BACT211 Clinical Bacteriology 2nd Semester 2023-2024 PDF

# BACT211: CLINICAL BACTERIOLOGY ## TOPIC: INTRODUCTION TO DIAGNOSTIC BACTERIOLOGY **2nd Semester | S.Y 2023-2024** **LECTURER:** Ma'am Christy Gonzales ## GENERAL DEFINITIONS - **Microbiology** - a branch of biology which deals with the study of living organisms that are small to be seen by t...

# BACT211: CLINICAL BACTERIOLOGY ## TOPIC: INTRODUCTION TO DIAGNOSTIC BACTERIOLOGY **2nd Semester | S.Y 2023-2024** **LECTURER:** Ma'am Christy Gonzales ## GENERAL DEFINITIONS - **Microbiology** - a branch of biology which deals with the study of living organisms that are small to be seen by the naked eye. - We need to use a microscope for us to be able to see/visualize them (microorganisms). - **Medical Microbiology** - a branch of medical science which deals with the study of medically important microorganisms specifically their role in human disease which includes diagnosis, treatment, and prevention of infectious diseases. - Focus of other medical courses: medicine, nursing, physical therapy - **Diagnostic Bacteriology** - a branch of medical microbiology that focuses on the laboratory identification of medically important bacteria by phenotypical and genotypical characterization including antibiotic susceptibility testing. - This is the focus of our program - Diagnostic Microbiology includes bacteriology, mycology, virology, and parasitology. - To be more specific, diagnostic bacteriology, we are dealing with the laboratory identification of medically important bacteria by their molecular characteristics. - Routinely [commonly performed], in the laboratory in the hospital settings, we are identifying the phenotypical [visible trait; seen by the naked eye; morphology, colonial morphology] of the bacteria. - We have two ways of visualizing bacteria: - **Microscopic** [with the aid of microscope; can know its morphology (coccus, spirochetes, etc.), and many more] - **Macroscopic** [we can see this without the use of microscope; colonial morphology (growth of bacteria in the surface of a culture medium)] - Bacteria, like human, have distinct/specific characteristics as well. - In specialized laboratories, they also examine genotypical characteristics [molecular; PCR, DNA composition, nucleic acid composition, etc.] - After identifying the bacteria, the genus and the species, antibiotic testing is also performed to identify what antibiotics/anti-microbial agents that could kill the bacteria. - Each bacterium or each family of bacterium has a unique set of antibiotics that could kill them. - Iba iba ang reaction ng bacteria sa particular antibiotic - There are certain bacteria that couldn't be killed by a particular antibiotic. Thus, the need to identify the antibiotic that could kill it. ## MICROBIOLOGY - Study of microorganisms - Study of certain nonliving entities as well as certain living organisms. - We have two types of microorganisms: - **Acellular infectious agents** - They do not have the characteristics that are similar to the characteristics of a cell - Instead, they do depend in other cells in terms of reproduction [use cellular organelles of their hosts] - Prions and Viruses [contain nucleic acid and protein] - **Cellular microorganisms** - Contains cellular organelles (nucleus, ribosomes, ER, etc.) ### MICROBES - Microbes are said to be ubiquitous. Meaning, they are seen everywhere; virtually everywhere. - **Origin of Bacteria:** - **Human** - normal flora; non-pathogenic (not capable of causing diseases in normal circumstances, but they have the possibility of transforming from non-pathogenic to pathogenic) - Human → Human - **Animals** - They are medically important if their bacteria are transmitted to humans - Animal → Human - **Environment** - Includes soil, water, and air - Reservoir of bacteria - Acquisition of bacteria from the environment - Microbes are subdivided into one of four groups: - **Virus** - Very simple microbes; consisting of nucleic acid, a few proteins, and (in some), a lipid envelope - Completely dependent on the cells they infect for their survival and replication - Specific to their host cell [lock-and-key; specific receptor] - HIV - CD4 cell - With both RNA and DNA; metabolic machinery for self-replication, and a complex cell wall structure (ASEXUAL) - **Bacteria** - Prokaryotic - simple unicellular organisms - **Fungi** - Subdivided into single-celled organisms (yeasts) or multi-celled organisms (molds), with a few medically important members existing in both forms (dimorphic fungi) - Monophormic (exists in uni or multi: yeast or mold; iisa lang ang form) - Dimorphic (has 2 forms: yeasts and molds) ## DEFINITION OF TERMS RELATED TO INFECTIOUS PROCESS AND DISEASE TRANSMISSION - **Pathogens** - disease causing microorganisms such as bacteria, fungi, protozoans, and viruses, as long as they are capable of causing diseases then they are pathogens - **Types of pathogens** - **True pathogens** - refers to an organism that will cause disease in a healthy host - **Opportunistic pathogens** - refers to organisms that will cause disease in an immunocompromised host [the immune system is compromised; immunity is low] - **Pathogenicity** - refers to the ability of an organism to cause disease in a host organism - **Virulence** - refers to the degree of pathogenicity; the power by which a pathogen can cause severe disease - Bawat microorganism have several power in which pathogens can cause disease. - Severity of diseases that a pathogen causes depends on their power. - Ex. Staphylococcus aureus in order for this to cause disease, it has virulence factor [any feature (biochemical/enzymes, genetic, or even the structure the bacteria) which will enable it to cause disease. - Ex. Biochemical - Endotoxin is a biochemical component of Staphylococcus aureus. When it have endotoxin B, this is capable of causing food poisoning. However, when you have Protein A [this is enabling the Staphylococcus aureus to be anti-phagocytic]. Protein A blocks the pathway of phagocytes. - Ex. Staphylococcus aureus is in our blood stream. Then, one of the members of our immune system will try to eliminate it, but if Staphylococcus aureus has Protein A, then it will inhibit or block the antibodies for it to be protected. Thus, Staphylococcus aureus can still cause infection. - Ex. Streptococcus pneumoniae's structure has capsule. Then, it has the same function as Protein A [anti-phagocytic]. Thus, causing infection. - **Pathogenic Determinants/Virulence Factors** – refers to any genetic, biochemical, or structural features that enable a pathogen to cause disease in a host organism - **Infection** - refers to the entry, invasion, and multiplication of pathogens in or on to the host body system which results to subsequent tissue injury and progress to overt disease. - Bacteria will attach to the host surface. - Ex. The mode of transmission is inhalation for it to go to the lining of our respiratory tract [invade and multiply]. The bacteria will multiply into that host's surface and will cause subsequent tissue injury. That is when manifestation of signs and symptoms occur. When the bacteria successfully passed our immune system, then that's the time na makakapaginvade siya and multiply. - **Types of Infection Based on Source of Pathogen** - **Infection arising from colonizing flora [also known as indigenous microflora; also known as resident flora, microbiota]** - **Normal flora - non-pathogenic under normal condition; have restricted number in the human system for it not to be pathogenic** - **Endogenous Infection** - **Normal flora can be pathogenic once an individual is immunocompromised; increase in number [low immunity; the bacteria will increase in terms of their number and when that happens, they will be able to cause disease].** - **It also can be pathogenic once they transfer site [Ex. GIT → urinary tract]. Once it happens, that could cause infection.** - **Subdivided into single-celled organisms (protozoa) or multi-celled organisms (worms and bugs)**