A PGY-1 GUIDE TO INFECTIOUS DISEASE AND SEPSIS

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A PGY-1 GUIDE TO INFECTIOUS DISEASE AND SEPSIS

• JAY SELLERS AND CHRIS MILLER

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COMMON BACTERIA WE ENCOUNTER IN THE HOSPITAL

• GRAM POSITIVES
• Staph
• Strep
• Clostridium
• GRAM NEGATIVES
• Neiserria
• E. coli
• Klebsiella
• Pseudamonas

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STAPHYLOCOCCOUS

• Gram Stain Gram-Positive Cocci in Clusters
• Staph aureus
• MSSA
• CA-MRSA
• HA-MRSA
• Staph epidermidis

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Staph aureus (SA)

• Coagulase Positive
• Community-Acquired MRSA (CA-MRSA)
• Cellulitis (a bug/spider bit me doc!)
• Severe invasive infections (endocarditis,
  cavitary pneumonia, epidural abscess,
  endopthalmitis)
• Hospital-Acquired MRSA (HA-MRSA)
• Line infections
• Pneumonia, especially VAP or in patients
  w/chronic lung dz
• Endocarditis

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Antibiotics vs. Staph aureus

• CA-MRSA
• PO options Bactrim, doxycycline, clindamycin,
  linezolid
• More serious infection vancomycin, daptomycin,
  linezolid, tigecycline
• HA-MRSA
• Vancomycin, daptomycin, linezolid, tigecycline
• At Jeff, we use dapto or linezolid for MICgt2
  (consider this VRSA
• MSSA- all of the above, but is oxacillin/nafcillin
  /methacillin susceptible
• Give penicillin to your mother if she gets MSSA.
  Give your mother-in-law vanco. -Joe Desimone

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Staph epidermidis (coagulase negative staph or
CNS)

• Usually a contaminant from the skin seen on an
  isolated positive blood culture
• Can cause pathology in patients with indwelling
  metal hardware (cardiac valves, artificial
  joints, pacers, Baclofen pumps)
• Antibiotics can be resistant to methacillin,
  usually start with vanco and await sensitivities

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Streptococcus

• Gram positive cocci in chains
• Beta-hemolytic strep (heavy hemolysis- TOXIC)
• Group A (Strep pyogenes, GABHS)
• Group B (GBS)
• Group C
• Alpha-hemolytic strep (medium hemolysis)
• Viridans group strep
• Strep pneumo
• Gamma-hemolytic strep (no hemolysis)
• Group D (Enterococcus)
• Strep bovis

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Beta-hemolytic Strep

• Group A Strep- Strep pyogenes
• Strep throat
• Pyotoxic infections- necrotizing fasciitis, toxic
  shock
• Group B Strep (GBS)
• Genito-urinary colonizer
• Neonatal infections (think back to prenatal
  testing on OB/GYN)- pneumonia, meningitis
• Elderly, immunocompromised
• Group C Strep
• Pyotoxic infections similar to GAS, less common

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Alpha-hemolytic Strep

• Viridans Strep
• Head and neck infections (sinusitis, orbital
  cellulitis)
• Endocarditis (associated with poor dentition)
• Strep pneumo
• Pneumonia
• Meningitis
• Otitis media

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Gamma-hemolytic Strep (non)

• Enterococcus
• Genitourinary infections
• Strep bovis
• Typical test question Strep bovis
  bacteremia/endocarditis, think colon cancer

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Antibiotics vs. Strep

• Most strep are not very resistant, can usually
  treat empirically with a beta-lactam up front
• Ex ceftriaxone for CAP, amoxiciilin for strep
  throat or otitis
• Exceptions
• Meningitis, endocarditis
• Enterococcus- often one of the MDRO (multi-drug
  resistant organisms)

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Antibiotics vs. Enterococcus

• Generally susceptible to same antibiotics that
  work vs MRSA (vancomycin, daptomycin, linezolid),
  usually Bactrim, cipro if infection acquired in
  community
• OFTEN see resistance to vancomycin now in
  hospital (VRE)
• Cover patients with chronic or hospital-acquired
  infections with dapto or linezolid up front

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Clostridium

• C. difficile
• Causes C.diff diarrhea
• Classic characteristics
• patient on recent abx or hospitalized or hx IBD
• Frequent diarrhea
• Fevers
• WBCgt20
• Toxic megacolon (severe)
• Antibiotics
• Metronidazole (Flagyl) or PO vancomycin
• New antibiotics emerging

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Neiserria

• Gram-negative diplococci
• N. gonnorhoeae
• Usually will see in clinic, STD causing
  infectious urethritis
• PID
• Dermatitis-arthritis
• N. meningitidis
• Meningitis- young patients living in close
  quarters (college students, army barracks)
• Need prophylaxis for close contacts
• Vaccine available
• Antibiotics usually ceftriaxone

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E.coli/Klebsiella

• Gram-negative rods
• Lactose fermenting
• Infections
• UTIs
• Pneumonia
• Gram-negative sepsis
• Travelers Diarrhea, hemorrhagic diarrhea
  (O157H7), HUS with E. coli

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Antibiotics vs E.coli/Kleb

• E.coli tends to be more susceptible and seen more
  in community (women with UTIs)- can use Bactrim,
  Cipro
• Klebsiella generally more resistant
• Most resistant strains in vented patients,
  nursing home patients, patients with bladder
  dysfunction, hospital frequent flyers
• Extended-Spectrum Beta-Lactamase (ESBLs)
• Knock out beta lactams, floroquinolones,
  late-generation cefalosporins, beta lactam/beta
  lactamase inhibitors (ampicillin-sulbactam,
  piperacillin-tazobactam)
• Use carbapenems, aminoglycosides, tigecycline,
  colistin
• Kleb pneumo Carbapenemase (KPCs)
• Knock out all of the above, PLUS carbapenems,
  often one or more aminoglycosides
• Can use tigecycline, sometimes an aminoglycoside,
  colistin
• Sometimes PAN-RESISTANT

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Pseudomonas aeruginosa

• Gram-negative rod
• Non-lactose fermenting
• Infections
• Hot tub cellulitis
• Otitis externa, malignant otitis
• Severe, hospital-acquired infections- UTIs,
  Pneumonia, sepsis

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Antibiotics vs. Pseudomonas

• Only PO option is Cipro (effective 50-ish of the
  time)
• Piperacillin (anti-pseudomonal penicillin)
• Some 3rd, 4th generation cephalosporins
  (ceftazidime, cefepime)
• Aminoglycosides
• Carbapenems (except ertapenem)
• Aztreonam (really only used to cover pseudamonas
  in penicillin-allergic pts)
• Can frequently be resistant to several of the
  above- we often DOUBLE COVER if we have a high
  suspicion

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Anaerobes

• Gram positives, gram negatives
• Can often produce a beta-lactamase, sometimes
  even ESBL
• Infections
• Head/neck
• Aspiration pneumonia/pulmonary abscess (people
  with poor dentition)
• below-the-diaphram infections
• Antibiotics
• Beta lactamase inhibitor combos amox-clav
  (Augmentin), ticarcillin-clav (Timentin),
  amp-sulbactam (Unasyn), piperacillin-tazobactam
  (Zosyn)
• Clindamycin
• metronidazole

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Atypicals

• Usually concerned with these in pneumonia (or
  chlamydia in non-gonnococcal urethritis)
• Chlamydia, mycoplasma
• Legionella (pneumonia w/hyponatremia, diarrhea,
  sick patient)
• Generally covered by floroquinolones, azithromycin

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Steps to treating an infection

• History/physical, differential
• Source identification
• Choose appropriate initial antibiotics to cover
  most serious pathogens that are associated
• In hospital, MRSA and pseudomonas will generally
  kill someone the fastest
• Check GRAM STAINS and cultures before abx IF
  POSSIBLE, multiple sources, multiple times
• Check gram stain- narrow coverage if confident
• Check culture- narrow again
• Check susceptibilities- choose final agents

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Pneumonia

• CAP
• Strep pneumo, H.flu, atypicals
• In community, treat with respiratory
  floroquinolone (moxifloxacin, levofloxacin)-
  rising resistance to azithro
• In hospital, treat with resp floroquinolone or
  ceftriaxone/azithro
• HAP
• Need to cover for MRSA and pseudamonas
• Generally start with vanco Zosyn
• If patient is a frequent flyer, might sub
  carbapenem for Zosyn
• VAP
• Need to cover MRSA worry about ESBLs/KPCs and
  pseudomonas
• High mortality
• Generally start vanc/Zosyn or vanc/carbapenem,
  sometimes will DOUBLE COVER with aminoglycoside
• EXTUBATE PATIENT

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Meningitis

• Fevers, HA, ill-appearing, neck/back pain, normal
  mental status
• Most common- strep pneumo
• N. meningitidis- young patients, close living
  quarters- RASH
• Listeria- gram-pos rod
• Patients with impaired immunity, age gt65
• Start with ceftriaxone vancomycin
• Small percent strep pneumo resistant to CTX,
  serious infection, this is why we add vanc
• Give STEROIDS before abx if suspect strep pneumo
• ADD ampicillin if at risk for Listeria

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UTI

• Avoid catheters- document Foley status in note
  EVERY DAY and ask can I remove this
• PLEASE CHECK GRAM STAIN
• If a GRAM POSITIVE shows up, probably going to be
  Enterococcus, can SIGNIFICANTLY narrow abx
• Entercoccos, E.coli, Proteus, Kleb, Enterobacter
• Simple bactrim, nitrofurantoin, cipro x 3 days
• Complicated cover for appropriate bacteria
  depending on suspected level of resistance
• In frequent/bladder dysfxn patients, may need to
  cover VRE (linezolid/dapto) and pseudomonas/ESBL
  (carbapenem)

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Cellulitis

• Most patients, cover MRSA and strep
• Bactrim, doxy, clinda, vanc, linezolid, dapto
• Diabetics/immunocompromised- also worry about
  anaerobes, pseudomonas
• May need to ADD coverage for these
• Necrotizing fasciitis- suspect in ill cellulitis
  pt, diabetics, patients with pressure ulcers,
  critically ill with no defined process
• PALPATE cellulitic areas/wounds for subQ air
• Check CPK
• IMAGE for free air- CALL SURGERY IMMEDIATELY
• ADD clindamycin- inhibits toxin production by
  strep
• Cat bites- Pasteurella, use Augmentin or Unasyn

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Sepsis

• Hypotensive, tachycardic patients, likely
  infectious source, febrile
• Examine vasodilated, warm
• AGGRESSIVE volume resuscitation (2-3L NSS, wide
  open up front, may need INTUBATION if pulm edema)
• Antibiotics targeted against likely pathogens
  (often cover MRSA/pseudomonas, often double
  cover)
• These take TIME to work, the fluid is most
  important
• Pressors- consider if hypotense after 2-3L or if
  pt hypoxic from fluid
• Need central venous catheter for administration
• Stress steroids- hydrocortisone 50mg IV q6hr
• Consider in patient not responding to all of
  above or if patient has taken gt10mg prednisone
  for any 3 wk over past yr
• Activated Protein C- no longer used

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Neutropenic Fever

• May be only clinical sign infection
• Patients with neutrophil fraction of total WBC
  (ANC) lt1000
• MUST start abx in these patients when they have
  fever
• MUST cover pseudomonas with a reliable agent
  (ceftaz, cefepime, piperacillin, aztreonam)
• Cover MRSA if invasive lines, rash, high
  suspicion, or if fever dose not relapse on above
  treatment at 24-48hr
• Cover fungus if high suspicion or no
  resolution/etiology in several days

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Endocarditis

• Suspect in patient with fevers, wt loss, poor
  dentition, IV drug use, previous IE or previous
  documented bacteremia, indwelling chronic lines
• Often sustained bacteremia
• If high suspicion, initial abx should cover
  MRSA/strep (usually vancomycin)
• Need to combine vanc with gentamicin for SYNERGY
  for empiric initial coverage

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Septic Arthritis

• Can be associated with patients with gout flares
• Must be tapped and sent for stain and culture
• Differential is gout, pseudogout
• Crystals will not be seen
• Extremely high WBC, bacteria on gram stain
• Often Staph
• May need washout in OR by ortho

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Fungemia

• Immunocompromised patients, neutropenic patients,
  TPN, ill patients
• Often yeast Candida albicans, can also see
  Candida glabrata and others
• C.albicans usually sensitive to azoles
  (fluconazole)
• C.glabrate and other hospital yeast often
  resistant to fluconazole, so start with
  eichinocandin (caspofungin, anidulofungin, etc)
• Remove invasive lines, stop TPN

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Influenza

• Suspect in winter
• Respiratory sxs, cough, fevers, muscle aches,
  N/V
• Tamiflu effective if given lt48hr after symptom
  onset
• If sick patient and high suspicion flu (like H1N1
  outbreak), would probably try Tamiflu regardless
  of time after onset

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Non-infectious fevers

• Gout flare- patients getting HD or diuretics
  often
• DVT/thrombosis
• Central fever
• NMS/malignant hyperthermia (suspect if Tgt103F)
• Post-transfusion (even days)
• Drug fever/allergy
• cancer

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Case 1

• 60yoF PMH CKD on HD via catheter, DM2, HTN.
  Recent hospitalization 1 month ago for bacteremia
  with coag-negative staph, had line change. Back
  in ED with fever to 102F. Also a cough/sputum,
  diffuse muscle aches.
• Differential?
• Potential pathogens?
• Testing?
• Initial therapy?

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Case 2

• 57yoM, DM2, CKD, gout, here for initiation of HD.
  No previous access. Was extremely hypoxic on
  admission. On Day 3 admission, spikes fevers to
  101F. Has diarrhea. Bilateral knee and shoulder
  pain. Normal WBC.
• Differential?
• Potential pathogens?
• Testing?
• Therapy?

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Case 3

• 55yoM PMH DM2, HTN presents to ED because his
  wife forced me. Hes not eating and hes
  vomiting she says. He admits nausea, vomiting,
  lethargy, fevers x3 days. Hes reclining on his
  side because my butt hurts where they lanced a
  boil 5 yr ago. He is tachycardic (sinus) to
  130s, BP 110/70. Temp of 102.5F. CXR clear.
  Normal obstxn series. ED has given him
  vanc/zosyn.
• Differential?
• Pathogens?
• Tests?

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Case 4

• 33yoM PMH quadraplegia 2/2 MVA, neurogenic
  bladder with suprapubic catheter, UTIs, resident
  of nursing facility, arrives in ED with fever to
  101.9F, tachy to 120s, BP is 85/52, RR 25. He
  is not vent dependent.
• Differential?
• Pathogens?
• Tests?
• Treatments?