Bacteremia and Sepsis Chapter 36

Bacteremia and Sepsis Chapter 36  Term s Bacteremia bacteria in bloodstream Septicemia bacteremia with clinical signs and symptoms fever, chills, hypothermia, hyperventilation septic shock exotoxins and/or endotoxins ev...

Bacteremia and Sepsis Chapter 36  Term s Bacteremia bacteria in bloodstream Septicemia bacteremia with clinical signs and symptoms fever, chills, hypothermia, hyperventilation septic shock exotoxins and/or endotoxins evoke massive immune response mortality rate >50%  Term s Primary bacteremia bacteremia with no other known infected site Secondary bacteremia bacteremia associated with an infected body site Occult bacteremia bacteremia with no known cause with or without symptoms mainly in children Pseudobacteremia false bacteremia contaminated materials are source of organisms in blood culture media  Bacteremia Patterns Transient minutes to hours in bloodstream body site with organisms traumatized mucous membrane or skin mild (teeth cleaning), severe (surgery) early stages of some diseases meningitis, osteomyelitis, infectious arthritis  Bacteremia Patterns Intermittent organisms periodically released into bloodstream (pneumonia, meningitis) caused by abscess Continuous organism present constantly in bloodstream individuals with infected intravascular sites  Bacteremia Sources Intravascular associated with vascular system infected heart valves, catheters, veins Extravascular outside vascular system lymphatic vessels carry organisms to bloodstream UT, RT, abscesses  Intravascular Bacteremia Endocarditis – infection of endocardium Viridans streptococci (normal oral flora) Enterococci Catheter, VP shunt associated bacteremia Coagulase negative staph (S. epidermidis) S. aureus Corynebacterium all normal skin flora  Extravascular Bacteremia Seed from localized site of infection Meninges N. meningitidis, H. influenzae type B, S. pneumoniae Other sites Enterics: E. coli, Klebsiella, Salmonella Anaerobes: Bacteroides, Clostridium NFGNR: Pseudomonas Other GNR  Detection of Bacteremia Mortality rates high prompt detection and recovery of organisms Obtain blood via aseptic venipuncture Blood culture Once growth detected Isolate, identify, and test for susceptibilities  Most Common Causes of Nosocomial Bacteremia Coagulase negative staphylococci S. ~50% aureus Enterococcus spp. Candida albicans Enterics E. coli, K. pneumoniae, Enterobacter spp., Serratia spp. Nonfermenting GNR P. aeruginosa, A. baumannii  Collection Sites Venipuncture Peripheral aseptic venipuncture Indwelling intravascular catheters not recommended - contamination used if it is only way to collect blood or patient evaluated for catheter-related bacteremia  Collection Methods Needle & syringe Syringe collection (preferred method) transfer into blood culture bottles using same needle Can use butterfly Tube method – lysis centrifugation system  Collection Procedure Specimen container preparation Site preparation Specimen collection Site care Specimen Container Preparation Disinfect tops of culture bottles and tubes with 70% alcohol or iodine  Site Preparation To avoid contamination with NF some NF can cause significant diseases Clean skin with alcohol to remove debris and oil Skin swabbed with iodine from inside out in concentric circles Allow iodine to dry at least 1 minute to ensure proper disinfection  Specimen Collection Venipuncture Blood collected in syringe Blood from syringe must immediately be inoculated into blood culture bottles Invert bottles Mix blood with broth media and anticoagulant Site Care Iodine can cause skin irritation Should be removed with alcohol  Specimen Collection Difficult to recover organisms in clotted specimens Anticoagulants Sodium polyanethol Sulfonate (SPS) recommended Inappropriate anticoagulants Citrate, heparin, oxalate, EDTA Toxic to some organisms  Sodium Polyanethol Sulfonate Prevents clotting Inhibits phagocytosis Inactivates complement Neutralizes some antimicrobial agents Inhibits some organisms N. gonorrhoeae N. meningitidis  Sodium Polyanethol Sulfonate 0.025% concentration in blood culture media Minimize its antibacterial effects SPS blood collection tubes available but not recommended  NOTE Blood collected from one venipuncture is considered ONE blood culture Even if blood is divided into several tubes  Blood Volume Larger volume = more likely to be positive Recommended amount varies with patient age children have high level of bacteremia children: 100-1000 organisms/mL adults: 1 ml CSF→ centrifuge sediment for smear and culture Gram stain smears sensitivity 75-90% Thick smears  Culture s Media BAP, CHOC most common MAC or EMB if GNR seen in gram stained smears anaBAP if requested anaerobes rarely isolated incubate at 35-37 C in CO2  Antigen Detection Tests Available for group B streptococci, Hib, meningococci, pneumococci Should supplement, not replace, smears and cultures  Other Types of Meningitis Spirochetes T. palladum and B. burgdorferi Viral Aseptic meningitis No growth from bacterial culture Mycobacterial M. tuberculosis  Other Types of Meningitis Fungal Rarely Chronic meningitis Immunocompromised Parasitic Rarely CSF Findings Organisms Cells Dx Bacterial Usually Neutrophils Ag, culture Fungal Occasional Lymphs Stain, Ag TB Rare Lymphs PCR, stain Syphilitic No Lymphs VDRL Viral No Lymphs Serology, PCR Parasitic Rare Lymphs/Eos Serology, biopsy  Brain Abscesses Caused by NF organisms anaerobic bacteria, staphylococci, viridans, other streptococci Aspirate and biopsy materials Transported in anaerobic conditions Examined microscopically Cultured aerobically and anaerobically  Encephalitis/ Meningoencephalitis Viruses Most common Bacteria L. monocytogenes, Rickettsia, Mycoplasma, B. burgdorferi Parasites Naegleria, Acanthamoeba  Reporting Results Critical values Immediate notification Verbal communication followed by written report