Gram Negative Coccobacilli Flashcards

Vocabulary flashcards covering the general characteristics, species, virulence factors, clinical symptoms, and laboratory diagnosis of Gram-negative coccobacilli including Hemophilus, Bordetella, Brucella, Pasteurella, and Francisella.

Hemophilus influenzae

A Gram-negative, coccobacillary, facultatively anaerobic, capnophilic, and pleomorphic pathogenic bacterium formerly called Pfeiffer's bacillus.

Richard Pfeiffer

The scientist who first described $H. influenzae$ in 1892 during an influenza pandemic.

Pittman

The researcher who identified six capsular polysaccharides (types a, b, c, d, e, and f) of $H. influenzae$, establishing that type b (Hib) causes most systemic infections.

Hib capsular polysaccharide

A virulence factor that shields deeper bacterial structures from the lytic activity of complement; composed of polyribosyl ribitol phosphate (PRP).

X Factor

A growth factor also known as hemin required by certain Hemophilus species.

V Factor

A growth factor also known as nicotinamide-adenine-dinucleotide (NAD) required by certain Hemophilus species.

Satellite Phenomenon

The growth of $H. influenzae$ in the vicinity of organisms like $Staphylococcus aureus$ that are capable of synthesizing the V factor.

Levinthal agar R colony

Small, granular, dew-like colonies produced by non-encapsulated $H. influenzae$ organisms from the respiratory tract.

Levinthal agar S colony

Mucoid, iridescent colonies produced by encapsulated, virulent forms of $H. influenzae$ from sites of invasive disease.

H. influenzae type b (Hib)

The serotype most often associated with serious disease in children, possessing a capsule that is a polymer of ribose and ribitol phosphate.

IgA1 protease

An enzyme produced by $H. influenzae$ that cleaves immunoglobulin A at the hinge region to prevent mucosal agglutination and clearance.

Meningitis

The most serious manifestation of Hib infection, primarily affecting children 9 months to 4 years of age.

Epiglottis

A life-threatening emergency involving marked edema and the development of micro-abscesses that may cause complete airway obstruction.

Pyarthosis

An infectious arthritis characterized by the presence of pus in the joint; also known as suppurative, septic, or bacterial arthritis.

Nontypeable Hemophilus influenzae (NTHi)

Strains of $H. influenzae$ that lack a specific polysaccharide capsule and are commonly associated with otitis media and sinusitis.

Porphyrin Test

An alternative method for determining growth factor requirements based on the ability to convert $\text{δ-aminolevulinic acid (ALA)}$ into porphyrins.

Hemophilus ducreyi

The causative agent of Chancroid (Soft Chancre), a highly contagious venereal disease characterized by painful genital ulcers.

Bubo

A medical term referring to an inflammatory enlargement of a lymph node, often with pus formation, typically in the groin or armpit.

School of red fish

The characteristic arrangement of $H. ducreyi$ seen in Gram-stained smears of exudates taken from the edge of a lesion.

Hemophilus aegyptius

Also known as Koch-Weeks Bacillus, it is the causative agent of acute purulent conjunctivitis (pink eye) and Brazilian Purpuric Fever (BPF).

Brazilian Purpuric Fever (BPF)

An acute septicemic fulminant illness affecting children, caused by a highly virulent clonal group of $H. influenzae$ biogroup aegyptius.

Bordetella pertussis

The highly communicable human pathogen that causes Whooping Cough (Pertussis).

Bordet-Gengou Agar (BGA)

A potato-blood-glycerol agar used for the cultivation of $B. pertussis$, on which the bacteria appear as smooth, convex colonies with a pearl-like luster.

Regan-Lowe Agar

A selective medium containing charcoal agar and 10% horse blood recommended for the isolation and cultivation of Bordetella species.

Pertussis Toxin (PT)

A protein exotoxin that promotes lymphocytosis, enhances insulin secretion, and causes sensitization to histamine.

Tracheal cytotoxin

A peptidoglycan fragment produced by $B. pertussis$ that kills ciliated respiratory cells and stimulates the release of Interleukin 1 (fever).

Catarrhal Stage

The initial prodromal stage of pertussis characterized by rhinorrhea, mild cough, and sneezing; at this time, the patient is highly infectious.

Paroxysmal Stage

The second stage of pertussis characterized by 5-20 forcible hacking coughs in 15-20 seconds, often ending with an "inspiratory whoop."

Brucella

A genus of small, non-capsulated, nonmotile, facultatively intracellular coccobacilli that cause zoonotic diseases like Malta fever or Undulant fever.

David Bruce

The officer who investigated Malta fever and in 1887 isolated the bacterium later named Brucella.

Erythritol

A sugar metabolized by Brucella strains that is found in animal tissues (placenta, uterus) and contributes to the organism's tissue specificity.

Brucella melitensis

The Brucella species primarily found in sheep and goats that causes severe, acute disease in humans.

Undulant Fever

A common name for Brucellosis due to the intermittent nature of the fever experienced by untreated patients.

Pasteurella multocida

A Gram-negative, penicillin-sensitive coccobacillus that is the most common cause of human infection following cat bites.

Safety pin appearance

The bipolar staining characteristic exhibited by Pasteurella species, especially in preparations from infected tissue.

Hemorrhagic septicemia

A severe disease in various animals, such as cattle and buffalo, commonly caused by $P. multocida$.

Francisella tularensis

A minute coccobacillus and obligate aerobe that causes Tularemia (Rabbit Fever, Deer Fly Fever, or Ohara's Disease).

Blood-cystine-Glucose Agar (BCGA)

An enriched medium required for the growth of $F. tularensis$, as the organism requires cysteine for stimulation.

F. tularensis biovar tularensis (Type A)

The more predominant and virulent biovar of $F. tularensis$ found in North America, usually transmitted by rabbits or ticks.

Ulceroglandular tularemia

The most common clinical presentation of tularemia, characterized by a local ulcer and lymphadenopathy.

Apoptosis

Programmed cell death; $F. tularensis$ induces this process in host macrophages after replicating in the cytoplasm.