Escherichia coli
Classification General Characteristics Pathogenesis and Virulence Factors Virulence Avirulent variants of Escherichia coli Pathogenic variants of Escherichia coli Table: Pathogenic variants of E. coli Pathogen Pathogenesis/Virulence factor Signs and Symptoms ETEC Fimbrial adhesins allow binding to the intestinal mucosa Heat-labile (LT) enterotoxin increases cAMP → altered electrolyte transport (↑ chloride secretion) and diarrhea LT: related […]
Coxsackievirus
Classification General Characteristics and Epidemiology General features of Coxsackievirus Family: Picornaviridae Genus: Enterovirus RNA virus: Linear Single stranded Positive sense Functions as mRNA Diameter: approximately 30 nm Icosahedral symmetry Lacks a lipid envelope Acid-stable viruses Clinically relevant species Coxsackie group A virus (23 serotypes): Herpangina Hand, foot, and mouth disease (HFMD): most frequently implicated is […]
Poliovirus/Poliomyelitis
Classification General Characteristics and Epidemiology General characteristics of poliovirus Family: Picornaviridae Genus: Enterovirus Classified as a strain of Enterovirus C RNA virus: Linear Single-stranded Positive-sense Functions as mRNA Diameter: 25–30 nm Icosahedral symmetry Lacks a lipid envelope Acid-stable Clinically relevant species Poliomyelitis is caused by 3 serotypes of poliovirus: Wild type 1 (most common) Wild […]
Malassezia Fungi
General Characteristics and Epidemiology General features of Malassezia Formerly known as Pityrosporum Taxonomy: Family: Malasseziaceae Genus: Malassezia Dimorphic: Yeast: spherical or oval Mycelial form: short hyphae Colonies are cream or yellowish in color. Lipophilic Most species are lipid-dependent. Not a dermatophyte Reproduce by unipolar budding Clinically relevant species There are a number of recognized species: […]
Aspergillus/Aspergillosis
General Characteristics of Aspergillus Characteristics: Exists only as a mold (not dimorphic) Highly aerobic Grows on plants, soil, household dust, and food Obtains nutrients from dead and decaying matter Best visualized with silver stains Morphology: Hyphae Long, filamentous structures Frequent septae Form dichotomous branches (45-degree angles) Walls are typically parallel Conidia Asexual, nonmotile spores Spherical […]
Toxoplasma/Toxoplasmosis
General Characteristics and Epidemiology General features of Toxoplasma General characteristics: Morphologic forms: Clinically relevant species Toxoplasmosis is caused by Toxoplasma gondii. Epidemiology Pathogenesis Hosts Transmission Life cycle and pathophysiology Life cycle: Life cycle and pathophysiology in humans: Clinical Presentation The clinical presentation of toxoplasmosis can vary depending on the host’s immune function and organs involved. […]
Ascaris/Ascariasis
General Characteristics and Epidemiology General features of Ascaris Ascaris is a genus of parasitic nematodes (roundworms). Adults: Eggs: Clinically relevant species Ascariasis is caused by: Epidemiology Ascariasis is one of the most common parasitic infections in humans. Pathogenesis Reservoirs A. lumbricoides: A. suum: Transmission Life cycle Pathophysiology Effect of larvae migration in the lungs → […]
Equine Encephalitis Viruses
Classification General Characteristics and Epidemiology General features of equine encephalitis virus (EEV) Family: Togaviridae Genus: Alphavirus Genome: Positive-sense, ssRNA 11–12 kb in size Properties: Enveloped Lipid bilayer envelope has viral-encoded glycoproteins E1 and E2. Small icosahedral capsid Clinically relevant viruses and geographic distribution: Eastern equine encephalitis virus (EEEV) complex: Eastern equine encephalitis (EEE) virus: North […]
Schistosoma/Schistosomiasis
General Characteristics and Epidemiology General features of Schistosoma Clinically relevant species Epidemiology Geographic distribution Pathogenesis Reservoir Transmission Transmission occurs through skin contact with infected fresh water. Host risk factors Schistosoma occupies freshwater environments in areas with poor sewerage management. Life cycle Pathophysiology Clinical disease is caused by: Clinical Presentation Most patients are asymptomatic. Symptomatic individuals […]
Helicobacter
Classification Characteristics Features: Helicobacter genus contains about 35 species, with H. pylori being the most well-known. Pathogenesis Transmission Pathogenic features of Helicobacter pylori Associated Diseases Gastritis Gastric and duodenal ulcers Gastric adenocarcinoma Iron deficiency anemia and vitamin B12 deficiency In H. pylori infection: References