Gram (+) and Gram (-) Cocci II Flashcards by Joel Glotfelty

Beta-hemolytic Bacitracin resistant

GBS

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Made up of many species of streptococci

Alpha-hemolytic streptococci

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Most of the a-hemolytic streptococci are considered together as Virians, except for

S. pneumonia

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Widespread residents of the oral cavity, i.e. gums and teeth

-Large complex group

Viridans Group Streptococci

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Not very invasive; dental or oral surgical procedures facilitate entrance

Viridans Group Streptococci

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What are the two clinical manifestations of the Viridans group streptococci?

Dental carries and subacute endocarditis

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Blood-borne bacteria settle and grow on heart lining or valves. Persons with preexisting heart disease are at high risk

Subacute Endocarditis

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Small, “lancet-shaped” cells arranged in pairs and short chains

-Causes 30-60% of all bacterial pneumonias

Streptococcus pneumoniae

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Streptococcus pneumoniae is also referred to as

Pneumococci

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There are over 85 capsule serotypes for

S. pneumoniae

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Capsule is a virulence factor: heavily encapsulated forms are more frequently associated with

Severe invasive disease

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Normal flora in the nasopharynx in carriers

-infections are often endogenous

S. pneumoniae

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Delicate organism, does not survive long outside of its habitat

S. pneumoniae

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Patients who are particularly susceptible to S. pneumoniae are those with

Sickle cell, or who have had a splenectomy

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Pneumococci are aspirated into the lungs where they multiply and induce an overwhelming inflammatory response

Lobar pneumonia

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Gains access to middle ear by way of eustachian tube

• Most frequent bacterial ear infection in children

S. pneumoniae causing Otitis Media

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S. pneumoniae is a common cause of adult bacterial meningitis. A characteristic of this is

Nuchal Rigidity

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High mortality rates in adults up to 60% in elderly

• Asplenic patients particularly susceptible

Bacteremia and sepsis from S. pneumoniae

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S. pneumoniae is sensitive to

Optochin

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S. pneumoniae now has an intermediate level resistance to penicillin. This resistance is mediated by altered

-acquired by genetic transmission from environmental streptococci

PBP

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Resistant strains of S. pneumoniae are sensitive to 3rd generation cephalosporins such as

Cefotaxime and Ceftriaxone

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Protects against 23 serotypes of S. pneumoniae, including strains that were known to be responsible for 85-90% of infections including common penicillin resistant strains

Pneumovax (PPV)

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Pneumovax is recommended for high risk individuals 2 years and older and

Adults older than 65

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Immune response to polysaccharide-only vaccines is limited in

Children

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Is strictly a polysaccharide vaccine

S. pneumoniae

To improve on the efficacy of the S. pneumonie vaccinem the polysaccharide was conjugate to protein (nontoxic diptheria toxin). This conjugated vaccine is

PCV13 or Prevnar 13

Recommended for all children under 5, immunocompromised adults, and adults older than 65

PCV13 or Prevnar 13

Have caused a shift in most commonly clinically encountered serotypes

Vaccines

Component of normal gastrointestinal flora and can grow in 40% bile

Group D streptococci (S. bovis)

Characterized as nonhemolytic (gamme-hemolysis) or alpha-hemolytic

S. bovis

Bacteremia caused by S. bovis associated with

GI malignancy and colon cancer

S. bovis is now called

S. gallolyticus

Group D antigen -Genetically distinct from Streptococci but sometimes still referred to as “Group D Strep”

Enterococci

Non-hemolytic or alpha-hemolytic, and infrequently may be B-hemolytic

Enterococci

Most clinical relevant species (cause >90% of enterococcal infections)

E. faecalis and E. faecium

Not very virulent but have become significant nosocomial pathogens due to multidrug resistant phenotype -Component of normal gastrointestinal flora

Enterococci

Enterococci are resistant to chemical agents and persist on

Fomites

Cause opportunistic urinary or biliary infections or intraabdominal abscesses in immune compromised individuals

Enterococci

Enterococci infections can lead to

Endocarditis or bacteremia/sepsis

Enterococcal resistance can be either

Intrinsic or acquired

An example of acquired resistance is enterococci resistance to

Vancomycin

Vancomycin resistance is common in

E. faecium -less so in E. faecalis

In enterococci, genes encoding regulated resistance are present on a

Transposable element

The gold standard for the laboratory identification of enterococci is

Bile Esculin Hydrolysis

This test is based on the fact that enterococci has the ability to grow in

40% bile and hydrolyze esculin

The ability to grow in 40% bile and hydrolyze esculin is the characteristic feature of

Group D streptococci and enterococci

Enterococci are salt resistant. They can grow in

6.5% NaCl broth

What differentiates group D streptococci from enterococci?

Enterococci's ability to grow in salt

What is the first line of treatment for enterococci?

Ampicillin + gentamycin or penicillin + streptomyci

What is the second line of treatment for enterococci?

Vancomycin

What do we use to treat multi-drug resistant enterococci?

Linezolid, Tigecycline, and Pristinamycin

The Gram negative cocci are

Neisseria

What are the two main types of Neisseria?

N. gonorrhoeae (gonococci) and N. meningitidis (meningococci)

One of the most common causative agents for bacterial meningitis

N. meningitidis (meningococci)

A Gram negative, kidney shaped diplococci

Neisseria spp.

Aerobically, Neisseria spp are considered to be

Aerobic

Like pneumococci, Neiserria spp. are sensitive to

Heat and Drying

In a Gram stain, Neisseria spp are often seen within

Neutrophils (PMNs)

Unlike meningococci, gonococci are

Unencapsulated

Gene conversion and phase variation mechanisms enable heterogeneity of

Cell surface antigens

Every population of Neisseria has subpopulations of bacteria that express antigenically distinct surface structures such as -The virulence factors

Pili, Opa, and LOS

Facilitate attachment to host mucosa/epithelia

Pili

Opacity proteins formerly called PII proteins

Opa

Endotoxin like LPS, but shorter, more branched side chains

LOS

One virulence factor of N. gonorrhea is

IgA protease

What are the 4 major clinical manifestations of N. Gonorrhea?

1. Genitourinary tract infections 2. ) Pharingitis and rectal infections 3. ) Opthalmia neonatorum 4. ) Bacteremia

Cervicitis in women, due to gonorrhea, can lead to

PID or Salpingitis

20% of women with salpingitis will experience

Infertility

Routine prophylaxis with erythromycin ointment or silver nitrate

Opthalmia neonatorum

Babies at high risk for opthalmia neonatorum are treated with

Ceftriaxone

Rare because gonococci multiply poorly in bloodstream (unlike meningococci)

Bacteremia

What are the 4 forms of N. gonorrhoeae diagnosis?

Specimins, smears, culture, and NAATs

Pus secretions from mucosal surfaces -Samples must be plated promptly

Specimens

Intracellular Gram negative diplococci are diagnosed via

Smears

Requires modified Thayer-Martin medium contains antimicrobial agents to suppress normal flora (TM media = VPN media = VCN media)

N. gonorrhoeae culture

What is the oxidase classification of N. gonorrhoeae?

Oxidase positive

The primary method for diagnosing gonococci infection

NAATs

Antibiotic resistance in gonococci is a significant problem. There is widespread resistance to

Penicillin, tetracycline, and quinolones

What are the three commonly resistant strains of N. gonorrhoeae?

PPNG, TRNG, and QRNG

What are the current guidelines for the first line of therapy for N. gonorrhoeae?

IM Ceftriaxone along with azithromycin or doxycycline for chlamydia

What is the one virulent factor that is present in N. menenditidis that is absent in N. gonorrhoeae?

Antigenic capsule

13 serogroups, with serogroups A, B (most common), C, Y and W-135 causing most infections

Antigenic capsule

We see epidemic waves in closed communities like dorms and military barracks of which bacteria?

N. meningitidis

Found in nasopharynx of carriers -Infants 6 months to 2 years are particularly susceptible to infection

N. meningitidis

Rapid onset and progression within 12-24 hours to a lifethreatening condition

Meningitis

What are the three characteristic clinical manifestations of meningococci?

Meningococcemia, meningitis, and fulminant septicemia/meningococcemia

Meningococcemia is rapidly multiplying N. mengitidis in the bloodstream. It is accompanied by fever, chills, and joint and muscle pain. What is a characteristic feature?

Meningococcemia

An inflammatory immune response in meninges -Purulent CSF

Meningitis

What are three characteristic symptoms of meningitis?

Severe headache, stiff neck, and sensitivity to light

LOS-mediated septic shock • Frequently seen in infants

Fulminant septicemia/meningococcemia

What is a characteristic feature of Fulminant Septicemia/ Meningococcemia

Large purplish blotchy hemorrhages

Bacterial Meningitis is a medical emergency. Therefore, even before a definitive diagnosis, we typically start

Antibiotics

Third generation cephalosporin – ceftriaxone or cefotaxime -- are used to treat

Meningitis

To treat meningitis, we can also give large doses of

Penicillin G or ampicillin

We prophylactically treat family members and medical personnel in contact with a patient who has meningitis with

Rifampin

Gram stain CSF, blood, skin or nasopharyngeal samples are used to make a clinical diagnosis of

Meningitis

What is the oxidase classification of Meningitis?

Oxidase positive

A major difference between N. meningitidis and N. gonorrhoeae, is that N. meningitidis can utilize

Glucose AND Maltose -Gonorrhoeae can only utilize Glucose

We can also use the rapid latex agglutination tests for

Capsular antigen

To vaccinate for meningitis, we use a tetravalent conjugate vaccine called -polysaccharides conjugated with diptheria toxoid

Menactra® and Menveo®