin

3. (cefuroxime or cefriaxone) + metronidazole

4. (cipro/levo) + metronidazole

risk for resistant or nosocomial pathogens drugs in intra-abdominal infections

1. carbapenem (except ertapenem)

2. pip/tazo

3. cefepime or ceftazidime + metronidazole

superficial SSTIs (3)

1. impetigo

2. furuncle

3. carbuncle

impetigo treatment

• honey-colored crusts in children

• limited, localized lesions: topical mupirocin

• numerous, extensive lesions: cephalexiin

folliculitis/furuncle/carbuncle tx

• CA-MRSA infection

SMX/TMP

doxycycline

cellulitis non-purulent infection tx

• GAS, staph

1. cephalexin

2. dicloxacillin

3. Beta-lactam allergy: clindamycin

duration: 5 days

cellulitis purulent (mild infection)

• CA-MRSA

SMX/TMP

doxycycline

minocycline, clindamycin, linezolid

**source control with I&D of pus recommended

severe SSTI purulent tx (3)

• vancomycin

• daptomycin

• linezolid

duration 7-14 days

necrotizing fasciitis (severe nonpurulent) tx

urgent surgical debridement

empiric tx is broad

• vancomycin or daptomycin + beta-lactam (pip/tazo, meropenem) + clindamycin (suppresses streptococcal toxin production)

DFI durations

• no bone: 2-4 weeks

• osteomyelitis: 4-6 weeks

• 2-5 days if amputation with no residual infection