Things your mother never told you about antibiotics

Rob Kaplan, MD

July 8 and 9, 2015

Objectives

• After this talk participants will:– Be able to articulate some of the principles and

pitfalls of antibiotic use– Have a working approach to antibiotic selection

for some common infections– Probably choose to subspecialize in infectious

diseases

Common misconceptions/distortions

about antibiotics

1. “Let’s just throw in some antibiotics-it can’t hurt…”

1. The Problem…

• Microbiome change->C. diff and other superinfections, resistance in patient and community

• Allergic and nonallergic drug toxicities

• Cost (materials,labor, indirect costs)

• Diagnostic pitfalls (impaired cultures, early closure, etc.)

2. Clindamycin above the diaphragm, metronidazole

below the diaphragm…

2. The Problem…

• Both have activity against strict anaerobes with metronidazole superior

• Clindamycin has activity against some Gram + aerobes so it can stand alone for infections caused by oral flora

• But the gap is filled when metronidazole combined with a penicillin

• And clinda has a heightened C. diff risk

3. With the high prevalence of MRSA, Vancomycin should be

used for all severe Staph infections…

3. Why not?

4. Osteomyelitis should be treated for 6 weeks with IV

antibiotics…

4. Not necessarily…

• Antibiotics can be stopped soon after definitive surgery.

• Sometimes therapy needs to be extended if active inflammation remains.

• Sometimes the wisest choice is brief therapy for soft tissue infection or no therapy at all!

5. I don’t feel comfortable changing from the empiric

regimen because the patient is doing well…

5. Let me help you with this…

• What does empiric therapy mean?

• What is the other kind of therapy?

• Why do we change regimens when a patient is dong poorly?

• Why do we change regimens when a patient is doing well?

• (DISCUSS WITH YOUR NEIGHBOR)

6. I know the organisms are sensitive to the antibiotics but

the patient’s not getting better…

6. Why?

• Is it the antibiotics?

• Or the patient?

• Or the anatomy?

• Or the organisms?

• (TALK AMONGST YOURSELVES)

UTI Cases

• A 21-year-old sexually active woman has one day of dysuria but no fever. Exam is normal; urinalysis shows many wbc and bacteria.

SIMPLE CYSTITIS

• 3 day therapy with trimethoprim-sulfa or 5 days with nitrofurantoin**

• Culture not mandatory!

• Quinolones no longer first line because of “collateral damage”**

UTI-2

• A 65-year-old man with BPH has 2 days of fever, rigors, vomiting, and severe left flank pain. T 102.8, marked left CVAT, moderately enlarged, nontender prostate. Urine-many WBC, WBC 16, cre 1.0.

GRAM STAIN????

• What if I told you urine Gram stain was loaded with Gram positive cocci?

• Or with thin Gram negative rods without bipolar staining?

COMMUNITY-ACQUIRED PYELONEPHRITIS

• Admit, IV antibiotics. Must cover enteric GNR’s, especially E. coli. Ceftriaxone fine. Don’t count on quinolones!

• But if Gram stain has a twist….add Vanco or change to antipseudomonal agent

• Switch to po when doing well, sensis known.

• Total duration at least 2 weeks (in men)**

UTI-3• A 50 year old quadriplegic, long

term resident of VA SCI service, develops fever, altered mentation, and hypotension. Exam shows no skin lesions or inflammation; CXR clear. Foley urine many wbc, mixed bacteria, pH8

HEALTH-CARE ASSOCIATED UROSEPSIS

• Supportive care with lots of fluid +/-pressors. Consider ICU.

• Empiric antibiotics to cover resistant GNR +MRSA. At VA Pseudomonas resistant to zosyn. Change based on results.

• Rec: Vancomycin, Cefepime, consider Amikacin

UTI-4

• Down the hall from case 3, another longterm resident of SCI gets a routine urinalysis from his Foley which shows 800 WBC and mixed bacteria. Afebrile, VSS, no new symptoms. No skin lesions; normal mental status. WBC 6, crea 0.5.

(Do not treat)

ASYMPTOMATIC BACTERIURIA

UTI-5

• A 79-year old paraplegic man with chronic neurogenic bladder has T 102.1, WBC 12, U/A 2600 WBC and many bacteria.

• Started on ceftriaxone. Urine grows Klebsiella pneumoniae resistant only to ampicillin.

• Fever continues…

NOT UTI-5**

• Exam reveals RUQ tenderness above level of SCI

• Abd CT reveals edematous GB wall

• Metronidazole added for anaerobic coverage

• Cholecystectomy performed: Acute cholecystitis

Soft Tissue Cases

ERYSIPELAS

• Very likely to be Strep.

• Good track record of studies supporting not covering MRSA

• Keflex, Augmentin (or even Penicillin, Amoxicillin) reasonable for outpatient use

Soft Tissue-2

• A top high school basketball player scraped against his agent’s Bentley .

CELLULITIS AND/OR SUPPURATIVE INFECTION

• Focus shifts to include MRSA

• If pus then DRAIN!

• For hospitalized patient vancomycin

• For outpatient TMP-sulfa or doxycycline/minocycline (or clindamycin)**

• Duration 5 days as good as 10 in uncomplicated**

Soft Tissue-3• After minor

trauma to the foot a healthy 30 year old develops fever, shock, & severe LE pain.

NECROTIZING FASCIITIS

• Representative of complex soft tissue infections with many names

• When to think of this?• Group A strep, or clostridial, or mixed

aerobes and anaerobes…• Initial rx: Vanco/Cefepime/Flagyl. May

substitute clinda for flagyl for Eagle effect.**• SURGERY!!!

Soft Tissue-3

• A poorly-controlled diabetic w/ neuropathy develops fever and foot drainage.

DIABETIC FOOT INFECTION

• Mixed aerobes and anaerobes. May include Pseudomonas.

• Often bone involved• Often with poor perfusion• Deep cultures to guide therapy.

Vancomycin/Cefepime/Flagyl• IF GANGRENE OR SEPSIS OR

CHRONIC OSTEO-->SURGERY

Pulmonary Cases

60-year old previously healthy smoker with fever, cough with purulent sputum.

COMMUNITY-ACQUIRED PNEUMONIA

• Pneumococcus, Haemophilus, Moraxella, maybe Legionella. Consider anaerobes, special exposure/risk history

• TRY TO GET SPUTUM GRAM STAIN AND CULTURE

• Ceftriaxone/Azithromycin or respiratory quinolone

Pulmonary-2

• Alcoholic with 4 weeks of fever, weight loss, fetid sputum, left-sided chest pain.

LUNG ABSCESS

• Add Klebsiella and anaerobes to usual causes of CAP

• Ceftriaxone/Flagyl

Pulmonary-3

• An SICU patient needs prolonged intubation after abd. surgery. Now fever, inc FiO2, purulent secretions.

VENTILATOR-ASSOCIATED PNEUMONIA

• Possibility of resistant hospital flora

• Get deep specimen Gram stain and culture

• Vancomycin, Cefepime (or Carbapenem if previously on beta lactam), probably Amikacin

• Consider hospital-acquired Legionella. At VA should probably include Azithromycin.**