BAHAGHARI Surgical Infection SURGERY

1 Surgery: Surgical Infections Lecturer: Dr. Acuna September 1, 2015
 HOST DEFENSES 1. Skin • resident microflora • Staphylococcus epidermidis • Propionibacteria • Corynebacteria • shedding of skin cells • chemicals from sebaceous gland • oily skin • Beta hemolytic step • 80% of damage from scratching; remaining 20% plucking hair, shaving, tight clothing insect bites Skin abscess board exam question: What is the first question you will ask for a patient complaining of skin abscess? A: Do you have history of chronic itching? ———————————————————— • make wide incision (as wide as as the lesion) incisional drainage: never squeeze

• incisional drainage: never squeeze

affected area to evacuate fluid; spread of

infection may go downward

• non-immunocompromised

• treatment: incisional drainage only

• immunocompromised

• acquired

• congenitally immunocompromised

• extremes of age

• steroids

• cancer therapy: chemo, radiation

• tx: incisional drainage + antibiotic

• S. aureus = non-foul smelling;

• E. coli = fouls smelling

Carbunle • crater-like, cluster of boils • polymicrobial: Staph and Strep • if with MRSA, tx: linezolin • and necessary debridement of wound

2. Respiratory Tract • cilia • mucus • macrophages (few in the upper RT) • normal flora • alpha and beta hemolytic strep • anaerobes • staph • diptheroids - commensals • neisseria (non-meningitidis) • hemophilus • mycoplasma • pneumococcus 3. Stomach • acidic environment kills most bacteria, except for H. pylori (highly resistant to acid • use of proton pump inhibitors (PPIs)
 -> acid reduction -> makes stomach susceptible for bacterial infection • highest bacterial count after eating • bacteria from oral cavity plus bacteria from food • bacteria almost undetectable after digestion (2-3 hours after eating) 4. Small bowel • streptococci - gram (+) • lactobacilli - gram (-) • bacteroides - anaerobes • these are more common in lower GI • all of these are transients, normal flora 5. Colon - polymicrobial • anaerobes (95-99%) antibiotics for • bacteroides anaerobes • bifidibacteria • clostrida metronidazole, • eubacterium clindamycin • lactobacillus • peptostreptococcus • aerobes • E. coli • enterobacteria • enterococci • candida • bacterial translocation to blood vessels is termed bacteremia.

Cellulitis • streptococcal = thin and watery • treatment: ??

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2 Sterile areas areas without the presence of bacteria

Microbial infection

• biliary and pancreatic • lower respiratory • urogenital tract *note: sepsis in these areas are very critical cases because they are supposed to be strictly sterile. introduction of micro-organismis may be due to the following conditions: • malignancy • inflammation • calculi • foreign body introduction of micro-organisms from external sources: • catheters • IFC • ET

Defenses in body cavities • lactoferrin and transferrin • iron is an important microbial growth factor stomata in diaphargm • omentum • • macrophages, complement, immunoglobulin, PMNs • fibrin - “langib ng sugat” For open wounds, do not remove fibrin; however, if fibrin deposits are found in the lungs, do remove them as these accumulations may impede respiratory function.

Consists of: • Eradication • competent immune system Containment • • failure to eradicate • collection of pus/abscess formation Locoregional infection • failed containment • • System infection • bacteremia, “pumasok sa dugo” • not yet sepsis Comments, in-lecture Reference value for blood sugar = 60-100 However, wounds will still heal well if level is at 250 or less. Therefore, diabetes by itself is not enough basis whether wounds will heal well or not.

RELEVANT DEFINITIONS: SIRS • may come from the ff: (2 out of 4) • trauma, • aspiration, • pancreatitis, • burn Infection: documented presence of microorganism 

sepsis: infection + SIRS 
 (a negative culture does not mean (-) sepsis) severe sepsis: +organ dysfunction septic shock: +organ failure

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3 INFECTIONS OF SIGNIFICANCE IN SURGICAL PATIENTS

• • • • •

Surgical site infections (SSI)

Intra-abdominal infection

Organ-specific

Skin and soft tissue infection

Post-op nosocomia infection

A. Surfical site infection (SSI)

• infection of tissues, organs and spaces exposed by surgeon during operation

• 0-30 days (occurence)

• 1 year if mesh, vascular graft, joint prosthesis, heart valves

• within 5 days (usual onset)

• severe if within 24 hours d/t Strep or Clostridias

Incisional

I. 
 CLEAN 
 1-2% infection rate

II. CLEAN CONTAMINATED 2-10 infection rate

Organ / Space

Superficial • skin and SQ only • fascia uninvolved

Body cavity involved

Deep • fascia involved

Peritonitis

III.
 CONTAMINATED 3-13% infection rate

Patient factors

Local factors

• older age • immunosuppression • obesity, malnutrition • DM • chronic inflamm • anemia • smoking (no. 1 volunatry cause of CA) • renal failure • peripheral vascular disease • radiation and previous sx

• open sx vs laporoscopy • poor skin prep • contaminated instruments • poor prophylactic antibiotic • prolonged procedure • local tissue necrosis • blood transfusion • hypothermia, and hypoxemia

Mga puwede mong sisihin sa pasyente :))

Microbial factors • prolonged hospitalization

• toxin secretion

• resistance to clearance (capsule)

IV. DIRTY 3-13% infection rate

• RT, GU, GI entered • uninfected, no contamination • closed primarily • examples: • MRM • thyroid • hernia • vascular splenectomy • RT, GU, GI entered • controlled contaminants • closed primarily • examples • chole • uncomplicated AA • gastric • small bowel • colon • trachea • bronchii • open, fresh accidental wounds • major breaks in sterile technique • gross spillage from GIT • examples • AA • Chole with bile spillage • diverticulitis • rectal surgery • penetrating wounds • old, traumatic wounds • existing infection or perforation • organism present before surgery • examples: • abscess • perforated viscus • peritonitis, • (+) pre-op cultures

Surgical wound classes • Class I and II = close primarily

• Class III, IV = primary closure assoc with 25-50 infection rate

• secondary intention (secondary wound closure

• tertiary intention (delayed primary wound closure)

• primary closure with drains


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4 B. Intra-abdominal 1. Primary peritonitis • sources: • hematogenous • direct innoculation • medical management • 2-3 weeks antibiotic • remove catheter • recurrent 2. Seconday peritonitis • secondary to another intra-abdominal case • appendicitis • meckel’s diverticulitis • diverticulitis (anaerobe) • treatment is surgical (source control) • mortality rate 5-6% • failure to achieve source control increases mortality rate to >40% • priorities: • resuscitation + antibiotic

3. Tertiary peritonitis • in immuno-compromised patients • reccurent type • polymicrobial • S. epidermidis • Candida • Enterococcus • Pseudomonas • >50% mortality rate even with antibiotics C. Organ specific 1. Liver abscess • CT scan - 10cm or more • non-septated • amoebic • septated • bacterial • most likely E. coli

2. Pancreatic abscess • polymicrobial • multibacterial - gram (-) aerobe

D. Soft tissue 1. Necrotizing fasciitis / Fournier’s disease • anaerobes • polymicrobial • source control




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5 2. Cellulitis • streptococcus 3. Lymphangitis • spreading cellulitis • streptococcus

Anaerobes Gram (+) Anaerobes Clostridium difificile Clostridium perfingens C. tetani, C. septicum Peptostreptococcus spp. Gram (-) Anaerobes Bacteroides fragilis Fusobacterium spp. Virus

E. Post-op nosocomial infections Review and memorize this table daw:

Cytomegalovirus Epstein-Barr virus Hepatitis A, B, C Herpes Simplex virus Human immunodefficiency virus Varicella zoster virus

Fungi MICROBIOLOGY OF INFECTIOUS AGENTS

Gram (+) Cocci Staphylococcus aureus Staphylococcus epidermidis Streptococcus pyrogens Streptococcus pneumoniae

Aspergillus fumingatus, A. niger, A. terreus, A. flavus
 Blastomyces dermatitidis Candida albicans
 Candida glabrata, C. paropsilosis, C. krusei
 Coccidiodes immitis
 
 Cryptococcus neoformans Histoplasma capsulatum
 Mucor/Rhizopus

Enterococcus faecum Enterococcus fecalis Other Bacteria Gram (-) Bacilli
 (*KEEPS*) Escherichia coli * Haemophilus influenzae Klebsiella pneumoniae * Proteus mirabilis Enterobacter cloacae, aerogenes * Serratia marcescens * Acinetobacter calcoaceticus Citrobacter fruendii Pseudomonas aeruginosa * Xanthomas maltophilia

Mycobacterium avium-intercellulare
 
 Mycobacterium tuberculosis 
 (old wound with multiple fistula)
 Nocardia asteroides 
 (black lesions which are highly contagious) Legionella pneumophilia
 Listeria monocytogenes

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6 PREVENTION OF SURGICAL INFECTIONS



A. Sepsis and antisepsis B. Prophylactic antibiotics • broad spectrum • given 30 minutes to one hour prior to incision • antibiotic should reach subcutaneous tissue before cutting • repeat dosing for prolonged surgery (>4 hours) • discontinued within 24 hours C. Shaving- done immediately prior to incision • risk for micro-wounds

1.Principles of antibiotic prophylaxis • select antibiotic for common bacteria on surgical site • give antibiotics 30 mins before surgery • redose antibiotics for prolonged operations • discontinue after 24 hours

D. Surgical scrub - routinely done E. Prepping • 7.5% betadine first -> 10% betadine • antiseptic effect is for 4 hours TREATMENT OF SURGICAL INFECTIONS A. Organized approach to therapy includes the ff: 1. rapid rescuscitation 2. antibiotics 3. source control • incision and drainage • wound debridement • abdominal exploration (7 days before air dissapears post op) • amputation B. Appropriate antimicrobial use • Knowledge of microflora in area involved • lower GI = Anaerobes > Gram(-) >Gram (+) • Knowledge of antimicrobial spectrum of activity • Monotherapy = Cefotixin or Cefotetan • Polytherapy • Metronidazole + Cefuroxime • Metronidazole + Aminoglycoside • Clindamycin + Quinolone

Other applications
 Diabetic foot = polymicrobial • monotherapy: sultamicillin • polytherapy: quinolone + clindamycin
 Skin and soft tissue infection = gram (+) • monotherapy: Sultamicilin • polytherapy: quinolone + clindamycin Bowel perforation • if it smells like poop, chances are it is poop • Give clindamycin Cefoxitin = 2nd gen cyclosporin with anti-anaerobic activity; used for GI infections, protocol worldwide

2. Empirical therapy • Progression from prophylactic therapy • no microbiologic data yet (C&S) • only gram stain available • short course of 3-5 days • indications • intraoperative findings (Class I to III) • critically ill patients • sepsis, severe sepsis, septic shock • discontinued after clinical improvement 3. Therapy of established infection • C & S available • de-escalation therapy • narrower spectrum but more precise • MONOMICROBIAL • most nosocomial infections DURATION OF TREATMENT (monomicrobial) UTI

3-5 days

pneumonia

7-10 days

bacteremia

7-14 days

endocarditis, osteomyelitis, prosthetic infections

6-12 weeks

• POLYMICROBIAL • treated primarily by debridement • Culture and sensitivity less important • clinical course dictates if antibiotics need to be changed or not after C & S are out Impact of antibiotic misuse include:
 increased health care cost, drug reactions and toxicity, development of new infections like Clostridium difficile colitis, and multi-drug resistance in nosocomial pathogens

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