DPT III Exam 2 (bragg)

typical organisms that cause neonate bone and joint infections

Staph, GBS, E. coli

typical organisms that cause diabetic foot ulcer bone and joint infections

Staph, GBS, E. coli, pseudomonas, anaerobes (worry about B. frag and often polymicrobial)

typical organisms that cause hematogenous vertebral bone and joint infections

Staph, GBS, E. coli, klebsiella

typical organisms that cause a 3-year-old child with osteo bone and joint infections

Staph, GBS, E. Coli, Kingella

typical organisms that cause an IV drug user neonate bone and joint infections

Staph, GBS, pseudomonas, anaerobes

typical organisms that cause prosthetic joint after surgery bone and joint infections

Staph, GBS

typical organisms that cause septic arthritis bone and joint infections

Staph, GBS, E. coli, gonorrhoeae, Kingella (if young), or strep pneumo/H. flu (if unvaccinated)

what are the categories for osteomyelitis?

acute

subacute

chronic

acute osteomyelitis

within 2 weeks of infections and typically symptomatic

hematogenous acute osteomyelitis

bone seeded through blood

contiguous acute osteomyelitis

local spread of infection

direct inoculation acute osteomyelitis

microorganisms introduced through surgery or trauma

subacute osteomyelitis

low grade infection with insidious onset

chronic osteomyelitis

necrotic bone; history of infection; more severe signs/symptoms

systemic risk factors for osteomyelitis

diabetes mellitus

peripheral vascular disease

immunodeficiencies

older age

nicotine use

renal or hepatic failure

cancer

IV drug or alcohol abuse

sickle cell

local risk factors for osteomyelitis

hypoperfusion

enous stasis

pressure ulcer

arteritis

severe scarring

surgical implants

social risk factors for osteomyelitis

homelessness

unemployment

poverty

zip code

lack of health insurance

prevention of osteomyelitis

-improve diabetes control

-treat peripheral vascular disease (e.g., statins, clopidogrel, surgery)

-if having alcohol abuse, IV drug use, or ESRD increase screening & involve additional resources when possible

-limit immunosuppressive situations (e.g., chemo, biologics, corticosteroids, transplant meds)

what are ways to improve diabetes control?

foot care counseling, neuropathy prevention

presentation of osteomyelitis

pain present around the site although maybe not with neuropathy; kids may limp or not use a part of their body

frequent symptoms

fatigue, malaise, headache, anorexia

local response

warmth, erythema, swelling

systemic signs

CSR, CRP, and procalcitonin often elevated; occasionally with fever or leukocytosis

diagnostic tests for osteomyelitis

probe to bone testing

-quick and easy to perform

-87% sensitivity and 83% specificity for osteo with a diabetic foot infection

imaging

-helpful tool with unclear physical exam

-may obtain x-ray, CT scan, or MRI

bone biopsy

-gold standard test

-helpful to identify organisms to treat

what is the gold standard test for osteomyelitis diagnosis?

bone biopsy

imaging for osteomyelitis

x-ray

-often positive with chronic osteomyelitis

-shows lytic lesions of cortical bone

MRI

-helpful if x-rays negative

-sensitivity 78-90% and specificity 60-90%

-CT

sensitivity 67% and specificity 50%

what is the first line for imaging of osteomyelitis?

x-ray

how long does it take for soft tissue edema to show up on an x-ray?

3-5 days

how long does it take for bone findings to develop?

10-14 days

what is helpful if x-rays are negative for osteomyelitis?

MRI

how long does it take for changes to show up on MRI?

3-5 days

what is the last line for imaging of osteomyelitis?

CT

true or false: regarding cultures for osteomyelitis, you should avoid regular wound cultures which may culture out normal skin flora

true

what cultures are prefered for osteomyelitis?

debridement or bone cultures

true or false: blood cultures are of mixed benefit for osteomyelitis

true

when may you consider delaying antibiotics to obtain debridement or bone cultures for osteomyelitis?

if not septic

when patient is septic with osteomyelitis, when should antibiotics begin?

immediately

if IV antibiotics are given to a patient with osteomyelitis, when should PO be considered?

after 1 week, but this decision depends on the bug, patient adherence, severity, location, and provider comfort

what is critical when picking an oral agent for osteomyelitis?

high oral bioavailability

what agents for osteomyelitis have good bioavailability?

fluoroquinolones, linezolid, trimethoprim-sulfamethoxazole, clindamycin, rifampin

oral drugs that cover MRSA

TMP/SMX

Clindamycin

Tetracyclines (e.g., doxy, mino, tetra)

Linezolid

Delafloxacin

Rifampin (only synergy)

IV drugs that cover MRSA

Vancomycin, telavancin, dalbavancin, oritavancin

Daptomycin

Linezolid, tedizolid

Ceftaroline

Delafloxacin

Quinupristin/dalfopristin

Tigecycline

Clindamycin

TMP/SMX

Doxycycline

oral drugs that cover Pseudomonas

ciprofloxacin, levofloxacin, delafloxacin

IV drugs that cover Pseudomonas

Pip/Tazo

Cefepime or ceftazidime

Meropenem, imipenem, doripenem

Aztreonam

Ciprofloxacin, levofloxacin, delafloxacin

Aminoglycosides

Colistin

surgical management of osteomyelitis

-bone biopsy/debridement culture

-debridement

-grafting

-vascular surgery

-amputation

bone biopsy/debridement culture

identies microorganisms

debridement

creates granulation tissue capable of re-epithelialization

grafting

provides protective barrier from chronic infection

vascular surgery

improves vascular perfusion

significant disparities exist with black and Latinx patients less likely to received limb salvage procedures

amputation

cures osteo as a last resort

typically, how long is osteomyelitis antibiotic duration?

4-6 weeks

how long is vertebral osteomyelitis antibiotic duration?

6-8 weeks

if treating vertebral osteomyelitis and there is a high risk of reccurence or Brucella species, how long is the antibiotic duration?

8-12 weeks

true or false: new evidence shows non-inferiority of 3 vs. 6 weeks after debridement of diabetic foot osteomyelitis

true

septic arthritis

-medical emergency that requires stat surgery consult

-typically affects 1 joint, but rarely can be polyarticular

-infection may occur via hematogenous spread, direct inoculation, or contiguous spread

what organisms may septic arthritis cover?

Staph, GBS, E. coli, gonorrhea, Kingella (if young), strep pneumo/H. flu (if unvaccinated)

may also involve gonococcus, fungi, or atypical organisms

what should be considered when diagnosing a septic joint?

-history of recent joint injection/surgery

-other tests: blood cultures, CBC with diff, CMP, CRP, ESR

-imaging: not helpful to distinguish from other causes of inflammatory arthritis

Which of the following meets the definition of a septic joint?

a. Clinical signs of infected joint/pathogenic organism in synovial fluid

b. Pathogenic organism isolated by culture with signs of an injected joint

c. Signs of infected joint and turbid synovial fluid with recent antibiotic treatment

d. Histologic or radiologic findings consistent with septic arthritis

e. All of the above

e

what may delayed antibiotics of septic arthritis cause?

bone loss, cartilage loss, joint dysfunction, and mortality

septic arthritis management

-stat needle aspiration vs. surgical decompression

-joint fluid analysis may help narrow antibiotics although often negative with gonococcal septic arthritis

-antibiotics

what's the empiric antibiotic therapy for septic arthritis?

-empiric coverage often vancomycin and ceftriaxone

what's the antibiotic therapy for septic arthritis if treating gonorrhea/chlamydia?

ceftriaxone + azithromycin

prosthetic joint infections

-common with hardware s/p surgery

-usually requires hardware removal

-consider urgent consults to surgery and ID

duration of antibiotic treatment for prosthetic joint infections

varies based on bug/surgical intervention; often 4-6 weeks but may require chronic suppression

what is often used in prosthetic joint infections as the infection clears and the patient awaits a joint surgery revision?

antibiotic spacers

what organisms usually cause cellulitis?

staph, strep

what organisms usually cause DM foot infections?

staph, streph, anaerobes, pseudomonas

pharmacodynamics of AUC/MIC

-mainly bacteriostatic concentration & time dependent with minimal post-antibiotic effect

antibiotics that follow AUC/MIC pharmacodynamic effects

macrolides, tetracyclines, linezolid, vancomycin

pharmacodynamics of time > MIC

mainly bactericidal: time-dependent

antibiotics that follow time > MIC pharmacodynamic effects

beta-lactams, clindamycin, vancomycin

pharmacodynamics of peak/MIC

mainly bactericidal: concentration-dependent with post-antibiotic effect (Peak/MIC)

antibiotics that follow peak/MIC pharmacodynamic effects

aminoglycosides, daptomycin, fluoroquinolones

how do you treat MSSA?

nafcillin, oxacillin, cefazolin

what should the MIC for vancomycin be?

≤ 1

vancomycin MIC of 2+

concerning, failure

linezolid

-broad gram + activity (great option for VRE)

-caution use >2 weeks (need weekly CBC if so)

possible adverse effects of linezolid

-myelosuppression, thrombocytopenia (esp. with liver or kidney impairment)

-serotonin syndrome (weak MAOI inhibitor)

-hypertension

-seizures

-neuropathy (peripheral and optic)

A patient is started on oral linezolid for MRSA osteomyelitis. What monitoring tests should be obtained on follow-up?

a. BMP

b. CBC

c. EKG

d. CPK

b

possible adverse effects of fluoroquinolones

-C diff

-QTc prolongation

-tendon rupture (caution in elderly)

-hepatoxicity (acute hepatitis and liver failure)

-nervous system (seizures, psychoses, peripheral neuropathy)

-hyper or hypoglycemia including hypoglycemic coma

-aortic aneurysm or dissection

Which antibiotic would we want to avoid in a patient with a baseline QTc of 528 ms?

a. Ceftazidime

b. Vancomycin

c. Daptomycin

d. Levofloxacin

d

daptomycin

broad gram + activity (covers VRE)

dosing for daptomycin

4-6 mg/kg IV daily (consider 8-10 mg/kg)

when should you dose adjust for daptomycin?

if CrCl < 30 mL/min (dose every 48 hours)

possible adverse effects of daptomycin

-peripheral neuropathy

-eosinophilic pneumonia

-drug reaction with eosinophilia and systemic symptoms (DRESS)

-rhabdo/myopathy (weekly CPK, possibly hold statins)

creatinine kinase should not be...

over 500

Which medicine should be monitored closely in a patient using daptomycin secondary to elevated CK and high rhabdomyolysis risk?

a. Atorvastatin

b. Metformin

c. Lisinopril

d. Amiodarone

a

A 72 y/o male presents w/ sepsis secondary to L foot osteomyelitis. PMH: DM2, CAD, neuropathy. Allergies: hives on penicillin. BP 102/64, HR 106, temp 38.4C. WBC 18 w/ 8% bands, Scr 2.4 (baseline 1). What is the best empiric antibiotic regimen?

a. Vancomycin + piperacillin/tazobactam

b. Meropenem

c. Trimethoprim/sulfamethoxazole + ciprofloxacin

d. Daptomycin + cefepime

e. No antibiotics, await surgical cultures

d

A 64 y/o female presents w/ MRSA bacteremia/septic joint s/p knee inj. PMH: knee OA & obesity. BP 108/68, T 39.2, WBC 24 w/ 15% bands, vanc AUC 375 after 1g q12h, CrCl 74, CK 1402. What should happen next?

a. Increase the vancomycin dose

b. Decrease the vancomycin dose

c. Continue the current vancomycin regimen

d. Switch vancomycin to daptomycin

a

trimethoprim/sulfamethoxazole possible serious adverse effects

-AKI (more common with IV) or false Scr elevations

-drug interactions

-bone marrow suppression

-hemolytic anemia (G6PD mediated)

-stevens-Johnson syndrome or TEN

-liver failure and pancreatitis

-avoid in pre-conception, pregnancy, and lactation

when may you steer away from trimethoprim/sulfamethoxazole?

when experiencing AKI

drug interactions with trimethoprim/sulfamethoxazole

NSAIDs, warfarin

what should you caution trimethoprim/sulfamethoxazole with?

warfarin

empiric warfarin decrease ~20%

piperacillin/tazobactam

-great spectrum, but limit use when possible (misses MRSA)

-time dependent: extended infusions

what does piperacillin/tazobactam not cover?

MRSA

enterococcus

anaerobes

possible adverse effects of piperacillin/tazobactam

-C diff

-bleeding/thrombocytopenia

-sodium content:13.5 g/day=31.7 mEq sodium

-acute renal injury (especially with vancomycin)

cephalosporins

-switch IV to PO within same generation

-time dependent-extended infusions

what are the go to cephalosporins for SSTIs?

cephalexin, cefadroxil, cefprozil, or cefdinir

what cephalosporin regimen should be considered in more severe SSTIs if needing an oral option with good bioavailability?

cephalexin 1 g every 8 hours

what cephalosporins are the best for anaerobic coverage?

cefotetan & cefoxitin (increases aPTT)

true or false: not all cephalosporins cover peptostreptococcus

false

what cephalosporins cover Pseudomonas?

ceftazidime and cefepime

what are the drugs of choice for ESBL or if failing other beta-lactams?

carbapenems

except if they are cabapenemase producing