Exam 1 Review PATH 3100-001 PDF

Exam 1 Review PATH 3100-001 Ashley & Nick (TAs) Gram Stain List Gram-Positive Cocci (GPC) - Bacteria that end in "-coccus" - Streptococcus, Staphylococcus, Enterococcus Gram-Negative Cocci (GNC) - Neisseria - Moraxella (Not Many...only 2 species) Gram-Positive Bacilli (GPR) - Everything else ***NO gram negative bacilli on exam 1*** Characteristics of Bacteria Compare and contrast the overall cell structure of prokaryotes and eukaryotes Prokaryotes Eukaryotes No true nucleus → Bacteria!! True nucleus → Animal cells, plant cells, fungi Nucleoid is single chromosome of double-stranded Nucleus contains double-stranded DNA DNA - DNA in a circular chromosome without a surrounding nuclear membrane Nuclear bound membrane No nuclear membrane Most do not have cell walls Cell wall: protein and peptidoglycan; rigid Sexual and asexual reproduction Asexual division Describe taxonomic classification and use Characteristics of Bacteria scientific nomenclature to accurately record the names of microorganisms Domain → Bacteria Genus Phylum → Firmicutes ○ First name, capitalized, either underlined or italicized (not Class → Bacilli both) Order→ Bacillales ○ Ex) Staphylococcus or Staphylococcus Family → Staphylococcaceae Species Genus → Staphylococcus ○ Comes second, not capitalized, either underlined or italicized Species → aureus (not both) ○ Ex) S. aureus or S. aureus Strain is a genetic variant or subtype, not italicized or underlined ○ Ex) E. coli O157:H7 ○ Ex) Methicillin-resistant S. aureus Describe the Gram stain procedure and what Characteristics of Bacteria is happening with the bacteria at each step Basis for initial grouping of medically important bacteria; most Gram-positive Gram-negative commonly used stain in clinical microbiology. Bacteria placed in 2 groups depending on what color they stain: gram positive Thick protective Thin inner or gram negative. They stain differently because their walls are peptidoglycan peptidoglycan different. layer layer lipoteichoic acid Outer membrane traverses wall, composed of anchored in lipoprotein and membrane polysaccharides Stain purple Stain pink/red Characteristics of Bacteria Describe the Gram stain procedure and what is happening with the bacteria at each step Reagents ○ Crystal Violet (CV): CV net pos (+) charge is attracted to bacterial neg (-) charged cells, penetrates cell wall and stains both GP/GN cells purple ○ Iodine: mordant; interacts with CV to set the dye ○ Alcohol: decolorize; removes thin peptidoglycan Exclusions: layer of GN cells. GP cells have a thick layer which Acid-fast bacteria are GP in the alcohol can’t remove all the way structure, but contain WAXY ○ Safranin: counterstain! At this point, your GP will be layer of glycolipids and fatty purple, but your GN will be colorless ): Counterstain acids that don’t stain well with them so you can see them! GN will now look pink (: gram stain Bacteria without a cell wall (Mycoplasma) don’t stain Outline the factors affecting Characteristics of Bacteria microbial growth and growth patterns. Temperature Chemical Requirements Psychrophiles: cold (4-15C) Carbon, water, nitrogen, sulfur, phosphorus, trace elements (iron, copper, zinc, etc.) Mesophiles: moderate (30-35C) Hydrogen Ion Concentration Thermophiles: hot (50-60C+) Medically important bacteria prefer pH 6.0-8.0 (body pH around 7) Osmotic Pressure Isotonic: solute concentration is similar both Atmosphere inside and outside cells Obligate aerobes: require oxygen Hypotonic: media with solute concentration Obligate anaerobes: will not grow in presence of lower than inside cell, so cells will increase in oxygen size and rupture Facultative anaerobe: grows with or without Hypertonic: external environment has higher oxygen solute concentration than the cell, so ﬂuid ﬂows Capnophilic: grows better with increased CO2 from cell to medium Outline the factors affecting Characteristics of Bacteria microbial growth and growth patterns. Replication is by binary fission. The time required for one cell to divide into two cells is generation time or doubling time. Equal # of cells dividing and Most cells are dead dying Constant, exponential growth; active Growth undetected Characteristics of Bacteria Define the following terms Flagella: protein filaments used for motility - exterior protein filaments that provide locomotion and propel Cocci: spherical bacteria toward food sources or away from chemicals; not all have flagella (non-motile) Bacilli: rod-like Pili: hair-like appendages used for adherence to cell surfaces - protein fibers smaller than flagella that do not provide motility but allow attachment to the host Pleomorphic: vary in shape Spirochete: helical Characteristics of Bacteria Define the following terms Endospores: dormant forms, highly durable dehydrated cells with thick walls and resistant to heat, drying, and chemicals; only some gram positive bacteria form these; Important in food industry as spores can survive food processing (think C. botulinum - botulism); most difficult condition to "kill" bacteria Lipopolysaccharide: essential component of the outer membrane of all Gram-negative bacteria that can also function as a virulence factor (fever and shock; attachment site; barrier) Capsules: organized polysaccharide layers on some bacteria - covers the cell wall and shields the bacteria from immune and phagocytic responses; important virulence factor Characteristics of Bacteria Define the following terms Microbiome: genetic material of all the microbes (bacteria, fungi, viruses, etc) that live on and inside the human body Microbiota: community of microbes that live in and on an individual (normal flora, includes bacteria, fungi, viruses) Biofilm: assemblage of microbial cells adhering to a surface and enclosed in a matrix of primarily polysaccharide material (ex. Dental plaque; heart valve infections); help make bacteria resistant List Koch’s postulates, define terms used to describe host-parasite interactions, describe Host-Parasite Interaction host barriers to infection Host: organism being infected by a pathogen (human patient) Koch’s Postulates (although we Host barriers: don’t really like these): Parasite: any invader or agent of infectious The microorganism must be disease Microbiome (normal flora) Anatomic barriers present in every case of the infectious disease Pathogen: microorganism capable of causing (skin) an infectious disease The microorganism can be Stomach acid isolated in pure culture Primary pathogen: microorganism that White blood cells Inoculation of the pure regularly causes infection and disease when (neutrophils) culture into animals produces it enters a non-immune host (high virulence) Antibodies a similar disease The same species of Opportunistic pathogen: microorganism that rarely causes disease in healthy humans microorganism must be but may in a host whose defense recovered from the diseased mechanisms have been compromised or animal weakened - behaviors that make an individual more susceptible to opportunistic infection: intravenous drug use, multiple sex partners, old age Describe host factors that lead to disease, describe organism capabilities that lead to disease, Host-Parasite Interaction & Terms summarize disease transmission Host Factors → Disease Organism Factors → Disease Disease Transmission Behavior Evasion of immune Endogenous (infected Occupation response (capsule) with own bacteria) Age, sex, race Ability to attach (pili) ○ Break in natural Exto/Endo/Enterotoxins barrier (stab wound, surgery) Bacteremia: bacteria multiplying in the bloodstream Exogenous (outside Virulence: ability of an organism to produce disease bacteria) ○ Inhalation, Pyogenic: pus-producing ingestion *** Phlebotomy cannot be performed by employees who have the Chicken Pox *** Compare and contrast the terms healthcare-associated infection (HAI), colonization, and infection, discuss the Hospital Epidemiology burden of HAIs in the U.S., list the more common bacteria that cause HAIs HAI: acquired while receiving healthcare treatment, hence the name (e.g.; Burden: Thinking about real-life hospital, long term care facility, dialysis center, etc.) (ex, catheter-associated problems, see HAI examples: you UTI) go into surgery and have a ○ C. difficile, S. aureus (MRSA), Klebsiella spp., E. coli, Enterococcus catheter inserted, which gets spp., P. aeruginosa, Candida spp., Streptococcus spp., coag-neg infected and you get a UTI); Staph spp., Enterobacter spp., S. maltophilia, P. mirabilis, potentially spending more money Acinetobacter baumannii and more time on treatments/time in hospital Colonization: Presence of organisms on a body surface without disease (ex, asymptomatic presence of MRSA in healthy adult’s axilla) Pili, capsules, and enterotoxins Infection: Organisms invade body tissues causing disease (clinical signs and symptoms) ex) MRSA bloodstream infection, ear infection are all bacterial structures / byproducts that aid an organism in initiating infection or Nosocomial infection: infection acquired by a patient after admission to the colonization hospital (UTI) Explain how patients acquire HAIs, describe the steps in an outbreak Hospital Epidemiology investigation, discuss how the laboratory can be helpful in an outbreak Transmission Steps in outbreak: Transmission → portal of entry → Lab ex) Seeing the same 1) Identify the etiologic agent, positive cultures in a vulnerable hosts → organism → reservoir, and mode of specific department reservoir → portal of exit transmission Contact: think multidrug resistant: 2) Eliminate the reservoir MRSA, VRE, CRE, also C. diff and 3) Prevent transmission norovirus 4) Prevent future outbreaks, Droplets: pertussis (whooping cough, how? → By confirming coughing baby spreading germs), H. outbreak, researching the influenzae, N. meningitidis, influenza, disease, implement control Air: think vaccine preventable diseases and prevention measures, (Tuberculosis, chicken pox, measles, communication, etc. influenza) Chain of infection: Source, mode of transmission, susceptible host Sterilization & Disinfection/Infection Control Explain principles of control of microorganisms, including definition of terms Antiseptic: inhibits microorganism growth (isopropyl Approaches to control alcohol, hydrogen peroxide); chemical agent applied to the The body's own defense skin that kills pathogens and reduces number of normal mechanisms flora organisms Chemotherapeutic agents Public Health measures Aseptic: used to sterilize (kill) (povidone iodine) – surgery, Sterilization & Disinfection phlebotomy Cide / Cidal: to kill Stasis / Static: to prevent multiplication without necessarily killing the agent Disinfectant: kill – equipment and surfaces; too strong for skin (10% bleach solution) Sterilization & Disinfection/Infection Control Describe how organisms are controlled in a hospital environment and in the laboratory Hospital Both Laboratory Surgery - cleaning patient’s Handwashing Universal/Standard skin (antiseptic), Precautions: ALL patients and instruments (autoclave), the ALL lab specimens should be room itself (disinfectants) handled as if they are infectious Medical - laundry, washing PPE Never pipette by mouth floor, dusting, waste removal Needle stick Utilizing sharps container Place every specimen of injury - 1st step (Most common exposure is blood or body fluid in a is to back bleed percutaneous (needle stick) well-constructed container and wash the and most common specimen with a secure lid to prevent wound type is blood → HIV, Hepatitis) leaking in transport Sterilization & Disinfection/Infection Control Explain methods of achieving sterility List the steps in hand washing Heat Hand washing! ○ Moist or dry heat 1) Turn on water and wet hands ○ Autoclave 2) Dispense soap ○ Pasteurization 3) Wash hands at least 20 seconds (lather, washing between fingers and on wrists, and under fingernails) ○ Flame 4) Rinse in a downward position Filters 5) Dry hands with clean paper towels ○ Membrane ﬁlter 6) Use paper towels to turn off faucet ○ High-eﬃciency particulate air ﬁlter 7) Discard paper towels in appropriate container (HEPA) Radiation ○ UV light (common in lab hoods) ○ Ionization radiation Soap (non-germicidal detergent): role in disinfecting hands or a contaminate surface is to remove organic material or loose skin cells that can harbor infectious bacteria Sterilization & Disinfection/Infection Control PPE PPE removal: Isolation PPE: 1*) Untie gown if Designed to control the transmission of wearing gown highly contagious diseases 1) Remove gloves Patient room door usually has sign of 2) Remove what protective isolation procedures goggles/face are in place shield Gloves, lab coat, surgical mask or n95 3) Remove gown respirator 4) Remove ○ N95 for highly infectious airborne mask/respiratory pathogens → sars covid, 5) Cleanse hands tuberculosis When instructed to use a gown when entering an isolation room, first perform hand hygiene. Then, don the gown, mask (if instructed), and gloves Staphylococcus Gram-positive cocci (GPC) in grape-like clusters Normal ﬂora of skin, mucous membranes, feces Catalase positive ○ Enzyme breaks down 3% H2O2 to form bubbles Coagulase ○ Enzyme binds plasma ﬁbrinogen to form clot ○ Staph aureus is coagulase positive ○ Other Staph species are negative https://www.studyblue.com/notes/note/n/micro-review/deck/7804009 https://www.studyblue.com/notes/note/n/a-d-bacteriolo gy/deck/5115268 Staphylococcus aureus “Aureus” = golden. Appears creamy on media that turns golden/yellow with age. Often colonizes the skin, nose, armpit, and groin Survives long time in environment Most virulent Staph ○ May be considered clinically signiﬁcant when isolated from any source Virulence Factors: ○ Coagulase and protein A both prevent phagocytosis ○ Enterotoxins cause vomiting and diarrhea ○ Lipase dissolves fats allowing the bacteria to spread ○ Hyaluronidase dissolves tissues ○ Hemolysins are toxic for many blood cells Remember: Staph aureus is catalase (+) & coagulase (+) Staph aureus Disease Associations Skin infections: ○ Impetigo, furuncles (boils), carbuncles, pyogenic abscesses (pus-filled pocket of fluid) Opportunistic infections resulting from skin injuries (cuts, burns, surgical incisions) ○ Scalded skin syndrome Toxin-mediated, typically in infants and children. Blisters and erythema on face that spreads; skin to looks scalded and eventually slough off Food poisoning: ○ Meat and milk products - often from the hands of food handlers ○ Toxin-mediated (heat stable enterotoxin), resulting in vomiting, diarrhea, cramping Toxic Shock Syndrome: ○ Associated with menstruating females and tampon usage ○ Multisystem febrile illness with shock, vomiting, diarrhea, rash, peeling of skin Also causes: Bacteremia, endocarditis, pneumonia, empyema, osteomyelitis, septic arthritis, gastroenteritis Not vaccine preventable Methicillin Resistant S. aureus (MRSA) Penicillin resistance emerged after WWII → Methicillin was the next line of treatment → MRSA was ﬁrst seen in 1961 Antibiotic resistance is related to acquisition of mec A or mec C gene MRSA strains are now resistant to all β-lactams ○ Vancomycin can be used for treatment, but there is risk of developing VRSA ○ Vancomycin is the drug of choice for IV therapy ○ Daptomycin, tigecycline, or linezolid are acceptable alternatives Methicillin Resistant S. aureus (MRSA) MRSA infections common among immunocompromised #1 cause of community-acquired skin and soft tissue infections ○ Red, swollen, pus, painful Also causes: pneumonia, bacteremia, endocarditis, and bone, joint and surgical site infections Approx. 5% of patients in US hospitals are colonized with MRSA in their nose or on their skin https://www.cdc.gov/mrsa/community/photos/pho to-mrsa-9.html Coagulase negative Staph species Staph Colonizes skin of most Bacteremia - IV site infections epidermidis people Endocarditis Surgical wounds Low virulence Opportunistic infections of catheters, shunts, and prosthetic devices (slime layer prevents phagocytosis) Likes to form biofilms Staph May have an affinity for Urinary tract infections - particularly among young, saprophyticus the binding to the sexually active females epithelium of the urethra Resistant to Novobiocin or bladder Streptococcus Gram-positive cocci in chains Normal ﬂora in upper respiratory and intestinal tracts Catalase negative ○ Does not form bubbles in H2O2 ○ Compare to Staph which is catalase positive https://s3.amazonaws.com/classconnection/246/flashcard s/2707246/jpg/1fdbeaf5fde2f65d62be57a306767fd4-150D 448EDDB2ADFF6CD.jpg Enterococcus Gram-positive cocci “Streptococci of fecal origin” → normal intestinal ﬂora Most human infections are caused by: ○ E. faecalis ○ E. faecium Relatively low virulence Causes UTIs, endocarditis, wound infections https://www.vectorstock.com/royalty-free-vector/intestinal-ﬂora-sign-vec tor-19816946 Classiﬁcation by Hemolysis Hemolysis Appearance on blood agar Examples Alpha (ɑ) Green/brown Strep pneumoniae “Bruising” Strep bovis RBCs partially lysed Viridans Strep Enterococcus Beta (β) Clear/colorless Strep pyogenes RBCs completely lysed Strep agalactiae Enterococcus (rarely) Gamma (ɣ) No hemolysis Strep bovis (Group D) Note: rarely cause disease Enterococcus Streptococcal Diseases Pharyngitis/Strep throat (sore throat + fever), otitis media, scarlet fever (Strep throat + rash), impetigo, S. pyogenes cellulitis (Group A) Sequelae due to autoimmune reaction to Streptolysin O ○ Rheumatic fever (heart muscle damage) ○ Acute glomerulonephritis (renal glomeruli damage) Both associated with auto-antibodies Humans are the only reservoir for Group A Strep S. agalactiae Neonatal infections (meningitis, septicemia, pneumonia) due to colonization of female gential tract (10-30%) (Group B) UTIs and bacteremia in elderly and immunocompromised S. #1 cause of otitis media in children, acute community acquired pneumonia, meningitis, sinusitis pneumoniae Can be normal flora in upper respiratory tract Gram positive cocci in pairs - lancet shape There is a vaccine available (PCV12 for kids, PPVSV for 65+) Viridans #1 cause of subacute bacterial endocarditis Strep Predominant organism of normal upper respiratory flora Group D S. bovis group is associated with GI diseases, particular GI carcinoma Strep Antibiotic Treatment of Strep and Enterococcus Streptococcus Enterococcus Penicillin = drug of choice Intrinsically resistant to β-lactams (penicillins Penicillin-resistant S. pneumo → or cephalosporins) Vancomycin or 3rd gen. Cephalosporin Must use a combination of a penicillin and an aminoglycoside If resistant to drug combo → vancomycin If VRE → Synercid or Linezolid Gram-Positive Bacilli Spore-formers Opportunistic Pathogens Strict Pathogens 1. Bacillus spp. Corynebacterium spp. Listeria monocytogenes 2. Clostridium spp. Gardnerella vaginalis Corynebacterium Bacillus spp. diphtheriae Clostridium difficile* Nocardia spp. (when broad-spectrum Bacillus anthracis antibiotics are used) Clostridium botulinum Non-Spore-Forming GPRs - Characteristics Corynebacterium spp. Found in the environment and ﬂora of humans and animals ○ Normal on skin, in oral cavity, and genitourinary tract ○ Often considered a contaminants when isolated Pleomorphic rods → form “L” and “V” shapes referred to as palisading on the gram stain Nocardia spp. Found in the environment (soil and water) NOT part of our normal flora - always considered a pathogen Partially acid-fast Affects lungs, brain, and skin ○ Respiratory and cutaneous infections disseminate to CNS Immunocompromised are most at-risk Gram-Positive Bacilli - Common Diseases Listeria Stillbirths and meningitis monocytogenes Infect neonates, pregnant women, and immunocompromised Epidemics with foodborne illness (unpasteurized meats and cheeses) Can grow in refrigerated temperatures Tumbling motility only at room temp - cannot move at body temps Corynebacterium Diphtheria (pharyngitis with thick, leathery, gray pseudomembrane plus a fever) diphtheriae Organism is infected with a phage carrying the TOX gene causing exotoxin production → toxin affects myocardium and peripheral nervous system Corynebacterium Normal skin flora jeikeium Opportunistic infections of prosthetic heart valves, septicemia, and skin Gardnerella Fastidious, Gram-variable pleomorphic rod (truly GPR) vaginalis Bacterial vaginosis (green frothy vaginal discharge w/ foul odor) Vaginal swab → wet prep to look for CLUE cells Spore-Forming GPRs - Characteristics Bacillus spp. Low virulence saprophytes in soil, water, dust, and animal products Common lab contaminants Gram stain: large, box-car rods that may stain gram variable Spores are resistant to the environment and can survive in soil for years Clostridium spp. Inhabit soil, water, vegetation, and the large bowel of humans and other animals Anaerobes Large, box-car GPRs (can be gram variable) Gram-Positive Bacilli - Common Diseases Bacillus Major pathogen of the genus anthracis Anthrax in humans (pulmonary, cutaneous, GI) and grazing animals Extremely virulent, potential agent of biological warfare Bacillus Food poisoning from rice dishes - spore survive cooking then germinate and multiply when food is inadequately refrigerated cereus All Clostridium spp. = large "box-car" Gram-positive bacilli Clostridium Food poisoning (common cause) perfringens Gas gangrene → necrosis following wound infection or surgeries Produces large amounts of gas, reproduces rapidly, has an exotoxin - causes necrosis of tissues by producing exotoxin Treat with surgical removal of tissues and high doses of antibiotics Clostridioides Found in the bowel of healthy individuals. If antibiotic therapy alters the normal fecal biome, C. difficile can overgrow, difficile causing disease. Pseudomembranous colitis (bloody diarrhea) due to toxins - from prolonged antibiotic treatment Clostridium Spores enter via wound and germinate into vegetative cells & produce toxins tetani Tetanus - simultaneous muscle contraction and relaxation; due to neurotoxin entering CNS Immunize in infancy. Treat with neutralizing antitoxin, relieve spasms, keep airways open. Clostridium Food botulism from inadequate food processing/cooking of canned vegetables botulinum Due to ingestion of neurotoxin Neisseria Many species are normal ﬂora of mucous membranes of respiratory and urogenital tracts Two primary pathogens of this genus: 0- N. gonorrhoeae (always a pathogen) 1- N. meningitidis (can be a commensal in the upper respiratory tract+ but can cause life threatening diseases like meningitis) Common Characteristics: Gram-negative diplococci (kidney or lima bean shaped) Pili for attachment to epithelial cells Often intracellular and often clustered Aﬃnity for mucous membranes Aerobic, non-motile https://step1.medbullets.com/microbiology/104044/neisser Prefer or require increased CO2 ia-gonorrhoeae Optimal growth at 35-37 C in moist environment Fastidious: sensitive to drying and temperature - don’t survive well in the environment Biochemical ID of Neisseria species Oxidase positive (purple) ○ Bacteria produce the enzyme cytochrome oxidase ○ When combined with the oxidase reagent, this enzyme produces a deep purple color in 10 seconds Biochemical tests used less frequently now (24-48 hrs) → Rapid tests https://microbiologyinfo.com/category/biochemical-test/ Neisseria gonorrhoeae Obligate human pathogen (humans are the only known reservoir) Gonorrhea is an acute pyogenic (pus-producing) infection of skin mucosum ○ Women → endocervix ○ Men → urethra Gram stain of urethral exudate can be diagnostic for men This organism also causes pharyngitis, suppurative arthritis, ophthalmitis in newborns from vaginal births If untreated, can lead to Pelvic Inﬂammatory Disease (sterility and ectopic pregnancies) Treatment: ○ Ceftriaxone with azithromycin ○ Many strains are penicillin resistant Identiﬁcation of Neisseria gonorrhoeae Specimen Test Methods Exudate from infected area NAAT ○ Genital, throat, anal ○ Urine or urethral swabs Immediately placed in transport media or Gram stain plated for cultures and sent to lab ○ Males only Use Dacron or rayon swabs ○ Low sensitivity for females - must follow up with molecular test or culture Culture (not preferred) ○ Must be plated to MTM or chocolate agar at 3-5% CO2 Neisseria meningitidis Nasopharynx of humans is the only reservoir ○ 5-15% of teens and young adults are carriers ○ 90% rates in closed populations (military barracks, fraternity houses, families) ○ Spread by respiratory droplets Meningitis ○ Medical emergency ○ Fever, headache, stiff neck, irritability, photophobia ○ Usually in kids and young adults ○ Meningococcemia Petechial rash, shock and disseminated intravascular coagulation (DIC) #1 cause of bacterial meningitis in infants - young adults in the US ○ Highest rates in kids

Exam 1 Review PATH 3100-001 PDF

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