(M) Lesson 7.2: Gram Positive and Gram Negative Cocci Flashcards
Staphylococcus
- Gram positive cocci in clusters
- Non-motile
- Non-sporeformer
- A facultative anaerobe
- Medically important species (pathogenic and are routinely isolated in the lab
Staphylococcus
Important biochemical property of Staphylococcus?
Catalase positive
What are the three medically important species of Staphylococcus?
- Staphylococcus aureus
- Staphylococcus epidermidis
- Staphylococcus saphrophyticus
Give the result with respect to Staphylococcus aureus.
Catalase
Positive
Give the result with respect to Staphylococcus aureus.
Coagulase
Positive
Give the result with respect to Staphylococcus aureus.
Salt (halo) (7.5 to 10% NaCl)
Tolerant
Give the result with respect to Staphylococcus aureus.
Mannitol
Fermenter
Give the result with respect to Staphylococcus aureus.
DNAse
Positive
Give the result with respect to Staphylococcus aureus.
Nitrate and Voges Proskauer (VP)
Positive
Give the result with respect to Staphylococcus aureus.
Gelatin
Positive
Give the result with respect to Staphylococcus aureus.
PYR
Negative
Give the result with respect to Staphylococcus aureus.
BAP
Yellow-orange colony
____, ____, and ____ are biochemically important in gram-negative organisms.
- Nitrate and VP
- Gelatin
- PYR
____, ____, ____, and ____ are mainly used for identification.
- Catalase
- Coagulase
- MSA
- DNAse
Having lipochrome results in?
Yellow-orange colony
Beta-hemolysis results in?
Yellow halo around the growth
What is the distinct smell of a pure colony of Staphylococcus?
Unwashed clothes or socks
Transmission routes from person to person happens through?
- Sneezing
- Formites
- Surgical wounds
- Infected patients
- Food
What are the virulence factors of Staphylococcus?
- Cell-associated factors
- Extracellular
Virulence Factors
- Already attached to the bacterial membrane, cytoplasm, or cell wall
- Ag in serology for identification
- Contributes to pathogenicity (how it can infect)
Cell-Associated Factors
Virulence Factors
- Released by bacterium depending on the environment
- Enzymes or toxins
- For protection
Extracellular
Cell-Associated Factors
Most important in Staphylococcus aureus
Protein A
Extracellular (Enzymes)
Familiarize yourself with the different enzymes.
- Catalase
- Free coagulase
- Lipase
- Hyaluronidase
- B-lactamase
- Staphylokinase
- Proteinases
Extracellular (Enzymes)
By all Staphylococcus
Catalase
Extracellular (Enzymes)
- By Staphylococcus aureus
- Protection from immune system
Free coagulase
Extracellular (Enzymes)
- Spreading factor
- Not unique to Staphylococcus aureus
- Infection spreads from one site to another
Hyaluronidase
Extracellular (Enzymes)
- Resistance to penicillin (and other antibiotics)
B-lactamase
Extracellular (Enzymes)
- Also known as fibrinolysin
- Lyses coagulase
- To undergo proper metabolism
Staphylokinase
Endotoxin or Exotoxin?
- By gram-negative organisms
- During cell death
- Less poisonous (lipopolysaccharide)
- Non-specific tissue affinity
Endotoxin
Endotoxin or Exotoxin?
- By gram-positive organisms
- During life cycle
- More poisonous (active)
- Specific tissue affinity
- More immunogenic
Exotoxin
Staphylococcus releases what type of toxins?
Exotoxins
Extracellular (Toxins)
What are the different types of toxins within Staphylococcus?
- Cytolytic Toxins (Hemolysin alpha, betta gamma, and delta + Leucocidin)
- Enterotoxin A-F
- Toxic Shock Syndrom Toxin-1 (TSST-1)
- Exfoliative
Determine the type of toxins.
- Targets cells like RBCs and WBCs
Cytolytic toxins
Determine the type of toxins (cytolytic toxins).
- Targets the RBC cells specifically
Hemolysin
Determine the type of toxins (cytolytic toxins).
- Used for Staphylococcus aureus
Hemolysin beta
Determine the type of toxins (cytolytic toxins).
- Targets WBCs cells specifically
Leucocidin
Extracellular (Toxins)
- Targets the intestine
- Heat-stable at 60°C for 10 minutes
Enterotoxin A-F
Extracellular (Toxins)
- Targets the nephrons (kidneys)
Toxic Shock Syndrome Toxin-1
Extracellular (Toxins)
- Also known as epidermolytic toxin
- Targets the skin
Exfoliative
Infections are caused by ____ or ____
- By a bacteria itself
- By an enzyme from bacteria as its virulence factor
This is due to toxins released by bacteria.
Intoxication
T or F: Patient may not react to the bacteria itself.
T
Skin and Soft Tissue Infections
- Follicle infection
- Site of Origin: Hair follicles
Folliculitis
Skin and Soft Tissue Infections
- Progression of untreated folliculitis
- Spread around the area of the follicle
Furuncle (Boil)
Skin and Soft Tissue Infections
- Spread to other areas
Carbuncle
Skin and Soft Tissue Infections
- Inflammation of the upper or lower eyelids
Styes
Skin and Soft Tissue Infections
- Starts as an untreated wound infection
Abscess
Skin and Soft Tissue Infections
- Staphylococcus aureus is the top causative agent regardless of morphology
Wound Infection
Skin and Soft Tissue Infections
- Painful crusts around the facial area
Impetigo
Skin and Soft Tissue Infections
- Nail infection from equipment used in nail care
- Either toes or hands
Paronychia
Skin and Soft Tissue Infections
- Inflammation of cellulites
Cellulitis
Name the affected system.
- Osteomyelitis (inflamed bone metaphysis)
- Arthritis
- Bursitis
- Pyomyositis
Musculoskeletal
Name the affected system.
- Tonsilitis
- Pharyngitis
- Sinusitis
- Otitis
- Bronchopneumonia
- Lung abscess
- Empyema
- Pneuomonia (rare)
Respiratory
Name the affected system.
- Abscess
- Meningitis
- Intracranial thrombophlebitis
Central Nervous System
Name the affected system.
- Bacteremia
- Septicemia
- Pyemia
- Endocarditis
Endovascular
Name the affected system.
- Urinary Tract Infection
Urinary
Name the affected system.
- Hospital-acquired
Nocosomial infection
Diseases caused by the bacterial exotoxin which are produced either in the infected host or performed in vitro.
Intoxications
What are the three types of intoxications?
- Gastroenterititis (Food Poisoning)
- Toxic Shock Syndrome
- Staphylococcal Scalded Skin Syndrome
Name the type of intoxication.
- Occurs 1 to 8 hours after ingesting toxin
- Manifestations include nausea, abdominal pain, vomiting followed by diarrhea and with no fever
- Caused by Enterotoxins A-F preformed in food
Gastroenteretitis (Food Poisoning)
Name the type of intoxication.
- Manifestations include abrupt high fever, vomiting, diarrhea, myaligias, scarlantiniform rash, hypertension, and severe case of cardiac or renal failure
- Caused by TSST-1
- Requires immediate treatment
Toxic Shock Syndrome
Name the type of intoxication.
- Caused by exfoliative toxin
- Common in children
Staphylococcal Scalded Skin Syndrome
We should collect specimen for treatment based on?
The type of infection
Name the specimen to be collected based on type of infection.
Wound infection from a suppurative lesion
Pus
Name the specimen to be collected based on type of infection.
Respiratory infection
Sputum
Name the specimen to be collected based on type of infection.
Bacteremia and septicemia
Blood
Name the specimen to be collected based on type of infection.
Food poisoning
Feces, vomit, remains of suspected food
Name the specimen to be collected based on type of infection.
Detection of carriers
Nasal swab
T or F: Carriers harbor the bacteria that show most if not all the symptoms.
F (do not show any symptom)
Staphylococcus aureus is highly susceptible to ____
Beta-lactam drugs like methicillin, nafcillin, oxacillin, and cloxacillin
T or F: Staphylococcus aureus can be resistant to methicillin.
T
Methicillin-resistant Staphylococcus aureus (MRSA) is challenging to treat because?
Methicillin is already a high-level drug
MRSA due to ____ is commonly resistant to antibiotics except vancomycin and fusidic acid.
Changes in major penicillin-binding proteins
T or F: Vancomycin and fusidic acid are usually given in low dosages as a last resort.
F (high dosages)
Nasal colonization in carriers can be treated with ____
Topical mupirocin
- A serological test
- Rapid test
- Coagulase test
BACTiStaph
- Normal flora of the skin and mucus membrane
- Predominance indicates infection
- Most common cause of CSF shunt infection
- Infections are related to intravenous catheters and prosthetic implants
Staphylococcus epidermidis
- Biochemically negative for coagulas and susceptible for novobiocin
Staphylococcus epidermidis
T or F: If normal flora leaves its natural habitat, it may cause infections.
T
Infection due to Staphylococcus epidermidis leaving normal flora usually occurs with what two procedures?
- Venipuncture
- Undergo shunt (catheter inserted in the body)
This happens with patients with renal failure who are undergoing peritoneal dialysis through an indwelling catheter.
Peritonitis
- Medically important cause of UTI (second most common causative agent) in sexually active young women
- Biochemically negative for coagulase and resistant to novobiocin
Staphylococcus saprophyticus
Most common causative agent of UTI?
Escherichia coli