Approach to pediatric Antibiotics

Gassem Gohal FAAP FRCPC Assistant professor of Pediatrics

objectives

To be familiar with common pediatric antibiotics o Classification

o Action

o Adverse effect

To discus common outpatient pediatric infections

Antibiotic choice

• How do you choose the proper antibiotic

It depends on:

causative organism

Site of infection

Host

susceptibility

narrow spectrum

Antibiotics classification:

• Sulfonamides

• Penicillins

• Cephalosporins

• Tetracyclines

• Aminoglycosides

• Quinolones

• Macrolides

Type of therapy

• Empiric therapy: treatment of an infection before specific culture

• Prophylactic therapy: treatment with antibiotics to prevent an infection

• Definitive therapy

How Antibiotics Work

• Inhibit cell wall formation - Penicillin

• Block protein formation - Macrolides, Aminoglycosides

• Interfere with DNA formation - Nalidixic acid

• Prevent folic acid synthesis - Sulfonamides

Penicillins

– Natural penicillins

PenG, PenV

– Aminopenicillins Ampicillin, Amoxicillin

– Anti-Staph penicillins Oxacillin, Dicloxacillin

– Anti-Pseudomonal Ticarcillin

Piperacillin

Penicillin

• Available PO, IM, IV (dosed in units)

• Drug of Choice – , Group A Strep, N. meningitidis,

• Adverse Reactions

– skin rash

serum sickness

– Hemolytic anemia, pancytopenia, neutropenia

Ampicillin Amoxicillin

• Amp (IV, PO) Amox (PO)

• Spectrum: PenG + H. flu and some E. coli,

• Listeria monocytogenes and, Enterococcus

Ampicillin Amoxicillin

• Amp (IV, PO) Amox (PO)

• Spectrum: PenG + H. flu and some E. coli,

• Listeria monocytogenes and, Enterococcus

Penicillin resistance

• Bacteria produce enzymes capable of destroying penicillin.

“beta-lactamases”

Penicillin resistance

• Chemicals to inhibit beta-lactamases clavulanic acid tazobactam Sulbactam

– amoxicillin + clavulanic acid = Augmentin

– ticarcillin + clavulanic acid = Timentin

– piperacillin + tazobactam = Tazocin

Cephalosporins

– 1st Generation

Cephalexin, Cefazolin

– 2nd Generation Cefoxitin, Cefuroxime,

– 3rd Generation Cefotaxime, Ceftriaxone, Ceftazidime

– 4th Generation Cefepime

Cephalosporins

1st Generation Gram (+)

2nd Generation Decreasing Gram (+) and Increasing Gram (-)

3rd Generation Gram (-), but also some GPC

4th Generation Gram (+) and Gram (-)

1st Generation:

Cefazolin

•Good for Gram (+) bugs

•Osteomyelitis

•Strep– Group A

•Staph– MSSA & MSSE

•Poorer choices: E. coli (50% resistant), Klebsiella

2nd Generations:

Cefuroxime

•Much better gram-negative coverage (except Pseudomonas)

•Good: Gram (+) (esp. Strep pneumoniae), Groups A&B, MSSA

– H. influenzae—but not meningitis! ?

– E. coli and Klebsiella

•

2nd Generations:

Cefuroxime (Zinacef®)

•Much better gram-negative coverage (except Pseudomonas)

•Good: Gram (+) (esp. Strep pneumoniae), Groups A&B, MSSA

– H. influenzae—but not meningitis! ? why

– E. coli and Klebsiella

•

3rd Generations

Ceftriaxone , Cefotaxime , Ceftazidime

• Ceftazidime :Pseudomonas,

•Ceftriaxone and Cefotaxime very good against S. pneumoniae (use with vancomycin if treating meningitis) and H. influenzae;

•Donʼt use for Staph aureus

•Drugs of choice for most CNS infections

3rd Generations

Ceftriaxone , Cefotaxime , Ceftazidime

• Ceftazidime :Pseudomonas,

•Ceftriaxone and Cefotaxime very good against S. pneumoniae (use with vancomycin if treating meningitis) and H. influenzae;

•Donʼt use for Staph aureus

•Drugs of choice for most CNS infections

Aminoglycosides

Gentamicin, Tobramycin, Amikacin

• Aerobic, gram-negatives only

• Good choice for Pseudomonas infections!

• Use for Synergy with Beta-Lactams for Enterococcus, and Group B Strep

• Toxic to otovestibular system and kidneys

Aminoglycosides

Gentamicin, Tobramycin, Amikacin

• Aerobic, gram-negatives only

• Good choice for Pseudomonas infections!

• Use for Synergy with Beta-Lactams for Enterococcus, and Group B Strep

• Toxic to otovestibular system and kidneys

QUINOLONES

Ciprofloxacin

•Don’t use in those under 18 years of age, except approved as 2nd line therapy for urinary tract infections in children.

•Why ?

Vancomycin

• MRSA, MRSE, and ampicillin-resistant Enterococcus

• S. pneumoniae meningitis—especially if resistant to beta-lactam antibiotics

• NOT for gram-negatives

• Red Man Syndrome :

• ***Resistance is quickly emerging in Enterococcus (vancomycin-resistant Enterococcus VRE)

Vancomycin

• MRSA, MRSE, and ampicillin-resistant Enterococcus

• S. pneumoniae meningitis—especially if resistant to beta-lactam antibiotics

• NOT for gram-negatives

• Red Man Syndrome :

• ***Resistance is quickly emerging in Enterococcus (vancomycin-resistant Enterococcus VRE)

Macrolides:

• Erythromycin, Clarithromycin, Azithromycin • Mycoplasma; Chlamydia; ,Staph and Strep • Azithromycin adds H. influenzae coverage • Erythromycin and clarithromycin lots of drug

interactions. Azithromycin doesn’t have same profile.

•

Macrolides

• Erythromycin, Clarithromycin, Azithromycin • Mycoplasma; Chlamydia; ,Staph and Strep • Azithromycin adds H. influenzae coverage • Erythromycin and clarithromycin lots of drug

interactions. GIVE ME Example Azithromycin doesn’t have same profile.

•

Some common pediatric infection

Acute bacterial sinusitis

Dx:

• Inflammation of the mucosal lining

• Usually viral URI ( resolve) Bacterial ( suspect if >10 days of URI)

• URI, allergic rhini1s predisposing factor

Acute bacterial sinusitis

• First line therapy is amoxicillin 45-90 mg/kg/day divided bid.

• Severe symptoms is high dose augmentin (90 mg/kg/day amox., 6.4 mg/kg/day clavulanic acid) divided bid.

• Allergies to penicillin, first line therapy is azithromycin 10 mg/kg kg x 1 day, followed by 5 mg/kg x 4 day,

Acute otitis media

• Dx of OM

• fluid in the middle ear plus acute signs of illness

• signs or symptoms of middle ear inflammation, including bulging

Acute otitis media

How should treats ?

•Less than 2 y = treat

• More than 2 y, treat if toxic, or not normal host

AAP guideline Rx of OM

AAP guideline Rx of OM

AAP guideline Rx of OM

Group A Strep Pharyngitis

First line therapy: Penicillin V is the recommended treatment.

Alternative therapy: For patients allergic to Penicillin, use erythromycin

. Length of treatment: Ten days of treatment are necessary to prevent the development of rheumatic fever.

Group A Strep Pharyngitis

How to differentiate viral from GAS Pharyngitis

First line therapy: Penicillin V is the recommended treatment.

Alternative therapy: For patients allergic to Penicillin, use erythromycin

. Length of treatment: Ten days of treatment are necessary to prevent the development of rheumatic fever.

Community acquired pneumonia

0-3 weeks GBS, Gram – rods, CMV

3 weeks – 3 months Chlamydia trachomatis, Strep pneumo, RSV, paraflu

4 months – 4 yrs Viruses most common, then strep pneumo, than mycoplasma pneumoniae (in older patients in age range

5 yrs – 15 yrs Mycoplasma pneumoniae, Chlamydia pneumoniae, Strep pneumo

Community acquired pneumonia-RX 0-3 weeks,

Patient must be admitted

3 weeks – 3 months Patient admitted if febrile. If afebrile, azithromycin, or erythromycin are recommended first line therapies. If the patient has a well defined, lobar infiltrate on CXR, however, amoxicillin should be used, either in combination with a macrolide or alone.

4 months – 4 years Amoxicillin

5 years-15 years Azithromycin, or erythromycin

Home work

• Review two approach to child with fever ( less than 3 months, 3 month to 3 years)

• Get an answer for all whys in this lecture plus what I asked you to check

Take Home massage

• Use of antibiotics based on knowledge of disease, host, character of antibiotics entity, not just by remembering these lecture

• Go back, check and read, things get forgotten

References

• Check the website www.pedsjazan.wordpress.com

• http://pediatrics.uchicago.edu/chiefs/cliniccurriculum/documents/JFLAbx4commonpedsinfxn.pdf

• http://www.medstudy.com/PedsAntibiotics/Pediatrics_Antibiotics.html