Salmonella and Shigella practice flashcards

Comprehensive vocabulary flashcards covering the classification, identification, pathogenesis, and epidemiology of Salmonella and Shigella species.

Kauffman-White Classification System

A system used to classify Salmonella serotypes based on their antigen structures, specifically Somatic (O), Capsular/Virulence (Vi), and Flagellar (H) antigens.

Somatic (O) Antigen

An antigen located on the bacterial cell wall used by the Kauffman-White system to define broader Salmonella serogroups like A, B, and C.

Capsular/Virulence (Vi) Antigen

An outer protective shield found on S. typhi that serves as an additional marker for virulence.

Flagellar (H) Antigen

An antigen located on the motility tails of Salmonella that allows for the subdivision of serogroups into specific serotypes.

Salmonella enterica

The primary clinical species of the genus Salmonella, encompassing six subspecies, including Subspecies 1 which contains common human and animal pathogens.

Salmonella bongori

A species within the Salmonella genus that is genetically distinct from Salmonella enterica.

Bismuth Sulfite Agar (BSA)

A highly selective medium used to isolate Salmonella, particularly S. typhi; positive identification is indicated by metallic colonies with a black ring.

Salmonella Biochemical Fingerprint

Characteristically lactose negative, $H_2S$ positive, Gas in TSI negative, Citrate negative, and Ornithine negative.

Enteric Fever (S. typhi)

A systemic infection with an exclusively human reservoir, transmitted via the fecal-oral route, involving invasion of lymphoid tissue and replication within monocytes.

Widal test

A serological test used to detect specific antibody responses to the O and H antigens of S. typhi.

Egg Products Inspection Act of $1970$

A mandate requiring the pasteurization of egg products to reduce Salmonella contamination from poultry sources.

Salmonella arizonae Differentiators

Unlike standard nontyphoid Salmonella, this subspecies is Malonate fermentation positive, Dulcitol fermentation positive, and ONPG positive.

Pulsed-Field Gel Electrophoresis (PFGE)

A technique that maps bacterial DNA into fragments to create a unique "barcode" for definitive strain matching.

PulseNet

A national molecular subtyping network used for the surveillance of foodborne infections by matching genetic fingerprints.

Shigellosis

Also known as bacillary dysentery, a GI tract infection caused by Shigella that primarily affects humans and large primates.

Shigella Laboratory Diagnostic Markers

Isolates that are non-lactose fermenters, non-motile, and $H_2S$ negative.

Shigella Group A (S. dysenteriae)

The most clinically severe Shigella subgroup; it produces enterotoxin, neurotoxin, and Shiga toxin, and is distinguished by its inability to ferment mannitol.

Shigella Group D (S. sonnei)

The most prevalent Shigella subgroup in the U.S. (65-75\text{%} of cases); it is differentiated by being Ornithine Decarboxylase (ODC) positive and ONPG positive.

$\beta$-galactosidase

The enzyme detected by a positive ONPG status, notably present in S. sonnei and S. arizonae.

Shigella Infectious Dose

An extraordinarily low dose of as few as $10-200$ organisms, making outbreak control difficult.

Dysenteric Phase (Shigellosis)

A clinical stage characterized by stools containing red blood cells (RBCs), white blood cells (WBCs), and mucus.