Infectious Diseases Potpourrikww.net/maofpdemo/images/nick-gilpin-powerpoint.pdf7/24/2014 2 Overview • Discuss evaluation and management (including antibiotic selection) for a variety

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Infectious Diseases Potpourri

Nick Gilpin, DO

Section Head, Infectious Diseases

Beaumont Health Systems – Grosse Pointe

Assistant Clinical Professor, OUWBSOM

Assistant Clinical Professor, MSUCOM

Presented for the MAOFP Conference

August 1-3, 2014

Traverse City, MI

Disclosures

• No conflict of interest to disclose

Pot-pour-ri \,pō-pu̇-’rē\ noun

: A mixture of dried flower petals, leaves,

and spices used to make a room smell

pleasant

: A miscellaneous collection

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Overview

• Discuss evaluation and management

(including antibiotic selection) for a variety

of commonly encountered infectious

diseases:

– Cellulitis; skin and soft tissue infections

– Pneumonia (community acquired)

– UTIs

– Diabetic Foot Infections; osteomyelitis

Scenario #1:

“Cellulitis”

Case Presentation

• 44 y/o male with history of “pre-diabetes”

• 3 day history of progressive swelling,

redness, pain involving his RUE…

• Discovered upon awakening…

• No fevers, chills, other symptoms..

• No history of prior cellulitis…

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Buzzwords!

• “I got bit by a spider…”

• “There’s this red streaking…”

• “It’s been itching like crazy…”

• “I had a DVT a while ago…”

• “My dog bit me…”

• “A person bit me…”

• “I was swimming in the ocean…”

• “I was cleaning my fishtank…”

• “I got this infection after a mud run…”

S. aureus (MRSA)

Group A strep (S. pyogenes)

Contact dermatitis?

Venous insufficiency?

Pasteurella multocida

Eikenella corrodens

Vibrio vulnificus

Mycobacterium marinum

“Fish-Tank granuloma”

Aeromonas hydrophila

An Evidence-Based Approach• First, is it NON-PURULENT or

PURULENT:– Non-purulent? – Think Group A Strep

• Fiery red, well-demarcated

• Lymphangitis or “streaking”

• No obvious “portal of entry”

– Purulent? – Think S. aureus• Redness surrounding some purulent focus

• Patient may have some historical clue (e.g., fitness club, close contact, etc.)

• Blood cultures, skin swabs, and biopsies are LOW YIELD!– Helpful if an abscess is present

– May help diagnose infectious mimics (pyoderma)

– They may be useful in immunocompromised patients, patients with penetrating trauma, or bites…

IDSA Practice Guidelines for SSTIs. Clinical Infectious Diseases. 2014; 1-43

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An Evidence-Based Approach

• Without systemic signs/symptoms (mild)– Oral therapy

– PCN, Dicloxacillin, Cephalosporin, Clindamycin

• With systemic signs/symptoms(moderate)– Consider hospitalization, IV

antibiotics

– PCN, Cefazolin, Clindamycin

• With severe

signs/symptoms

(sepsis), trauma, or

suspicion of MRSA

(severe)

– Consider imaging,

debridement

– IV antibiotics

– Vanco PLUS Zosyn (broad

spectrum antibiotics)

• For non-purulent cellulitis (Group A Strep):


An Evidence-Based Approach

• Small abscess without

systemic illness (mild)

– I+D only

– Culture is optional

• Abscess/cellulitis with

systemic illness

(moderate)

– I+D, culture

– Oral antibiotics: Bactrim or

Doxycycline

– Maybe Clindamycin?

• With severe

signs/symptoms

(sepsis), hypotension

(severe)

– I+D, culture

– IV antibiotics: Vanco,

Linezolid, Daptomycin, etc.

• For purulent cellulitis (Staph aureus, MRSA):



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Remember Adjunctive Therapies

• Elevate the leg to promote gravity drainage of edema

• Warm compresses to facilitate drainage of purulent abscesses

• Limit ambulation

• Corticosteroids may be beneficial in uncomplicated cases, non-diabetics (shortens healing time by ~1 day)

• Treat underlying conditions like tinea pedis and eczema to prevent recurrences

• Decolonization with topical chlorhexidine and intranasal mupirocin may be useful in cases of recurrent MRSA abscesses– 5 days of intranasal mupirocin twice daily plus daily

chlorhexidine washes

Clinical Infectious Diseases 2005; 41:1373–406


“How long should I treat??”

• Depends…– Uncomplicated cellulitis: About 5 days (maybe more)

– “Complicated” (hospitalized) cellulitis: 7-14 days

• May be significantly longer in patients with “unusual” pathogens like mycobacteria, fungi, Nocardia, etc.

• How I approach cellulitis:

– Oral therapy is preferred

– If hospitalization/parenteral is required, treat until 60-70% improvement in cellulitis, then transition to oral therapy

Clinical Infectious Diseases 2005; 41:1373–406


Scenario #2:

Pneumonia

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Case Presentation

• 70 y/o male is brought to the EC

• Increased cough, chest discomfort, SOB

• Some sputum production

• Feels “feverish”

Not so subtle…

Guidelines for

CAP

Guidelines for

HCAP

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Is it CAP or HCAP?

• HCAP

– Antibiotics within the

preceding 90 days

– Hospitalization in the

preceding 90 days

– ECF resident

– Home infusion therapy or

wound care

– Family member with MDR

pathogen

– Dialysis within past 30 days

• CAP

– No healthcare-associated

exposure…

IDSA Guidelines for CAP. Clinical Infectious Diseases 2007; 44:S27-72.

ATS Guidelines for HCAP. Am J Respir Crit Care Med ; 2005 ; 171 : 388 -416

CAP Pathogens

Outpatient Inpatient ICU

S. pneumoniae S. pneumoniae S. pneumoniae

Mycoplasma pneumoniae Mycoplasma pneumoniae S. Aureus (MRSA?)

Haemophilus influenzae Haemophilus influenzae Legionella species

Chlamydophila pneumoniae Chlamydophila pneumoniae Gram-negative bacteria

Respiratory viruses Legionella species Haemophilus influenzae

Aspiration

Respiratory viruses

Diagnosis of CAP

• Remember that pneumonia is a CLINICAL diagnosis (cough, fever, sputum production, chest pain) supported by radiographic findings!

• All patients with suspected pneumonia should have some form of imaging (CXR or CT)

• Additional testing (e.g., performing cultures) is discretionary– Cultures are often falsely negative or do not impact clinical

management

• Blood cultures are only positive 5-14% of the time…

• Sputum cultures are probably not much better…

– A good rule of thumb: Perform a test only when the result will change your management

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Clinical Infectious Diseases 2007; 44:S27–72

Management of CAP

• To admit or not to admit…

– CURB-65 (score ≥ 2 may warrant admission)

• Confusion

• Uremia (BUN ≥ 20)

• Respiratory rate ≥ 30

• Blood pressure (hypotension)

• Age > 65

• ICU admission?

– Septic shock and/or mechanical ventilation

– More than 3 criteria for “severe” pneumonia

Clinical Infectious Diseases 2007; 44:S27–72

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Treatment of CAPOutpatient Inpatient ICU• If previously healthy and

no abx in prior 3 months:

– Azithromycin or

clarithromycin alone

– Doxycycline

• If comorbidities present or

recent abx use:

– A β-lactam plus a

macrolide (e.g.,

cefuroxime plus

azithromycin)

– A respiratory

fluoroquinolone

(moxifloxacin or

levofloxacin)

• A β-lactam plus a

macrolide (e.g., ceftriaxone

plus azithromycin)

• A respiratory

fluoroquinolone

(moxifloxacin or

levofloxacin)

• A β-lactam plus either a

macrolide or respiratory

fluoroquinolone (e.g.,

ceftriaxone plus

azithromycin or

moxifloxacin/ levofloxacin)

• If PCN-allergic, consider

aztreonam plus a

respiratory fluoroquinolone

• Have a very low threshold

for adding MRSA coverage

(e.g., vancomycin or

linezolid)!

IDSA Guidelines for CAP. Clinical Infectious Diseases 2007; 44:S27-72.

HCAP Pathogens

S. aureus (especially MRSA)

Pseudomonas

E. coli

Klebsiella species

Other enteric Gram-negatives

Acinetobacter and Stenotrophomonas species

Legionella species

Aspiration pathogens

Polymicrobial

Viruses, fungal organisms

Almost

always

multi-drug

resistant!!

Pathogenesis of HCAP

• Patients are likely to be colonized with MDR

organisms

• Most cases are bacterial, with a small

percentage being polymicrobial

• The source of pathogens includes:

– The environment (hospital, ECF, etc.)

– Devices

– The transfer of microorganisms from healthcare

provider to patient

– Aspiration


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HCAP Management Algorithm


Treatment of HCAP

“Early” (≤ 5 days) Onset

HCAP or Low Risk of MDR

Pathogens*

“Late” Onset or Risk of

MDR Pathogens

Ceftriaxone Anti-Pseudomonal penicillin or

cephalosporin (cefepime or

piperacillin/tazobactam)

OR a respiratory fluoroquinolone PLUS a respiratory

fluoroquinolone or aminoglycoside

OR amoxicillin/clavulanate or

ampicillin/sulbactam

PLUS vancomycin or linezolid

*includes patients receiving outpatient antibiotics in the past 90 days, but is mostly discretionary


“How long should I treat??”

• For CAP, a 5-7 day course of antibiotics is

usually enough

• For HCAP (including VAP), a 7-8 day

course is usually enough

• Research has not found prolonged

courses of antibiotics to be beneficial…

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Scenario #3:

Urinary Tract Infections

Case Presentation

• 33 y/o female presents with 4 day history

of burning with urination, fevers, and chills

• She also notes back pain, worse on the

left side

• She has had UTIs previously, with the last

one being about 6 months ago

Guidelines for Acute Cystitis

And Pyelonephritis

Guidelines for Catheter-

Associated UTIs

Guidelines for

Asymptomatic Bacteriuria

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Diagnosis of UTIs

• History

– Ask about prior infections, stones, urological

procedures, indwelling catheters, etc.

• Physical

– Look for CVA or suprapubic tenderness

• Urinalysis

• Urine culture (especially if there is

suggestion of “upper tract” involvement)

When to evaluate the urinary tract

• Pyelonephritis with bacteremia not responding to

therapy

– CT scan (abscess?)

• Nephrolithiasis

– Ultrasound or CT scan (hydronephrosis?)

• Neurogenic bladder

– Bladder/renal ultrasound (post-void residuals?)

• Men with a urinary tract infection

– Prostate exam, ultrasound, post-void residuals, etc.

Microbiology of UTIsBug Acute

uncomplicated

cystitis

Acute

uncomplicated

pyelonephritis

Complicated

UTI

Catheter-

associated

UTI

E. coli 79% 89% 32% 24%

S. saprophyticus 11% 0% 1% 0%

Proteus 2% 4% 4% 6%

Klebsiella 3% 4% 5% 8%

Enterococcus 2% 0% 22% 7%

Pseudomonas 0% 0% 20% 9%

Mixed 3% 5% 10% 11%

Other* 0% 2% 21% 46%

*includes S. epidermidis, Candida spp., and other Gram-negatives

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Treatment of

Acute Uncomplicated Cystitis• Macrobid 100 mg bid x 5 days

• TMP-SMX DS 1 bid x 3-5 days

• Fosfomycin 3g in a single dose

• Fluoroquinolones (e.g., ciprofloxacin) should generally be reserved for selected patients where 1st line therapy is not feasible

• β-lactams (cephalexin, amox-clav) should also be reserved for selected patients due to increasing failure rates

• Amoxicillin by itself should NOT be used empirically (too much E. coli resistance)

Guidelines for Acute Cystitis/Pyelonephritis. Clinical Infectious Diseases 2011;52(5):e103–e120

Treatment of

Acute Pyelonephritis• Pyelo = fever, flank pain, pyuria

• Remember to obtain a urine culture

• If hospitalization not required:– Fluoroquinolone x 7-10 days

– β-lactams x 10-14 days

– TMP-SMX x 10-14 days

• If hospitalization required:– Ampicillin/gentamicin, fluoroquinolone, or extended

spectrum β-lactams should be given intravenously initially

– You no longer need to keep the patient hospitalized until they are afebrile…

Guidelines for Acute Cystitis/Pyelonephritis. Clinical Infectious Diseases 2011;52(5):e103–e120

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Treatment of

Other Complicated UTIs

• If a renal/perinephric abscess is present, it

should be drained appropriately and

cultures

– Treatment is generally considered for 2-3

weeks based on treatment response

– Close urology follow-up is necessary

Catheter-Associated UTIs

• The diagnosis is much trickier...

– Not all pyuria and bacteriuria means infection!

– Look for “true symptoms”• New onset or worsening of fever, rigors

• Altered mental status

• Malaise or lethargy with no other identified cause

• Flank pain or costovertebral angle tenderness

• Acute hematuria

• Pelvic discomfort;

• In those whose catheters have been removed, dysuria, urgent or frequent urination, or suprapubic pain or tenderness

Guidelines for Catheter-Associated UTI. Clinical Infectious Diseases 2010; 50:625–663

Treatment of

Catheter-Associated UTIs

• Selection of antibiotics should be based upon cultures (both old and new)

• Duration of treatment:

– 7 days of treatment (based on culture results) is recommended for patients with a brisk response to therapy

– 10-14 days is recommended for patients with a delayed response to therapy

– Shorter durations can be considered in some circumstances


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What about prophylaxis for patients

with indwelling catheters?• For prevention of catheter-associated UTIs, there is no

documented benefit with:– Antibiotics

– Methenamine

– Cranberry products

– Routine catheter changing

– Enhanced meatal care

– Antimicrobials in the drainage bag

– Catheter irrigation

– Antimicrobial-coated catheters

• The best practice: use the catheter for the shortest duration feasible– For men, consider condom catheters if appropriate

– Intermittent catheterization appears to be somewhat better than indwelling catheter use

– Suprapubic catheters should be considered an alternative to long-term indwelling catheters


What about asymptomatic

bacteriuria?• What is it?

– For asymptomatic women, bacteriuria is defined as 2 consecutive voided urine specimens with isolation of the same bacterial strain in quantitative counts >100,000 cfu/mL

– For asymptomatic men, a single, clean-catch voided urine specimen with 1 bacterial species isolated in a quantitative count >100,000 cfu/mL identifies bacteriuria

– A single catheterized urine specimen with 1 bacterial species isolated in a quantitative count >1000 cfu/mL identifies bacteriuria in women or men

• When is asymptomatic bacteriuria treated?– Pregnancy

– Persons with structural/neurological abnormalities of the urinary tract

– Persons undergoing urologic surgery

• If you’re treating asymptomatic bacteriuria, duration should be 3-7 days (same as for cystitis, based on culture results)

Guidelines for Asymptomatic Bacteriuria. Clinical Infectious Diseases 2005; 40:643–54

Dilemma #4:

Diabetic Foot Infections

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Case Presentation

• 60 y/o diabetic female

• “Cut my foot on something a while ago…”

• Progressively worsening ulceration with

drainage

• No fevers, chills

• No other complaints

How do I know if it’s infected?

How can I tell if it’s a bone infection?

• Look for “classic” signs of infection (local inflammation, purulence, and systemic signs/symptoms)

– Beware of not-so-classic signs

• Consider using a validated “scoring system” to aid in diagnosis

– Example: International Working Group on the Diabetic Foot has a scoring criteria to assist in diagnosis of osteomyelitis (versus a skin/soft tissue infection)

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Diabetic Foot Infections:

PresentationMILD MODERATE SEVERE

More than 2 of: Any of the following: Patient is systemically

toxic or unstablePurulence, erythema,

pain, tenderness,

warmth, induration

Cellulitis >2 cm

around ulcer

Any cellulitis

extending <2 cm

around ulcer

Lymphangitis

Infection is limited to

skin/superficial tissue

Deep tissue abscess

No systemic illness Gangrene

Muscle, tendon, joint,

or bone involvement

Guidelines for Diabetic Foot Infection. Clinical Infectious Diseases. 2004; 39: 885-910.

Diabetic Foot Infections:

• International Working Group on the

Diabetic Foot (IWGDF) has attempted to

formulate a criteria-based approach to

diagnosis

– Similar to other diagnostically challenging

conditions (e.g., infective endocarditis)

• Not validated in practice, but appears

promising, particularly for osteomyelitis

Definite

Positive bone culture

Pus in bone

Atraumatically detached bone fragment removed from ulcer

Intraosseous abscess on MRI

Probable

Visible bone in ulcer

MRI showing bone edema with other signs of osteomyelitis

Bone sample with positive culture but negative histology

Bone sample with positive histology but negative culture

Possible

Plain X-rays show cortical destruction

MRI shows bone edema

“Probe to bone” positive

Bone visible

ESR > 70 without a reasonable explanation

Non-healing ulcer present for >2 weeks

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SCORE PROBABILITY

OSTEOMYELITIS

IS PRESENT

MANAGEMENT

1 definite >90% Treat

2 probable

1 probable + 2

possible

4 possible

50-90% Consider

treating, but may

require further

investigation

2 possible 10-50% Further

investigation

advised before

treatment

Berendt et al. Diabetes Metab Res Rev 2008.

Who should be hospitalized?

• Patients with a severe infection

• Selected patients with a moderate

infection and significant comorbidities

• Any patient who is unable to comply with a

prescribed regimen

• Patients who fail an outpatient regimen

(maybe…)

How should cultures be obtained?

• If it’s not infected, DON’T CULTURE IT!

• For infected wounds, get the deepest and

best sample possible

– Debrided tissue or bone is best

– Preferable to get cultures OFF antibiotics


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“To swab or not to swab…”

• Generally deep cultures and/or

aspirates are preferred over superficial

swabs

• Two main reasons a swab may be

helpful:

– Identification of resistant pathogens (MRSA,

VRE) indicates need for special contact

precautions

– Isolation of MRSA often correlates with deep

cultures (other “junk”…not so much)

What other diagnostic studies

may be helpful?

• Adjunctive labs and imaging are helpful in

the following situations:

– Patient is not responding appropriately to

“correct” therapy

– Suspicion exists for a deeper infection

• All patients with a new diabetic foot

infection should have a plain radiograph


Pitfalls of Osteomyelitis

• Osteomyelitis can be a significant

diagnostic challenge

• Patients at greatest risk are typically

immunocompromised

– Less likely to have febrile/inflammatory response

• High risk diabetic patients will frequently have

absent sensation in affected areas (e.g., the

diabetic foot)

• The labs may not support your diagnosis

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Labs which may aid in the

diagnosis of osteomyelitis

• WBC (elevated?)

– Beware: this may be helpful in an acute process, but is rarely helpful in a chronic process

• ESR/CRP (elevated?)

– USUALLY elevated, but how much is enough

– Best utility may be to “trend” these data over time to monitor clinical response

• Blood cultures

– Highest yield in settings of acute hematogenous osteomyelitis or vertebral osteomyelitis

– Yield is still much less than 50%

Imaging which may aid in the


• Plain X-ray:

– Low sensitivity (~15-

40%); moderate

specificity (~70%)

– Abnormalities are

usually seen 10-14

days after onset of

infection

Periosteal

Reaction



• MRI:

– Very sensitive (~85%),

somewhat less specific

– High negative predictive

value in appropriate

clinical setting

– Typically regarded as the

“imaging modality of

choice”

http://www.ajronline.org/content/vol193/issue4/images/large/10_09_3300_03.jpeg

http://www.ajronline.org/content/vol193/issue4/images/large/10_09_3300_03.jpeg

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• CT scan:

– Next best modality when MRI cannot be used

– Beware metallic artifact in setting of hardware

• Nuclear modalities:

– High sensitivity, generally poor specificity

– “Three phase bone scan” is reasonable in the

appropriate clinical setting

• Consider nuclear modalities in patients where MRI

or CT cannot be reasonably performed

Three Phase Bone Scan

• Uses a radionuclide tracer that accumulates in areas of bone turnover

• Scans are performed at three points following tracer: – immediately after injection (blood “flow” phase)

– 15 minutes after injection (blood pool “tissue” phase)

– 4 hours after injection (“osseous” phase)

• In osteomyelitis, expect high uptake in all three phases– Contrast with cellulitis: NO activity in the “osseous” phase

• NOT the same thing as a “Triple Tracer Bone Scan” (bone marrow scan, bone scan, WBC scan)

EARLY

Uptake occurs

in areas of the

L foot in all 3 phases –

This is consistent

with OSTEOMYELITIS

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What treatment?

• If it’s not infected, don’t treat (Duh…)

• Topical antibiotics are probably worthless

• For infected wounds, consider the severity and degree of infection:– Mild-to-moderate infections: target Gram-positive cocci (most

common), and think about MRSA…

• Keflex; Cefazolin; Vanco…

– More severe infections: go broad (target Gram-positives AND Gram-negative, and potentially anaerobes)

• Zosyn; Vanco + Zosyn; Vanco + Cefepime +/- Flagyl

– Targeting Pseudomonas is probably overrated unless your patient has risk factors or known colonization

• Once your cultures are back, treat what is growing


Principle of Antimicrobial Therapy

in Osteomyelitis/DFI

“All antimicrobials should be withheld if

possible until percutaneous aspirate or

surgical deep cultures have been

obtained.”**

**Unless patient is “sick”…

Microbiology of Osteomyelitis/DFI

COMMON

(>50%)

OCCASIONAL

(>25%)

RARE (<5%)

S. aureus Strep MTB

CoNS Enterococcus Dimorphic

fungi

Pseudomonas Candida

E. coli Aspergillus

Other

Enterobacteriaciae

Brucella

Anaerobes Salmonella

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Targeted Antimicrobial Therapy

in Osteomyelitis/DFIBug Preferred Alternative

MSSA Nafcillin

Cefazolin

Vanco (+/- Rifampin)

MRSA Vanco

Dapto

Linezolid (+/- Rifampin)

Strep PCN

Ceftriaxone

Cefazolin

Vanco

Enterococcus PCN or Amp

(+/- Gent)

Vanco

Enterobacteriaceae Ceftriaxone Cipro

Pseudomonas Cefepime, Pip-Tazo Cipro

Osteomyelitis “Buzzwords”

• Post-surgical osteo?

• Osteo in a “sickler”?

• Man in a tennis shoe steps on a

nail?

• Spinal osteo in a person from India?

• Sacroiliac joint osteo?

• Osteo in a dialysis patient?

• Osteo in IV drug users?

S. aureus or CoNS

Salmonella

Pseudomonas

MTB

S. aureus

S. aureus, MRSA

S. aureus, Pseudomonas, Candida

How long should I treat a diabetic

foot infection?

• Continue antibiotics until the infection is

resolved

– You don’t need to treat until the wound is

healed!!

– General rule: 1-2 weeks for mild infections, 2-

3 weeks for moderate-to-severe infections


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How long should I treat

osteomyelitis?

• Optimal duration is not well established…

– Lack of prospective trials

• What do we know?

– 4 weeks is better than 2 weeks

– 6 weeks is about how long it takes for debrided bone

to be covered by vascularized soft tissue

– A shorter duration may be reasonable when extensive

debridement/amputation is performed

– Treatment should be given parenterally (if feasible)

General Principles of Osteomyelitis

Treatment

• Goal: eradicate infection, restore function

• Understand that you are potentially fighting a losing battle

– Antimicrobial therapy alone is not curative in most cases of osteomyelitis

– Surgical debridement will increase your chances of cure

– Chronic osteomyelitis (devitalized bone) is virtually incurable with antibiotics alone

• Consider surgery/amputation

Thank you!

Infectious Diseases Potpourri

Nick Gilpin, DO

Infectious Disease

Beaumont Health Systems – Grosse Pointe

Documents

Infectious Diseases Potpourrikww.net/maofpdemo/images/nick-gilpin-powerpoint.pdf7/24/2014 2 Overview • Discuss evaluation and management (including antibiotic selection) for a variety