Miscellaneous Gram-Negative Bacilli

Capnocytophaga

A 45-year-old patient with leukemia undergoing chemotherapy presents with fever, malaise, and oral ulcers. Blood cultures grow a facultative anaerobic, fastidious organism from the oral microbiota. It also Ferments sucrose, glucose, maltose, and lactose but is indole negative.What is the most likely causative agent?

Gliding motility and its presence as normal microbiota in the oral cavity.

A patient with neutropenia develops sepsis following a dental procedure. Laboratory findings reveal a Gram-negative bacillus that has no flagella but exhibits gliding motility on solid surfaces. What key characteristic helps identify this organism?

Gram-negative, thin, fusiform-shaped bacillus

What is the shape and Gram reaction of Capnocytophaga?

• Blood culture from patients who have neutropenia

• Soft tissue infections

• Peritonitis

• Endocarditis

Common site of clinical Isolation for Capnocytophaga

Capnocytophaga ocracea

Most common clinical isolate

Capnocytophaga oracea,

Captocytophaga canimorsus,

Capnocytophaga cynodegmi

What are the Capnocytophaga species?

Captocytophaga canimorsus

Normal inhabitants of the oral cavity of dogs and cats

Cpatocytophaga cynodegmi

Infection from dog or cat

Non-spore forming, thin, gram-negative bacilli, Faintly staining

What is the Gram reaction and shape of Legionella?

Up to 3 mg/mL

What level of chlorine concentration can Legionella tolerate?

Exposure to contaminated water

How is Legionella transmitted ?

Hot water systems, cooling towers, evaporative condensers

What are common reservoirs of Legionella?

Legionella pneumophila

First recognized to cause human disease during an epidemic of pneumonia that occured among members of the Pennsylvania American Legion who had gathered in Philadelphia to celebrate the 1976 bicentennial

• Exist as intracellular pathogens

• Survive inside phagosomes

• Prevent formation of phagolysosome

• Multiply at 20°C and 43°C.

• survive between

Virulence Factors of Legionella

Legionnair’s Disease

Febrile disease with pneumonia,

community acquired pneumonia

Pneumonia

Predominant manifestation of Legionnair’s Disease

2-10 days

Legionnair’s Disease Incubation period

Legionnair’s Disease symptoms

Nonproductive cough, Fever, Headache, Myalgia, Sputum may be bloody or purulent, may lead to extrapulmonary infection

Pontiac Fever

Influenza-like febrile disease,

Non-pneumonic form of legionellosis

Flu-like symptoms

2 days

Pontiac Fever Incubation period

Pontiac Fever symptoms

Fever, Headache, Myalgia that last 2-5 days and then subside without medical intervention

Combination of culture and urine antigen detection

Legionnair’s disease diagnosis

Serology

Pontiac fever diagnosis

Sputum, bronchoalveolar lavage, and bronchial washings

Specimen for culture and direct examination(Legionella)

Pleomorphic, weakly staining, gram-negative bacilli

Legionella microscopic evaluation

Diff-Quick and Giemsa

Stains used for microscopic evaluation

Buffered charcoal yeast extract (BCYE) agar with L-cysteine

Best culture media for Legionella isolation

grayish white or blue-green, convex, and glistening

Colonies of Legionella on Buffered charcoal yeast extract (BCYE) agar with L-cysteine

ground-glass appearance

Central portion of young colonies of Legionella has a?

Bordetella pertussis,

Bordatella parapertussis

Bordetella species

Whooping cough or pertussis

Transmission occurs person to person through inhalation of respiratory droplets.

Highly contagious, acute infection of the upper respiratory tract.

Catarrhal Stage

Symptoms are the same as for a mild cold with a runny nose and a mild cough, lasts several weeks

Paroxysmal Stage

Severe and violent coughing (15-25 paroxysmal coughing episodes in 24 hours)

Convalescent phase

Begins within 4 weeks of onset with a decrease in frequency and severity of the coughing spells, mild illness and asymptomatic infection (unvaccinated children)

Adhesion, Toxicity, Overcome host defenses

Major Virulence Determinants of Bordatella pertussis

Adhesion

Fimbriae, Filamentous hemagglutinin, Pertactin, Tracheal colonization factor

Fimbriae (FIM) types 2 and 3

Serotype-specific agglutinins for colonization of respiratory mucosa

Filamentous Hemagglutinin

Mediates adhesion to the ciliated upper respiratory tract

Peractin (PRN)

Mediates eukaryotic cell binding and is highly immunogenic

Pertussis toxin,

Adenylate cyclase toxin ,

Dermonecrotic toxin,

Tracheal cytotoxin,

Endotoxin,

Type II secretion

Toxicity

Pertussis toxin

Induces lymphocytosis and suppresses chemotaxis and oxidative responses in neutrophils and macrophages

Adenylate cyclase toxin

Hemolyzes red cells and activates cyclic adenosine monophosphate, thereby inactivating several types of host immune cells

Dermonecrotic toxin

Exact role unknown

Tracheal cytotoxin

Ciliary dysfunction and damage

Endotoxin

Lipopolysaccharide

Outer membrane

Inhibits host lysozyme

Siderophore production

Prevents host lactoferrin and transferrin from limiting iron

Nasopharyngeal aspirates or swab

Specimen for Bordatella laboratory diagnosis

Half-strength Regan-Lowe agar,

Cold Casein hydrolysate medium,

Casamino acid broth

Transport media that can be used for Bordatella

Half-strength Regan-Lowe agar

enhances recovery when used as a transport and enrichment medium

• Bordet- Gengou

• Modified Jones-Kendrick charcoal

• Regan-Lowe

• Stainer-Scholte

Culture media for Bordatella

Bordet Gengou

Potato infusion agar with gylcerol and sheep blood with methicillin or cephalexin

Cephalexin

is superior to methicillin and penicillin for inhibiting normal respiratory flora

Modified Jones-Kendrick charcoal

Charcoal agar with yeast extract starch, and 40 ug cephalexin

Regan-Lowe

Best for the recovery of B. pertussis from nasopharyngeal swabs.

Charcoal agar with 10 % horse blood and cephalexin

Stainer-Scholte

Synthetic agar lacking blood products

35 degrees celsius

In culture media of Bordatella, plates are inoculated at _________in humidified atmosphere without elevated carbon dioxide for 12 days

mercury drop

Young colonies of B. pertussis and B. parapertussis

whitish gray with age

colonies of Bordatella pertussis

Erythromycin

Drug of choice for Bordatella pertussis

B. pertussis

Catalase (+)

Oxidase (+)

Motility, Nitrate, Urease (-)

Growth in Regan-Low agar (3-6 days)

BA and MAC = no growth

B. parapertussis

Catalase (+)

Oxidase (-)

Motility, Nitrate (-)

Urease (+ 24 hours)

Growth in Regan-Low agar (2-3 days)

BA = no growth

MAC = ±

B. bronchoseptica

Catalase (+)

Oxidase (+)

Motility, Nitrate (+)

Urease (+ 4 hours)

Growth in Regan-Low agar (1-2 days)

BA and MAC = growth

Pasteurella

Normal flora of oral cavity in birds and mammals.

Zoonosis - a disease that humans acquire from exposure to infected animals

Septicemia, Arthritis, Endocarditis, Osteomyelitis, Meningitis

Causes of Pasteurella

Pasteurella Multocida

Commensal found in nasopharynx and gastrointestinal tract of wild and domestic animals.

Bite or scratch from variety of veterinary hosts

Pasteurella Multocida Mode of transmission

Pasteurella Canis

Dogs, Gram-negative coccobacilli , non-motile, Facultative anaerobic coccobacilli

Safety pin

Bipolar staining appearance of Pasteurella canis

Growth on SBA and Chocolate Agar,

Nonhemolytic colonies on SBA, mucoid

Diagnosis for Pasteurella

Grayish colonies

Pasteurella color of colonies

narrow green-to-brown halo around colonies

Pasteurella colonies after 48 hours

Brucella

Small, facultative, intracellular , nonmotile, aerobic, gram-negative coccobacilli or short rods.

Brucellosis

a zoonotic disease

10 weeks

Brucella survival on soil

11 weeks

Brucella survival Aborted fetuses

17 weeks

Brucella survival on bovine stoon

3 weeks

Brucella survival on milk & ice cream

Several weeks

Brucella survival Fresh cheese

Brucella

A cause of devastating economic loss among domestic livestock.

Considered as category B select biological agents by the CDC

• Ingestion of unpasteurized animal milk products

• Inhalation of infected aerosolized particles

• Direct contact

• Accidental inoculation

Brucella Mode of transmission

cattle

Brucella abortus

Sheep or goats

Brucella melitensis

Swine

Brucella suis

dogs

Brucella canis

Rams

Brucella ovis

Desert and wood rats

Brucella neotomae

Blood, Blood marrow, Cerebrospinal fluid, Pleural and synovial fluids, urine, Abscesses, Other tissues

Specimen for Brucella

small, convex, smooth, translucent, nonhemolytic, and slightly yellow

Brucella colonies

5% heated horse or rabbit serum

Enhances growth on medias of Brucella

Small coccobacilli that resemble fine grains of sand

Graim stain for Brucella

Brucella

oxidase, urease, Catalase positive

Francisella

Facultative, Intracellular pathogens, Nonmotile, Non-spore-forming, Strict aerobes, require cysteine, or another sulfhydryl and a source of iron for enhanced growth

Francisella

Oxidase and Urease negative,

Catalase positive

• Rabbit fever

• Deerfly fever

• Lemming fever

• Water rat trappers’ disease

Infections for Francisella

Francisella tularensis

Causes human and animal tuleremia,

wild rodents, rabbits, beavers, and muskats in North A merica

Inhaling aerosols or ingesting contaminated water

Francisella tularensis mode of transmission

deerflies and ticks

Francisella tularensis insect vectors

Tularemia

most common laboratory-acquired infections

• Ulceroglandular

• Glandular

• Oculoglandular

• Oropharyngeal

• Systemic tularemia

• Pneumonic tularemia

Clinical manifestations of Francisella