InstituteInstitute forfor Microbiology, Medical Faculty of Masaryk UniversityMicrobiology, Medical Faculty of Masaryk University and St. Anna Faculty Hospitaland St. Anna Faculty Hospital in Brnoin Brno Agents ofAgents of bloodstreambloodstream infectionsinfections Bloodstream infectionsBloodstream infections • less common than respiratory or urinary tractless common than respiratory or urinary tract infections, butinfections, but severe and lifethreateningsevere and lifethreatening • Types of bloodstream infections:Types of bloodstream infections: 1) Infection of the complete bloodstream =1) Infection of the complete bloodstream = sepsissepsis 2) Infection of a part of bloodstream (endocarditis,2) Infection of a part of bloodstream (endocarditis, tromboflebitis), leads to sepsistromboflebitis), leads to sepsis BacteremiaBacteremia = mere= mere presence of bacteria in bloodpresence of bacteria in blood.. BacteriaBacteria (at least in higher ammounts)(at least in higher ammounts) == starting mechanism of sepsisstarting mechanism of sepsis Interaction of microbial products withInteraction of microbial products with macrophages releases a lot ofmacrophages releases a lot of cytokinescytokines →→ systemic inflammatory response syndromesystemic inflammatory response syndrome (SIRS)(SIRS) characterized by:characterized by: – elevated temperatureelevated temperature – accelerated pulse and breathingaccelerated pulse and breathing – leukocytosisleukocytosis SepsisSepsis SepsisSepsis = suspect or proved= suspect or proved infection +infection + systemicsystemic inflammatory response syndromeinflammatory response syndrome Severe sepsisSevere sepsis == sepsis + organ dysfunctionsepsis + organ dysfunction (hypotension, hypoxemia, oliguria, metabolic(hypotension, hypoxemia, oliguria, metabolic acidosis, thrombocytopenia, confusionacidosis, thrombocytopenia, confusion, DIC, DIC)) Septic shockSeptic shock == severe sepsis + hypotensionsevere sepsis + hypotension despite adequate supply of fluidsdespite adequate supply of fluids FeaturesFeatures of sepsisof sepsis ClinicClinicalal:: fever or hypothermiafever or hypothermia (often changing)(often changing) ↑↓ T↑↓ T tachycardiatachycardia ↑↑ PP tachypnoetachypnoe ↑↑ BB lowered blood pressurelowered blood pressure ↓↓ BPBP confusionconfusion PatPathhophysiologophysiologicalical:: higher heart outputhigher heart output lower peripheral vascular resistancelower peripheral vascular resistance Laboratory:Laboratory: leuleuccocytesocytes ↑↓ Leu↑↓ Leu serum bicarbonateserum bicarbonate ↓ HCO↓ HCO33 -- bacteremia may not be already demonstrablebacteremia may not be already demonstrable Types of bacteremia – ITypes of bacteremia – I Intermitent – in localized infectionsIntermitent – in localized infections pneumoniapneumonia ((for examplefor example pneumococci)pneumococci) meningitismeningitis ((for examplefor example meningococcmeningococcii)) pyelonephritispyelonephritis ((Escherichia coliEscherichia coli)) osteomyelitisosteomyelitis ((Staphylococcus aureusStaphylococcus aureus)) septic arthritisseptic arthritis ((S. aureus,S. aureus, gonococci)gonococci) Types of bacteremiaTypes of bacteremia – II– II Continual – in generalized infectionsContinual – in generalized infections typhoid fevertyphoid fever ((SalmonellaSalmonella Typhi)Typhi) brucellosisbrucellosis ((Brucella melitensisBrucella melitensis)) plagueplague ((Yersinia pestisYersinia pestis)) Types of bacteremiaTypes of bacteremia – III– III Bacteremia in bloodstream infectionsBacteremia in bloodstream infections thrombophlebitisthrombophlebitis ((S. aureus, S. pyogenesS. aureus, S. pyogenes)) acute endocarditisacute endocarditis ((S. aureus, S. pyogenesS. aureus, S. pyogenes,, S.S.  pneumoniae,pneumoniae, Neisseria gonorrhoeaeNeisseria gonorrhoeae)) subacute bacterial endocarditissubacute bacterial endocarditis == sepsis lentasepsis lenta ((viridansviridans streptococci, enterococci,streptococci, enterococci, HACEK group =HACEK group = HHaemophilus aphrophilusaemophilus aphrophilus AActinobacillus actinomycetemcomitansctinobacillus actinomycetemcomitans CCardiobacterium hominisardiobacterium hominis EEikenella corrodensikenella corrodens KKingella kingaeingella kingae)) „„culture-negative“ endocarditisculture-negative“ endocarditis (bartonellae, coxiellae,(bartonellae, coxiellae, legionellae)legionellae) Types of bacteremiaTypes of bacteremia – IV– IV Special circumstansesSpecial circumstanses Bacteremia inBacteremia in some malignitiessome malignities ((colonic Cacolonic Ca –– Streptococcus bovisStreptococcus bovis,, leukemialeukemia -- various bacteriavarious bacteria)) Bacteremia inBacteremia in intravenous drug usersintravenous drug users (( skinskin floraflora –– staphylococci, corynebacteriastaphylococci, corynebacteria;; mouthmouth floraflora andand bacteria from thebacteria from the environmentenvironment)) !!!!Bacteremia inBacteremia in iatrogeniciatrogenic infectionsinfections (e. g. mouth floora after(e. g. mouth floora after tooth extractiontooth extraction, pharyngeal flora, pharyngeal flora after bronchoscopy etc.after bronchoscopy etc.)) Types of bacteremia – VTypes of bacteremia – V Bacteremia related to artificial materialBacteremia related to artificial material VVascular cathetersascular catheters,, invasive devices and implantsinvasive devices and implants,, endoprotheses etc. (biofilm)endoprotheses etc. (biofilm) ICU, immunocompromised,ICU, immunocompromised, febrile neutropeniafebrile neutropenia CoagulaseCoagulase-neg. staphylococci,-neg. staphylococci, S.aureus,S.aureus, enteenterococci, corynebacteria,rococci, corynebacteria, yeasts etc.yeasts etc. True bacteremia vs contaminants!True bacteremia vs contaminants! Biofilm on a catheter (stafylococci and candidae): a) - canaliculus, b) - porous structure Photo: Dr. Veronika Holá, MÚ Sepsis according to the originSepsis according to the origin • Wound sepsisWound sepsis ((Staphylococcus aureusStaphylococcus aureus,, Streptococcus pyogenesStreptococcus pyogenes and otherand other beta-betahemolytic streptococcihemolytic streptococci,, PseudomonasPseudomonas aeruginosaaeruginosa inin burns)burns) • UUrorosepsissepsis ((Escherichia coliEscherichia coli,, Proteus mirabilisProteus mirabilis andand other enteric bacteriaother enteric bacteria)) • AbdominalAbdominal sepsissepsis (often p(often polymicrobialolymicrobial etiologyetiology, a, anaerobesnaerobes (Bacteroides etc.) and(Bacteroides etc.) and facultative anaerobesfacultative anaerobes ((Escherichia coliEscherichia coli)) FulminantFulminant sepsissepsis ... a quick course; when it is not diagnosed... a quick course; when it is not diagnosed in time, it often kills the patientsin time, it often kills the patients Clonal strains ofClonal strains of Neisseria meningitidisNeisseria meningitidis (sepsis with or without meningitis)(sepsis with or without meningitis) Streptococcus pyogenesStreptococcus pyogenes (often together(often together with necrotizing fasciitis)with necrotizing fasciitis) Yersinia pestisYersinia pestis Nosocomial sepsisNosocomial sepsis - Staphylococci, coagulase-negative- Staphylococci, coagulase-negative (intravenous catheter-associated sepsis, infections of(intravenous catheter-associated sepsis, infections of plastic devicesplastic devices in situin situ, febrile neutropenia), febrile neutropenia) - Staphylococcus aureus- Staphylococcus aureus (infected surgical(infected surgical wounds)wounds) - E. coli- E. coli + other enterobacteria+ other enterobacteria (catheter-(catheterassociated infections of the urinary tract)associated infections of the urinary tract) - Gram-negative non-fermenting rods- Gram-negative non-fermenting rods (contaminated infusion fluids)(contaminated infusion fluids) - yeasts- yeasts (catheter-associated sepsis, febrile neutropenia)(catheter-associated sepsis, febrile neutropenia) - Enterococci- Enterococci andand many other microbesmany other microbes Staphylococci in blood cultureStaphylococci in blood culture www.medmicro.info Diagnostics of sepsisDiagnostics of sepsis • Blood culturesBlood cultures (not clotted blood;(not clotted blood;  blood for serological examintion!)blood for serological examintion!) – special vessels, authomated culturespecial vessels, authomated culture – two, but better 3 blood culturestwo, but better 3 blood cultures – At least one blood culture should be takenAt least one blood culture should be taken from venepunction (i. e. not only centralfrom venepunction (i. e. not only central venous cathether)venous cathether) • parts of blood catethersparts of blood catethers ContaminantsContaminants • Inproper samplingInproper sampling, insufficient disinfection, insufficient disinfection • Sampling fromSampling from cathehers only and notcathehers only and not venepunctionvenepunction (the bacterium colonizing the(the bacterium colonizing the venous catether is not necesarilly a realvenous catether is not necesarilly a real bloodstream pathogen)bloodstream pathogen) • Coagulase-negative staphylococciCoagulase-negative staphylococci Examples of blood culture vesselsExamples of blood culture vessels www.medmicro.info Blood culture deviceBlood culture device Foto: O. Z. The same device openThe same device open Foto: O. Z. Treatment of sepsisTreatment of sepsis ICUICU • antibioticsantibiotics –– empiric therapy in theempiric therapy in the beginningbeginning, targeted therapy later, targeted therapy later • removal of all infected tissuesremoval of all infected tissues or devicesor devices • ssupport of breathing and hemodynamicsupport of breathing and hemodynamics (artificial ventilation, oxygen, fluids,(artificial ventilation, oxygen, fluids, vasopressors etc.)vasopressors etc.) Michael SweertsMichael Sweerts (1618-1664):(1618-1664): Plague in an AncientPlague in an Ancient CityCity