Gram Positive Bacteria Flashcards by Tim Velde

Microscopically, the gram-positive cells within the genus Streptococcus are generally arranged in what form?

pairs or chains

How well did you know this?

Not at all

Perfectly

Streptococcus can be differentiated based on traditional systems of classification. These systems of differentiation include

1) hemolysis
2) cell wall structure
3) Lancefield Classification
4) antibody reactions to specific bacterial antigen
5) biochemical identification

How well did you know this?

Not at all

Perfectly

T/F Enterococci are commensal organisms of the human gastrointestinal (GI) tract causing variety of opportunistic infections.

TRUE

How well did you know this?

Not at all

Perfectly

Name the two most common Enterococci causing infection in humans.

E. faecalis

E. faecium

How well did you know this?

Not at all

Perfectly

Beta-hemolytic streptococci are characterized by ____________ __________, based on carbohydrates within their cell wall.

Lancefield groups

How well did you know this?

Not at all

Perfectly

Beta-hemolytic streptococci include large colony-forming pyogenic strains representing what Lancefield groups?

group A antigen

group B antigen

group C antigen

group G antigen

group L antigen

How well did you know this?

Not at all

Perfectly

The viridans group contains small colony-forming beta-hemolytic strains which may type with what Lancefield groups?

group A antigen

group C antigen

group F antigen

group G antigen

How well did you know this?

Not at all

Perfectly

S. pyogenes, of Lancefield group A, produces two virulence factors contributing to its hemolysis profile. What are they?

streptolysin O

streptolysin S

How well did you know this?

Not at all

Perfectly

S. pyogenes produces Streptolysin S.

Is Streptolysin S oxygen-stable or oxygen-labile?

Streptolysin S is an oxygen-stable.

How well did you know this?

Not at all

Perfectly

Streptolysin S and Streptolysin O are capable of lysing what cell types?

erythrocytes

leukocytes

platelets

How well did you know this?

Not at all

Perfectly

S. pyogenes produces Streptolysin O.

Is Streptolysin O oxygen-stable, or oxygen-labile?

Streptolysin O is an oxygen-labile.

How well did you know this?

Not at all

Perfectly

S. pyogenes may release what elements producing scarlet fever?

streptococcal pyrogenic exotoxins (SPEs)

How well did you know this?

Not at all

Perfectly

T/F

S. pyogenes SPE’s act as supertoxins.

TRUE

How well did you know this?

Not at all

Perfectly

Immune system poststreptococcal diseases are mediated by the presence of what?

The M protein (found only in Lancefield Group A)

How well did you know this?

Not at all

Perfectly

S. dysgalactiae subsp equisimilis (Lancefield groups A, C, G, and L) clinically produces a similar spectrum of disease as what other S. species?

S. pyogenes

(i.e., pharyngitis, skin and soft tissue infections, and bacteremia)

How well did you know this?

Not at all

Perfectly

The viridans group of streptococci includes five groups, each containing several species. Name the viridans groups.

mitis group

mutans group

anginosus group (previously S. milleri group)

bovis group

salivarius group

MMA is BS

How well did you know this?

Not at all

Perfectly

Veridans group S. anginosus group are normal microbiota of what sites?

oropharynx

GI tract

urogenital GI tract

How well did you know this?

Not at all

Perfectly

Veridans S. anginosus group are normal microbiota of what sites?

oropharynx

GI tract

urogenital tract

How well did you know this?

Not at all

Perfectly

A wide variety of enterococci species can be isolated from human infections.

What two species of enterococci are more pathologically involved?

E. faecalis

E. faecium

How well did you know this?

Not at all

Perfectly

PYR stands for what?

pyrrolidonyl arylamidase

How well did you know this?

Not at all

Perfectly

Streptococci and enterococci are observed primarily in pairs or chains due to what factor?

Cellular division for streptococci and enterococci occurs along a single axis.

How well did you know this?

Not at all

Perfectly

The ixodes tick is a vector for what three diseases?

Borrelia burgdorferi

Ananplasma

Babesia

How well did you know this?

Not at all

Perfectly

The differentiation of enterococci, group D streptococci, and lactococci from other Streptococci has been traditionally based on what?

The organisms ability to hydrolyze esculin in the presence of 40% bile.

Enterococci, group D streptococci, and lactococci can all hydrolyze esculin in the presence of bile.

How well did you know this?

Not at all

Perfectly

What is a bile esculin test used for?

The bile esculin test is used to differentiate Enterococci and Group D Streptococci from other Gram+, CoN streptococci.

How well did you know this?

Not at all

Perfectly

T/F Bile esculin agar is both selective and differential.

TRUE

What makes bile esculin agar selective?

sodium azide and oxagall; which inhibit the growth of G- and most G+.

What makes bile esculin agar differential?

Esculin. Very few organisms can hydrolyze in the presence of bile. Enterococci and Group D Streptococci both hydrolyze esculin in the presence of bile.

Enterococci and Group D Streptococci both hydrolyze __________ in the presence of \_\_\_\_\_\_\_\_\_.

esculin (in the presence of ) bile

S. agalactiae types to what Lancefield Group(s)?

Lancefield Group B

S. dysgalactiae subsp. equisimilis may type to what Lancefield Group(s)?

Lancefield Groups A, C, G, & L

S. pyogenes may type to what Lancefield Group(s)?

Lancefield Group A

S. anginosus group may type to what Lancefield Group(s)?

Lancefield Group A, C, G, & F

The beta-hemolytic streptococci may have a distinctive odor resembling what?

butter

Viridans streptococci have what type of odor?

Butterscotch odor, especially on chocolate agar.

Grouping of organisms based on cell wall carbohydrate structure is known as what?

Lancefield classification

S. pyogenes is the only species of beta-hemolytic streptococci associated with human infections that will produce what?

A positive PYR reaction.

A brown halo around colonies on bile esculin agar and a positive PYR reaction is generally indicative of what genus?

Enterococcus

Colonies suspected as S. pneumoniae would be further verified by what additional tests?

optochin sensitivity (+) bile solubility (+)

A positive PYR identifies what Lancefield Group?

Lancefield Group A (S. pyogenes)

A positive hippurate or CAMP test identifies what Lancefield Group?

Lancefield Group B (S. agalactiae)

What does CAMP stand for?

Christie, Atkins, Munch-Petersen

Describe gross morphology of S. pneumoniae on visual inspection.

small gray moist center of colony may be depressed alpha-hemolytic

Name a singular key species that is optochin sensitive. (Producing zone of inhibition.)

S. pneumoniae

Name an organism that is optochin resistant. (Growth up to the disk.)

S. viridans group (with the exception of S. pneumoniae).

Name four GPC's that are optochin sensitive, producing zones of inhibition.

S. pneumoniae S. pseudopneumoniae S. mitis S. oralis

An organism reveals as a G+ alpha-hemolytic isolate. Name a key species and two aditional groups or genus to be considered.

**S. pneumoniae** viridans group enterococci

For antimicrobial susceptibility testing, what does MIC stand for?

minimum inhibitory concentration

All gram-positive bacteria demonstrate intrinsic antibiotic resistance to what three agents?

colistin nalidixic acid aztreonam

In association with S. pyogenes, streptococcal pyrogenic exotoxins (SPEs) may be released resulting in scarlet fever. Scarlet fever occurs in association with, or subsequent to, what ailment?

streptococcal pharyngitis

Beta-hemolytic streptococci are also referred to as __________ \_\_\_\_\_\_\_\_\_\_.

pyogenic streptococci MCM, p 411

Name three key species of beta-hemolytic streptococci.

S. pyogenes S. agalactiae S.dysgalactiae subsp. equisimilis

Name three key species of the small-colony-forming S. anginosus group.

S. anginosus S. constellatus S. intermedius

Transmission of streptococcal infections can occur by different routes. Pathogenic species like S. pyogenes and S. pneumoniae are primarily transmitted through __________ or \_\_\_\_\_\_\_\_\_\_.

droplets direct contact

All pathogenic streptococci are __________ \_\_\_\_\_\_\_\_\_\_ upon exposure to 3% hydrogen peroxide

catalase negative

A false-positive catalase reaction may occur if bacteria are grown on or contaminated with what?

blood agar / blood media

The cell wall composition of typical Gram-positive bacteria consists mainly of

peptidoglycan, with glucosamine and muramic acid as amino sugars and galactosamine as a variable component.

T/F Streptococci are facultative anaerobes.

TRUE

The optimum temperature for growth of most streptococcal species lies between

35°C and 37°C

Group B streptococcal (GBS) attack rates are highest in what patient populations?

\< 1 yoa and \> 65 yoa

Asymptomatic pharyngeal colonization with **S. pyogenes** occurs in what % of the adult population?

less than 5% of the adult population

S. agalactiae colonization rates of the urogenital and gastrointestinal tracts in women and men is demonstrated in what percent of the adult population?

10% - 30%

Nonsuppurative S. pyogenes complications include __________ & \_\_\_\_\_\_\_\_\_\_.

acute rheumatic fever glomerulonephritis

poststreptococcal glomerulonephritis is linked with skin infections from what organism?

S. pyogenes

STSS may be associated with S. pyogenes. What does STSS stand for?

streptococcal toxic shock syndrome

The clinical spectrum of disease caused by S. dysgalactiae subsp. equisimilis resembles infections caused by what other bacterial species?

S. pyogenes

The clinical spectrum of disease caused by S. pyogenes resembles infections caused by

S. dysgalactiae subsp. equisimilis

S. pneumoniae belongs to what two more broad groups?

S. mitis group S. viridans group

Members of the S. mitis group are regular commensals of what regions of the body.

oral cavity gastrointestinal tract female genital tract

Streptococcus anginosus Group are all small-colony-forming bacteria (colony size, ≤0.5 mm) that can display variable patterns of

hemolysis (alpha, beta, or gamma)

S. bovis group blood infections particularly S. _______ are associated with gastrointestinal disorders, including colon cancer and chronic liver disease

S. gallolyticus subsp. gallolyticus

S. bovis group blood infections particularly S. gallolyticus subsp. gallolyticus are associated with gastrointestinal disorders, including __________ & \_\_\_\_\_\_\_\_\_\_.

colon cancer chronic liver disease

Name three species of GPC from the Streptococcus anginosus group.

S. anginosus S. constellatus S. intermedius

S. pyogenes is the most common cause of acute

pharyngitis

This antigen is common to all S. pneumoniae serotypes

C-polysaccharide antigen

T/F Several nucleic acid-based methods for the detection of S. agalactiae colonization in pregnant women have been developed.

TRUE

With respect to potential rapid methods for the detection, what does "NAAT" stands for?

nucleic acid amplification tests

Name the beta-hemolytic streptococci of the pyogenic group.

S. pyogenes S. agalactiae S. dysgalactiae subsp. equisimilis

Colony size of the beta-hemolytic streptococci pyogenic group are about what size after 24 hours of incubation?

\>0.5 mm after 24 hours

Within the viridans group, **nonhemolytic** gray colonies are typical for what two species?

S. bovis S. salivarius

Detection of the Lancefield group F antigen in small-colony- forming streptococci allows a fairly reliable identification of a strain as a member of what group.

S. anginosus group

The presence of the enzyme __________ \_\_\_\_\_\_\_\_\_\_ is often tested to distinguish S. pyogenes from other beta- hemolytic streptococci.

pyrrolidonyl aminopeptidase

Pyrrolidonyl aminopeptidase is produced by what species of beta-hemolytic streptococci?

S. pyogenes

It is important to distinguish Streptococcus from Enterococcus prior to performing what test?

PRY testing. Other genera including Abiotrophia, Aerococcus, Enterococcus, Gemella, and Lactococcus may also be PYR positive.

Does S. pyogenes generally reveal to be bacitracin susceptible or resistant?

bacitracin susceptible

The CAMP factor reaction was first described in 1944 by Christie, Atkins, and Munch-Petersen and refers to the __________ \_\_\_\_\_\_\_\_\_\_ of erythrocytes by the beta-hemolysin of staphylococcus aureus and the extracellular CAMP factor of streptococcus agalactiae.

synergistic lysis

Peptidoglycan is a crystal lattice structure composed of two primary amino polysaccharides. Name them.

N-acetylglucosamine / NAG N-acetylmuramic acid / NAM

DD-transpeptidases bind the sublayers of peptidoglycan (NAG & NAM) and are better known as what?

penicillin binding proteins (or PBPs)

Beta lactam antibiotics are similar in structure to transpeptidas. As such beta lactams bind penicillin binding proteins rending them unable to bind to the corresponding layer of peptidoglycan. In this way beta lactams interfere with what?

Bacterial cell wall synthesis.

How do beta lactam antibiotics interfere with cell wall synthesis?

Beta lactam binds to penicillin binding protein; rendering the PBP (DD-transpeptidase) unable to bind to the a corresponding NAG/NAM.

Streptoccocus _________ is the species of viridans streptococci most commonly associated with dental caries.

mutans

Streptococcus sanguinis, of the viridans group streptococci, make __________ , which bind to fibrin platelet aggregates on damaged heart valves.

dextrans

The M protein represented within the cell wall of some streptococci are found within what Lancefield group?

Group A (only)

A positive bile esculin test is generally indicative of what?

Species belonging to **S. bovis group** or **enterococci**

Arginine hydrolysis is a key reaction for the identification of what?

viridans group streptococci.

A positive esculin agar slants reveals as what?

**A blackening of the media** indicates esculin hydrolysis. No color change indicates a negative esculin hydrolysis test result.

Name this typical nonhemolytic “comet tail or Medusa head or groundglass" colonies observed on 5% sheep-blood agar.

B. Anthracis Gram +ve, bacillus, endospore forming

B. anthracis, along with the other species within the genus, are capable of forming spores within the mother cell called what?

endospores

Streptococci and enterococci are catalase (+ tive or - tive )

Catalase negative - tive