• Gram-Negative Rods Related to Animal Sources (Zoonotic Organisms)

Question 1

WHAT ARE • Gram-Negative Rods Related to Animal Sources

Zoonotic Organisms

Answer 1

Genus –; Brucella  
Genus – Francisella; 
Genus – Yersinia;  
Genus – Pasteurella;  
Genus – Bartonella;

Question 2

TALK ABOUT GENUS BRUCELLA

Answer 2

Gram-negative bacteria, nonencapsulated, nonmotile, facultatively intracellular coccobacilli. • Brucella species are intracellular organism

Brucella spp. are the cause of brucellosis, which is
a zoonosis transmitted by ingesting contaminated food (such
as unpasteurized milk products), direct contact with an infected
animal

Brucella species are members of especially dangerous pathogens and all laboratory work must be conducted in BSL-3
level

Question 3

what is the transmission of brucella ?

Answer 3

pigs, cattle ,goats, sheep

and it goes to humans by unpasteurized milk or undercooked meat

Question 4

Pathogenesis & Epidemiology of brucella

Answer 4

They localize in the, the lymph nodes, liver, spleen, and bone marrow.

• Many organisms are killed by macrophages, but some survive within these
cells, where they are protected from antibodies.

The host response is granulomatous, which can progress to form focal abscesses. endotoxin is involved. No exotoxins are produced

Question 5

Clinical manifestations of brucella

Answer 5

the gastrointestinal tract is affected 70% of cases
The skeletal system is affected in 20–60% of cases,
Cardiovascular involvement is low
Pulmonary infection can be from inhalation
Genitourinary infection can include epidydemoorchitis ( rare )

Question 6

laboratory diagnosis of brucella

Answer 6

• Oxidase and catalase tests are positive for all species of the genus Brucella

Question 7

treatment and prevention for Brucella

Answer 7

• Antibiotic treatment is useful. The treatment of choice is a tetracycline
plus rifampin

• Prevention of brucellosis involves pasteurization of milk,
immunization of animals, and slaughtering of infected animals.

• There is no human vaccine.

Question 8

TALK ABOUT - FRANCISELLA

Answer 8

It is non-spore-forming, non-motile, aerobic bacterium, is
causative agent of Tularemia , it is faculitative intracellular
classified as select agent because it has low infectious dose

it cause tularema , it has two types
Type A is more virulent. and associated with rabbits;
Type B is found in rodents and water sources

Question 9

Pathogenesis & Epidemiology of

• Francisella tularensis

Answer 9

it transmits from animals to humans by vectors which are ticks
The tick maintains the chain of transmission by passing the bacteria to its offspring by the transovarian route

• The organism is ingested with infected meat, causing gastrointestinal
tularemia, or is inhaled, causing pneumonia with a very low infecting dose – 10-50 bacteria, the mortality rate is very high

The bacterium enters through the skin, forming an ulcer and then localizes and granulomas are formed, with a low mortality rate.

Question 10

Life-cycle (Propagation in macrophages)

F. tularensis

Answer 10

it is a facultative intracellular bacterium that infects macrophages in the host organism.

Entry into the macrophage occurs by phagocytosis and form inside phagosome

. F. tularensis then breaks out of this phagosome into the cytosol and rapidly proliferates.

Question 11

treatment and prevention of francisella

Answer 11

Treatment
• Streptomycin

Prevention
• Prevention involves avoiding both being bitten by ticks
• There is a live, bacterial vaccine but it is experimental and not available commercially.

Question 12

TALK ABOUT YERSINIA

Answer 12

Yersinia species are Gram- negative, coccobacilli bacteria, and are facultative anaerobes. IT is the causative agent of the plague. facultative
intracellular parasites

It is one of the most virulent bacteria known and has a strikingly low
ID50 ,• Yersinia strains are members of especially dangerous pathogens and all
laboratory work must be conducted in BSL-3 level.

Question 13

Pathogenesis & Epidemiology of Yersinia

Answer 13

transmission of the bacteria among urban rats (the reservoir), with the rat flea as
vector, the transmission of the bacteria among urban rats (the reservoir), with the rat flea as a vector

the organism spread to the regional lymph nodes, which become swollen and tender. swollen lymph nodes are the buboes that have led to the name bubonic plague

type III secretion systems

Question 13

virulence factors of Yersinia

Answer 13

1) the envelope capsular antigen, called F-1, which protects against phagocytosis;
• (2) endotoxin;
• (3) an exotoxin;
• (4) two proteins are known as V antigen and W antigen. allow the organism to survive and grow intracellularly,

Question 14

Treatment and prevention of YERSINIA

Answer 14

doxycycline

Reporting a case of plague to the public health authorities is
mandatory

• A vaccine consisting of formalin-killed organisms provides partial
protection against bubonic but not pneumonic plague.

Question 15

TALK ABOUT GENUS - PASTEURELLA

Answer 15

Gram-negative, nonmotile, encapsulated, penicillin-sensitive
causes wound infections associated with cat and dog bites

The organism is part of the normal flora in the mouths of many animals,
particularly domestic cats and dogs, and is transmitted by biting

expresses a range of virulence factors including
a polysaccharide capsule and lipopolysaccharide (LPS) endotoxin

A rapidly spreading cellulitis at the site of an animal bite is indicative
of P. multocida infection

Treatment Penicillin G
Prevention anyone is bitten (ampicillin )

Question 16

TALK ABOUT BARTONELLA

Answer 16

Bartonella henselae, is a proteobacterium that is the
the causative agent of cat-scratch disease (bartonellosis). NATURAL HABITAT IS CATS MOUTH
• It is a facultative intracellular microbe that targets red
blood cells

It infects the host cell by sticking to it using trimeric autotransporter
adhesins. ( This disease is characterized by fever and tender, enlarged lymph nodes, )

B. henselae causes bacillary angiomatosis (BA). BA is characterized by raised, cherry-red vascular lesions in the skin and visceral organs.

Question 17

treatment and prevention of bartonella

Answer 17

no drugs for CSD ( cat scratch )
Treatment of Bacillary angiomatosis (BA with) doxycycline or
erythromycin is effective

There is no vaccine