Bordetella pertussis is a clinically important member of the Bordetella genus and is known for causing whooping cough. Some other members of this genus include Bordetella hinzii, Bordetella holmesii, and Bordetella trematum [1]. Staining and microbiologic features:  Aerobic coccobacilli that are gram-negative and non-motile [1]  It does not rely on the presence of factor V or factor X for its growth and virulence. [2]  Tests positive for oxidase and catalase and tests negative for nitrate, citrate, and urea [1]  It has a capsule [1]  Can be cultured on enriched media ..read more

  Yersinia enterocolitica is a gram-negative bacillus that is known for causing gastroenteritis. [1] Staining and microbiologic features:      Test positive for urease and negative for catalase [2] Motile and unable to ferment lactose [1,2]  Safety pin-like/ bipolar appearance on staining [3]  Culture on MacConkey agar yields non-lactose fermenting colonies [4]  It shows optimum growth at low temperatures, i.e., at 25°C [2] Its motility can be absent at high temperatures, i.e., at 37°C [2] Cefsulodin-irgasan-novobiocin (CIN) agar is a yersinia sele ..read more

Pasteurella derives its name from the French scientist Louis Pasteur (Pasteur→Pasteurella) and belongs to the Pasteurellaceae family. [1] Staining and microbiologic features:   It is a facultative anaerobic/ aerobic coccobacillus that is gram-negative and non-motile [2]     It is indole positive and exhibits a bipolar appearance on staining [2,3]  Pasteurella Multocida tests positive for catalase and oxidase. [2] Blood and chocolate agars can be used to culture Pasteurella multocida. [3] It exhibits poor growth on MacConkey agar. [3] Production of polysaccha ..read more

Some clinically important members of the Brucella family include  Brucella abortus, Brucella melitensis, Brucella canis and Brucella suis. [1] Staining and microbiologic features:   Facultative intracellular organisms [2] Aerobic coccobacilli that are gram-negative and non-motile [1]   Brucella by Anna Carla Silva Cunha is licensed under CC BY-SA 4.0. Growth of certain brucella strains (such as B. abortus) requires CO2. [3] Brucella strains infecting humans can test positive for catalase and oxidase [3] Non-encapsulated and does not form spores [1,3] Brucella colon ..read more

The organism is known for causing plague/black death that resulted in millions of deaths in the past. Reservoirs for Yersinia pestis include wild rodents, squirrels, prairie dogs, and city rats. [1,2] Staining and microbiologic features:    Facultative anaerobic bacilli that are gram-negative and non-motile [3]    Wright, Giemsa, Wayson, or methylene blue staining can be used to visualize Yersinia pestis. [3] Safety pin-like/ bipolar appearance on staining [4] “uu yersinia pestis” by isis325 is licensed under CC BY 2.0. Yersinia pestis tests positive for cat ..read more

Some subspecies of Francisella tularensis are the following [1]:  Subspecies tularensis (type A)-most virulent Subspecies Holarctica (type B) subsp. mediaasiatica Staining and microbiologic features:   Coccobacilli that are gram-negative and non-motile [1,2]  A photomicrograph reveals numerous Gram–negative, Francisella tularensis coccobacilli, the bacterium responsible for causing the disease, tularemia. Original image sourced from US Government department: Public Health Image Library, Centers for Disease Control and Prevention. Under US law this image is ..read more

 A pneumonia outbreak occurred in 1976 among American Legion members at a convention in Philadelphia. Subsequent investigations identified Legionella pneumophila as the causative organism for this outbreak. Legionella was an unknown organism before that outbreak because it exhibits poor gram staining and needs specific culture media for optimum growth. (named so: legion →legionella) [1,2] Staining and microbiologic features:   Gram-negative aerobe and pleomorphic [1]   Facultative intracellular organism [3] Tests positive for catalase and oxidase [4] Charcoal yeast ex ..read more

Mycoplasma pneumoniae is a pleomorphic free-living organism that belongs to the Mycoplasmataceae family [1]. It is also sometimes referred to as the Eaton agent, named so after the name of the researcher who initially isolated the organism [2]. Virulence and microbiologic features:    The peptidoglycan-containing cell wall is absent in mycoplasma pneumoniae, rendering it resistant to antibiotics that target cell wall synthesis, such as penicillin and cephalosporins [1]. It has a sterols-containing cell membrane [1]. The organism is motile and depends on the presence of cholesterol f ..read more

Treponema pallidum is a thin spirochete that is known for causing syphilis [1]. Other species of this group and the corresponding diseases they cause are the following [2]: Treponema pallidum pertenue: yaws Treponema pallidum endemicum: endemic syphilis Treponema pallidum carateum: pinta ff treponema pallidum by isis325 is licensed under CC BY 2.0. Virulence and microbiologic features: Treponema pallidum is catalase negative and microaerophilic [1]. Since it lacks tricarboxylic acid, it relies on host metabolic machinery to meet its amino acids and nitrogenous base requirements. Therefore ..read more

Some clinically important species of the Borrelia family include Borrelia burgdorferi and Borrelia recurrentis. Virulence and microbiologic features:   Borrelia is a corkscrew-shaped spirochete [1] It exhibits poor gram staining [2]. However, Giemsa and Wright staining can help visualize the organism [1]. It is microaerophilic [3] and motile [4]. White-footed mice and white-tailed deer are reservoirs for Borrelia burgdorferi [1]. Wild rodents in the western U.S. are reservoirs for relapsing fever causing Borrelia species [6]. Borrelia species responsible for relapsing fever have dev ..read more