Chapter 23. ID II: Bacterial Infections

How early should IV abx infusion be started prior to surgery if vancomycin or quinolones are used?

120 minutes

How long before surgery should cefazolin or cefuroxime be infused before surgery?

60 minutes

*usually cefazolin 1g

When would additional intra-operative abx doses be considered?

- Longer surgeries (>4 hrs)

- Major blood loss

What is the alternative perioperative abx of choice if patient has beta-lactam allergy?

clindamycin or vancomycin (vanco with MRSA, too)

Which abx is preferred for most surgeries to prevent MSSA and streptococcal infections?

cefazolin

Which abx should be used for GI surgeries?

Cefazolin + one of the following:

- metronidazole

- cefotetan

- cefoxitin

- ampicillin/sulbactam

skin flora + gram negative/anaerobes

How is meningitis diagnosed?

- lumbar puncture for a sample of CSF

- high CSF pressure detected during LP

What bacteria most commonly cause meningitis?

- Neisseria meningitidis

- Streptococcus pneumoniae

- Listeria monocytogenes in specific populations

Which populations commonly have meningitis d/t listeria monocytogenes?

- neonates

- >50 yrs

- immunocompromised

What should be given with an abx prior to or with the first dose for meningitis treatment and why?

dexamethasone IV to prevent neurological complications

What treatment should be used for people ages 1 month to 50 years for meningitis?

ceftriaxone + vancomycin

What treatment should be used for neonates (<1 month old) for meningitis?

ampicillin (for listeria) +

cefotaxime, ceftazidime, or cefepime +

gentamicin

What treatment should be used for >50 years or immunocompromised patients with meningitis?

ceftriaxone + vancomycin + ampicillin (for listeria coverage)

What bacteria commonly cause acute otitis media?

- S. pneumoniae

- H. influenzae

- Morazella catarrhalis

If a patient is >6 months with non-severe AOM, what is a treatment option?

Observation for 48-72 hours

When can observation be considered for AOM?

for 2-3 days with non-severe symptoms, no otorrhea, and temp <102.2(39C):

- 6-23 months: sx in one ear only

- ≥ 2 years: sx in one or both ears

First-line treatment for AOM?

high-dose amox or amox/clav with lowest dose of clav to prevent diarrhea (90 mg/kg/day)

Preferred brand for treating AOM?

Augmentin ES-600 (600mg/42.9mg per 5mL)

Alternative treatment for AOM in children with non-severe penicillin allergy?

second or third generation cephalosporin

Which medication is used for treatment failure (after 2-3 days) of the first-line drug for AOM?

Ceftriaxone IM daily x 3 days

What criteria is required to receive anti-infective treatment for pharyngitis (strep throat)?

rapid antigen test positive for s. pyogenes

Treatment for pharyngitis with s. pyogenes (strep throat)?

penicillin or amoxicillin

What bacteria commonly cause acute sinusitis?

- s. pneumoniae

- h. influenzae

- m. catarrhalis

What is the criteria for using anti-infectives in acute sinusitis?

≥ 10 days of persistent symptoms

or

≥ 3 days of severe symptoms (temp >102)

What is the treatment of choice for acute sinusitis?

amox/clav

What are key defining features of acute bronchitis?

- cough lasting 1-3 weeks

- preceded by upper respiratory tract virus

- chest xray normal

Treatment for acute bronchitis?

abx not recommended; supportive care

What is another name for pertussis caused by bordetella pertussis?

whooping cough

What is the treatment of choice for pertussis?

Macrolides (azithromycin, clarithromycin)

What are the cardinal symptoms of COPD exacerbation?

1. increased dyspnea

2. increased sputum volume

3. increased sputum purulence

What bacteria commonly trigger COPD exacerbations?

h. influenzae, s. pneumoniae, m. catarrhalis

When should abx be given to those experiencing a COPD exacerbation

- all 3 cardinal sx

- increased purulence + 1 other sx

- mechanically ventilated

What is the preferred abx for COPD exacerbation?

- augmentin

- azithromycin

- doxy

- respiratory quinolone (levofloxacin, moxifloxacin)

What is the gold-standard for diagnosing CAP?

rales (crackling in lungs); chest xray with infiltrates, opacities, or consolidations

What is the typical duration of tx for CAP?

5-7 days

Outpatient CAP treatment - Healthy (no comorbidities)

- Amoxicillin high dose (1g TID)

- Doxycycline

- Macrolide (azithromycin or clarithromycin if local pneumococcal resistance <25%)

Outpatient CAP treatment - High Risk (comorbidities)

- BL (augmentin or cefpodoxime, cefuroxime) + macrolide or doxycycline

- Respiratory quinolone monotherapy (L or M)

Inpatient CAP treatment - nonsevere (general medicine unit admission)

- BL (unasyn, ceftriaxone) + macrolide or doxycycline

- respiratory quinolone monotherapy

Inpatient CAP treatment - severe (ICU)

BL + quinolone or macrolide -> DO NOT USE quinolone monotherapy

What drugs should be added on for inpatient CAP treatment if there is a risk for MRSA?

Vancomycin or Linezolid

What drugs should be added on for inpatient CAP treatment if there is a risk for Pseudomonas?

- Pip/tazo

- cefepime

- meropenem

When should a CAP regimen cover both MRSA and pseudomonas?

Hospitalization and use of parenteral abx in past 90 days

How long do HAP and VAP occur after admission?

> 48 hours

HAP/VAP empiric regimen

need antibiotic for pseudomonas and MSSA (Cefepime or Zosyn)

-If MRSA add Vanco or linezolid

How many abx should be used for pseudomonas if there is a risk for MDR gram-negative pathogens in HAP/VAP?

two - (three drugs total)

Abx for Pseudomonas in HAP/VAP

• Beta-lactams (not 2 together): piperacillin/tazobactam, cefepime, ceftazidime, imipenem/cilastatin, meropenem

• Levofloxacin or ciprofloxacin

• Aztreonam

• Aminoglycosides (typically tobramycin) - used in combo w/other antipseudomonal

What causes tuberculosis?

Mycobacterium tuberculosis

How does active TB transmission occur?

aerosolized droplets

How does latent TB present?

lacks symptoms

Active TB presentation

- cough/hemoptysis

- fever/night sweats

Isolation requirements for TB

- isolation in a single negative-pressure room

- healthcare workers wear respirator mask

How is latent TB diagnosed?

- tuberculin skin test (TST)/PPD

- interferon-gamma release assay (IGRA) blood test

How does the PPD test work for TB?

Solution injected intradermally and inspected for induration (raised area) 48-72 hrs later

What TB test is preferred in patients who have received the bacille Calmette-Guerin (BCG) vaccination?

IGRA blood test (false positive TST in these patients)

Criteria for a positive TB test

≥ 5 mm induration

- HIV

- immunosuppression

≥ 10 mm induration

- residents/employees of "high risk congregate" settings (e.g. prison, healthcare facilities, shelters)

What is the preferred length of time for treatment of latent TB in adults to minimize hepatotoxicity/higher completion rates?

3 to 4 months

Latent Tuberculosis Regimens

• INH and rifapentine once weekly x 12 weeks via direct observation (NOT IN PREGNANCY)

• INH + rifampin daily x 3 months

• Rifampin 600 mg daily x 4 months

• INH 300 mg daily for 6 or 9 months

What latent TB regimen might be preferred in HIV patients taking ART d/t lower risk of drug interactions?

INH for 9 months

How can active TB be confirmed?

Acid-fast bacilli smear of sputum sample

-> slow growing organism; sputum culture may take up to six weeks

Active TB treatment regimens

1. Intensive Phase:

• RIPE x 2 months (rifampin, isoniazid, pyrazinamide, ethambutol)

2. Continuation Phase:

• Rifampin + isoniazid x 4 months

Side Effects associated with Rifampin

- increased LFTS

- hemolytic anemia (positive Coombs test)

- flu-like syndrome

- orange-red discoloration of body secretions that may stain (saliva, sweat, urine, tears)

- Many DDIs

Which drug may have fewer DDIs than rifampin and can potentially replace it in RIPE therapy?

rifabutin

Boxed Warning for isoniazid

severe and fatal hepatitis

How to decrease the risk of peripheral neuropathy associated with isoniazid?

Pyridoxine (vitamin B6) 25-50 mg PO QD

Side effects associated with Isoniazid

- increased LFTs

- DILE

- hemolytic anemia (positive Coombs test)

Contraindications to pyrazinamide for RIPE therapy?

acute gout

Side effects of pyrazinamide for RIPE therapy?

- increased LFTs

- hyperuricemia, gout

Side effects associated with ethambutol from RIPE therapy?

- increased LFTs

- optic neuritis (dose-related)

- confusion, hallucinations

What are the most common organisms that cause infective endocarditis?

- staphylococci

- streptococci

- enterococci

What antibiotic is often added onf or synergy in infective endocarditis?

gentamicin

True or false - infective endocarditis can be treated outpatient

false, IV medications must be used for 4-6 weeks

What are peak and trough goals when gentamicin is used for synergy in infective endocarditis?

Peak: 3-4 mcg/mL

Trough: < 1 mcg/mL

What medication is given to high risk adults prior to dental work to prevent IE?

Amoxicillin 2 grams PO 30 to 60 minutes prior dental procedure

Alternatives to prophylactic IE medication for adults with penicillin allergy prior to dental procedures?

- azithromycin or clarithromycin 500 mg

- doxycycline 100 mg

- unable to take oral: cefazolin 1g im/iv, ampicillin 2g im/iv

When is an SBP infection suspected?

Ascitic fluid sample collected via paracentesis reveals > 250 cells/mm^3 PMNS (along w/ cirrhosis and ascites)

Empiric treatment for SBP

ceftriaxone x 5-7 days (target PEK and strep)

Secondary prophylaxis medications for SBP

- SMX/TMP

- Ciprofloxacin

Typical intra-abdominal infections have cultures of....

polymicrobial

- streptococci

- enteric gram negatives

- anaerobes (i.e. bacteroides fragilis)

What treatment for IAIs is typically added on if the original abx of choice does not have anaerobic activity?

Metronidazole

What are systemic signs that one might see w/ a moderate to severe SSTI, but are absent in a mild SSTI?

- Temperature >100.4

- Heart rate >90 BPM

- WBC >12,000 or <4000 cells/mm^3

How does the superficial infection, impetigo, present?

honey-colored crusts over ruptured pustules

Impetigo treatment

- limited: topical abx (i.e. mupirocin)

- numerous/extensive lesions: cephalexin

Folliculitis/furuncle/carbuncle most common bacterial cause?

CA-MRSA

Folliculitis/furuncle/carbuncle treatment options

ABX that covers both MSSA and MRSA:

- SMX/TMP

- Doxycycline

Preferred treatment for a mild cellulitis infection?

ABX that covers both strep and MSSA:

- cephalexin

Treatment of choice for mild abscess (purulent infections)?

MSSA and MRSA coverage:

- SMX/TMP

- Doxycycline

Severe purulent infection treatment options?

Cover MRSA:

- Vancomycin

- Daptomycin

- Linezoolid

Necrotizing fasciitis (severe, non-purulent SSTI) treatment options?

Vanco or dapto + BL (pip/tazo, meropenem) + clindamycin

What laboratory results point to a positive urinalysis for UTI?

pyuria

bacteria

positive leukocyte esterase/nitrites

Cystitis (lower UTI) symptoms

- urgency/frequency/nocturia

- Dysuria (pain/burning)

- suprapubic tenderness

- Hematuria

What symptom is associated with pyelonephritis (upper UTI)

flank pain

What pathogen commonly causes acute cystitis?

E. coli

DOCs for acute cystitis?

- nitrofurantoin (Macrobid) 100mg PO BID x 5 days (not in crcl <60)

- SMX/TMP DS 1 tab PO BID x 3 days (not in sulfa allergy)

- Fosfomycin 3g x 1 dose

What are treatment options for UTI in pregnancy?

- Amoxicillin

- Cephalexin

(as well as other typical options)

When should quinolones not be used as an alternative option for UTI?

- pregnancy

- children

- seizures

- neuropathy

- qt prolongation risk

- diabetic patients (BG changes)

Which quinolone should NOT be used for UTI?

moxifloxacin

How is acute pyelonephritis treated for a moderately ill patient?

PO, outpatient

local quinolone resistance <10%

• ciprofloxacin bid

• levofloxacin qd

local quinolone resistance >10%

• treat w/ 1 dose of IM/IV ceftriaxone, ertapenem, or aminoglycoside extended-interval

• follow with quinolone

• if cant use quinolone, SMX/TMP or BL

How is acute pyelonephritis treated for a severely ill hospitalized patient?

Carbapenem (if ESBL-producing)

Phenazopyridine brand names

• Pyridium

• Azo Urinary Pain Relief

Counseling points for Azo?

• Take for 2 days max

• take w/ 8oz of water or immediately following food (minimize stomach upset)

• red-orange coloring of urine and other body fluids (stain contacts and clothes)