Ready…Set…Go! Carolyn Fiutem, MT(ASCP), CIC Infection Prevention Officer, TriHealth October 10, 2012 Recognize epidemiologically significant organisms Interpret results of lab tests Identify indications for biologic monitoring Fundamental Principles of Infection and Immunity Colonization – organisms in or on a host; growth but no tissue invasion or damage Infection – entry of an infectious agent in tissues of a host; growth and create symptoms Contamination – presence of microorganisms on inanimate objects, skin, or in substances Components of the Infectious Disease Process SUSCEPTIBLE HOST A person who cannot resist a microorganism invading the body, multiplying, and resulting in infection. The host is susceptible to the disease, lacking immunity or physical resistance to overcome the invasion by the pathogenic microorganism. INFECTIOUS AGENT /Causative Agent A microbial organism with the ability to cause disease. The greater the organism's virulence (ability to grow and multiply), invasiveness (ability to enter tissue) and pathogenicity (ability to cause disease), the greater the possibility that the organism will cause an infection. RESERVOIR A place within which microorganisms can thrive and reproduce. PORTAL OF EXIT A place of exit providing a way for a microorganism to leave the reservoir. PORTAL OF ENTRY An opening allowing the microorganism to enter the host. MODE OF TRANSMISSION Method of transfer by which the organism moves or is carried from one place to another. Virulence Environmental survival in transit BBP in blood outside the body, Protection against drying, Vectors Effective mechanism for transmission Vectors, Motility, Airborne, Fomites Ability to attach Electrostatic charge, Adhesion Reproduction/Proliferation Enzymes, Endotoxins, Capsules, Biofilms Invasion and Dissemination Rigid cell wall, Cell surface components, ability to alter cell surface, Deterrents to intracellular killing after phagocytosis Bacterial Toxins Exotoxins – potent toxin secreted by a bacterial cell Excreted in environment Gram-positive bacteria More susceptible to heat Neutralized by antibodies Enzymatic activity PVL of MRSA, and Toxins A/B of C. diff Endotoxin – heat-stable toxin in cell wall; pyrogenic; increase capillary permeability Surface of GNRs Partially neutralized by antibodies Produce physiologic changes in host Cholera toxin – fluid in the GI tract E. coli 0157 T-lymphocytes & mononuclear phagocytes Originate in bone marrow Migrate to thymus fetus/infancy T-cells from spleen, lymph nodes, bone marrow Receptors on surface of Tlymphocytes Review cellular immune response Cytokines Interleukin – 1: pyrogen, stimulate macrophage chemotaxis Interleukin – 2: made by CD4, enhance NK cell activity Interleukin – 4: made by T-cells and mast cells, stimulate growth Interleukin – 6: pyrogen, B-cell/T-cell differentiation Interferon: made by WBCs & fibroblasts; inhibit virus growth; α, β, γ Tumor Necrosis Factorcause protein catabolism in host w/ loss of muscle mass Lymphotoxin: promotes inflammation; stimulates neutrophils Granulocyte and Monocyte Stimulating Factors - reproduction T-lymphocytes CD3 surface marker – IDs them CD4 marker – helper lymphocytes for phagocytosis, release cytokines, long-term memory (vaccines) CD8 cells – cytotoxic and suppressor lymphocytes Natural killer cells – lyse tumor & virus infected cells Cellular Sources of Antibodies Precursors from fetal liver and bone marrow to spleen and lymph nodes Antibody producing plasma cells Classes of Immunoglobulin IgG – late occurring in Immune response (I’ve got it and it’s gone) IgM – first reacting , present for only ~ 6 months (I’m mopping it up) IgA – secretory antibody, plasma cells in mucous membranes IgD – surface of lymphocytes – antigen specificity IgE – allergy inducing; histamine & inflammatory substances; mucous membranes Genetic Constitution Caucasians, African-Americans, Asians, Alaskan/Hawaiian natives Mechanical Barriers Skin, mucous membranes, normal flora Physiological Barriers Fever, secretions, motility Vascular Circulating Defenses Natural/cross-reactive antibodies, fibronectin, estrogens, circulating WBCs •Activated by contact with IgG or IgM or certain microorganisms •Genetic deficiencies 10 Neutrophils (Polys) • Most dominant WBC (40-70%) • “First Responder” • Acts against pyogenic (pus-forming) bacteria • Life expectancy ~ 7 hours in circulatory system • Large reserve in bone marrow • Leukopenia – can be poor prognostic indicator • Hypersegmentation – suggest B12 or folate deficiency Neutrophil Ratios Degenerative Left Shift – increase in bands with no leukocytosis; poor prognosis Regenerative Left Shift – increase in bands with leukocytosis; good prognosis Right Shift – few bands with increase in segmented neutrophil seen in liver disease, hemolysis, drugs, cancers, allergies, or megaloblastic anemia Hypersegmentation – with no bands is seen in megaloblastic anemia and chronic morphine addiction Myeloid Left Shift – Bands, Metamyelocytes (Metas), Myelocytes, Promyelocytes (Pros), Blasts Neutropenia • Acute overwhelming bacterial infections – poor prognosis • Viral infections • Rickettsial and some parasitic diseases • Drugs, chemicals, radiation, toxic chemicals • Anaphylactic shock • Severe renal disease • Sepsis due to E. coli – reduced survival of polys • Hormonal Disorders Neutropenia in Neonates • Maternal neutropenia • Maternal drug ingestion • Maternal isoimmunization to fetal WBCs • Inborn errors of metabolism (i.e., maple syrup urine disease) • Immune deficits • Myeloid disorders • Defective intrinsic factor secretion Absolute WBC Counts 1. 2. 3. 4. 5. 6. Relative Number = percentage Absolute Count = Percentage X Total WBC Ct. Can have normal WBC count yet be neutropenic Need to look at WBC count and differential Normal WBC ranges: Adults ~ 3.5-10, 000 Newborns ~ 9-30,000 2 weeks ~ 5-20,000 1 yr ~ 6-18,000 4 yr ~ 5500-17,000 10 yr ~ 4500 – 13,500 Basophils 0-1% of WBCs Mast Cells are tissue basophils Secrete histamine, seratonin, & prostaglandins – increase blood flow to area Hodgkin’s Disease Parasitic infections Inflammation Allergy Sinusitis After splenectomy TB Smallpox, Chickenpox Influenza Eosinophils 1-4% of WBCs Are cytotoxic NAACP…. Neoplasm Asthma/Allergy Addison’s Disease Collagen/Vascular Disease Parasitic Infections Lymphocytes 25-40% of WBCs Fight viral infections Pertussis Chronic granulomatous diseases, i.e., TB Crohn’s disease Ulcerative Colitis Addison’s Disease Brucellosis Lymphopenia Chemotherapy After administration of cortisone Obstruction of lymphatic drainage, Whipple’s disease or tumors Hodgkin’s disease HIV/AIDS Trauma Monocytes Fight severe infection via phagocytosis 3-7% of WBCs Bacterial infections TB SBE Syphilis Parasitic, fungal, rickettsial diseases 20 Which of the following is not a mechanical barrier? a. Intact skin b. Mucous membranes c. Secretions d. Normal bacterial flora Knowledge Check… What is the name for a substance that prevents water-soluble elements such as antibiotics and disinfectants form reaching pathogens? a. Cell wall b. Biofilm c. Sludge d. Biocarbon Knowledge Check… Patients with cell-mediated immunity dysfunction are susceptible to infections attributed to pathogenic intracelluar bacteria. Examples of these organisms include: 1. Salmonella typhi 2. Bacteroides fragilis 3. Listeria monocytogenes 4. Staphylococcus aureus a. b. c. d. 2,3 1,3 1,2 3,4 Knowledge Check… Which organism found in food poisoning causes the most rapid onset of symptoms? a. Salmonella enteritidis b. Shigella sonnei c. Staphylococcus aureus d. Escherichia coli Knowledge check… The IP is teaching nurses how to assess infection risks in patients. Depletion of what cell type provides the BEST indication of susceptibility to most bacterial infections? a. Monocyte b. Eosinophil c. Neutrophil d. Lymphocyte Knowledge Check… 1. 2. 3. 4. a. b. c. d. Your patient has a low absolute neutrophil count. Of the following choices, which is true of your patient? They are especially susceptible to disease. You can determine the absolute neutrophil count by multiplying the total WBC count by the percentage of mature and immature neutrophils. The patient’s WBC count is between 4000 & 10,000. The patient’s complement system will only be activated through the alternate pathway 1 1&2 3 1, 2, & 4 Bacteria Internal structures – familiarity External structures – cell wall, glycocalyx, flagella, fimbriae and pili Size/Shape – 0.2-2 u X 2-8 u; cocci, rods, spirals Replication – cell division every 15-24 hours Genetic variation Plasmids found in cytoplasm, circular pieces of DNA Transformation – free DNA in cell Transduction – DNA carried by bacteriophage (virus) Conjugation – direct sharing of DNA Mutations – random base pair substitution Submicroscopic bacteria – Mycoplasma, Chlamydiae, Rickettsiae Yeasts Single-celled, budding or fission 2-60 u Smooth, creamy colonies Candida, Cryptococcus Molds Multinucleated network of filaments (hyphae) Can reproduce asexually or sexually Can reproduce via spores Aspergillus, Rhizopus Dimorphic fungi Grow as yeast or fungi depending on conditions Mold form at room temp (25°C) Yeast form at body temp (37°C) Histoplasma, Coccidioides, Blastomyces, Paracoccidioides Viruses Replicate only in cells of host/reservoir RNA or DNA in a protein coat Classified using genome, number of strands and presence or absence of envelope Parasites Blood - Plasmodium Protozoa - Giardia Helminths – pinworm Ectoparasites – scabies, lice, bedbugs Prions Infectious pieces of proteins Only replicate in cells of living organisms Neurotropic Untreatable and universally fatal Creutzfeld- Jakob disease (CJD, vCJD) – transmissible spongiform encephalopathy (TSE) 30 Microscopy – light & electron Specimen Preparation – direct/wet prep, stains Culture – agar, broth, biphasic, tissue Antimicrobial Susceptibility Testing (AST) Enzyme Immunoassay (EIA) Latex Agglutination DNA Probes Polymerase Chain Reaction (PCR) Serologic Anatomic Pathology General Laboratory Bacteria – stains, culture, serology, molecular Fungi: yeasts, molds – direct preps, culture, biochemical tests, direct antigen tests, serology Viruses – direct antigen tests, antibody tests, tissue culture Parasites – microscopy, serology Mycobacteria – culture, molecular, direct detection Mycoplasma - serology Chlamydiae – direct antigen tests Rickettsiae/Other Tick-borne Microbes – serology, ELISA Disk Diffusion – Kirby Bauer Broth Dilution – Minimum Inhibitory Concentration (MIC); manual or automated E-Test Beta-lactamase – penicillins resistance Disk Approximation – inducible clindamycin resistance Synergy Test – combinations of antibiotics Hodge Test – Extended Spectrum Betalactamase in gnrs Minimal Bacteriocidal Concentration (MBC) Types of ß – lactamases produced by Enterobacteriaceae Examples Broad Spectrum TEM-1 TEM-2 SHV-1 Extended Spectrum BetaLactamase Hydrolyzes Basic Pens Cephalosporins Inhib by CA I II III IV Cephamycins (FOX, CTE) Carbapenems (IMI, MERO) AZT Y Y Y/N N N N N N +/+++ TEM family SHV family Y Y Y Y Y N N Y ++++ Amp-C ACC CMY CFE DHA Y Y Y Y Y Y N Y N CarbapenEmases (NDM-1) KPC Y Y Y Y Y Y Y Y +++ IMP, GIM Y Y Y Y Y Y Y Y ++ OXA Y Y Y Y Y Y Y Y + Courtesy of Dr. Larry Gray Antibiotic Stewardship Surveillance Antibiograms Appropriate use of vaccines Appropriate transmission-based precautions Hand Hygiene Barriers Susceptible (S) Intermediate (I) Resistant (R) Therapy/Treatment Prophylactic Therapy Empiric Therapy Staphylococcus aureus Ciprofloxacin >=8 R Clindamycin >=8 R Erythromycin >=8 R Gentamycin <=5 S Levofloxacin >=8 R Linezolid 2 S Oxacillin >=4 R Penicillin G >=0.5 R Rifampin <=0.5 S Tetracycline <=1 S Tigecycline <=0.12 S Sulfa/Tri <=10 S Vancomycin <=0.5 S Gram positive coverage: Penicillins (ampicillin, amoxicillin) penicillinase resistant (Dicloxacillin, Oxacillin)* Cephalosporins (1st and 2nd generation)* Macrolides (Erythromycin, Clarithromycin, Azithromycin)* Quinolones (gatifloxacin, moxifloxacin, and less so levofloxacin)* Vancomycin* (MRSA) Sulfonamide/trimethoprim*(Increasing resistance limits use, very inexpensive) Clindamycin* Tetracyclines Chloramphenicol (causes aplastic anemia so rarely used) Other: Linezolid, Synercid (VRE) Gram negative coverage: Broad spectrum penicillins (Ticarcillinclavulanate, piperacillin-tazobactam)* Cephalosporins (2nd, 3rd, and 4th generation)* Aminoglycosides (Gentamicin; nephrotoxic)* Macrolides (Azithromycin)* Quinolones (Ciprofloxacin)* Monobactams (Azetreonam)* Sulfonamide/trimethoprim* Carbapenems (Imipenem) Chloramphenicol Pseudomonas coverage: Ciprofloxacin* Aminoglycosides* Some 3rd generation cephalosporins 4th generation cephalosporins Broad spectrum penicillins* Carbapenem Atypical coverage: Macrolides (Legionella, Mycoplasma, chlamydiae)* Tetracyclines (rickettsiae, chlamydiae)* Quinolones (Legionella, Mycoplasma, Chlamydia)* Chloramphenicol (rickettsiae, chlamydiae, mycoplasma) Ampicillin (Listeria) Anaerobic coverage: Metronidazole* Clindamycin* Broad spectrum penicillins* Quinolones (Gatifloxacin, Moxifloxacin) Carbapenems Chloramphenicol Antifungal spectrum of activity against common fungi. © 2006 by the Infectious Diseases Society of AmericaAshley E S D et al. Clin Infect Dis. 2006;43:S28-S39 Prompt institution of treatment “Bug Factor” – virulence and susceptibility “Drug Factor” – Activity of site of infection “Host Factor” – co-morbids and immunocompetence “Site Factor” – easily accessible site by antimicrobials Problems with administration – timeliness, storage, deterioration, patient compliance, absorption failure Renal/Liver Failure 40 Specimen quality is key Need to reduce colonizing bacteria prior to specimen collection – If you can touch the site with your finger, the specimen will be contaminated! Refrigerate/keep cold when necessary Use preservatives when applicable Tissues/Body fluids, Anaerobic cultures, CSF – stat specimens Label all specimens at the bedside/where collected with 2 patient identifiers and pertinent specimen information (D/T coll, source/site, abx, who coll) 1. 2. 3. 4. CSF should be clear & colorless Glucose 40-70 mg/dl Protein 15-45 mg/dl CSF Glucose = ~2/3 serum glucose Bacterial Meningitis: WBC = increased Diff – neutrophils Protein = marked increase Glucose =markedly decreased 1. 2. 3. 4. 1. 2. 3. 4. Viral (Aseptic) Meningitis: WBC = increased Diff – lymphs Protein = moderate increase Glucose = Normal TB/Fungal Meningitis: WBC = increased Diff – Lymphs and Monos Protein = moderate to marked increase Glucose = Normal to decreased The validity of a culture report is dependent on the quality of the specimen sent. To determine if an expectorated sputum specimen is sputum and not saliva, the gram stain should show: a. < 10 epithelial cells per low power field (lpf) b. > 10 epithelial cells/lpf and moderate polys c. > 10 epithelial cells/lpf and many Pseudomonas in culture d. Many WBCs and organisms on low power field To increase recovery of AFB from expectorated or induced sputum, specimens should be collected: a. b. c. d. Once a week for 3 consecutive weeks Every day for 1 week First morning specimen for 3 consecutive days Three specimens 1 hour apart on the same day 1. 2. 3. 4. 5. Microorganisms are grown on culture media made of an agar base. Additives to media vary according to growth requirements of organisms and/or the desire to select out a specific organism. Fastidious organisms require______ media, and ______ media is used to inhibit normal commensals. Differential Enrichment Selective Nutrient broth Synthetic sheep blood agar a. 1, 3 c. 3, 4 b. 2, 3 d. 5, 1 Gram stains classify an organism as grampositive or gram-negative. The determinant factors for Gram stains are cell wall component of: a. b. c. d. Peptidoglycans Lipids Polysaccharides Mycolic acids A liquid stool specimen is collected from a 10 yo boy at 9 p.m. The physician has ordered a culture and O&P. The specimen is refrigerated until 9 a.m. the following day, when the physician calls and requests the laboratory to look for amoebic trophozoites. The best course of action is: a. Request a fresh specimen. b. Perform a concentration on the specimen. c. Perform a trichrome stain on the specimen. d. Perform a saline wet mount on the specimen. When reviewing microbiology data looking for isolates of MRSA, the laboratory does not use methicillin for testing. Which of the following antimicrobial agents is the MOST similar to methicillin and is most commonly used in AST? a. b. c. d. Carbenicillin Oxacillin Gentamicin Amikacin An IP is asked to review with a group of staff nurses how to interpret ASTs. The susceptibility test that allows a determination of the least amount of antibiotic per milliliter that impedes the growth of an organism is know as a: a. b. c. d. Minimum inhibitory concentration (MIC) Kirby-Bauer disk diffusion Minimum bacteriocidal concentration Serum-cidal levels Not recommended Costly Requires special procedures No standards for comparison May have adverse intervention implemented When investigation suggests a source or reservoir Use quantitative methods Routine monitoring Biological monitoring of sterilization processes Month culture colony counts and endotoxin testing of water and dialysate in HDUs Short term evaluations of interventions implemented as anew process or to stop an outbreak 50 Normal Flora – commonly found on healthy human body surfaces (endogenous source) Colonization – microorganisms in the absence of symptoms or deep tissue invasion Asymptomatic Infection – viable organisms without causing any obvious symptoms (latent TB) Opportunistic Infections – cause disease primarily in immunodeficient hosts Pathogenic Organisms – causes tissue damage Infection – invasion by and multiplication of organisms causing tissue damage and disease Etiology (Organism) Pathogenesis (Life cycle understanding) Identification (S/S) Diagnostic Testing Incubation Period Transmission-based Precautions Treatment Case Fatality Anthrax (Class A) Aspergillosis: environmental Chicken pox/Herpes zoster Conjunctivitis Cryptosporidiosis Dengue – Flaviviruses 1, 2, 3, 4 Foodborne Diseases Hanta virus Hepatitis – A, B, C, D, E HIV Influenza Legionellosis Measles Meningitis – bacterial vs viral Mumps Pediculosis/Phthiriasis – lice Pertussis – Bordatella pertussis Plague (Class A) – Y. pestis Rabies RSV (pediatric/geriatric) Rubella SARS Scabies – Sarcoptes scabei TB – M. tuberculosis Typhoid Fever (Salmonella typhi) Typhus Fever - Rickettsia West Nile Virus Yellow Fever - Flavivirus A 27 yo man is admitted with symptoms suggestive of meningitis. The patient has a history of head trauma from MVA. The lab calls to report that a g+c is noted on the gram stain. What is your next action? a. Have the charge nurse compile a list of exposed staff. b. Notify EH that several employees will need prophylaxis c. Tell the staff that no one should be treated until the culture report is final d. Ensure that staff understand which organisms are treated and which are not. A gram negative bacterium responsible for chronic antral disease and a major factor in peptic ulcer disease is: a. b. c. d. H. pyogenes S. typhi C. difficile H. pylori An example of an obligate intracellular parasitic bacterium would an organism responsible for: 1. 2. 3. 4. Hepatitis Q Fever Malaria Epidemic typhus a. b. c. d. 2, 3 2, 4 3, 4 1, 2 1. 2. 3. 4. You are notified by the lab that 3 patients on the oncology ward have cultures (2-BAL, 1-sinus) positive for Aspergillus fumigatus and chart review indicates invasive disease. All 3 cultures were taken on the same day. Your FIRST course of action is: Notify the head nurse and medical director of the unit. Set up a meeting with engineering to discuss the air handling system. Ask micro to do a retrospective review of Aspergillus cultures. Notify administration of the outbreak. a. 1, 3 b. 1, 2 c. 3, 4 d. 1, 4 Review of micro logs revealed 4 more +Aspergillus cultures in the last 6 months. Chart review indicate the patients were from different units and were community-associated colonization. Based on this, you: a. Decide no follow-up is necessary since oncology patients are high-risk for Aspergillus. b. Look for a common factor in all 7 patients. c. Look for a common factor among the 3 oncology patients only. d. Continue investigating all 7 patients via phone interview. 1. 2. 3. 4. While touring the oncology unit and outside perimeter of the hospital, you observe road construction one block form the hospital. (The oncology is a street level, facing the construction.) You decide this could be the source of the Aspergillus. Possible factors include: Staff props the outside doors open when they go outside. Pigeons roost on the unit’s windowsill. The air intake system on the roof faces the construction. The unit’s utility room has an open window. a. 1, 3 b. 2, 4 c. 1, 4 d. None, construction is too far away. A meeting was called with the head nurse, medical director, and vice president of engineering. Proposed interventions included adding an alarm to sound when the outside door was open longer than 30 sec., placing a positive airflow vent over the door way, and locking the utility room window. To determine whether these measures were effective, you will: 1. Monitor every patient on the unit for the next 6 mo. 2. Have the micro lab notify you immediately in the event of another + culture. 3. Tour the unit daily to ensure the engineering controls are in place. 4. Consider the problem solved and move on. 60 A patient has a perirectal swab positive for VRE. This is an example of: a. b. c. d. Normal flora Colonization Asymptomatic infection Symptomatic infection Of the following viruses, which is the most common healthcare-associated pathogen in pediatric wards? a. b. c. d. Respiratory syncytial virus (RSV) Adenovirus Herpes simplex virus Cytomegalovirus A 10 - yo boy is admitted to the hospital with a 3 day history of fever, abdominal pain, diarrhea, and vomiting. He and his family have just returned from a week long camping trip in the mountains that included trips to the seashore. The next 4 questions refer to this scenario. A stool culture is reported with many lactose negative colonies. The most probable causing organism is: a. b. c. d. Providencia alcalificiens Providencia stuartii Yersinia enterocolitica Providencia rettgeri Which of the following organisms can grow in the small bowel and cause diarrhea in children and traveler’s diarrhea through the production of enterotoxins? a. b. c. d. Yersinia enterocolitica Escherichia coli Salmonella typhi Shigella dysenteriae Which disease requires a very small inoculum of organisms to cause disease? a. b. c. d. Dysentery (Shigella) Salmonella Campylobacter Giardia Which organism found in food poisoning causes the most rapid onset of symptoms? a. b. c. d. Salmonella enteritidis Shigella sonnei Staphylococcus aureus Escherichia coli A 14 uo boy form rural Maryland was seen in the ED with fever, fatigue, chills, headache and a large annular lesion on his left thigh which the patient described as burning and itching. What is the most probable vector of this child’s illness? a. b. c. d. Tick Mosquito Flea Louse You receive a call from a young man who thinks he was exposed to HIV. His baseline HIV test (ELISA) was negative. At what time period after the exposure would we be most likely to detect HIV antibodies? a. 6 months b. 1-3 months c. 12 months d. 3 weeks A preadmission serum sample and a current sample from a patient is used for antibody testing for HSV. ELISA is performed on paired sera with the following titers: previous = 1:8, current = 1:128. The results indicate: a. b. c. d. Acute HSV infection Indeterminate infection Chronic infection Immunity to HSV 70 A single serum sample is sent for ELISA antibody testing. The following titers are reported: HSV titer = 1:128, CMV = <1:8, EBV = <1:8. These results indicate: a. b. c. d. Immunity the HSV Confirmation of acute HSV infection Presumptive identification of HSV infection Immunity to CMS and EBV An emaciated homeless person is admitted with suspicion of TB. He had an upper lobe cavitary lesion and a +PPD of 10 mm. He is placed in Airborne precautions in negative pressure. The lab indicates 3 +AFB smears. This indicates: a. b. c. d. Confirmed diagnosis of TB Presumptive mycobacterial infection Presumptive diagnosis of TB No conclusion is possible from this information.