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Questions and Answers
Which of the following groups of bacteria thrives in cold environments?
Which of the following groups of bacteria thrives in cold environments?
- Thermophiles
- Mesophiles
- Psychrophiles (correct)
- Capnophiles
What is the name given to the time required for bacterial cells to double in number?
What is the name given to the time required for bacterial cells to double in number?
- Binary fission time
- Doubling time
- Generation time (correct)
- Replication time
What type of environment would bacteria that require oxygen for growth be classified as?
What type of environment would bacteria that require oxygen for growth be classified as?
- Microaerophiles
- Obligate anaerobes
- Facultative anaerobes
- Obligate aerobes (correct)
What type of environment would a bacterium be growing in if the solute concentration is higher outside the cell than inside?
What type of environment would a bacterium be growing in if the solute concentration is higher outside the cell than inside?
Which of these chemical requirements is NOT a key element needed for bacterial growth?
Which of these chemical requirements is NOT a key element needed for bacterial growth?
Which type of bacteria would struggle to grow in the presence of oxygen?
Which type of bacteria would struggle to grow in the presence of oxygen?
What type of environment is best suited for medically important bacteria?
What type of environment is best suited for medically important bacteria?
Which of the following is a characteristic of bacteria that can grow with or without oxygen?
Which of the following is a characteristic of bacteria that can grow with or without oxygen?
What is the function of the coagulase enzyme produced by Staphylococcus bacteria?
What is the function of the coagulase enzyme produced by Staphylococcus bacteria?
Which characteristic is particularly associated with Staphylococcus aureus?
Which characteristic is particularly associated with Staphylococcus aureus?
Which of the following is NOT considered a virulence factor of Staphylococcus aureus?
Which of the following is NOT considered a virulence factor of Staphylococcus aureus?
Which condition is associated with a heat-stable enterotoxin produced by Staphylococcus aureus?
Which condition is associated with a heat-stable enterotoxin produced by Staphylococcus aureus?
What is the main route of transmission for Staphylococcus aureus food poisoning?
What is the main route of transmission for Staphylococcus aureus food poisoning?
Scalded skin syndrome, caused by Staphylococcus aureus, is characterized by which of the following symptoms?
Scalded skin syndrome, caused by Staphylococcus aureus, is characterized by which of the following symptoms?
Which of these conditions is associated with tampon use?
Which of these conditions is associated with tampon use?
What role does hyaluronidase play in the virulence of Staphylococcus aureus?
What role does hyaluronidase play in the virulence of Staphylococcus aureus?
What is the Gram stain and shape of Staphylococcus bacteria?
What is the Gram stain and shape of Staphylococcus bacteria?
Which of the following describes the action of the enzyme catalase?
Which of the following describes the action of the enzyme catalase?
Which of the following is a characteristic of alpha-hemolytic bacteria on blood agar?
Which of the following is a characteristic of alpha-hemolytic bacteria on blood agar?
A patient presents with a sore throat, fever, and a rash. Which bacterium is most likely the causative agent?
A patient presents with a sore throat, fever, and a rash. Which bacterium is most likely the causative agent?
A newborn is diagnosed with meningitis and sepsis. Which bacterial species is a likely cause, given maternal colonization?
A newborn is diagnosed with meningitis and sepsis. Which bacterial species is a likely cause, given maternal colonization?
A patient has been diagnosed with subacute bacterial endocarditis. Which of the following is most likely to be identified?
A patient has been diagnosed with subacute bacterial endocarditis. Which of the following is most likely to be identified?
What is the primary antibiotic treatment for infections caused by most Streptococcus species?
What is the primary antibiotic treatment for infections caused by most Streptococcus species?
A patient with a penicillin-resistant Streptococcus pneumoniae infection requires alternative antibiotic therapy. Which treatment is most appropriate?
A patient with a penicillin-resistant Streptococcus pneumoniae infection requires alternative antibiotic therapy. Which treatment is most appropriate?
Why are beta-lactam antibiotics usually ineffective against Enterococcus infections?
Why are beta-lactam antibiotics usually ineffective against Enterococcus infections?
Which of the following best describes the difference between colonization and infection?
Which of the following best describes the difference between colonization and infection?
Which of the following is a correct definition of a nosocomial infection?
Which of the following is a correct definition of a nosocomial infection?
What does the phrase 'portal of entry' refer to in the context of disease transmission?
What does the phrase 'portal of entry' refer to in the context of disease transmission?
Which of these is NOT a primary step in an outbreak investigation?
Which of these is NOT a primary step in an outbreak investigation?
Which bacterial structural components are important for initiating infection and colonization?
Which bacterial structural components are important for initiating infection and colonization?
A healthcare-associated infection (HAI) is mentioned as impacting patients by:
A healthcare-associated infection (HAI) is mentioned as impacting patients by:
What is an example of a bacterial species that is categorized as a multidrug-resistant organism?
What is an example of a bacterial species that is categorized as a multidrug-resistant organism?
If the lab starts to see an increase in the same positive cultures from a specific department, this may indicate:
If the lab starts to see an increase in the same positive cultures from a specific department, this may indicate:
Which transmission route is most relevant for the spread of multidrug-resistant organisms in healthcare settings?
Which transmission route is most relevant for the spread of multidrug-resistant organisms in healthcare settings?
Which of the following is an appropriate example of a portal of exit?
Which of the following is an appropriate example of a portal of exit?
What is the primary mechanism of antibiotic resistance in Methicillin-resistant Staphylococcus aureus (MRSA)?
What is the primary mechanism of antibiotic resistance in Methicillin-resistant Staphylococcus aureus (MRSA)?
Which of the following represents the progression of antibiotic resistance in Staphylococcus aureus as described?
Which of the following represents the progression of antibiotic resistance in Staphylococcus aureus as described?
What is a common first-line treatment option for MRSA infections, especially when intravenous therapy is required?
What is a common first-line treatment option for MRSA infections, especially when intravenous therapy is required?
A patient presents with a red, swollen, painful skin infection that is exuding pus. Which of the following pathogens should be considered as the most likely cause?
A patient presents with a red, swollen, painful skin infection that is exuding pus. Which of the following pathogens should be considered as the most likely cause?
What is a key characteristic that differentiates Staphylococcus from Streptococcus species?
What is a key characteristic that differentiates Staphylococcus from Streptococcus species?
Which Staphylococcus species is most associated with biofilm production and infections of prosthetic devices?
Which Staphylococcus species is most associated with biofilm production and infections of prosthetic devices?
A young, sexually active female presents with a urinary tract infection. Which Staphylococcus species is most likely to be the causative agent?
A young, sexually active female presents with a urinary tract infection. Which Staphylococcus species is most likely to be the causative agent?
What is a characteristic shared by both Streptococcus and Enterococcus species?
What is a characteristic shared by both Streptococcus and Enterococcus species?
How does the classification of Enterococcus relate to its usual habitat?
How does the classification of Enterococcus relate to its usual habitat?
Choose the most accurate statement about MRSA colonization rates:
Choose the most accurate statement about MRSA colonization rates:
Flashcards
Difficult pathogens
Difficult pathogens
Pathogens resistant to multiple antibiotics, e.g. MRSA, VRE.
Colonization
Colonization
Presence of organisms on body surfaces without causing disease.
Infection
Infection
Organisms invade tissues causing signs and symptoms.
Nosocomial infection
Nosocomial infection
Infection acquired after hospital admission.
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Transmission
Transmission
Pathway by which an infection spreads to others.
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Portals of entry
Portals of entry
Routes through which pathogens enter the body.
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Vulnerable hosts
Vulnerable hosts
Individuals at increased risk for infections.
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Etiologic agent
Etiologic agent
Specific pathogen responsible for an infection.
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Reservoir
Reservoir
Natural habitat where pathogens live and multiply.
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Mode of transmission
Mode of transmission
Method by which an infectious agent spreads.
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Staphylococcus
Staphylococcus
Gram-positive cocci in grape-like clusters, normal flora of skin and mucous membranes.
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Catalase Positive
Catalase Positive
An enzyme that breaks down hydrogen peroxide (H2O2) into bubbles, indicating Staphylococcus presence.
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Coagulase
Coagulase
An enzyme that binds plasma fibrinogen to form a clot, found in Staphylococcus aureus.
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Staphylococcus aureus
Staphylococcus aureus
Most virulent staph species, golden in color, commonly found on skin and mucous membranes.
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Staphylococcus aureus Virulence Factors
Staphylococcus aureus Virulence Factors
Include coagulase, protein A, enterotoxins, lipase, hyaluronidase, hemolysins.
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Impetigo
Impetigo
A skin infection caused by Staphylococcus aureus characterized by pustules and crusty sores.
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Toxic Shock Syndrome
Toxic Shock Syndrome
A severe illness linked to menstruating women, presenting with fever, vomiting, and rash.
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Food Poisoning by Staph aureus
Food Poisoning by Staph aureus
Caused by heat-stable enterotoxins in contaminated food, leads to vomiting and diarrhea.
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Scalded Skin Syndrome
Scalded Skin Syndrome
A toxin-mediated condition in infants causing skin to blister and peel, resembling scalded skin.
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Methicillin Resistant Staph aureus (MRSA)
Methicillin Resistant Staph aureus (MRSA)
A type of Staphylococcus aureus resistant to methicillin, complicating treatment.
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MRSA
MRSA
Methicillin-resistant Staphylococcus aureus; a type of bacteria resistant to many antibiotics.
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Penicillin resistance
Penicillin resistance
Resistance developed after WWII leading to the use of methicillin.
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mecA gene
mecA gene
Gene associated with methicillin resistance in Staphylococcus aureus.
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Vancomycin
Vancomycin
Antibiotic used to treat MRSA infections, but may lead to VRSA.
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Community-acquired infections
Community-acquired infections
Infections caused by MRSA, common in community settings.
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Staphylococcus epidermidis
Staphylococcus epidermidis
Coagulase-negative Staphylococcus; low virulence, opportunistic infections.
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Biofilms
Biofilms
Protective layer formed by bacteria like Staphylococcus epidermidis on devices.
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Catalase negative
Catalase negative
Characteristic of Streptococcus; does not bubble in hydrogen peroxide.
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E. faecalis
E. faecalis
Main species of Enterococcus causing human infections, found in intestines.
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Bacteremia
Bacteremia
Presence of bacteria in the bloodstream, sometimes caused by infections like MRSA.
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Gram-negative bacteria
Gram-negative bacteria
Bacteria that stain pink during the Gram stain process.
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Mycoplasma
Mycoplasma
Bacteria that lack a cell wall and do not stain in Gram staining.
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Psychrophiles
Psychrophiles
Bacteria that thrive in cold temperatures (4-15°C).
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Mesophiles
Mesophiles
Bacteria that grow best at moderate temperatures (30-35°C).
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Thermophiles
Thermophiles
Bacteria that flourish in hot environments (50-60°C or more).
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Obligate aerobes
Obligate aerobes
Bacteria that require oxygen for growth.
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Facultative anaerobes
Facultative anaerobes
Bacteria that can grow with or without oxygen.
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Generation time
Generation time
The time taken for one bacterial cell to divide into two cells.
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Enterococcus faecium
Enterococcus faecium
A bacterium with relatively low virulence causing UTIs, endocarditis, and wound infections.
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Hemolysis Types
Hemolysis Types
Classification of bacteria based on their hemolytic activity: Alpha (ɑ), Beta (β), Gamma (ɣ).
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Alpha Hemolysis
Alpha Hemolysis
Bacteria partially lyse RBCs, leading to a green/brown appearance on blood agar.
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Beta Hemolysis
Beta Hemolysis
Bacteria completely lyse RBCs, resulting in a clear colorless zone around colonies on blood agar.
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Group A Streptococcus
Group A Streptococcus
Known for causing conditions like pharyngitis, scarlet fever, and can lead to rheumatic fever and glomerulonephritis.
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Streptococcus pneumoniae
Streptococcus pneumoniae
Leading cause of pneumonia, otitis media, and meningitis, typically appears as gram-positive cocci in pairs.
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Enterococcus Antibiotic Resistance
Enterococcus Antibiotic Resistance
Enterococcus species are intrinsically resistant to beta-lactams (like penicillins), needing alternative treatments.
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Gram Stain List
- Gram-Positive Cocci (GPC): Bacteria ending in "-coccus" (Streptococcus, Staphylococcus, Enterococcus)
- Gram-Negative Cocci (GNC): Neisseria, Moraxella (few species)
- Gram-Positive Bacilli (GPR): Everything else
- No Gram-negative bacilli on Exam 1
Characteristics of Bacteria
- Prokaryotes: Lack a true nucleus, DNA in a circular chromosome without a nuclear membrane, rigid cell walls with peptidoglycan, asexual reproduction
- Eukaryotes: Possess a true nucleus, DNA within a membrane-bound nucleus, diverse cell wall structures, both sexual and asexual reproduction
Characteristics of Bacteria - Classification
- Domain: Bacteria
- Phylum: Firmicutes
- Class: Bacilli
- Order: Bacillales
- Family: Staphylococcaceae
- Genus: Staphylococcus
- Species: aureus
- Strain: a genetic variant or subtype (e.g., Methicillin-resistant S. aureus)
- Genus is capitalized and either underlined or italicized
- Species is lowercase and either underlined or italicized
Characteristics of Bacteria - Gram Stain Basis
- Gram staining groups medically important bacteria
- Gram-positive bacteria have a thick peptidoglycan layer and stain purple
- Gram-negative bacteria have a thin peptidoglycan layer and stain pink/red due to their outer membrane
Characteristics of Bacteria - Gram Stain Procedure
- Crystal Violet (CV): Attracted to negatively charged bacterial cells, enters cell wall
- Iodine: Mordant, sets the dye (CV) in the cell wall
- Alcohol: Decolorizer, removes the thin peptidoglycan layer in Gram-negative bacteria
- Safranin: Counter stain, colors Gram-negative bacteria pink/red
Characteristics of Bacteria - Bacterial Growth Factors
- Temperature: Psychrophiles (cold), Mesophiles (moderate), Thermophiles (hot)
- Osmotic Pressure: Isotonic, hypotonic, hypertonic
- Chemical Requirements: Carbon, water, nitrogen, sulfur, phosphorus, trace elements (iron, copper, zinc), hydrogen ion concentration (pH)
- **Atmosphere:**Obligate aerobes, obligate anaerobes, facultative anaerobes, capnophiles
Characteristics of Bacteria - Bacterial Growth
- Replication: Binary fission
- Growth curve: Lag phase, Log phase, Stationary phase, Death phase
Characteristics of Bacteria - Bacterial Structures
- Cocci: spherical bacteria
- Bacilli: rod-shaped bacteria
- Pleomorphic: varying shapes
- Spirochetes: helical bacteria
- Flagella: protein filaments for motility
- Pili: hair-like appendages for adherence
- Capsules: polysaccharide layers for protection and attachment.
- Endospores: dormant forms; highly durable
- Lipopolysaccharide (LPS): component of Gram-negative bacteria cell walls
Characteristics of Bacteria - Microbiome and Microbiota
- Microbiome: genetic material of all microbes in the human body
- Microbiota: community of microbes on or inside the human body
- Biofilm: Assemblage of microbes adhering to a surface
Host-Parasite Interaction
- Host: organism being infected
- Parasite: invader or agent
- Pathogen: microorganism capable of causing disease
- Primary pathogen: frequently causes disease in healthy hosts
- Opportunistic pathogen: causes disease in immunocompromised hosts
- Host barriers: microbiome (normal flora), anatomic barriers (skin), stomach acid, white blood cells, antibodies.
Additional (Bacteria)
- Bacteremia: bacteria multiplying in the bloodstream
- Virulence: ability of an organism to produce disease
- Pyogenic: pus-producing
Hospital Epidemiology
- HAI: healthcare-associated infection.
- Colonization: presence of organism without disease
- Infection: organisms invade body tissues
- Nosocomial infection: infection acquired in a hospital setting
- Transmission : Portal of entry, vulnerable hosts, Organism, Reservoir, Portal of exit, contact, droplets, air
- Steps in outbreak investigation: identify agent, eliminate, prevent, prevent future
- Laboratory in outbreak: seeing same positive cultures in a specific department
Sterilization & Disinfection/Infection Control
- Antiseptic: inhibits microbial growth
- Aseptic: used to sterilize (used in surgery, phlebotomy)
- Cide/Cidal: to kill
- Stasis/Static: prevent multiplication. (Without necessarily killing)
- Disinfectant: kill equipment and surfaces
- Methods for sterility control: Heat (moist and dry), Autoclave, Pasteurization, Flame, Membrane filtration, High-efficiency particulate air (HEPA) filters, Radiation (UV light, ionization)
Staphylococcus aureus
- "Aureus" = golden
- Often colonizes skin, nose, armpits, and groin
- Virulence factors: Coagulase, Protein A, Enterotoxins, Lipase, Hyaluronidase, Hemolysins
- Diseases (Staph aureus): Skin infections (impetigo, furuncles, carbuncles, pyogenic abscesses, scalded skin syndrome), Food poisoning (toxin-mediated), Toxic Shock Syndrome (associated with menstruation and tampon usage).
- MRSA: Methicillin-resistant Staphylococcus aureus (Antibiotic resistance.)
Coagulase-negative Staphylococcus species
- Staphylococcus epidermidis: Colonizes most people, low virulence, forms biofilms. Associated with bacteremia and device-related infections
- Staphylococcus saprophyticus: May have affinity for the urethra and bladder epithelium, linked with urinary tract infections, resistant to Novobiocin
Streptococcus
- Gram-positive cocci in chains
- Normal flora of upper respiratory and intestinal tracts
- Catalase-negative, compared to Staph
- Types based on hemolysis: Alpha (partially hemolyzes), Beta (completely hemolyzes), Gamma (no hemolysis)
Enterococcus
- Gram-positive cocci
- Often part of the streptococci intestinal flora
- Relativley low virulence
- Causes UTIs, endocarditis, wound infections
Moraxella catarrhalis
- Gram-negative diplococci
- Normal flora in upper respiratory tract.
- Not fastidious
- Common in otitis media, sinusitis in children, pneumonia in the elderly
Neisseria gonorrhoeae
- Obligate human pathogen
- Causes localized inflammation, “Gonococcus,” “GC”
- Transmitted primarily by sexual contact, rarely lethal
- Quickly killed in blood stream
- Often resistant to penicillin
- Women - endocervix, Men - urethra
- Can cause pelvic inflammatory disease (PID) and ectopic pregnancies if left untreated.
Neisseria meningitidis
- Obligate human pathogen
- Normal nasopharyngeal flora in some
- Life-threatening infections
- Causes meningitis, septicemia.
- Transmitted by respiratory droplets
Gram Positive Bacilli
- Spore formers: Bacillus spp, Clostridium spp.
- Opportunistic pathogens: Corynebacterium spp., Gardnerella vaginalis
- **Strict pathogens:**Nocardia spp., Corynebacterium diphtheriae, Listeria monocytogenes
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Description
Test your knowledge on bacterial classification and the Gram stain technique with this quiz. Explore the characteristics that distinguish Gram-positive and Gram-negative bacteria, as well as the classification hierarchy from domain to species. Perfect for microbiology students and enthusiasts alike.