Miscellaneous Gram-negative Bacilli

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89 Terms

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CAPNOCYTOPHAGA

• Normal microbiota of the oral cavity of humans
• Causes septicemia in patients with neutropenia
• Fastidious, facultative anaerobe
• Thin and often fusiform (pointed ends) resembling Fusobacterium spp.
• No flagella but can produce gliding motility on solid surfaces
• (+) Ferment sucrose, glucose, maltose, and lactose
• (-) Indole negative

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Blood cultures from patients who have neutropenia with oral ulcers

(source of the Capnocytophaga)

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Capnocytophaga ocracea

Most common clinical isolate

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Capnocytophaga canimorsus and Capnocytophaga cynodegmi

Normal inhabitants of the oral cavity of dogs and cats Infection from dog or cat bite

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LEGIONELLA

• Non-spore forming, thin, gram-negative bacilli • Faintly staining • Found in the environment especially water

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LEGIONELLA

• Tolerate chlorine concentrations of 3 mg/L

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LEGIONELLA

• Transmission: exposure to contaminated water (faucets, showerheads, public fountains, aircon) • Reservoirs: Hot water systems, cooling towers, and evaporative condensers are major reservoirs

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LEGIONELLA

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

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Legionella pneumophila

Legionella was first recognized to cause human disease during an epidemic of pneumonia that occurred among members of the Pennsylvania American Legion who had gathered in Philadelphia to celebrate the 1976 bicentennial. The causative agent was?

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Intracellular pathogens

Legionella has the ability to exist as pathogens (amebae and mammalian cells)

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Phagolysosome

Legionella can survive inside phagosomes, prevent the formation of _

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Multiply and survive

Legionella has the ability to _________over the temperature range of 20C to 43C and _ for varying periods at 40C to 60C

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Legionella

has the capacity to adhere to pipes, rubber, plastics, and sediment and persist in piped water systems, even when flushed.

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Legionnaire’s Disease

• Febrile disease with pneumonia
• Predominant manifestation: pneumonia
• Community acquired bacterial pneumonia Incubation Period: 2-10 days

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Pontiac Fever

Influenza-like febrile disease
• Non-pneumonic form of legionellosis
• Inhalation of bacterial toxins or an acute allergic reaction to the bacteria
• Previously healthy individuals who complain of flu-like symptoms

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Pontiac Fever

causes myalgia that lasts 2 to 5 days and then subside without medical intervention

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Legionnaire’s disease

LD (Lab Diagnosis) uses combination of culture and urine antigen detection

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Serology

Lab diagnosis for pontiac fever

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Microscopic examination of Legionella

Pleomorphic, weakly staining, gram-negative bacilli found outside of and within macrophages and segmented neutrophils

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Diff- quik

a stain used in ME for Legionella

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BCYE (Buffered charcoal yeast extract) agar with L cysteine

Best culture media for Legionella isolation

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Legionella on BCYE

grayish white or blue-green, convex, and glistening, measuring approximately 2 to 4 mm in diameter

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Legionella on BCYE

Central portion of young colonies has a “ground-glass” appearance, light gray and granular

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Legionella on BCYE

The periphery of the colony has pink or light blue or bottle green bands with a furrowed appearance

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Selective BCYE agar

contains polymyxin B, anisomycin, and either vancomycin or cefamandole

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Legionella

Fastidious, aerobic bacteria that do not grow on SBA and require L-cysteine for growth and needs ACID treatment of specimen before inoculation

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Acid treatment

Since we are treating a non-sterile specimen, it should first have a pre-treatment in order to kill the bacteria so only Legionella will remain. This is done through

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1:10 with 0.2N potassium chloride, 4 minutes – hydrochloric acid

Aliquot of the Legionella specimen is first diluted in and is allowed to stand for no more than ____

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1:10 in tryptic soy broth or distilled water

Specimens from normally sterile sites should be diluted (Done in order to dilute microbial inhibitors such as complement antibodies and antimicrobial agents)

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WHOOPING COUGH OR PERTUSSIS

• Transmission occurs person to person through inhalation of respiratory droplets
• Highly contagious, acute infection of the upper respiratory tract
• Caused by Bordetella pertussis

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CATARRHAL STAGE

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

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PAROXYSMAL STAGE

• Severe and violent coughing
• 15 to 25 paroxysmal coughing episodes can occur in 24 hours
• Vomiting and “whooping” (the result of air rapidly inspired into the lungs past the swollen glottis)
• Lasts 1-4 weeks

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CONVALESCENT PHASE

• Begins within 4 weeks of onset with a decrease in frequency and severity of the coughing spells
• Cause mild illness and symptomatic infection, primarily in household contacts and in a number of unvaccinated and previously vaccinated children

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Fimbriae (FIM), types 2 and 3

Serotype-specific agglutinins for colonization of respiratory mucosa

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Filamentous hemagglutinin (FHA)

Mediates adhesion to the ciliated upper respiratory tract

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Pertactin (PRN)

: Mediates eukaryotic cell binding and is highly immunogenic

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Pertussis toxin (encoded by the ptx gene, an A/B toxin related to cholera toxin)

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

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Adenylate cyclase toxin

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

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Dermonecrotic toxin

Exact role unknown

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Tracheal cytotoxin

Ciliary dysfunction and damage

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Endotoxin

Lipopolysaccharide

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Outer membrane

: Inhibits host lysozyme

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Siderophore production

: Prevents host lactoferrin and transferrin from limiting iron

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ciliated epithelium

Specimens for Bordetella obtained from the throat, sputum, or anterior nose are not accepted because these sites are not aligned with ___

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Half-strength Regan-Lowe agar

: enhances recovery when used as a transport and enrichment medium

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Cold casein hydrolysate medium, Casamino acid broth, Half-strength Regan-Lowe agar

transport medium for Bordetella

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Bordet-Gengou

: Potato infusion agar with glycerol and sheep blood with methicillin or cephalexin (short shelf-life)

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Cephalexin

is superior to methicillin and penicillin for inhibiting normal respiratory flora

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Modified Jones Kendrick charcoal

: Charcoal agar with yeast extract, starch, and 40 ug cephalexin (2- to-3-month shelf-life but inferior to Regan-Lowe agar)

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Regan-Lowe

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

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Stainer-Scholte

: Synthetic agar lacking blood products

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mercury drops

Young colonies of B. pertussis and B. parapertussis: “__ ”

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Erythromycin

: Drug of choice for pertussis

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Zoonosis

a disease that humans acquire from exposure to infected animals

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PASTEURELLA

• Normal flora of oral cavity in birds and mammals
• Soft tissue (cutaneous) infection from animal bites

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PASTEURELLA MULTOCIDA

• Commensal found in nasopharynx and gastrointestinal tract of wild and domestic animals
• Potential upper respiratory commensal in humans having extensive occupational exposure to animals

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PASTEURELLA MULTOCIDA

• MOT: Bite or scratch from variety of veterinary hosts (usually feline or canine) Infections may be associated with non bite exposure to animals Less commonly, infections may occur without history of animal exposure

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PASTEURELLA CANIS

• Dogs
• Gram-negative coccobacilli
• Non-motile
• Facultative anaerobic coccobacilli
• Bipolar staining: “Safety pin” appearance

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PASTEURELLA CANIS

LABORATORY DIAGNOSIS • (+) Growth on SBA and CHOC agar
• Nonhemolytic colonies on SBA that may appear mucoid after 24 hours of incubation at 37C
• Grayish colonies
• Production of a narrow green-to-brown halo around the colony after 48 hours

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Brucellosis

is a zoonotic disease

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BRUCELLA

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

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BRUCELLA

A cause of devastating economic loss among domestic livestock, Considered category B select biological agents by the CDC

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BRUCELLA

Occurs worldwide, especially in:
o Mediterranean and Persian Gulf countries
o India
o parts of Mexico
o Central and South America

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BRUCELLA

MODE OF TRANSMISSION (Humans can be infected by:) - Ingestion of infected unpasteurized animal milk products (most common means of transmission)

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Brucella abortus

Cattle

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Brucella melitensis

Sheep or goats

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Brucella suis

Swine

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Brucella canis

Dogs

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Brucella ovis

Rams (not associated w/ human infection)

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Brucella neotomae

Desert and wood rats

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BRUCELLA

Colonies appear small, convex, smooth, translucent, nonhemolytic, and slightly yellow and in Gram stain: Small coccobacilli that resemble fine grains of sand

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FRANCISELLA

• Facultative
• Intracellular pathogens
• Nonmotile
• Non-spore forming
• Strict aerobes
• Require cysteine, cystine, or another sulfhydryl and a source of iron for enhanced growth
• (-) Oxidase
• (-) Urease
• (+) Catalase

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FRANCISELLA

•Infection is also called: Rabbit fever Deerfly fever Lemming fever Water rat trappers’ disease

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FRANCISELLA TULARENSIS

• Causes human and animal tularemia
• Wild rodents, rabbits, beavers, and muskrats in North America
• Humans become infected by handling the carcasses or skin of infected animals
• Inhaling infective aerosols or ingesting contaminated water

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FRANCISELLA TULARENSIS

Through insect vectors (primarily deerflies and ticks in the United States)
• Being bitten by carnivores that have themselves eaten infected animals

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Tularemia

is one of the most common laboratory acquired infections

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F. tularensis subsp. tularensis

Most severe: Tularemia (all forms) and requires cysteine

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F. tularensis subsp. holartica

Least severe: Tularemia (all forms) and require cysteine

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Systemic (typhoidal) tularemia

acute illness with septicemia; 30% to 60% mortality rate; no ulcer or lymphadenopathy

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Pneumonic tularemia

acquired by inhalation of infectious aerosols or by dissemination from the bloodstream; pneumonia; most serious form of tularemia

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BSL II

F. tularensis is a BSL __ pathogen

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GARDNERELLA VAGINALIS

• Thin, gram-variable rod or coccobacillus
• Part of the anorectal flora of healthy adults of both sexes, as well as of children
• Part of the endogenous vaginal flora of women of reproductive age

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GARDNERELLA VAGINALIS

• Causes bacterial vaginosis
• Has been called Haemophilus vaginalis and Corynebacterium vaginale

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Clue cells

: epithelial cells covered with bacteria on the cell margins used in the diagnosis of vaginosis

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GARDNERELLA VAGINALIS

Fishy amine odor after addition of 10% potassium hydroxide (KOH) to the secretions

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STREPTOBACILLUS

• Facultatively anaerobic
• Fermentative
• Non-encapsulated
• Nonmotile
• Pleomorphic gram-negative rod
• String-of-beads appearance

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STREPTOBACILLUS MONILIFORMIS

• Rat-bite fever or Haverhill disease
• Indigenous flora in the upper respiratory tract of wild and laboratory rodents

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STREPTOBACILLUS MONILIFORMIS

• Local lymphangitis and lymphadenitis, migratory polyarthritis
• Fever, chills, malaise, and, later, a general morbilliform maculopapular or petechial rash

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False-negative

Whole blood is acceptable in Francisella but results may occur during early stages of disease