Bacterial Infections and Prokaryotes

• Prokaryotes are single-celled organisms without a nucleus or complex organelles.
• Bacteria and archaea are the two primary categories of prokaryotes.
• Prokaryotes have a key role in medicine as disease agents and biotechnology tools.

Bacterial Infections

• Bacteria are a significant cause of infectious illnesses in people.
• Bacterial illnesses vary from moderate to fatal.
• Pneumonia, urinary tract infections (UTIs), skin infections, food poisoning, and sepsis are typical examples.
• Bacteria induce disease through direct tissue invasion, toxin production, and harmful immune responses.
• Diagnosis includes culture, staining, and molecular methods like PCR.
• Antibiotics are commonly used to treat bacterial infections.
• Antibiotics target cell wall synthesis, protein synthesis, and DNA replication.
• Antibiotic resistance is a major public health concern due to the widespread use of antibiotics.

Antibiotic Resistance

• Antibiotic resistance allows bacteria to survive antibiotic exposure.
• Resistance mechanisms include enzymatic inactivation, target modification, reduced permeability, and efflux pumps.
• Antibiotic resistance spreads through overuse, misuse, horizontal gene transfer (plasmids, transposons), and poor infection control.
• Strategies to combat resistance include new antibiotics, antibiotic stewardship, improved infection control, and alternative therapies like phage therapy or immunotherapy.

Bacterial Virulence Factors

• Virulence factors are produced by bacteria which enhances the ability to cause disease.
• Enable bacteria to adhere to host cells, invade tissues, evade the immune system and cause damage.
• Adhesins (pili, fimbriae), invasive enzymes (hyaluronidase, collagenase), toxins (exotoxins, endotoxins), capsules, and siderophores are examples of virulence factors.
• Understanding virulence factors is essential for developing focused medicines and vaccinations.

Probiotics and the Microbiome

• The human microbiome consists of microorganisms living in and on the human body.
• Bacteria are a major component of the microbiome, particularly in the gut.
• Probiotics are live microorganisms providing a health benefit when administered adequately.
• Common probiotics include Lactobacillus and Bifidobacterium.
• Probiotics improve gut health by modulating microbiome composition, enhancing gut barrier function, reducing inflammation, and producing beneficial metabolites.
• Probiotics are used to treat or prevent diarrhea, irritable bowel syndrome (IBS), and other gastrointestinal disorders.
• The use of probiotics is an area of active research to explore their potential benefits for various health conditions.

Bacterial Biotechnology

• Bacteria have a wide range of applications in biotechnology.
• Production of pharmaceuticals (e.g. insulin, antibiotics), industrial enzymes, bioremediation and biofuels.
• Bacteria serve as protein expression systems and tools for genetic engineering.
• Escherichia coli (E. coli) is used for cloning and protein production.
• Bacillus species are used for the production of enzymes and biopesticides.
• Streptomyces species are a major source of antibiotics.

Vaccines

• Vaccines are biological preparations providing immunity to infectious disease.
• Many vaccines target bacterial pathogens.
• Live attenuated, inactivated, subunit, and conjugate vaccines are types of bacterial vaccines.
• BCG vaccine for tuberculosis is a live attenuated vaccine.
• Whole-cell pertussis vaccine is an inactivated vaccine.
• Tetanus toxoid vaccine is a subunit vaccine.
• Haemophilus influenzae type b (Hib) vaccine is a conjugate vaccines. Stimulation of the immune system to produce antibodies and cellular immunity occurs through vaccines which also provide long-term protection against infection.

Emerging Bacterial Pathogens

• Emerging infectious diseases are those newly appeared or rapidly increasing in incidence/range.
• Methicillin-resistant Staphylococcus aureus (MRSA), Carbapenem-resistant Enterobacteriaceae (CRE), and Clostridioides difficile are examples posing a threat to public health.
• Factors contributing to emergence include antibiotic resistance, globalization, human behavior, and environmental changes.
• Surveillance and rapid response are crucial for controlling emerging bacterial pathogens.

Diagnostic Microbiology

• Diagnostic microbiology involves identifying disease-causing microorganisms.
• Microscopy, culture, biochemical tests, serology, and molecular methods are techniques used.
• PCR and DNA sequencing are molecular methods.
• Rapid and accurate diagnosis helps to initiate appropriate treatment which further helps to prevents spread of infection.

Archaea in Medicine

• Archaea are less commonly associated with human disease compared to bacteria.
• Some archaea are part of the human microbiome.
• Methanogens (methane-producing archaea) are found in the human gut.
• Periodontal disease has been linked to certain archaea.
• Archaea are of interest in biotechnology due to their unique metabolic capabilities and ability to thrive in extreme environments.
• Archaeal enzymes are used in industrial and research applications.
• Research is ongoing to explore the potential medical applications of archaea and their products.

Host-Pathogen Interactions

• Host-pathogen interactions refer to the complex relationships between a host organism and a pathogenic microorganism.
• Bacteria interact with the host via adhesion, invasion, toxin production, and immune modulation.
• The host immune system responds via innate immunity (phagocytosis, complement activation) and adaptive immunity (antibody production, T cell responses).
• Understanding host-pathogen interactions is crucial for developing effective therapies and preventive strategies.

Personalized Medicine and Prokaryotes

• Personalized medicine aims to tailor treatment to individual patient characteristics.
• The microbiome plays a significant role in personalized medicine.
• Analysis of the microbiome can provide insights into an individual's risk of disease and their response to treatment.
• Tailoring antibiotic therapy based on microbiome composition shows active research.
• Personalized probiotic interventions may also be possible based on an individual's microbiome profile.

Bacteria, a type of prokaryote, are a major cause of infectious diseases. Infections range from mild to life-threatening, including pneumonia and UTIs. Diagnosis involves culture and molecular methods, with treatment primarily using antibiotics.