Module 8 - LESSON 1

• Brucella spp are small, non-motile, aerobic, gram-negative coccobacilli or short rods that stain poorly by conventional gram stain.
• Many Brucella spp isolates require Carbon Dioxide (CO2) for growth.
• Brucella spp are considered potential bioterrorism agents.
• Francisella tularensis is susceptible to aminoglycosides and streptomycin is the drug of choice.
• Doxycycline and chloramphenicol have been used in the treatment of tularemia, but these two agents have been associated with a higher rate of relapse after treatment.
• Gentamycin is a possible alternative drug to streptomycin.
• Fluoroquinolones appear promising for the treatment of even severe tularemia.
• Brucella spp are facultative, intracellular parasites (able to exist in both extracellular and intracellular environments) following infection, brucellae are ingested by neutrophils within which they replicate resulting in cell lysis.
• Brucellae exhibit a tendency to invade and persist in the human host through inhibiting apoptosis.
• Brucella spp can change from smooth to rough colonial morphology based on the composition of their cell wall lipopolysaccharide; those with smooth LPS are more resistant to intracellular killing by neutrophils than those with rough LPS.
• Brucella abortus is the preferred animal host of Brucella spp.
• Brucella melitensis is the preferred animal host of Brucella spp.
• Brucella suis is the preferred animal host of Brucella spp.
• Brucella canis is the preferred animal host of Brucella spp.
• Brucella spp are differentiated by the rapidity with which they hydrolyze urea, relative ability to produce H2 S, requirements for CO2, and susceptibility to the aniline dyes and basic fuchsin.
• The preferred specimen for isolation of Bordetella spp is a nasopharyngeal swab.
• Most Brucella species do not grow in air but show growth in the candle jar.
• Bordetella pertussis is the etiologic agent of whooping cough and only infects and causes disease in humans.
• Bordetella pertussis does not survive well outside the host and can be cultured on Bordet-Gengou agar, which is a type of selective media.
• Brucella species cause Malta/Crimean/Mediterranean fever or undulant fever (Brucellosis).
• Bordetella spp are obligatory aerobic, fastidious gram-negative coccobacilli that replicate on ciliated respiratory epithelial cells of humans.
• Bordetella spp are identified by their biochemical characteristics which include positive catalase, negative indole, and growth factors such as Nicotinic Acid, Cysteine, and methionine.
• The most virulent Brucella species are B. melitensis and B. suis.
• Brucella spp are non-motile, urease- and nitrate-positive, and strictly aerobic.
• Brucella species can be identified by their biochemical characteristics which include positive catalase and oxidase, rapid urease production, and the inability to grow in the presence of 5% CO2.
• The Convalescent stage of Whooping cough is the stage in which the symptoms slowly decline, and this period may last for six months after infection.
• Whooping cough, also known as Pertussis, is a highly contagious, acute infection of the upper respiratory tract (URT) that primarily affects children.
• Bordetella spp cannot grow on MAC except B. bronchiseptica because it is less fastidious.
• The Catarrhal stage of Whooping cough is a highly communicable stage characterized by mucous membrane inflammation and mild coughing with runny nose.
• Bordetella spp have hemolytic reactions in Bordet-Gengou potato infusion agar.
• The favorable transport and enrichment medium for Bordetella spp is Regan-Lowe agar.
• Blood, Chocolate and MacConkey agars cannot be used for primary isolation of Francisella spp.
• Whooping cough has three stages: Catarrhal stage, Paroxysmal stage, and Convalescent stage.
• Differential tests for Bordetella spp include Motility Test, Nitrate reduction, Oxidase Test, Urease Test, and BAP growth.
• The Paroxysmal stage of Whooping cough is associated with vomiting and “whooping” or hurried, deep respiration that may last for six weeks.
• Francisella spp are facultative, intracellular pathogens that require cysteine and a source of iron for growth.
• Laboratory diagnosis of Whooping cough involves collecting specimens such as Nasopharyngeal swab and Broncho alveolar lavage.
• Culture media used for Bordetella spp include Regan-Lowe agar, Bordet-Gengou potato infusion agar, modified Jones-Kendrick charcoal agar, and Casamino acid broth.
• The Casamino acid broth is used for transporting swab specimens for Bordetella spp.
• Infected individuals experience severe coughing for at least 15 to 25 times in 24 hours during the Paroxysmal stage of Whooping cough.