Sensitivity and Specificity- Definition, Formula, Calculation, Relationship

Sensitivity and Specificity- Definition, Formula, Calculation, Relationship

When developing diagnostic tests or evaluating results, it is important to understand how reliable those tests and therefore the results obtained are. By using samples of known disease status, values such as sensitivity and specificity can be calculated that allow its evaluation. Therefore, when evaluating diagnostic tests, it is important to calculate the sensitivity and specificity for that test to determine its effectiveness. Image Source: Wikipedia Sensitivity The term sensitivity was introduced by Yerushalmy in the 1940s as a statistical … Read more

Terminology used in Basic Microbiology

Terminology used in Basic Microbiology

Terminology used in Basic Microbiology Aerobe = organisms that grow in the presence of atmospheric oxygen Anaerobe = grows in absence of free oxygen aerotolerant anaerobes = microbes that grow equally well whether or not oxygen is present facultative anaerobes = microbes that don’t require oxygen for growth but do grow better in its presence microaerophile= requires a low level of oxygen for growth around 2 to 10% but is damaged by normal atmospheric oxygen level monotrichous = having a … Read more

Capsule, Flagella, Pili (Fimbriae), Glycocalyx (Slime Layer)

Capsule, Flagella, Pili (Fimbriae), Glycocalyx (Slime Layer)

Capsule, Flagella, Pili (Fimbriae), Glycocalyx (Slime Layer) Capsule The capsule is a gelatinous layer covering the entire bacterium. It is composed of polysaccharide, except in the anthrax bacillus, which has a capsule of polymerized d-glutamic acid. The sugar components of the polysaccharide vary from one species of bacteria to another and frequently determine the serologic type (serotype) within a species. For example, there are 84 different serotypes of Streptococcus pneumoniae, which are distinguished by the antigenic differences of the sugars … Read more

Effect of pathogens on plants

Effect of pathogens on plants

Effect of pathogens on plants What is Pathogen? A pathogen or infectious agent is a biological agent that causes disease or illness to its host. The term is most often used for the agent that disturb the normal physiology. The main pathogen are the virus, bacteria, and fungi. The physiological function includes: Pathogenesis Respiration Permeability of cell membrane Translocation of water and nutrient Transcription and translation Pathogenesis Pathogenesis is a basic function of plant It transforms light energy into chemical … Read more

VIVA Alert: Basic Microbiology with mnemonics

VIVA Alert Basic Microbiology with mnemonics

VIVA Alert: Basic Microbiology with mnemonics Name one cluster shaped (grape-like) cocci? Staphylococcus aureus Name one chain shaped cocci? Streptococcus spp. What is the difference between Staphylococcus aureus and Streptococcus? S. aureus is cluster shaped and Streptococcus is chain shaped. S. aureus is catalase-positive and Streptococcus is catalase negative. Name any five lactose fermenting organisms? Escherichia coli, Klebsiella spp. , Enterobacter spp. , Citrobacter spp @ KC Enter cold Serrak ( laughing) Name any seven non-lactose fermenting organisms? Salmonella, Shigella, Proteus, … Read more

Culture media used in microbiology

Culture media used in microbiology

Culture media used in microbiology Image Source: Sigma-Aldrich Nutrient agar(1% to 2%) –> Basal media in microbiology, Supports the growth of all non-fastidious organisms MacConkey Agar—> Differential media for Enterobacteriaceae ( i.e. Lactose fermenting and non-lactose fermenting) Mannitol Salt Agar–> Selective and indicator media for S. aureus Triple Sugar Iron(TSI) medium–> Differentiation of various members of Enterobacteriaceae Robertson Cooked Meat Broth(RCMB)–> Growth of anaerobes (e.g Clostridium) Alkaline peptone water–> Enrichment media for Vibrio cholerae Castaneda Medium–> Biphasic medium for isolation … Read more

Bacteriophage- Structure, Classification, Application

Bacteriophage- Structure, Classification, Application

Bacteriophage- Structure, Classification, Application The virus that infects only bacterial cells (bacteria eater) Known as naturally abundant obligate intracellular parasites Niche- present where bacteria or archaea reside Diversity is more than the number of bacteria in nature Small size causes it to beyond the limits of light microscope resolution Smallest bacteriophage: 20 nanometers in diameter, largest bacteriophage: 500 nanometers in diameter Structure of Bacteriophage Each bacteriophage consists of the nucleic acid genome that enclosed in a protein coat, known as … Read more

Environmental Factors affecting Microbial Growth

Environmental Factors affecting Microbial Growth

Environmental Factors affecting Microbial Growth Apart from nutritional components growth of the microbes are also dependent on several environmental factors. These factors play an important role in understanding the growth pattern of a microbe. Apart from that, it is important to understand these factors especially in an industrial set up where a huge amount of biomass is needed. The environmental factors include: 1. Moisture Water is an essential component for the growth of the bacteria. 80% of the bacterial cell … Read more

Probiotic strains and their Human benefits

Probiotic strains and their Human benefits

Probiotic strains and their Human benefits What are Probiotics? Probiotics are living microorganisms that are intended to have health benefits when consumed or applied to the body. They are majorly found in milk products like yogurt, cheese, fermented foods, and food supplements. The Science of microorganisms has shown that most bacterial characteristics are similar morphologically and even on biochemical characterization but not all microorganisms are harmful. Some like probiotics are very helpful in digestion, killing some disease-causing bacteria and producing … Read more

Microbial Growth and Nutrition

Microbial Growth and Nutrition

Microbial Growth and Nutrition Micro and Macro Nutrients The microbial cell is made up of several elements such as carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, potassium, calcium, magnesium, and iron. These are also known as macro elements or macronutrients because these elements are required in high amounts by the microbes. Among these, C, H, O, N, S, and P are the major elements required for carbohydrates, lipids, proteins, and nucleic acids. Apart from these, the other macronutrients are found to … Read more