561P09 Black Beta Lac Tams

8/8/2019 561P09 Black Beta Lac Tams

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CLINICAL USE OF BETA-LACTAMS

Douglas Black, Pharm.D.

Associate Professor

School of Pharmacy

University of [email protected]


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WHY IS INFECTIOUS DISEASEPHARMACOTHERAPY SO CONFUSING?

Microbial taxonomy constantly changes

New antimicrobials are continually beingdeveloped, although maybe not at the ratewe would like

Treatment is straightforward when thepathogen is known, but empiric therapy isdifficult

Antibiotic resistance must always be takeninto account

There are often many possible treatmentchoices but usually only one best choice


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MASTERING TREATMENT OF ANINFECTIOUS DISEASE

Know the most common pathogens in rankorder of likelihood or importance

Know the resistance patterns of thepathogens in question

Know the drug(s) of choice in a patientwith a classic case

Know the best alternative for a patientunable to receive the drug of choice forwhatever reason (e.g. allergy, pregnancy)


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CASE 1. A 5-year-old boy presents withfever, purulent tonsillar exudate, andcervical lymphadenopathy. No rash isevident.

Diagnosis: Tonsillopharyngitis


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CASE 1: TONSILLOPHARYNGITIS

Most likely pathogens: Virus

Streptococcus pyogenes (also known asGroup A -hemolytic Streptococcus or

GABS) Arcanobacterium haemolyticum (rare)

Drug of choice

Penicillin VK (wont cover A. haemolyticum)

PEARL: Penicillin-resistant S.pyogenes has never been reported


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CASE 2. A 20-month-old girl comes to

the clinic with a cough and runny nose.She is very fussy and continually tugsat her left ear. Her temperature is 102F, her left ear drum is red and

immobile, and bony landmarks are notvisible.

Diagnosis: Acute otitis media

Most likely pathogens: Streptococcuspneumoniae, Hemophilus influenzae,Moraxella catarrhalis


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CASE 2: ACUTE OTITIS MEDIA

Most likely pathogens: Streptococcus pneumoniae Hemophilus influenzae

Moraxella catarrhalis

Drug of choice Amoxicillin (90 mg/kg/day, divided

bid)

PEARL: amoxicillin/clavulanate is notconsidered a better initial choice


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CASE 3. Same 20-month-old girl, 48hours later, no improvement.

Diagnosis: Refractory acute otitismedia


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CASE 3: REFRACTORY AOM

Most likely pathogens: Hemophilus influenzae Moraxella catarrhalis

Could be something unusual

Drug of choice

Amoxicillin/clavulanate (Augmentin)

PEARL: cefdinir is the best-tastingliquid cephalosporin


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CASE 4. A 46-year-old male complainsof headache and facial pain aggravatedby stooping, and continuous nasaldischarge. He says he caught a cold ten

days ago and has had symptoms eversince. Decongestants provide littlerelief.

Diagnosis: Acute bacterial sinusitis


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THE PARANASAL SINUSES

(The sphenoidsinuses are betweenthe eyes and locatedposteriorly)


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CASE 4: ACUTE BACTERIAL SINUSITIS

Most likely pathogens: Streptococcus pneumoniae Hemophilus influenzae

Moraxella catarrhalis

Drug of choice Amoxicillin

PEARL: Some otolaryngologists preferamoxicillin/clavulanate for initialtherapy


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CASE 5. A 35-year-old construction

worker complains of a tender and swollenright arm. The arm is erythematous andwarm to the touch.

Diagnosis: Cellulitis

Most likely pathogens: Staphylococcusaureus, Streptococcus pyogenes

Complicating issue: the possibility of CA-MRSA


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IMPORTANT MILESTONES IN THEHISTORY OF RESISTANT

STAPHYLOCOCCUS AUREUS

EVENT YEAR COMMENT

Penicillinase-producingS. aureus appears in anOxfordshire constable

1942Penicillin introduced

into clinical practice in1942

Emergence of MRSA 1961Methicillin approved in

1961

Emergence of VISA

(GISA)1996

Vancomycin approved in

1958Clinical emergence of

CA-MRSA1999

TMP/SMX may be thebest initial option

Emergence of VRSA 2002 Reported 3 times so far


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20.3

43.3

0

5

10

15

20

25

3035

40

45

50

MSSA MRSA

Mortality,%

Overall risk = 2.97 (95% CI: 1.12 - 7.88)*

IMPACT OF MRSA ON BACTEREMIA

P= .03

Methicillin resistance is anindependent predictor forshock and risk factor for

death in S aureusbacteremia

MRSA is also associatedwith increased length ofstay and higher hospital

costs, although data areconflicting (Engemann etal, CID 2003; 36: 592)

*Talon D, et al. Eur J Intern Med. 2002; Soriano A, et al. Clin Infect Dis. 2000.

S aureus bacteremia: mortality


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CASE 5: CELLULITIS

Most likely pathogens: Staphylococcus aureus Streptococcus pyogenes

Drug of choice (if using oral therapy) Dicloxacillin or cephalexin?

Drug of choice (if using IV therapy) Nafcillin or cefazolin?

PEARL: the choice depends in part

on the patient


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CASE 6. A 67-year-old man is seen byhis physician for fever, chills, malaise,and night sweats. A new heart murmuris audible. The man mentions a visit tothe dentist a month ago. He has poordentition.

Diagnosis: Acute bacterial endocarditis


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CASE 6: ENDOCARDITIS

Most likely pathogens: Viridans group Streptococcus Fastidious Gram-negative bacillus

(part of oral flora)

Drug of choice Penicillin G (s gentamicin)

Ceftriaxone

PEARL: oral beta-lactams shouldnever be used for endocarditis


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C

ASE 7. A 24-year-old woman developsfever, chills, flank pain, abdominal pain,nausea, and vomiting. She is barely ableto get out of bed. She is flushed and

diaphoretic.

Diagnosis: acute pyelonephritis

Most likely pathogens: E. coli, maybeanother enteric Gram-negative bacillus


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CASE 7: PYELONEPHRITIS

Most likely pathogens: E. coli

Maybe another enteric Gram-negativebacillus, e.g. P. mirabilis

Drug of choice

Ceftriaxone (used to be, anyway)

Levofloxacin is cheaper

PEARL: pyelonephritis (upper UTI) is muchdifferent than cystitis (lower UTI),despite the pathogens being the same


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CASE 8. A 56-year-old intubatedpatient in the ICU recovering fromheart surgery spikes to 39.9 C. HisWBC is 25,900 with a neutrophilpredominance and he has impressiveinfiltrates on chest x-ray. SputumGram stain reveals 4+ WBC, 4+ GNR, 2+GPC.

Diagnosis: Hospital-acquired pneumonia


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CASE 8: HOSPITAL-ACQUIREDPNEUMONIA

Most likely pathogens: Enteric Gram-negative bacilli, especially

resistant strains

Pseudomonas aeruginosa

Staphylococcus aureus, possibly MRSA

Drug of choice

Imipenem/cilastatin or meropenem

Vancomycin might be added

PEARL: The offending organism will beconclusively identified


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CASE 9. A 55-year-old diabetic malecomplains of fevers to 38.3, worseningerythema, and purulent drainage from achronic foot ulcer. His WBC is 14,800

with 83% neutrophils. ESR (erythrocytesedimentation rate) is 76 mm/hr.

Diagnosis: Diabetic foot ulcer, possible

osteomyelitis


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CASE 9: DIABETIC FOOT

Most likely pathogens: Just about anything: Gram-negative

bacilli including Pseudomonas, Gram-positive cocci, anaerobes

Drug of choice Piperacillin/tazobactam

Ticarcillin/clavulanate

PEARL: not all infections areapproached with curative intent

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561P09 Black Beta Lac Tams