Chapter 4d Podiatric Infectious Diseases
Transcript of Chapter 4d Podiatric Infectious Diseases
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
1/20
4.4 Podiatric Infectious DiseasesMark Kosinski, DPM
Assessment of the Patient with InfectionIn addition to performing the requisite history, review of systems and physical examination, it may be helpful
include the following questions and observations when assessing a patient with infection.
History
When did the infection begin? Where and how was it acquired ? Distinguish between community and noso-
comial (hospital acquired) infections.
Past Treatment
What previous treatment if any, has the patient received? Has the patient been taking antibiotics?
Drug Allergies/Sensitivities
Does the have an allergy to penicillin or another antimicrobial agent? What form did the allergy take? Was it
an anaphylactic reaction or delayed hypersensitivity ? How long ago did it occur and with what drug?
Review of Systems
Inquire about the presence of fever, chills, nausea, vomiting, diarrhea, weakness, malaise, and diaphoresis
Past Medical History
Including diabetes, HIV, IVDA, tuberculosis, STDs , sickle cell anemia, renal or hepatic disease, and risk fac-
tors for infective endocarditis
Medications
Is the patient currently receiving antibiotic therapy or taking any medication which could affect immune
response or mask the signs of infection (e.g., corticosteroids, cyclosporine)
Past Surgical History Does the patient have implanted biomaterials, prosthetic joints, heart valves or shunts that might become
secondarily infected ? Has the patient recently been hospitalized, putting them at risk for MRSA?
Social History
Ask about travel, jobs and pets
Physical Examination
Vital Signs
Include oral temperature, blood pressure, pulse and respiration
Area of Chief Complaint
Note the presence and extent of cellulitis, lymphangitis, and regional lymphadenopathy (inguinal and
popliteal). Note the odor and appearance of exudate and the extent and depth of the wound or ulcer.
Lab Tests
Appropriate lab tests for a patient with infection include a CBC with differential, renal and hepatic functiontests, ESR, blood glucose with glycosylated hemoglobin, urinalysis, X-rays, wound cultures and Grams stain.
Consultations
Consult other medical services (eg., infectious diseases, internal medicine, vascular surgery) as needed
Medicine | Podiatric Infectious Diseases 283
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
2/20
Five Basic Principles of Antibiotic Selection and Empiric Treatment
1. Your antibiotic choice should be governed by the organisms you expect to find in agiven situation
2. Distinguish between community and hospital acquired infections3. Use an antibiotic with proven efficacy to the suspected or known organism(s)4. Change or continue antibiotics based on culture results as soon as possible. Avoid
prolonged empiric therapy5. When sensitivities are known, choose the narrowest spectrum agent with the highest
efficacy and the lowest toxicity
Odor, Color and Appearance as Clues to the Infecting Organism
Yellow pus S. aureus (coagulase positive Staph.)
White pus S. epidermidis (coagulase negative Staph.)
Green pus/exudate P. aeruginosa
Dishwater pus Strep. group A (necrotizing fasciitis)
Draining sinuses /granules* Actinomyces, Nocardia
Fruity odor P. aeruginosa
Foul, fetid odor Anaerobes (B.fragilis in diabetic foot)
Woods Light flourescence Coral red C. minitissimum
Green P. aeruginosa
Red Bacteroides melaninogenicus
Yellow Pityriasis versicolor
* sulfur granules are composed of colonies of Actinomyces or Nocardia surrounded by inflammatory cells.
Distinguish actinomycosis from nocardiosis by culture and biopsy.
When you hear Think Paronychia S. aureus Diabetic foot infection Polymicrobial (Staph., Strep.,B. fragilis) Sickle cell disease OM Salmonella Puncture wound OM P. aeruginosa Post op infection S. aureus (MSSA/MRSA) Post op infection (implant) S. aureus (MSSA/MRSA), S. epidermidis Human bites Eikenella corrodens. HIV, syphillis, hepatitis Cat bites Pasturella multocida, Bartonella henselae Dog bites DF-2 (Capnocytophaga canimorsus) Burn wounds (acute) nitially sterile, then S. aureus Burn wounds (chronic) P. aeruginosa IVDA MRSA, P.aeruginosa, human oral flora (Eikenella corrodens)
Florists/Rose bushes Sporothrix schenkii
Fish tanks, pools Mycobacterium marinum Salt / brackish water Vibrio vulnificus Superficial Impetigo Group A Beta hemolytic Streptococci (Strep. Pyogenes) Bullous Impetigo S. aureus Erysipelas Group A Beta hemolytic Streptococci (Strep. Pyogenes)
Occasionally streptococci group C and G Web spaces T. mentagrophytes, T. rubrum, C. minitissimum, Gram negative
bacteria (e.g., pseudomonas, klebsiella, proteus) Scaulded Skin Syndrome S. aureus
284 The 2005 Podiatry Study Guide
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
3/20
Empiric Therapy
Empiric Therapy for Diabetic Foot Infections
Your empiric antibiotic(s) should cover S. aureus, Group B Strep and in more serious infections, Gram negativebacteria and anaerobes (B. fragilis).
It is therefore useful to choose an antibiotic based on the severity of infection
Mild Infection:
Local cellulitis (< 2 cm) No proximal spread No systemic S & S
Normal labs
Contrary to previous belief that ALL diabetic infections werepolymicrobial; these (mild infections) frequently
are not.
Cover for: Staphylococcus aureus(MSSA/MRSA) Increasing community-acquired MRSA
Group B Streptococcus
Drugs used to kill S. aureus will almost always kill Strep.
MRSA
TMP/SMX
Minocycline
MSSA
Cephalosporins (cephalexin, cefdinir) Amoxicillin/clavulanate Levofloxacin
Clindamycin
Moderate to Severe Infection Significant cellulitis (> 2 cm)
Gas Proximal spread - lymphangitis Constitutional S & S Laboratory changes
Elevated WBC, left shift
Although moderate to severe infections are commonly polymicrobial, S.aureus and Strep still predominate.
Organisms Found in Moderate to Severe Diabetic Infections:
Staphylococcus aureus(MSSA/MRSA) Group B Streptococcus
Gram-negatives Pseudomonasstill uncommon as a pathogen Anaerobes B. fragillis
Peptococcus, Peptostreptococcus
Medicine | Podiatric Infectious Diseases 285
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
4/20
Some Antibiotic Choices to Treat Moderate to Severe Infections:
b-lactamase inhibitor compounds Ampicillin/sulbactam Ticarcillin/clavulanate Piperacillin/tazobactam
Imipenem/cilistatin, ertapenem
Clindamycin + a gram-negative agentFor MRSA
Linezolid ( plus gram negative agent + anaerobic agent)
Vancomycin ( plus gram negative agent + anaerobic agent)
Empiric Therapy for Mammalian Bite Wounds
Ampicillin/sulbactam (Unasyn). Amoxicillin/ clavulante (Augmentin).
Ciprofloxacin/Clindamycin (Cipro/Cleocin) *
*for pcn allergic patients
Empiric Therapy for Post-Operative Wound Infections
S. aureus is the most commonly isolated organism in post operative wound infections.In addition, S. epidermidis is a common organism in post operative infections involving implants.
MRSA
TMP/SMX Minocycline For more sever infections, vancomycin or linezolid
MSSA
Cephalosporins (cefazolin, cephalexin, cefdinir) Amoxicillin/clavulanate Levofloxacin
Clindamycin
Antibiotic Therapy for Methicillin Resistant Staph. aureus (MRSA)
Differentiate Community Acquired MRSA (CA-MRSA) from Hospital Acquired MRSA
(MA-MRSA)
In general, CA-MRSA retains susceptibility to TMP/SMX and Tetracycline.HA-MRSA is resistant to TMP/SMX and tetracycline and like CA-MRSA is sensitive to vancomycin and
linezolid.
What both CA-MRSA and HA-MRSA have in common is the mec-A gene, making them resistant to all beta-
lactam drugs.
MRSA Risk Factors
Patients in acute care and nursing facilities. Individuals who have undergone previous antibiotic therapy
Those in proximity to patients infected or colonized with MRSA
Patients with CA-MRSA may have no known risk factors.
286 The 2005 Podiatry Study Guide
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
5/20
Antimicrobial Therapy for MRSA
Vancomycin Tetracycline (minocycline/doxycycline) TMP/SMX Quinupristin/Dalfopristin Linezolid
Vancomycin (Vancocin)
Drug of Choice (DOC) for MRSA Use parenterally for systemic infections. Use orally for C. difficile colitis Concomitant use with an aminoglycoside can lead to additive nephrotoxicity Monitor serum concentration (peak and trough levels) and renal function (serum creatinine) Hemodialysis removes little or no vancomycin. Use 1g Q7-10 days in functionally anephric adults If red-man/red neck (anaphylactoid) reaction occurs, infuse slowly(over 60 minutes ) and pre-medicate with
Benedryl. Administration of vancomycin 500mg q6h as opposed to 1g q12h will also minimize reaction Poor bone penetration. Combine with rifampin for additive effect
Trimethoprim/Sulfamethoxazole (TMP/SMX) (Bactrim/Septra)
Do not use in patients with an allergy to sulfa drugs Most common adverse effect is skin rash which may limit its use Hematologic adverse reactions and bone marrow toxicity / neutropenia have also been reported Commonly used in the treatment of urinary tract infections and by patients with HIV disease for
Pneumocystis carinii pneumonia (PCP) prophylaxis Combine with Rifampin for additive effect.
Quinupristin/Dalfopristin (Synercid):
Active against MRSA/VRE. Parenteral only.
Use within 30 minutes of reconstitution to prevent crystallization.
Linezolid (Zyvox)
Active against MRSA/VRE. Oral and parenteral forms available. High bioavailability after oral administration . In terms of blood levels; 600mg BID P.O. = 600mg BID I.V.
Medicine | Podiatric Infectious Diseases 287
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
6/20
288 The 2005 Podiatry Study Guide
OralAntibiotics
(+)good
(+/-)fair
(-)noactivity
Generic
UsualDose
TradeName
MRSA
Gram
+
Gram-
P.aeruginosa
Anaerobes
Cephalexin
250mg-500mg
Q6h
Keflex
(-)
(+)
(+)
(-)
(-)
Dicloxacillin
500mgQ6h
Dynapen
(-)
(+)
(-)
(-)
(-)
Clindamycin
150mg-450mg
Q6h
Cleocin
(-/+)
(+)
(-)
(-)
(+)
Ciprofloxacin
500mgQ12h
750mgQ12h
Cipro
(-)
(+/-)
(+)
(+)
(-)
Azithromycin
500mgday1then
250mgday2-5
Zithromax
(-)
(+)
(-)
(-)
(-)
TMP/SMX
1DSQ12h
Bactrim
(+)
(+)
(+)
(-)
(-)
Amoxicillin/Clav
500mgQ12h
875mgQ12h
Augmentin
(-)
(+)
(+)
(-)
(+)
Metronidazole
500mgQ8H
Flagyl
(-)
(-)
(-)
(-)
(+)
Theabovetablesareintendedonlyasastudyguideandarebasedonpodiatricallyreleva
ntpathogenswithinagivenclass.Definitivean
tibi-
otictherapyshouldbebasedoncultureresults
andMICs.
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
7/20
ParentalAntibiotics
(+)g
ood
(+/-)fair
(-)noactivity
Medicine | Podiatric Infectious Diseases 289
Generic
UsualDose
TradeName
MRSA
Gram
Positive
Gram
Negative
P.aerugoinosa
A
naerobes
Cefazolin
1g
Q6-8H
Ancef
(-)
(+)
(+)
(-)
(-)
Clindamycin
15
0mg-900mg
Q6-8H
Cleocin
(-)
(+)
(-)
(-)
(+)
Vancomycin
1g
Q12H
Vancocin
(+)
(+)
(-)
(-)
(-)
(exceptC.
difficile
(+))
Nafcillin
500mg-1.5mg
Q
4-6H
Unipen
(-)
(+)
(-)
(-)
(-)
Aztreonem
1gQ8H
Azactam
(-)
(-)
(+)
(+)
(-)
Ampicillin/
Sulbactam
3gQ6H
Unasyn
(-)
(+)
(+)
(-)
(+)
Ticarcillin/
Clavulanate
3.1gQ6H
Timentin
(-)
(+)
(+)
(-)
(+)
Piperacillin/
Tazobactam
3.375gQ6H
Zosyn
(-)
(+)
(+)
(-)
(+)
Imipenem/
Cilistatin
50
0mgQ6H
Primaxin
(-)
(+)
(+)
(+)
(+)
Cefipime
2g
Q12H
Maxipime
(-)
(+/-)
(+)
(+)
(-)
(exceptC.perfringens(+/-))
Thea
bovetablesareintendedonlyasastudyguideandarebasedonpodiatricallyrelevantpathoge
nswithinagivenclass.Definitiveantibi-
otictherap
yshouldbebasedoncultureresultsandMICs
.
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
8/20
Antibiotic Caveats and Facts
Ticarcillin/ Clavulanate
High sodium load (avoid in patients with CHF).
Imipenem/Cilistatin
Associated with dose-related seizures (use with caution in patients with seizure history). Cross
reativity in patients with anaphylaxis to penicillin
Quinolones
Associated with tendinitis and tendon rupture. Studies involving the use ofciprofloxacin in children with cyctic fibrosis have shown that quinolones can be used
with relative safety in this age group Ciprofloxacin: Most active quinolone against P. aeruginosa Levofloxacin : More active against gram positive aerobic cocci than ciprofloxacin
Clindamycin
Associated with C. difficile colitis. Active against Gram positive aerobes and anaerobes.Combine with a quinolone for gram negative coverage
Metronidazole
Has no aerobic coverage (do not use it as single agent therapy in foot infections) Metronidazole has been shown to be more active against B. fragilis bloodstream isolates
than clindamycin. Mild disulfuram reaction. Drug of choice for C. difficile colitis
Rifampin
An anti-tuberculous drug with activity against S. aureus. Rifampin should not be usedalone since rapid resistance can develop. Use in combination with vancomycin forMRSA. May impart an orange color to the urine and cause a pink staining of soft contactlenses. May interfere with activity of oral contraceptives
Aminoglycosides
Nephrotoxic and ototoxic. Monitor serum levels with peaks and troughs. Try not to use
for diabetic patients. There are better, albeit more expensive ways to cover gram negatives(e.g., quinolones, aztreonam)
Piperacillin/Tazobactam
Not recommended for monotherapy of P.aeruginosa at3.375g q6h. (Med Lett Drugs Ther 1994 Nov 25;36(936):110). Many strains of P. aerugionsa have becomeresistant to the anti-pseudomonal penicillins by virtue of their hyperproduction of beta-lactamase
Cefepime
Fourth generation cephalosporin. Good activity against P.aeruginosa
Bactrim
Good bioavailability after oral administration. Can cause neutropenia. No anaerobic coverage
290 The 2005 Podiatry Study Guide
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
9/20
Antibiotic Selection in Pregnant Patients / FDA Risk Categories
Base your antibiotic choice on the FDA assigned risk category. Choose the drug from the safest category that
will cover the infecting organism. A= safest / D= least safe.
FDA Category A
NONE
FDA Category B
penicillins, cephalosporins clindamycin aztreonam meropenem erythromycin/azithromycin metronidazole terbinifine
FDA Category C
imipenem/cilistatin quinolones trimethoprim/sulfamethoxazole vancomycin rifampin itraconazole
FDA Category D
aminoglycosides
tetracyclines
Ordering Lab Tests
CBC/ Differential
Acute infection is characterized by an elevated WBC count (absolute leukocytosis), as well as a shift to the left
(increased number of immature or band cells)
Renal Function Tests
Evaluate renal function and dose adjust antibiotics accordingly BUN largely dependant on the hydration status of the patient and therefore of limited use. Serum Creatinine - a more sensitive indicator of renal function than BUN. Serum creatinine may not
accurately reflect the patients renal function in the elderly who may have decreased creatinine production.Creatinine clearance is a better measure.
Creatinine Clearance most useful for antibiotic dose adjustment. Can either be had via a 24 hour urine
collection or derived using the patients serum creatinine and the equation ofCockroft and Gault
Medicine | Podiatric Infectious Diseases 291
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
10/20
Estimating creatinine clearance using serum creatinine
Modified equation of Cockroft and Gault
Intended for ages 18-110, serum creatinine 0.6-7 mg/dl
NOTE: This is the more popularly used version of the Cockroft-Gault formula at present. See literature for
supporting data (e.g., Hutson P et al. Carboplatin Dosing in Obese Patients. Proc Am Soc Clin Oncol 2000, abstract
725). Ccr = (140-age) (weight in kg) For females multiply result by 0.8572 X serum creatinine (1kg = 2.2 lbs)
Note: the following antibiotics do not need dose adjustment for patients with renal impairment: amphoterecin B,
azithromycin, ceftriaxone, clindamycin, nafcillin, trovafloxacin
ESR
Non-specific. Although elevated in any inflammatory process, a patient with a non-healing foot ulcer and a sig-
nificantly elevated ESR is suspicious for underlying osteomyelitis.
Wound, Bone and Blood Cultures
Order aerobic, anaerobic, acid-fast and fungal cultures where clinically indicated.
Principles of Wound Cultures
Prep wound site to remove surface bacteria Take a deep culture. Avoid contact with surrounding skin Include tissue if possible (pus is a sub-optimal culture source since it contains mainly WBCs and phagocy-
tized bacteria) Use proper transport media with respect to the organism being cultured Rapid transport to lab
Principles of Bone Cultures
With the possible exception of S. aureus, sinus tract cultures are rarely helpful in establishing the causative
organism in osteomyelitis. The diagnosis of osteomyelitis rests with the isolation of the organism from bone Sinus tract cultures are unreliable in predicting the infecting organism in bone Bone biopsy is diagnostic If possible, approach bone through uninfected tissue Send bone for microscopic diagnosis. Send bone for Grams stain Order aerobic and anaerobic cultures If clinically indicated, also order acid fast and fungal cultures and stains
Principles of Blood Cultures
Draw 2 sets 15 minutes apart (from different sites) If an organism grows from only one bottle, suspectcontamination.
Drawing blood cultures on a fever spike may be of benefit
292 The 2005 Podiatry Study Guide
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
11/20
Ordering Stains
Results of cultures and MICs can take days (bacterial) to weeks (fungal and mycobacterial) to return. Ordering
the appropriate stain/smear can provide a clue to the infecting organism in the interim.
Bacteria Grams stain
Fungi KOH prep., PAS stain
Mycobacteria Acid fast stain Virus Tzanck smear
Grams Stain
Terminology relates to appearance
Staphlococcus = cluster of berries Streptococcus = twisted chain of berries
A Grams Stain That Reveals Would be
Gram positive cocci in clusters Staphlococcus
Gram positive cocci in chains Streptcoccus
Coagulase Positive vs. Coagulase Negative Staph
Coagulase positive (invasive) Staph aureus
Coagulase negative (non-invasive) Staph. epidermidis
Soft Tissue Infections
Necrotizing Fasciitis
Infection characterized by rapidly progressing necrosis and edema of subcutaneous fat and fascia.
Patient is acutely ill with fever, tachycardia and leukocytosis with bandemia Extremity is initially hot, erythematous, edematous and exquisitely tender Edema is hard and non-pitting and may extend beyond erythema Skin becomes dusky with vesicles and bullae filled with deep purple fluid
Process spreads rapidly along subcutaneous tissue and undermines superficial fasciaproducing cutaneous anesthesia and eventually skin gangrene and slough
Grey, stringy, subcutaneous fascia, liquefaction necrosis and the presence of a thin, watery, foul smelling exu-date (dishwater pus) are characteristic
Rapid progression may result in loss of limb or death Bacteriology varies widely. No single organism is pathogneumonic. Aerobic and anaerobic bacteria have been
identified including Streptococci group A, Clostridia spp. and Bacteroides spp. Treatment is directed toward aggressive surgical debridement, broad spectrum antibiotics and stabilization of
the patient medically
Common Cutaneous Viral Infections
Herpes Zoster (Shingles)
Painful vesicles on an erythematous base in a dermatomal distribution.Etiology: reactivation of Varicella Zoster (chickenpox) virus (VZV).
More common in elderly and immunocompromised patients.
Herpes simplex (HSV)
Painful vesicles or pustules on an erythematous base, but no dermatomal distribution as in Herpes Zoster.
HSV-1 typically affects above the waist, HSV-2 typically below
Molluscum Contagiosum
Painless 3-6mm pearly papules with central umbilication. Etiology: Molluscum contagiosum virus
(poxvirus). Spread by person to person contact
Medicine | Podiatric Infectious Diseases 293
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
12/20
Verruca
Etiology: Human Papilloma Virus (HPV). Distinguishing features include the presence of punctate black dots(thrombosed capillaries) and interruption of skin lines
Joint Infections
Infectious ArthritisAny warm, swollen joint should be considered infected until proven otherwise.Antibiotic therapy should be guided by the patients age, the results of the synovial fluid analysis, culture and
Grams stain.
Commonly Isolated Organisms
Infants and young children (
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
13/20
Gonococcal Arthritis (GCA)
Usually develops within 3 weeks of onset of genitourinary infection Patient may be otherwise asymptomatic Migratory polyarthralgia with periarticular inflammation is typical in the early phase of GCA.
Vesiculopustular skin lesions may be present As the disease progresses, skin lesions resolve. Arthritis settles into one or two joints. The arthritis of dissemi-
nated GCA is asymmetrical The diagnosis of gonococcal arthritis depends on culture and identification of the organism. Obtain cultures
of blood, joint fluid and skin lesions
HIV-related Arthropathy
More than half of all patients infected with HIV will experience some bone or joint symptom during thecourse of their disease
Reiters syndrome and reactive arthritis are the most common etiologies followed by Psoriatic arthritis and Septic arthritis (Candida species, C. neoformans, H. capsulatum, Salmonella, S. schenkii, M. avium intracel-
lulare, M. tuberculosis)
Infectious Causes of Heel Pain
Heel pain accompanied by inflammatory signs should raise the suspicion of osteomyelitis.
Although the most common pyogenic organism responsible for puncture wound osteomyelitis is P. aeruginosa,virtually any organism implanted into soft tissue or bone has the potential to cause osteomyelitis. Foreign body pen-etration may inoculate not only pyogenic bacteria, but fungi and mycobacteria as well. Lymphocutaneous sporotri-chosis, chromoblastomycosis, phaeohyphomycosis and mycetoma are among the more common mycotic syndromesarising from puncture wounds associated with soil, thorns and wooden splinters.
Routine bacterial culture and Grams stain may not demonstrate the presence of these organisms. Negative bac-terial cultures of clinically infected areas should raise suspicion. It is therefore prudent to perform biopsy of boneand soft tissue as well as aerobic, anaerobic, acid-fast and fungal cultures when clinically indicated.
Reactive arthritis, including Reiters syndrome must be considered in any evaluation of heel pain. Reactivearthritis is an aseptic synovitis arising from a previous non-articular infection.. Reiters syndrome requires host pre-disposition, which is thought to be linked to human leukocyte antigen HLA-B27.Reactive arthritis can be triggeredby various organisms, including species of Campylobacter, chlamydia, Salmonella, Shigella and Yersinia.
Bone Infections
Diagnosis of Osteomyelitis
X-ray changes lag 10-14 days behind bone changes 99Tc-HMPAO(Ceretec) Scansand the gadolinium enhanced-fat suppressed MRIare the 2 most sensitive
imaging modalities. They are particularly useful in differentiating chronic osteomyelitis from Charcotosteoarthropathy
Biopsy, culture and Grams stain of bone are the gold standards of diagnosis
Treatment
Acute osteomyelitis can be cured by antibiotics alone. Chronic osteomyelitis requires surgical debridement of
the infected bone for cure. Antibiotics directed against the causative organism are adjunctive.
General Principles
Debride area clean of infected and devitalized bone. Be certain arterial supply to area is adequate to supporthealing
Medicine | Podiatric Infectious Diseases 295
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
14/20
Remove implanted biomaterials and fixation devices unless such device is providing osseous stability to afracture site or osteotomy
Obliterate dead space with appropriate packing material If there is any question as to whether infected bone remains, follow debridement by 4-6 weeks of antibiotic
therapy directed against the causative organism. If possible, administer antibiotics parenterally
Assessing Efficacy of Treatment After Debridement
Monitor for signs of clinical improvement Compare plain x-rays at 7-10 day intervals against post-debridement films.
Monitor WBC and differential, ESR and oral temperature
Osteomyelitis: Classification Systems
Waldvogel Classification System
hematogenous direct extension vascular insufficiency
Cierney - Mader Classification System
Anatomic Type Stage 1: Medullary osteomyelitis Stage 2 : Superficial osteomyelitis Stage 3: Localized osteomyelitis Stage 4 Diffuse osteomyelitis
Physiologic Class
A Host: Normal host B Host: Systemic compromise (Bs)
Local compromise (Bl)Systemic and local compromise (Bls)
C Host: Treatment worse than the disease
Systemic or Local Factors That Effect Immune Surveillance, Metabolism and Local Vascularity
Systemic (Bs) Local (Bl) Malnutrition Chronic lymphedema Renal, hepatic failure Major vessel compromise Diabetes mellitus Small vessel disease Chronic hypoxia Vasculitis Immune disease Venous stasis Malignancy Extensive scarring Extremes of age Radiation fibrosis Imunosupression or immune deficiency Neuropathy
Tobacco abuse
Osteomyelitis: Commonly Isolated OrganismsCierney-Mader Stage 1 (Monomicrobic Infection)
Infant Childhood Adults
< 1 year 1-16 years > 16 yearsGroup B Strep S. aureus S. aureusStaph. aureus Strep. Pyogenes S. epidermidisE. coli H. influenzae Gram positive bacilli
P. aeruginosaS. marcescensE. coli
296 The 2005 Podiatry Study Guide
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
15/20
Cierney-Mader Stages 2,3 and 4 (Polymicrobic Infection)
S. aureus Diabetic Foot Osteomyelitis S. epidermidis S. aureus Strep pyogenes Streptococcus species Enterococcus species Enterococcus species Gram negative bacilli Proteus mirabilis
Anaerobes P. aeruginosaAnaerobes (B. fragilis)
Update on the diagnosis and management of osteomyelitis
Mader J, Ortiz M, Calhoun J. Clinics in Podiatric Medicine and Surgery Vol 13, No 4 October 1996
Infections in the Surgical Patient
Surgical Wound Prophylaxis
The goal of an effective prophylactic regimen is to decrease the numbers of pathogenic organisms below levelsnecessary to cause infection.
Surgical Wound Prophylaxis Has Been advocated in four clinical situations
Implant usage
Trauma surgery Prolonged operating time (>2-3 hours) The immunocompromised patient
To be effective, a prophylactic regimen must satisfy two criteria. First, the antibiotic must be active against thepathogen most likely to be encountered in a given situation and second, peak serum concentrations should beachieved at the time of inoculation.
S. aureus is the most commonly isolated organism in post operative wound infections.For orthopedic procedures therefore, cefazolin (Ancef) has proven effective. In settings where MRSA is an
important pathogen, vancomycin (Vancocin) should be used.
Trauma
The severity of the fracture is the major determining factor as to whether or not infection will occur.Infection following fracture varies with the degree of injury
Grade I fracture 0 - 9% Grade II fracture 1% - 12% Grade III Fracture 9% - 55%
In the case of open fractures the length of antibiotic administration is proportional to the severity of the infection.
Prophylactic antibiotics for Type 1 and II fracture is maximally effective if given for no more than 24 hoursafter surgery.
For type III fractures continuation of antibiotics for 48 hours appears warranted assuming adequate soft tis-sue coverage after surgery.
The length of antibiotic administration should be extended if there appear to be signs and symptoms ofinfection.
Although statistically S. aureus is the most common infecting organism in traumatic fractures, one must becognizant of organisms which inhabit the environment in which the trauma was sustained . Antibiotic choicesshould be made accordingly.
When instituting antibiotic prophylaxis for patients with distant prosthetic joints who undergo incision anddrainage of infected tissue, base antibiotic selection on preoperative Grams stain and culture results or the antici-pated organism. It is not necessary to use antibiotic prophylaxis to protect distant prosthetic joints who are under-going clean orthopedic surgery, since bacteremia is unlikely to occur.
Medicine | Podiatric Infectious Diseases 297
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
16/20
Lower Extremity Surgery and Patients with HIV
Regardless of their CD4 lymphocyte count, HIV-infected patients undergoing surgery have not been demon-strated to have a greater than usual rate of complication or a greater than usual rate of post-operative wound infec-tion.
T-cell mediated immunity is severely impaired in HIV infected patients, which is reflected by an increase in thenumber of intracellular pathogens such as viruses and non-pyogenic organisms as well as some extra-cellular organ-
isms such as fungi and Pneumocystis, for which T-cell mediated immunity is the primary defense. Neutrophil medi-ated immunity on the other hand remains largely intact in HIV-infected patients.
Infections for which the bodys primary defense is the T-cell mediated immunity (TB, parasites, mycobacteria)are thus more common in the HIV infected population. However, those infections for which the primary defense isthe white blood cell or neutrophil (pyogenic bacteria such as Staph and Strep) are not significantly more common
in non-neutropenic HIV patients.
Recommendations for perioperative surgical prophylaxis remain identical for HIVpositive and HIV negative patients
The choice of antibiotic and dosage for a given infection is identical whether a patientis HIV positive or HIV negative and regardless of CD4 lymphocyte count
The use of markers such as viral load and CD4 lymphocyte count as an arbitraryqualification for surgery (e.g., CD4 cutoff lines as a criterion) is both unwarrantedand unsubstantiated in the literature
Common Causes of CD4 Lymphocytopenia (CD4 Count Less Than 300)
Human immunodeficiency virus infection Mycobacterium tuberculosis infection Granulomatous disease (e.g., sarcoid) Malignancy Acute viral infection Immunosuppressive medication (corticosteroids, cyclophosphamide, cyclosporine)
Pregnancy
Malnutrition
Aging
CD4 Counts at which Opportunistic Infections Occur
< 200/mm3
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
17/20
Moderate Risk Category (endocarditis prophylaxis recommended)
Acquired valvular dysfunction Hypertrophic cardiomyopathy
Mitral valve prolapse with valvular regurgitation and/or thickened leaflets
Negligible Risk Category (endocarditis prophylaxis NOT recommended)
Previous coronary bypass surgery (CABG) Mitral valve prolapse withoutregurgitation Physiologic, functional or innocent heart murmurs Previous rheumatic fever w/o valvar dysfunction Cardiac pacemakers and implanted defibrillators
Endocarditis prophylaxis regimen for patients undergoing lower extremity surgery
Based on AS, Taubert KA, Wilson W, Bolger AF, Bayer A, Ferrieri P, et al. Prevention of bacterial endocarditis. Recommendations
bythe American Heart Association. JAMA 1997;277:1794-801.
Oral
No Penicillin allergy
Cephalexin 2g PO 1 hour before surgery
Penicillin allergy
Clindamycin 600mg PO 1 hour before surgery
Parenteral
No Penicillin allergy
Cefazolin 1g IV 30 minutes before surgery
Penicillin allergy
Clindamycin 600mg 30 minutes before surgery
C. difficile Colitis
Consider C. difficile colitis in any patient who develops diarrhea while on antibiotics.C. difficile colitis can also occur after antibiotics are stopped. Although it is most commonly associated withclindamycin, it can occur with most any antibiotic. Symptoms can range from mild diarrhea to crampy abdominal
pain, fever, leukocytosis and watery diarrheal stools > 4 /day.
Diagnosis is by C. difficile toxin titers (from stool sample). Definitive diagnosis is by colonoscopy (visualizingthe pseudomembranes on the bowel wall).
Treatment of C. difficile colitis:
Orally administered Metronidazole. Parenteral metronidazole can also be used if patients cannot use oral route Orally administered vancomycin (for patients fail metronidazole therapy) Vancomycin is poorly absorbed
from the gastrointestinal tract resulting in high intraluminal concentrations. Nephrotoxicity from orally
administered vancomycin can occur.
Tetanus
Symptoms of tetanus usually appear within of 3-21 days after inoculation but can occur between 1 day toseveral months
Localized tetanus- muscle spasm and rigidity begin local to the area of injury. May progress to generalized form Generalized tetanus- muscle spasm begins with masseter and spreads to affect entire body Clostridium tetani is an obligate anaerobe. Treat with metronidazole 500mg q6h or 1g q12h IV Diazepam can be used to control muscle spasms.
Medicine | Podiatric Infectious Diseases 299
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
18/20
Prevention of Tetanus
Categorize wound as being either low or high risk If wound is tetanus prone, begin prophylaxis
Clean (Low Risk)
Clean incised wound Superficial graze
Scald
Tetanus Prone (High Risk)
Wounds neglected > 24 hours Any wound with one or more of the following:
Contact with soil, manure, compost Open fracture Puncture type wound Large amount of devitalized tissue Gunshot wound Animal or human bite Infected wound Foreign bodies
*TIG-tetanus immune globulin.Unless more than 10 years since last dose.Unless more than 5 years since last dose.
Note: Tetanus immune globulin and Td may be given simultaneously but in different sites. Substitute DTP orDTaP vaccine for children under 7 years of age.
New York State Dept. of HealthImmunization Guidelines for Health Care Providers 2001
300 The 2005 Podiatry Study Guide
History of tetanus Immunization (doses) Clean, minor wounds
Td (Adult) TIG*All other woundsTd (Adult) TIG
Uncertain or
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
19/20
References
1. Antrum R, Solomkin J. A review of Antibiotic Prophylaxis For Open Fractures. Orthop review. 16: 246-254,1987.
2. AS, Taubert KA, Wilson W, Bolger AF, Bayer A, Ferrieri P, et al. Prevention of bacterialendocarditis (Recommendations by The American Heart Association.) JAMA
1997; 277:1794-801.
2. Gilbert D, Moellering R, Sande M. The Sandford Guide to Antimicrobial Therapy. Antimicrobial Therapy
Inc. pub.30th edition. 2000
3. Armstrong D, Cohen J. Infectious Diseases, eds. Mosby ed. 1999.
4. Joseph W, Kosinski M.Prophylaxis in Lower Extremity Infectious Diseases.Clinics in Podiatric Medicine and Surgery, Vol 13, No 4. October 1966.
5. Kosinski, MA, Lilja E. Infectious causes of heel pain.J Am Podiatr Med Assoc.January; 89(1): 20-3. 1999.
6. Kosinski M, Rodriguez A. Bone and Joint Manifestations of Systemic Infectious Diseases. Clinics inPodiatric Medicine and Surgery, Vol 1,5 No 4. October 1996.
7. Mader J, Ortiz M, Calhoun J. Update on the Diagnosis and Management of Osteomyelitis.Clinics in Podiatric Medicine and Surgery, Vol 13, No 4. October 1996.
8. Med Lett Drugs Ther 1994 Nov 25;36(936):110
9. Saxon A, Adelman DC. Imipenem cross-reactivity with penicillin in humans.
J Allergy Clin Immunol. 1988. Aug; 82(2): 213-7.
Medicine | Podiatric Infectious Diseases 301
-
8/2/2019 Chapter 4d Podiatric Infectious Diseases
20/20