Relapsing Fever
Overview Causative organism Borrelia spp.: Spirochetes (spiral morphology) Gram negative (weak) Can be visualized using dark-field microscopy, Wright stain, or Giemsa stain Possess axial filaments for motility Microaerophilic Difficult to culture Associated diseases: Tick-borne relapsing fever (TBRF) is caused by multiple species of Borrelia including: B. hermsii, B. turicatae: most common in North America B. […]
Salmonella
Classification General Characteristics Salmonella spp. Clinically relevant species Salmonella enterica is the primary species and has the following serotypes: Pathogenesis Transmission and virulence Disease process Diseases Caused by Salmonella Typhoidal species (Salmonella typhi and paratyphi) Typhoid fever or enteric fever: Chronic carrier state: Nontyphoidal species (Salmonella enteritidis and typhimurium) Enterocolitis/gastroenteritis: Bacteremia: Comparison with Shigella Both […]
Rocky Mountain Spotted Fever
Overview Definition Rocky Mountain spotted fever (RMSF) is an infectious disease caused by the bacteria Rickettsia rickettsii, which is usually transmitted by ticks. Epidemiology Etiology Pathophysiology Clinical Presentation Symptoms usually occur within 2–14 days of exposure to an infected tick bite. Initial symptoms may be vague and non-specific (fever, generalized malaise). Patients may not be […]
Vibrio
Classification General Characteristics Basic features of Vibrio Curved gram-negative bacilli Facultative anaerobes Highly motile: 1–3 polar flagella Non-spore forming Oxidase positive Major pathogenic species Vibrio cholerae (V. cholerae) V. vulnificus V. parahaemolyticus Biochemistry and growth characteristics Halophilic: require sodium chloride (NaCl) for growth Acid labile: grows well in alkaline media Thiosulfate-citrate-bile-sucrose (TCBS) agar: V. cholerae […]
Human Immunodeficiency Virus (HIV)
Classification and Subtypes Classification Two subtypes of human immunodeficiency virus (HIV) Structure and Genome HIV virion HIV genome (9 genes that encode 15 viral proteins) Genetic variability (very high) Life Cycle Tropism HIV replication cycle HIV Infection Transmission Pathophysiology Clinical presentation Identification References
Shigella
Classification General Characteristics Shigella spp. General characteristics: Structure: bacilli Gram stain: gram negative Facultative intracellular Motility: immotile, non-flagellated Lactose fermentation: non-lactose fermenting Oxidase negative Acid stable Culture: No hydrogen sulfide (H₂S) production On Hektoen enteric (HE) agar: green transparent colonies Associated disease: shigellosis (dysentery or Shigella diarrhea) Clinically relevant species Serogroups defined by specific O […]
Giardia/Giardiasis
General Characteristics of Giardia Giardiasis is caused by the flagellated protozoan, Giardia lamblia (G. lamblia, also known as G. duodenalis or G. intestinalis). Characteristics Unicellular Eukaryotic Oval shaped Anaerobic Reproduces through binary fission Contains a mitosome in place of mitochondria Forms Trophozoites: Active, feeding, and replicating stage Contain 2 nuclei 4 pairs of flagella Cannot […]
Treponema
Classification General Characteristics of Treponema Basic features of Treponema species Clinically relevant species Pathogenesis Reservoirs and transmission Virulence Diseases Caused by Treponema Syphilis The most common treponemal disease caused by T. pallidum pallidum: Table: Syphilis Stage Primary syphilis Secondary syphilis Tertiary syphilis Congenital syphilis Transmission Sexual contact Skin contact with disseminated rash Patients are not […]
Borrelia
General Characteristics of Borrelia Basic features of Borrelia species Clinically relevant species Pathogenesis Reservoirs Transmission Virulence At-risk populations Diseases Caused by Borrelia The following diseases are caused by Borrelia: Table: Diseases caused by Borrelia Disease Lyme disease Relapsing fever Associated species B. burgdorferi (United States) B. afzelii and B. garinii (Europe) B. hermsii, B. turicatae, […]
Leishmania/Leishmaniasis
General Characteristics Leishmania spp. Structure: Unicellular, with slender body and polar flagellum (depending on form) Species morphologically similar, with differing molecular features 2 forms: Promastigote: extracellular flagellate organism in the phlebotomine sandfly Amastigote: obligate intracellular non-flagellate ovoid organism in human or animal host Associated diseases: Cutaneous leishmaniasis (CL), also called: Oriental sore Chiclero ulcer Baghdad […]