introduction to bacterial infections

antibiotics that cover MRSA

• TMP/SMX

• doxycycline

• linezolid

• rifampin

• gentamicin

• dalbavancin

• oritavancin

• vancomycin

• clindamycin

• ceftaroline

• daptomycin

common antiobiotics that cover MRSA

• TMP/SMX

• doxycycline

• linezolid

• vancomycin

• daptomycin

antiobiotics with pseudomonas coverage

• piperacillin/taxobactam

• ceftazidime

• cefepime

• meropenem, imipenem (NOT ertapenam)

• aztreonam

• ciprofloxacin, levofloxacin (NOT moxifloxacin)

• tobramycin

ertapenam

• carbapenam that does not cover pseudomonas

moxifloxacin

• fluoroquinolone that does not cover pseudomonas

antibiotics with gram negative anaerobic coverage (bacteroides fragilis)

• amoxicillin/clavulanate

• ampicillin/sulbactam

• piperacillin/tazobactam

• carbapenems (ertapenem, meropenem, imipenem/cilastin)

• metronidazole

ceftazidime/avibactam

• antibiotic with beta lactamase inhibitor that does not cover gram negative anaerobes (specifically bacteroides fragilis)

clindamycin

• notable excpetion that does not cover baceriodes fragilis (gram negative anaerobes)

prophylaxis

• best antibiotics for prevention of infection

empiric therapy

• best guess antibiotics for suspected/known infection prior to culture results

• use antibiogram

definitive/targeted therapy

• best antibiotics for known infection after culure results reported

• do not care about antibiogram

surgical prophylaxis approach

• antibiotic selection is made based on site of surgery

  • coverage includes at least common skin flora- streptococcus and staphylococcus (MSSA)

• IV antibiotic is usually completely pushed/infused within 1 hour prior to surgery for optimal drug levels

• antibioitcs are discontinued < 24 hours post op since they are just being used to prevent an infection, rare excpetions may extend to <48 hours post op

cefazolin (Ancef)

• is the most commonly used antibiotic for surgical prophylaxis

• narrow spectrum, IV push instead of IV infusion

how to approach empiric therapy

• determine if the patient has a possible infection requiring antimicrobials

• utilize infectious disease society of america (IDSA) guidelines and or other resources for evidence based therapy

• review local antibiogram and previous patient specific culture results if available

• avoid antibiotics with susceptibilities < 80%

• gather additional patient specific data

80

• do not use antibiotics with susceptibilities less than __% on antibiogram

how to approach definitive/targeted therapy

• typically choose most narrow spectrum PO antibiotic if able to absorb via GI tract and not severely ill that is appropirate based on guidelines for type/site of infection and culture and susceptibility results

• utilize infectious disease society of america guidelines and or other resources for evidence based therapy

• review current patient specific culture results - no longer need antibiogram

• gather additional patient specific data

pan

• __ susceptible means the organism is susceptble to all tested antibiotics

immediate allergic reaction examples

• anaphylaxis, laryngeal edema, urticaria, hives

• cytopenia

• serum sickness

delayed allergic reaction examples

• contact dermatitis

• erythema with necrosis and detachment

• cutaneous eruptions, multi-organ failure

R-group side chains

• penicillins and cephalosporins with identical ___ have corss reactivity reaching 40%

safely use any beta lactam

• penicillin allery side effect → stomach upset, headache

safely use non-cross reactive cephalosporin, carbapenem, aztreonam

• penicillin intermediate non-severe allergic reaction

• isolated urticaria or mild rash such as maculopapular rah

avoid penicillin and cross reactive cephalosporins unless desensitization utilized or additional skin testing/drug challenges completed

• penicllin immediate severe reaction

• anaphylaxis, shortness of breath, angioedema, extensive urticaria

unsafe to use any beta lactam

• penicillin delayed, severe reaction

• serum sickness, stevens johnson syndrome, DRESS

maculopapaular rash

urticaria (wheal and flare) rash

how to obtain a thorough allergy history

• ask specific questions

• what specific medication were you taking when the reaction occured?

• what kind of reaction occurred?

• how was the reaction managed?

• how long ago did the reaction occur?

• have you taken similar antibiotics since that time without reaction?

steps to evaluate a penicillin allergy

• obtain thorough allergy history

• determine type and severity of allergic reaction

• implement treatment options based on PCN allergy risk