CH 18 SMARTBOOK: Gram Positive Cocci of Medical Importance

HABITAT: Staphylococcus aureus (p. 583)

- Carried by 20% to 60% of healthy persons in the nostrils, skin, nasopharynx, and intestine - very resistant to harsh environmental conditions - routinely present on fomites

MICROSCOPIC MORPHOLOGY: Staphylococcus aureus (p. 583)

- Gram-positive cocci in irregular clusters - nonmotile - non-spore forming - may form biofilm infections on catheters and other indwelling devices

Streptococcus agalactiae qualities

- Group B - exemplified by S. agalactiae - primarily implicated in neonatal meningitis, wound & skin infections, & endocarditis

IDENTIFIED BY: Staphylococcus aureus (p. 583)

- Growth on high-salt (7.5% NaCl or more) media, Gram reaction, and arrangement - fermentation of sugars distinguishes Staphylococcus from Micrococcus - catalase production distinguishes Staphylococcus from Streptococcus - Coagulase production distinguises S. aureus from other species of Staphylococcus - Rapid ID tests rely on antibody-coated latex beads that bind specifically with S. aureus

Select all that apply Which of the following are contributing factors to the pathogenicity of N. gonorrhoeae? - Lipase damaging cell membranes of the host - Sex pili promoting attachment of cocci to each other - Surface molecules promoting attachment to other cocci and to tissue surfaces - Fimbriae promoting attachment to other cocci and to tissue surfaces - Protease cleaving IgA on mucosal surfaces

- Protease cleaving IgA on mucosal surfaces - Fimbriae promoting attachment to other cocci and to tissue surfaces - Surface molecules promoting attachment to other cocci and to tissue surfaces

VIRULENCE FACTORS: Staphylococcus aureus (p. 583)

- S. aureus possesses enzymes that destroy host tissue (hyaluronidase), digest blood clots (staphylokinase), colonize oily skin ...

Select all that apply Why are Moraxella and Acinetobacter included in the same family as Neisseria? - These general are biochemically similar. - These genera cause similar diseases. - These genera are morphologically similar.

- These general are biochemically similar. - These genera are morphologically similar.

Characteristics of Streptococcus

- arrangement of cocci in long, bead-like chains (especially if grown in a liquid culture) - often found in pairs - generally, spherical but can also appear ovoid or rodlike, especially in actively dividing young cultures - sensitive to drying, heat, disinfectants, & drugs

Select all that apply Signs and symptoms that may be caused by gonorrhea include: - skin rash - urethritis in males - PID in females - herpetic keratitis - sterility in females only - eye infections in newborns

- urethritis in males - PID in females - eye infections in newborns

The infectious dose of gonorrhea is __________ to _________ colony-forming units.

100 to 1,000

Streptococcus pyogenes belongs to which group of streptococci? B A C

A

Define virulence factor.

A product of microbes such an enzyme or toxin that increases the microbe's invasiveness or pathogenicity

Lancet-shaped cells

Arrowhead

Common microbiota of domestic animals that can be isolated from the human upper respiratory tract, occasionally causing pharyngitis similar to group A streptococci, are known as groups _______ and __________ streptococci.

C & G Often imitate group A strep in causing pharyngitis & glomerulonephritis. More often they cause bacteremia (the presence of bacteria in the bloodstream) and disseminated deep-seated infections in severely compromised patients.

A test that monitors the ability of group B streptococcus to enhance hemolysis of a synergistic strain of S. aureus is the ______ test. bacitracin-sensitivity CAMP esculin hydrolysis SXT-sensitivity

CAMP REASONING: - Bacitracin-sensitivity: Sensitivity to the antimicrobial bacitracin is monitored with a drug-containing disc. - Esculin hydrolysis: The esculin hydrolysis test monitors the ability to cleave a specific sugar. - SXT-sensitivity: Sensitivity to the combination of sulfamethoxazole and trimethoprim is monitored with the SXT-sensitivity test.

The test that is most often used to distinguish S. aureus from other staphylococcal species is the __________ test.

Coagulase

Which of the following tests is often used to distinguish S. aureus from other staphylococcal species? Gram staining reaction Catalase test Coagulase test Growth on mannitol salt agar Sugar fermentation tests

Coagulase test S. aureus may be distinguished from other species of Staphylococcus, as it is the only species within the genus to produce coagulase. REASONING: All staphylococcal species are catalase positive therefore this test cannot distinguish between S. aureus and other staphylococcal species. The catalase test distinguishes between staphylococci and streptococci.

______ acquired MRSA is most often acquired outside of the hospital setting. Environmentally Medically Community

Community

Most Neisseriaceae are primary human pathogens, while a few are commensals of humans. T/F

F REASONING: Most Neisseriaceae are commensals, while only two are primary pathogens. Members of the Family Neisseriaceae are residents of the mucous membranes of warm-blooded animals. Most species are relatively innocuous commensals, but two are primary human pathogens with far-reaching medical impact. Greatest clinical significance

Only pathogenic Neisseria species can be present in infectious fluids. T/F

F Reason: Normal, nonpathogenic Neisseria species can be present in infectious fluids and must be differentiated from true pathogens.

S. aureus exhibits fewer virulence factors than S. epidermidis. T/F

F Reason: S. aureus produces more virulence factors than other pathogens.

Select all that apply Which describe metabolic characteristics of Streptococci? Catalase positive Obligate aerobes Facultative anaerobes Produce lactic acid by sugar fermentation Endospore forming Capable of inactivating hydrogen peroxide

Facultative anaerobes Produce lactic acid by sugar fermentation Capable of inactivating hydrogen peroxide

Which are the main virulence factors of N. gonorrhoeae? Coagulases Sex pili Hemolysins Fimbriae

Fimbriae

Which are the main virulence factors of N. gonorrhoeae? Sex pili Coagulases Hemolysins Fimbriae

Fimbriae

Characteristics of the members of the Family Neisseriaceae

Members of the Family Neisseriaceae are residents of the mucous membranes of warm-blooded animals. Most species are relatively innocuous commensals, but two are primary human pathogens with far-reaching medical impact. Greatest clinical significance - Bean-shaped & paired, with their flat sides touching - No flagella or spores - Capsules are found - gram-negative posessing an outer membrane with lipopolysaccharides in the cell wall and, in many cases, fimbriae - strict parasites, do not survive long outside of host - aerobic or microaerophilic & have an oxidative form of metabolism - produce catalase enzymes for fermenting various carbohydrates - the enzyme cytochrome oxidase that can be used in ID

The two genera Acinetobacter and ________ are morphologically and biochemically similar to the Neisseria, and are therefore included in the same __________.

Moraxella family

Which species causes gonorrhea? S. pyogenes N. meningitidis N. gonorrhoeae Chlamydia trachomatis

N. gonorrhoeae

Because nonpathogenic ____________ species can be found in the human body in infectious fluid, they must be differentiated from true pathogens in order to diagnose diseases like meningitis and gonorrhea.

Neisseria

The species responsible for the sexually transmitted disease gonorrhea is _________ ____________.

Neisseria gonorrhoeae

Select all that apply Signs and symptoms that may be caused by gonorrhea include: - PID in females. - sterility in females only. - herpetic keratitis. - urethritis in males. - skin rash. - eye infections in newborns.

PID in females. urethritis in males. eye infections in newborns.

Streptococcal pharyngitis should be treated with which drug? Penicillin Chloramphenicol Vancomycin

Penicillin REASONING: Chloramphenicol: The preferred antibiotic is penicillin. Vancomycin: The preferred antibiotic is penicillin.

Which of the following host defenses is considered the most effective in combating S. aureus infection? B cell response Phagocytic response Antibody production

Phagocytic response

Coagulase is produced by S. aureus and S. epidermidis S. hominis and S. capitis S. aureus only S. epidermis and S. capitis

S. aureus only S. aureus may be distinguished from other species of Staphylococcus, as it is the only species within the genus to produce coagulase.

Select all that apply Which of the following are types of infections caused by S. agalactiae? Endocarditis Rheumatic fever Skin infections Wound infections Neonatal infections

Skin infections Wound infections Neonatal infections Endocarditis

Which of the following species uses coagulase to cause plasma clotting? Staphylococcus aureus Alpha-hemolytic streptococcus Micrococcus luteus Staphylococcus epidermidis Candida albicans

Staphylococcus aureus

The pathogen that causes pneumonia and otitis media, _________ __________, is a small, gram-positive, lancet-shaped cell that is arranged in pairs and short chains.

Streptococcus pneumoniae (aka pneumococcus)

Which of the following causes of pneumonia matches this description: small, gram-positive lancet-shaped cells arranged in pairs and short chains? Legionella pneumophila Streptococcus pneumoniae Mycoplasma pneumoniae Pneumocystitis jiroveci Histoplasma capsulatum

Streptococcus pneumoniae (aka pneumococcus) Involved in the majority of bacterial PNAs which primarily affect immunocompromised patients. Also is a major cause of meningitis and otitis media in young children.

The common name for Neisseria gonorrhoeae is the ____________.

Gonococcus

Which is the common name for Neisseria gonorrhoeae? Pneumococcus Meningococcus Gonococcus

Gonococcus

______ is a sexually transmitted disease, known since ancient times, that is transmitted by a member of the Neisseria genus. Gonorrhea Trichomoniasis Syphilis Chlamydia

Gonorrhea Reason: - Trichomoniasis is caused by Trichomonas vaginalis. - Syphilis is caused by Treponemia pallidum. - Chlamydia is caused by Chlamydia trachomatis.

Streptococcus pyogenes is a member of the group ________ streptococci.

Group A By far the most serious streptococcal pathogen of humans is Streptococcus pyogenes. It is a beta-hemolytic species that is the main representative of group A. Inhabits the throat, nasopharynx, and occasionally the skin.

Select all that apply Which groups of beta-hemolytic, bacitracin-resistant streptococci are found in the human respiratory tract and are responsible for disseminated infections in immunocompromised patients? Group A (S. pyogenes) Group B (S. agalactiae) Group G (S. equisimilis) Group C (S. equisimilis) Group D (E. faecalis)

Group C (S. equisimilis) Group G (S. equisimilis)

Which group of bacteria plays a significant role in development of tooth decay (dental caries)? Staphylococcus aureus Neisseria gonorrhoeae Viridans streptococci Streptococcus pyogenes

Viridans streptococci In the presence of sugar, S. oralis and S. gordonii (the S. mutans group) produce slime layers made of glucose polymers that adhere tightly to tooth surfaces. These sticky polysaccharides are the basis for plaque, the adhesive white material on teeth that becomes coinfected with other bacteria and fosters dental disease.

A local staphylococcal infection often manifests as an inflamed, fibrous lesion enclosing a core of pus called a(n) ___________.

abscess

All of the following are types of infections caused by S. agalactiae EXCEPT __________. neonatal infections acute glomerulonephritis endocarditis skin infections

acute glomerulonephritis REASONING: Acute glomerulonephritis can result from group A streptococcal infections.

Most Neisseriaceae species are ___________, while two species are ______. obligate parasites; pathogens commensals; pathogens pathogens; commensals commensals; obligate parasites

commensals; pathogens

In the presence of sugar, S. oralis, S. gordonii, and S. mutans produce slime layers made of _______ polymers that adhere to ____________ surfaces, leading to plaque formation and tooth decay.

glucose tooth

Neisseria ___________ causes the sexually transmitted disease known as _____________.

gonorrhoeae Gonorrhea

The most significant infectious agents of humans, as well as prevalent members of the normal microbiota of the skin, oral cavity, and intestine, include _______ cocci. gram-negative and gram-positive only gram-negative only gram-negative

gram-negative and gram-positive

To distinguish between beta-hemolytic streptococci, the CAMP test identifies S. agalactiae through its ability to enhance the ______________ of S. aureus.

hemolysis (Hemolysis is the destruction of red blood cells, called erythrocytes)

The most powerful host defenses used to combat S. aureus infection phagocytosis by neutrophils and ________, aided by the opsonic action of ___________.

macrophages complement (aka antibodies)

Select all that apply: Gram-positive and gram-negative cocci are prevalent members of the normal flora of the: oral cavity intestine skin nervous system

oral cavity intestine skin

The antibiotic of choice for pharyngitis caused by S. pyogenes is __________ ____________.

penicillin V

An abscess is an inflamed fibrous lesion enclosing a core of __________. interstitial fluid lymphatic fluid pus pathogenic microbes

pus

CA-MRSA stands for _________-aquired methicillin ____________ Staphylococcus aureus.

resistant

Staphylococci are common inhabitants of the ________ and mucous membranes.

skin

Staphylococci are common inhabitants of the _________ and mucous membranes.

skin

The genus of bacteria that is a common inhabitant of the skin and mucous membranes, causing a significant proportion of human infections is _____________.

staphylococcus

When growing in liquid culture, __________ generally have a spherical shape arranged in long chains.

streptococcus

Typical signs and symptoms of gonorrhea include ________ in males, eye infections in _________, and PID in women.

urethritis newborns

S. aureus exhibits more ____________ factors than almost any other pathogen.

virulence