Gram Negative Rods II Flashcards by Joel Glotfelty

Yersinia grow at

4 degrees celcius

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Penetrate intestine via M cells and multiply inside phagocytic vacuole, spread throughout body

Typhoidal Salmonella

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Typhoidal Salmonella does not cause

Macrophage apoptosis

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The capsule of Typhoidal Salmonella is the

Virulence antigen

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Can establish chronic carrier state in gall bladder [scars, stones pre-dispose]

Typhoidal Salmonella

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The gallbladder carrier can then shed Salmonella for years and

Infect others

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Urinary Tract Infections [UTI], Septicemia and Meningitis, Nosocomial [Hospital-Acquired] Infections, and Opportunistic Infections are all examples of

Extra-intestinal infections

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Causes >80% of uncomplicated UTIs

E. coli

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Urinary tract infections can lead to infection of the bladder, which is called

Cystitis

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P-fimbrae –bacteria adhere to UT epithelium and can cause

Pyelonephritis

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What are the three characteristic symptoms of UTIs?

Urgency, Frequency, and Dysuria

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Causes neonatal infections of sepsis and meningitis

E. coli K1

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Adhere to endothelium, choroid plexus

S fimbrae

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Polymer of sialic acid

-not immunogenic and resembles the host

K1 capsule

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The K1 capsule does not activate

Compliment

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Patients rapidly colonized by hospital flora

-More frequently antibiotic-resistant than community-acquired isolates

Nosocomial Infections

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What are three nonsocomial pathogens?

Enterobacter spp, Klebsiella spp, Serratia

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Multiple antibiotic resistance mechanisms (ESBL, carbapenemases, etc)

Enterobacter spp.

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Multiple antibiotic resistance mechanisms (ESBL, carbapenemases, etc)

Klebsiella spp.

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Highly encapsulated organisms that can cause necrotizing pneumonia

Klebsiella spp.

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Have a bloody “currant jelly” sputum

Klebsiella spp.

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Colonies with red pigment, often multi-drug resistant

Serratia

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Haemophilus, Bordetella, and Legionella are all

Respiratory pathogens

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Brucella, pasteurella, francisella, and yersinia are all

Zoonotic bacteria

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An opportunistic Gram negative Rod is

Pseudomonas aeruignosa

Haemophilus influenzae has special growth requirements and requires

NAD and hemin, and chocolate agar

Slender, pleiomorphic Gram negative rods

Haemophilus influenzae

Only colonizes/infects humans -Common in upper respiratory tract (unencapsulated)

Haemophilus influenzae

What are the three virulence factors for Haemophilus influenzae

Capsule, IgA protease, and Iron acquisition mechanisms

Type b was most frequently encountered until the introduction of the “Hib” conjugate vaccine

Haemophilus influenzae capsule

In individuals, bacteria may spread locally from URT to middle ear, sinuses and lungs

Haemophilus influenzae

Haemophilus influenzae can result in a life threatening

URT infection (epiglottis)

Given to all children beginning at 2 mos of age

Hib conjugate vaccine

25% of H. influenzae produce -as a result are resistant to ampicillin

B-lactamase

Essentially all isolates of Haemophilus influenzae | are susceptible to

3rd generation cephalosporins

Has a school of fish Gram stain morphology - Chancroid - Affects penis

Haemophilus ducreyi

Only colonizes/infects humans -Survives for only short periods in the environment

Bordetella pertussis

Seen as small colonies on blood agar

Bordetella pertussis

The best diagnostic method for Bordetella pertussis is

NAAT

Highly infectious, cold like prodrome, followed by period of paroxysms of coughing

Pertussis

The pertussis cough is also called the

Whooping cough

Spread by the respiratory route and has a 2 week incubation period

Pertussis

Bordetella pertussis Virulence factors are

Adhesins and Toxins

Promote attachment and prevent clearance by phagocytes

Bordatella pertussis Adhesins

Binds integrins on ciliated epithelial cells

Filamentous Hemagglutinin

Give Bordatella pertussis resistance to complement

BrkA protein

What are the three Bordatella pertussis toxins?

Tracheal toxin, adenylate cyclase toxin, and pertussis toxin

Stimulates IL-1 mediated killing of ciliated epithelial cells

Tracheal cytotoxin

Inhibits phagocyte function

Adenylate cyclase toxin

Has system effects such as lymphocytosis, sensitization to histamine and enhanced insulin secretion

Pertussis toxin

Due to concerns about reactogenicity, an acellular vaccine is currently used for

Bordatella pertussis (DTaP vaccine)

The aP component was rationally designed to include parts of proteins considered to be

Virulence factors

Causes respiratory infection in humans but unlike Haemophilus and Bordetella it is acquired from an environmental source

L. pneumophila

Serology later revealed a milder form of legionella pneumophila termed

Pontiac Fever

What are the growth requirements for Legionella pneumophila?

Highly fastidious and BCYE agar

Slender Gram negative rod -Hard to see in stained sputum smears

Legionella pneumophila

We use a direct fluorescent antibody stain to test for

Legionella pneumophila

Helpful for Serotype 1 infection of Legionella pneumophila

Urine Ag test

Heavily colonizes warm bodies of water in the environment as well as potable sources

Legionella pneumophila

Legionella pneumophila multiplies in

Protozoan (amoebae) host and in macrophages

Legionella pneumophila multiplication in macrophages actively blocks

Phgosome/lysosome function

Usual source of exposure is aerosal from water supply

Legionella pneumophila

What is required to control growth of Legionella pneumophila?

Hyperchlorination and high heat

Pathogens transmitted from animals directly or by insect vector

Zoonoses

Small Gram-negative rods or coccobacilli

Zoonotic bacteria

Little or no human to human transmission

Zoonotic bacteria

Zoonotic bacteria multiply in

Phgocytes

Small Gram-negative coccobacillus -Source: Livestock, unpasteurized dairy

Brucella spp.

Poses a significant threat to laboratory workers -Can cause systemic febrile illness

Brucella spp.

Small Gram-negative coccobacillus -Normal oral flora of domestic animals (cats and dogs)

Pasteurella multocida

In rabbits, Pasteurella multocida causes the

Snuffles

Pasteurella multocida infection is associated with

Animal bites

Rapidly progressive soft tissue infection

Pasteurella multocida

Small Gram-negative coccobacillus -Transmission from wild animals, especially rabbits, by direct contact or via an insect vector

Francisella tularensis

Highly infectious organism with low infectious dose required (~3 organisms)

Francisella tularensis

Most labs lack facilities for culture, diagnosis based on serology or NAAT at special labs

Francisella tularensis

What are the 4 points of entry for Francisella tularensis disease?

Ulceroglandular, oculoglandular, oral or pharyngeal, respiratory infection

Ulcer at site of inoculation –Lymphadenopathy –Most common

Ulceroglandular entry

Eye is site of inoculation –Lymphadenopathy

Oculoglandular entry

The cause of the bubonic plague -Transmitted from rodents to human by flea bite

Yersinia pestis

Enter human host through flea bite wound

Yersinia pestis

Multiplies in lymph nodes which become enlarged (buboes)

Yersinia pestis

After it infects the lymph nodes, the Yersinia pestis bacteria is then spread to the

Blood, lung, and meninges

Lung involvement can lead to human to human transmission, This is then classified as the

Pneumonic plague

Diagnosis made by NAAT and/or culture in specially equipped laboratory -Grows on a variety of media

Yersinia pestis

An opportunistic pathogen that is ubiquitous in the environment

Pseudomonas Aeruginosa

Has multiple mechanisms of antimicrobial resistance

Pseudomonas Aeruginosa

Gram-negative rod, polar flagella

Pseudomonas aeruginosa

Pseudomonas aeruginosa | creates no acids from sugars on test media. This it is an

Obligate oxidizer

Many Pseudomonas aeruginosa isolates produce

Siderophores (pyoverdin)

Community acquired infections in immunocompetent people

P. aeruginosa Disease

Also results in nosocomial infections and cystic fibrosis

P. aeruginosa Disease

Burkholderia spp. Stenotrophamonas maltophila, and Acinetobacte are other examples of

Gram negative Rods