INFECTION AND SEPSIS

Surrounded by pathogens Surrounded by pathogens

Infection is the exceptionInfection is the exception

Protective from infectionProtective from infection Physical barriersPhysical barriers Chemical barriersChemical barriers Immunological functionImmunological function

Physical and ChemicalBarriers to Infection

SkinSkin stronger in hands and feetstronger in hands and feet

sebaceous secretions lower sebaceous secretions lower pHpH

Mucous membranes Mucous membranes ciliary functionciliary function mucous barriermucous barrier acid mileu in stomachacid mileu in stomach

Barriers breached in Surgery

Barriers Breached in Trauma

Immune Defense Humoral defenseHumoral defense

antibodiesantibodies complementcomplement

Cellular defenseCellular defense

CytokinesCytokines potential for deleterious potential for deleterious

effectseffects

Interaction of mechanismsInteraction of mechanisms

Breakdown of Host Defense Physical, chemical and immunological Physical, chemical and immunological

breakdown -act synergisticallybreakdown -act synergisticallye.g. patient withe.g. patient with

diabetesdiabetes immunosuppresionimmunosuppresion surgerysurgery

Potential for deleterious effectsPotential for deleterious effects

Fourniers Gangrene

Commensal Microbial Flora

Important for immune developmentImportant for immune development

Occupy binding sites for pathogensOccupy binding sites for pathogens

Provide mucobacterial barrierProvide mucobacterial barrier

Anerobic bacteriaAnerobic bacteria present in greatest quantity in GITpresent in greatest quantity in GIT Greatest diversityGreatest diversity Prevent invasion by gram neg. Prevent invasion by gram neg.

aerobesaerobes

Breakdown of Host Defense- GIT Flora

Transmigration of bacteriaTransmigration of bacteria Lack of feedingLack of feeding Overuse of antibioticsOveruse of antibiotics Absence of bileAbsence of bile Protein malnutritionProtein malnutrition Immune deficiencyImmune deficiency

ICU patient fed enteralyTo preserve GIT integrity

Infection Manifestation Local signsLocal signs

pain,redness,swelling, warmth loss of pain,redness,swelling, warmth loss of functionfunction

Systemic signsSystemic signs Fever, somnolence, confusion, ileus, Fever, somnolence, confusion, ileus,

hypotensionhypotension

Lab testsLab tests TW, polymorphs, CulturesTW, polymorphs, Cultures

Non infective- causes may manifest as Non infective- causes may manifest as infection infection

Common Infections

Wound infectionWound infection

Initial inoculum overwhelms host defenseInitial inoculum overwhelms host defense Occurs at 5 - 7 days post opOccurs at 5 - 7 days post op

FactorsFactors host - immune suppression, DM, renal host - immune suppression, DM, renal

failurefailure surgeon - techniquesurgeon - technique environment - contaminationenvironment - contamination

Common InfectionsTypes of WoundsTypes of Wounds

1.1. Clean - no viscus, no sterile breachClean - no viscus, no sterile breach

2.2. Clean contaminated - controlled entry into Clean contaminated - controlled entry into viscusviscus

3.3. Contaminated - emergency bowel resection, Contaminated - emergency bowel resection, perforated appendixperforated appendix

4.4. Dirty - heavy contamination / long durationDirty - heavy contamination / long duration

Antibiotics usedAntibiotics used type 2 as prophylaxistype 2 as prophylaxis type 3,4 as treatmenttype 3,4 as treatment

Wound Closure

WoundsWounds

Closure byClosure by primary intentionprimary intention secondary intentionsecondary intention

Timing of closureTiming of closure delayed primary delayed primary

closureclosure secondary closuresecondary closure

Closure by Secondary Intention

Intraabdominal Infection

DefenseDefense Bacterial clearance - stomata between Bacterial clearance - stomata between

mesothelial cells under diaphragm lead to mesothelial cells under diaphragm lead to lymph vesselslymph vessels

Phagocytosis - both resident and recruited Phagocytosis - both resident and recruited phagocytesphagocytes

Sequestration - by fibrin rich inflammatory Sequestration - by fibrin rich inflammatory exudate, with omentum/viscera exudate, with omentum/viscera

Intraabdomianal Infection Signs of peritonitisSigns of peritonitis Pain Pain

sharp in character, well localised at firstsharp in character, well localised at first spreads to surrounding areasspreads to surrounding areas involuntary guarding, rigidityinvoluntary guarding, rigidity absent bowel soundsabsent bowel sounds

PosturePosture lying still, rapid breathing ,no lying still, rapid breathing ,no

movementmovement

General conditionGeneral condition ill, septic, dehydrated, hypotensionill, septic, dehydrated, hypotension

Intraabdominal Infection Usually viscus perforationUsually viscus perforation

colon worse than upper GITcolon worse than upper GIT

Isolates Isolates aerobic - E. Coli, klebsiella other aerobic - E. Coli, klebsiella other

enterobacter, strep, enterococci, enterobacter, strep, enterococci, proteus, pseudomonasproteus, pseudomonas

anaerobic - bacteroides, Clostridiumanaerobic - bacteroides, Clostridium

Treatment is surgical and aggressive Treatment is surgical and aggressive antibiotic treatmentantibiotic treatment

Enterocutaneous Fistula

PneumoniaPneumonia Protein malnourishedProtein malnourished upper abdominal wounds ® poor upper abdominal wounds ® poor

coughcough bed bound - atelectasisbed bound - atelectasis elderlyelderly ventilatorventilator

Occurs from 3 days post opOccurs from 3 days post op careful clinical exam,CXRcareful clinical exam,CXR Routine chest physiotherapyRoutine chest physiotherapy

Common Post Surgical Infections

Urinary Tract InfectionUrinary Tract Infection catheterscatheters dehydrationdehydration

Remove catheters Remove catheters earlyearly

Ensure hydrationEnsure hydration

Antimicrobial therapyAntimicrobial therapy

Common Post Surgical Infections

Catheter and prosthetic devicesCatheter and prosthetic devices I/v canulasI/v canulas central linescentral lines meshmesh

Skin organisms- S aureus, S Skin organisms- S aureus, S epidermidisepidermidis

Aseptic techniqueAseptic technique

Remove if infectedRemove if infected

Common Post Surgical Infections

Less Common Post

Surgical Infections

Necrotising soft tissue Necrotising soft tissue infectioninfection

ParotitisParotitis

SinusitisSinusitis

TonsillitisTonsillitis

Treatment of Infection

General principlesGeneral principles incise and drain pusincise and drain pus

antibiotics as neededantibiotics as needed

debride dead tissuedebride dead tissue

remove foreign bodiesremove foreign bodies

Antibiotic Therapy

ProphylaxisProphylaxis Short course to prevent infectionShort course to prevent infection Must be on board before contaminationMust be on board before contamination Antibiotics with activity against expected Antibiotics with activity against expected

inoculation organismsinoculation organisms Avoid extended spectrum agentsAvoid extended spectrum agents Post op benefit not provenPost op benefit not proven Topical antibiotics - not provenTopical antibiotics - not proven

Antibiotic Therapy

Empirical therapyEmpirical therapy based on clinical informationbased on clinical information search for source must continuesearch for source must continue limit duration of empirical therapylimit duration of empirical therapy use known institution pattern of infectionuse known institution pattern of infection multi agent vs broad agentmulti agent vs broad agent

Antibiotic Therapy

Directed therapyDirected therapy target identified pathogenstarget identified pathogens choose suitable efficacy /minimal choose suitable efficacy /minimal

toxicity agenttoxicity agent cover aerobic and anaerobic if cover aerobic and anaerobic if

likelihood exist for bothlikelihood exist for both extended spectrum as last resortextended spectrum as last resort

Multiple System Organ Failure

AKA - Gram neg. bacterial AKA - Gram neg. bacterial sepsissepsis

30% mortality30% mortality

Healthy and compromised hostHealthy and compromised host

3-13 cases per 1000 3-13 cases per 1000 admissionsadmissions

NosocomialNosocomial

FactorsFactors Host compromiseHost compromise Elderly, disabilityElderly, disability MalnutritionMalnutrition Antimicrobial therapyAntimicrobial therapy Major surgeryMajor surgery Cavity manipulationCavity manipulation Immunosuppression e.g. steroidsImmunosuppression e.g. steroids

Multiple System Organ Failure

MSOF FeverFever Acidosis, hypoxemiaAcidosis, hypoxemia Disordered oxygen and substrate useDisordered oxygen and substrate use HyperglycaemiaHyperglycaemia Decreased systemic vascular Decreased systemic vascular

resistanceresistance Elevated cardiac outputElevated cardiac output HypotensionHypotension

MSOF Evidence for LPS - endotoxinEvidence for LPS - endotoxin

LPSLPS O antigen - specific for each organismO antigen - specific for each organism core LPScore LPS membrane lipid Amembrane lipid A

LPS - EFFECTS non specific polyclonal b cell proliferationnon specific polyclonal b cell proliferation

macrophage activation, cytokine releasemacrophage activation, cytokine release

hypotension, hypoxemiahypotension, hypoxemia

bacterial translocationbacterial translocation

complement and coagulation activationcomplement and coagulation activation

platelet and white cell marginationplatelet and white cell margination

LPS - Mechanism Direct effect of bacteriaDirect effect of bacteria

Indirect (mediated) effectIndirect (mediated) effect trigger macrophages to release TNFa, IL-1, trigger macrophages to release TNFa, IL-1,

IL-6, aIFNIL-6, aIFN TNFa, IL-1, - primary mediators but may TNFa, IL-1, - primary mediators but may

be deleterious in large amountsbe deleterious in large amounts aIFN- causes continued activation of aIFN- causes continued activation of

macrophagesmacrophages Permeability defects in microcirculationPermeability defects in microcirculation ARDS, GUT, Hepatic, renal failureARDS, GUT, Hepatic, renal failure

Problem

A 23 year old man A 23 year old man had a perforated had a perforated appendix. Three appendix. Three days post op this days post op this was his temperature was his temperature chart. What is your chart. What is your interpretation.interpretation.

Problem

What is your choice for antibiotic What is your choice for antibiotic prophylaxis for prophylaxis for

colorectal surgerycolorectal surgery biliary surgerybiliary surgery upper GI surgeryupper GI surgery

Problem

A 75 year old diabetic had an operation for A 75 year old diabetic had an operation for perforated diverticular disease. His wound perforated diverticular disease. His wound was found to be infected on the 5th POD.was found to be infected on the 5th POD.

What factors may have contributed to this?What factors may have contributed to this?