Chapter 14: Staphylococci Exam 2

Is attached to the cell wall of the organism:

Bound coagulase

The coagulase slide test is simple and rapid to perform, but detects only which coagulase?

Bound coagulase

Occurring primarily in newborns or young children. Caused by exfoliative or epidermolytic toxins. Cases have occurred in adults but usually they are immunocompromised.

Bullous exfoliate dermatitis

Large pustules surrounded by a zone of erythema. Highly contagious infection that is easily spread by direct contact, fomites, or auto inoculation. Identified by thin walled, yellow-fluid filled pastures.

Bullous impetigo

-Mild infection of hair follicle/oil gland. -Infected area is raised and red.

Folliculitis

Is an intracellular enzyme produced when the organism is cultured in broth.

Free coagulase

Can be an extension of folliculitis; large, raised, superficial abscesses.

Furuncles/Boils

S. aureus enterotoxins have been associated with ___ ___. The source of contamination is usually an infected food handler. Staphylococcal food poisoning is a type of intoxication resulting from ingestion of a toxin formed outside the body.

GI disturbances

Which coagulase test coagulase test detects both bound and free coagulase and is sensitive because it can pick up smaller quantities of coagulase?

Tube test

Which coagulase test liberate free coagulase from the cell which acts on prothrombin in coagulase plasma?

Tube test

-Can cause vomiting and diarrhea -Heat stable at 100C for 30 minutes -Reheating contaminated food will NOT prevent disease -Food poisoning

Virulence Factors: S. aureus--Enterotoxins

-Causes nearly all menstruation-associated TSS (Toxic Shock Syndrome) -It is a super antigen stimulating T-cell proliferation -The subsequent production of a large amount of cytokines that are responsible for the symptoms. -Absorbed through the vaginal mucosa leading to the systemic effects seen in TSS associated with tampon use.

Virulence Factors: S. aureus--Toxic Shock Syndrome Toxin-1 (TSST)

S. epidermidis has been know to cause various

HAIs (hospital-acquired infections) such as prothetic or indwelling devices.

Hydrolyzes hyaluronic acid present in the intracellular ground substance that make up connective tissues, permitting the spread of bacteria during infection.

Hyaluronidase

_____ are initiated when a breach of the skin or mucosal barrier allows Staphylococci access to adjoining tissues or the bloodstream. Any event that compromises the host's ability to resist infection encourages colonization and infection.

Infections

Produced by both CoNS and S. aureus; acts on lipids present on the surface of the skin, particularly fats and oil secreted by the sebaceous glands.

Lipase

S. aureus the primary pathogen of the genus Staphylococcus. It is an important human pathogen because many strains have become resistant to antibiotics commonly used to treat the infection. An example is

MRSA (Methicillin-resistant S. aureus)

-Cell wall component -Binds to Fc of IgG -Blocks phagocytosis -Is one of several cellular components that have been identified in the cell wall of S. aureus. The most significant role is its ability to bind the Fc portion of IgG, blocking phagocytosis and negating the protective effect of the Ig.

Protein A

The species of Staphylococcus are gram positive cocci and may RARELY occur:

RARELY occur singly, occasionally in pairs, but most often in clusters.

Exfoliation toxin is also known as epidermolytic toxin. It causes the epidermal layer of the skin to slough off and is known to cause SSS (Staphylococcal Scalded Skin Syndrome) sometimes referred to as:

Ritter disease

Staph Scalded Skin Syndrome is also known as

Ritter disease

Coagulase positive staph is:

S. aureus

Which Staphylococci is more pathogenic than the other common members of the the genus?

S. aureus

Which Staphylococcus bacteria is distinguished by the presence of the enzyme catalase?

S. aureus

___ ____ is the primary pathogen of the genus Staphylococcus. Primary reservoir is the human nares. Can also colonize the axillae, vagina, pharynx, and other skin surfaces. Superficial to systemic infections.

S. aureus

Coagulase negative staph are:

S. epidermidis S. saprophyticus S. haemolyticus

-Infections due to ____ are predominantly hospital-acquired (HAIs). -Skin flora introduced by catheters, medical implantation, immunosuppressive therapy, CSF shunts, heart valves and other prosthetic devices. -Common cause of healthcare acquired UTIs. -Biofilm production is a key component in bacterial pathogenesis. -Septicemia has been reported in immunocompromised patients.

S. epidermidis (CoNS or CNS=Coagulase Negative Staph)

S. aureus is the major cause of:

SSTI (skin and soft tissue infections) and wound infections.

Ritter disease is also known by:

Staph Scalded Skin Syndrome

Bullous exfoliate dermatitis occurring primarily in newborns or young children. Caused by exfoliative or epidermolytic toxins. Cases have occurred in adults but usually they are immunocompromised.

Staph Scalded Skin Syndrome/Ritter disease

Role in pathogenicity uncertain; considered a virulence marker

Staphylocoagulase

The grape like cluster orientation is the most common arrangement associated with the:

Staphylococci

S. aureus the primary pathogen of the genus

Staphylococcus

The infectious agent of scalded skin syndrome, impetigo, toxic shock syndrome and MRSA are housed within genus

Staphylococcus

The Staphylococci are catalase-producing, gram positive cocci.

True

Some of the infections of humans in which S. aureus is the etiological agent are:

boils, carbuncles, impetigo, meningitis, osteomyelitis, urinary infections, and food poisoning.

When mixed with 3% hydrogen peroxide, catalase positive organisms will generate

bubbles of oxygen which are visible to the naked eye.

Staphylococcus specie contain the enzyme:

catalase

Micrococcus are:

catalase-producing, coagulase negative, gram-positive cocci found in the environment and as normal skin flora.

In the tube test procedure, free coagulase is liberated from the cell which acts on prothrombin in coagulase plasma. This product then acts on

fibrinogen to form a clot.

Bound coagulase is also known as:

clumping factor

Persons with ____, ____, and ___ are particularly at risk for developing infections.

compromised immune system, indwelling devices, and immune response defects

The presence or absence of hemolytic properties cannot be used as a:

definitive identification of Staphylococcus species.

Staph ___ are heat-stable exotoxins that can cause various symptoms including vomiting and diarrhea....entero = GI.

enterotoxins

What would an S. aureus look like on a Blood Agar Plate?

golden-yellow and beta-hemolytic

The species of Staphylococcus are gram:

gram positive cocci (npc)

A substance in the blood that destroys red blood cells and liberates hemoglobin.

hemolysin

Is an exoenzyme that lyses red blood cells.

hemolysin

Catalase will break down

hydrogen peroxide.

Some bacteria may possess enzymes other than catalase that can decompose hydrogen peroxide, a few tiny bubbles forming after 20 to 30 seconds is considered or not considered a positive test.

not considered

S. aureus pathogenic or non pathogenic?

pathogenic

Staphylococcal leukocidin, PVL, is an exotoxin lethal to ______. It has been implicated as contributing to the invasiveness of the organisms by suppressing phagocytosis and has been associated with severe cutaneous infections and necrotizing pneumonia. Although produced by relatively few strains S.aureus, it is often associated with community-acquired staphylococcal infections.

polymorphonuclear leukocytes

Infections caused by S. aureus are suppurative, meaning they cause the formation of _____. Once an organism has crossed the initial host barriers, it activates the host's acute inflammatory response. This leads to the proliferation and activation of PMNs. However, the organisms are able to resist the action of the inflammatory cells using enzymes/toxins.

pus

If a colony of bacterial cells is producing hemolysin and secreting it into the medium, there will be a

round, clear zone surrounding the colony because the red blood cells in that area have been lysed (zone of hemolysis).

Staphylococci species are gram positive cocci that can occur as:

singly, in pairs, tetrads or in grape like clusters (o.5-1.5um) "bunches of grapes"

When performing bound coagulase, all negative slide coagulase must be followed by a:

tube test

Staphylococcus aureus can be spread person-to-person and this is particularly troublesome in the healthcare setting. If a patient who is a nasal carrier is admitted to the hospital it is very likely that the organism will spread from patient to healthcare workers. Transmission occurs from direct contact with: Patient and hospital workers are often colonized at a higher rate vs. general population.

unwashed, contaminated hands and by contact with inanimate object (fomites).

S. saprophyticus is mainly associated with:

urinary tract infections in young females who are sexually active.

Identify what a CNS or CoNS (Coagulase Negative Staph) would look like on an agar plate:

white/greyish-white, creamy and non-hemolytic

It is preferable to test colonies from media with or without blood, and why?

without blood since erythrocytes possess catalase activities.

Streptococcus is catalase positive. T/F

False

The genus name, Staphylococci, is derived from the Greek term for:

"bunches of grapes"

Common skin infections caused by S. aureus; considered opportunistic because they usually occur as a result of previous skin injuries such as cuts, burns, and surgical incisions. Can be secondary to skin disease of different etiologies. Dry, irritated skin combined with poor personal hygiene encourages the development of infection. Immunocompromised individuals-particularly patients who are receiving chemotherapy/have chronic illnesses/implanted devices-are predisposed to developing staph skin infections such as:

-Folliculitis -Furuncles/boils -Carbuncles -Bullous impetigo -Staph Scalded Skin Syndrome

-Source: infected food handler -Caused by enterotoxin -Most commonly affected foods are those with mayonnaise or eggs. -Onset of symptoms in 2-8 hours -Resolution in 24-48 hours

-Food poisoning -Staphylococcus aureus (Staphylococcal food poisoning)

What two forms of coagulase may be produced by S. aureus?

-Free -Bound

What are the mode of transmission for Staphylococcus aureus?

-Traumatic introduction -Direct contact -Inanimate objects -Predisposing conditions: indwelling devices, immune response defects

What are the general characteristics of Staphylococcus?

-nonmotile -non spore-forming -nonencapsulated -catalase producing -oxidase negative -glucose fermenters -primarily aerobic -some facultative anaerobes -Bacitracin resistant -grow on peptone agar -inhibited by bile salt media -medium sized (4-8mm), creamy, white, golden, "buttery" -can be B-hemolytic

Occur when larger, more invasive lesions develop from multiple furuncles, which can progress into deeper tissues. Patients often present with fevers and chills (not in furuncles) indicating a systemic spread of the bacteria.

Carbuncles

Is an exoenzyme that causes fibrin of blood plasma to clot.

Coagulase

-Often found as Normal flora -Presence can indicate contamination -Predisposing factors to infection: Catheterization, Medical device implantation, and immunosuppressive therapy -Abbreviated CNS or CoNS -Infections are predominantly hospital-acquired -ALL plate reading look very similar: white-grayish/white, maybe creamy, and non-hemolytic

Coagulase Negative Staph

What does CNS or CoNS stand for?

Coagulase Negative Staph

Staph are just one of the many genera found in Family Staphylococcaceae. There are many members Staphylococcus but not all of the members cause disease. In fact, many members are considered normal flora living on our skin and mucous membrane. The Staphylococci can be further divided in the

Coagulase positive staph and the Coagulase negative staph.

4 hemolysis 1 leukocidin: Panton-Valentine Leukocidin (PVL)

Cytolytic toxins

Exfoliation toxin is also known as:

Epidermolytic toxin

Staphylococcal SSS( Scalded Skin Syndrome) or Ritter Disease.

Exfoliation toxin

______ is a toxin protein produced by a bacterium and released into its environment; may exert adverse effects on sites far from infection.

Exotoxin

-Hyaluronidase -Lipase -Staphylocoagulase

Extracellular enzymes

Genus Staphylococcus is part of the newly-formed Family Staphylococcaceae. Previously, genus Staph was classified under Family Micrococcaceae along side another similar genus Micrococcus. ______ are catalase-producing, coagulase negative, gram-positive cocci found in the environment and as normal skin flora.

Micrococcus

Do Catalase negative organisms generate bubbles of oxygen when mixed with 3% hydrogen peroxide? Y/N

No

S. aureus is novobiocin resistant or susceptible?

Susceptible

Is a rare but potentially fatal multi system disease characterized by sudden onset of fever, chills, vomiting, diarrhea, muscles aches, and rash, which can progress to hypotension and shock. Usually results from a LOCALIZED infection with S. aureus. Only the toxin, TSST-1, is SYSTEMIC.

TSS (Toxic Shock Syndrome)

How are Staphylococci and Streptococci differentiated?

The appearance of a gram stained smear due to the cell grouping (grape-like clusters) of staphylococci.

Pathogenic S. aureus produces coagulase. T/F

True

S. aureus is more pathogenic than the other common members of the genus, S. epidermidis and S. saprophyticus. T/F

True

S. aureus is positive for all hemolysis, catalase, coagulase, novobiocin, and mannitol.

True

S. aureus is usually hemolytic, but sometimes it is not. T/F

True

S. epidermidis is negative for hemolysis, coagulase, and mannitol. It is positive for catalase and susceptible for novobiocin.

True

S. saprophyticus is negative for hemolysis, coagulase, and mannitol. It is positive for catalase and resistant for novobiocin.

True

~30% of the population are colonized with S. aureus in the _____.

nares

The organisms are able to resist the action of the inflammatory cells using enzymes/toxins. The resulting abscess is filled with pus comprised of

necrotic tissue and the damaged or killed leukocytes, extravascular fluid, and live/dead organisms.