3. PBSN 520 - Gram Positive Bacteria (1).pdf

PBSN 520 Immunology & Microbiology Fall 2024 Block 1 – Medical Microbiology Dr. Sid Ray Gram Positive Bacteria Wed: 9:30 to 10:30 AM Thurs: 2:00 PM to 4:15 PM  Course-Specific Objectives 1. List various groups of...

PBSN 520 Immunology & Microbiology Fall 2024 Block 1 – Medical Microbiology Dr. Sid Ray Gram Positive Bacteria Wed: 9:30 to 10:30 AM Thurs: 2:00 PM to 4:15 PM  Course-Specific Objectives 1. List various groups of gram positive (+ve) & gram negative (-ve) pathogenic bacteria. 2. Discuss the etiology, pathogenesis, morphology and clinical symptoms of selected bacterial infections of the musculoskeletal, nervous, endocrine, hematological, cardiopulmonary, gastrointestinal, respiratory, renal, and reproductive systems. 3. Describe the mechanisms underlying bacterial infections and discuss the increasingly serious problem of drug- resistant pathogens. 4. Define the significance of the following in relation to bacterial infections: exotoxins, enterotoxins, endotoxins, antitoxins, special pathogenic factors associated with various groups of bacteria, role of spores and bacterial structures. 5. Explain how to apply pathophysiological mechanisms of disease to client care. 6. Suggest appropriate use of antimicrobials in the prevention of bacterial infections.  Watch Osmosis.org animations: How to visit Osmosis.org via our library? Google -- Sirota Library A to Z resources Letter ‘O’ Click on Osmosis Sign on with Touro credentials Type what you want in the search box……  * List various groups of Gram positive (+ve) pathogenic bacteria. Gram Positive Facultative Cocci Bacilli Lactobacillus Anaerobic Aerobic Anaerobic Aerobic Clostridium (C. tetani, C. botulinum, Bacillus anthracis C. perfringens) Corynebacterium diphtheriae Actinomyces Listeria monocytogenes Peptococcus Propionibacterium, Gardnerella Peptostreptococcus Staphylococcus Streptococcus Catalase positive Catalase negative (grows in clusters) (grows in chains) Coagulase positive Coagulase negative a-hemolytic b-hemolytic g -hemolytic Staphylococcus aureus Staphylococcus epidermidis Streptococcus pneumoniae Streptococcus pyogenus (Grp-A) Enterococcus faecium Staphylococcus saprophyticus Viridans Strepto Streptococcus agalactae (Grp-B) Enterococcus faecalis FYI https://step1.medbullets.com/microbiology/104192/gram-positive-bacteria#popup/image/111549  List various groups of gram positive (+ve) pathogenic bacteria. GRAM-POSITIVE BACTERIA: MICROSCOPIC VIEW Staphylococci Streptococci Bacillus Clostridium Lactobacillus Propionibaterium Corynebaterium Actinomycetes Micrococcus Listeria OBJ: Discuss the etiology, pathogenesis, morphology and clinical symptoms of selected bacterial infections of the musculoskeletal, nervous, endocrine, hematological, cardiopulmonary, gastrointestinal, respiratory, renal, and reproductive systems. OBJ: Explain how to apply pathophysiological mechanisms of disease to client care. OBJ: Suggest appropriate use of antimicrobials in the prevention of bacterial infections Gram positive Cocci Aerobic bacteria – Catalase Positive Stapyhlococci ¨ Gram +ve cocci; prolific toxin producers ¨S. aureus has been found to be the causative agent in such ailments as: 1. Pneumonia ¨ S. aureus is a leading cause of soft tissue infections; 2. Endocarditis 3. Meningitis ¨ Prime cause of Toxic Shock Syndrome (TSS; caused by TSST- 4. Boils 1 toxin) and Staphylococcal Scalded Skin Syndrome (SSSS; 5. Arthritis SSSST) 6. Carbuncles 7. Furuncles ¨ SSSS-T is an exfoliative toxin; causes sloughing-off of skin 8. Wound infections/Sepsis (bacterimia) 9. Foliculitis 11. Osteomyelitis (chronic bone infection) ¨ Most Staphs species are coagulase +Ve ¨ TRX: ¨ The S. aureus enterotoxin causes quick onset food poisoning Most S. aureus are penicillin resistant (ß-Lactamase producers) (cramps and severe vomiting) MRSA (Methicillin Resistant S. aureus) are treated with either Vancomycin or Linezolid (methicillin, oxacillin, Nafcillin, penicillin, and amoxicillin) ¨ Infection can be traced to contaminated meats which have not been fully cooked *Of the non-aureus species, S. epidermis is clinically significant since it is an opportunistic pathogen and a part of common human microflora (skin). ¨ Emergence of MRSA (Methicillin Resistant S. aureus) has been a serious problem; these are drug-resistant MRSA COLONIES  SSSS OBJ#8. Determine what aspects of the physical examination and what diagnostic tests are to be conducted to evaluate normal and abnormal health conditions. 8  KEY PATHOGENIC CONCEPTS: STAPHYLOCOCCAL VIRULENCE FACTORS Define the significance of the following in relation to bacterial infections: Exotoxins, enterotoxins, endotoxins, antitoxins, special pathogenic factors associated with various groups of bacteria, role of spores and bacterial structures. P-V-Leucocidin Proteases & Nucleases Aka: Immunoglobulin binding protein α –Toxin; β –Toxin; δ-Toxin Staphylokinase: Converts plasminogen to fibrinolytic plasma 9 What does Staphylococcal alpha-toxin do to host cells? A. It induces cell proliferation B. It inhibits DNA gyrase C. It promotes DNA synthesis D. It induces pore formation E. It inhibits protein synthesis What does Staphylococcal superantigen enterotoxins do to host cells? A. Food poisoning & cell division B. Toxic shock & cell division C. Inhibits DNA synthesis D. It induces pore formation E. Food poisoning & toxic shock  Gram positive Cocci Aerobic bacteria – Catalase Negative Streptococci ¨ Gram-positive, aerobic, appear as chains under microscope ¨ Thick cell wall, presence of ‘M’ proteins’ in their cell wall. ¨ Depending on the composition of their cell walls they are divided. ¨ Groups A and B are the most common and devastating human pathogens. ¨ Clinically classified as pyogenic streptococci, oral streptococci and enteric streptococci. ¨ Also classified based on pattern of RBC- hemolysis: 1. Alpha (a)-hemolytic 2. Beta (ß)-hemolytic 3. Gamma (g)-hemolytic or Non-hemolytic 11 1. Protein G Molecular Organization of Streptococcal Cell Wall 2. Protein F 3. ‘M’ Protein KEY PATHOGENIC CONCEPTS: STREPTOCOCCAL 4. Hyaluronic Acid capsule VIRULENCE FACTORS 5. Lipoteichoic acid  Hemolytic characteristics of Streptococcus spp. GREENISH ZONE CLEAR ZONE or ZONE OF LYSIS NO HEMOLYSIS a-Hemolytic (or alpha- hemolytic): They b-Hemolytic: This produce a substance group produce a g (gamma)- called a-hemolysin hemolysin that Hemolytic: This that oxidizes forms a clear zone group do not hemoglobin (red) to of hemolysis on hemolyze RBC; methemoglobin blood agar. This is Therefore, non- (green). Greenish zone due to hemolysis of hemolytic surrounds the colony. RBC. GREENISH ZONE CLEAR ZONE or ZONE OF LYSIS Apply principles of biochemistry, molecular NO HEMOLYSIS biology and physiology to understand a disease sequel in biologic systems.  Streptococcal Classification 1. Alpha-Hemolytic 2. Beta-Hemolytic 3. NO HEMOLYSIS GREENISH ZONE CLEAR ZONE of Lysis Enterococcus fecalis around the colony Enterococcus faecium Group-A Group-B S. pyogenes S. agalactiae S. pneumoniae (Bacitracin sensitive) (Bacitracin resistant) (Optochin sensitive);Capsulated S. Viridans (Optochin resistant) S. mutans, S. sanguis  OBJ: Explain how to apply pathophysiological mechanisms of disease to client care. OBJ: Suggest appropriate use of antimicrobials in the prevention of bacterial infections. What is OPTOCHIN test? It is a presumptive test used to identify strains of Streptococcus pneumoniae. Optochin (ethyl hydrocupreine) disks are placed on inoculated blood agar plates. Because S. pneumoniae is not optochin resistant, a zone of inhibition will develop around the disk where the bacteria have been lysed. This zone is typically 14mm from the disk or greater. TRX: Penicillin, (ampicillin or amoxicillin), Clindamycin, Erythromycin and certain Cephalosporins and macrolides are effective (Penicillin allergy). LEFT— Optochin-resistant (no zone) RIGHT—Optochin-sensitive (zone > 14mm) Streptococcus pyogenes Streptococcus pneumoniae 15  Streptococcus pneumoniae (a)-hemolytic ¨ Gram positive, nonmotile, encapsulated cocci: ¨ Most common cause of community acquired pneumonia ¨ Pneumococcal pneumonia; facultative anaerobe ¨ Adult bacterial meningitis ¨ Otitis media (most common in children/middle ear infection) ¨ Sinusitis ¨ Mastoiditis [result of an infection that extends to the air cells of the skull behind the ear] ¨ Responds quickly to Optochin test! TRX: Penicillin G in most cases. 3rd generation Cephalosporins (cefoxatime) is good for all resistant strains. All are sensitive to Vancomycin Prevention: PPV (Pneumococcal polysaccharide vaccine) – 23 serotypes Polyvalent PCV-13: Pneumococcal conjugate vaccine 13 Pneumococcal antigens  Streptococcus pyogenes Group A : b-hemolytic ¨ Streptococcal sore throat (strep throat) to necrotizing fasciitis (flesh-eating disease). ¨ The strain is normally not so aggressive-- it is thought that its sudden virulence is triggered by lateral gene transfer by a bacteriophage. S. pyogenes is one of the major pathogens and Clinically, the most important. Scarlet fever Rheumatic fever Postpartum fever Streptococcal toxic shock syndrome Strep throat Impetigo Glomerulonephritis TRX: Penicillin G in most cases. Macrolide (Clarithromycin/Clindamycin) in penicillin allergic patients. Penicillin G + Clindamycin in Necrotizing Fasciitis!! By all accounts, flesh-eating disease is as dreadful as it sounds, the disease is caused when the dangerous group a streptococcus bacteria march relentlessly through the body, devouring tissue. Necrotizing fasciitis is one of the deadliest strep infections, due to its rapid progression. When strep invades areas of the body where it's normally not found, such as the blood and organs, it can be deadly. RIGHT & LEFT FLESH-EATING DISEASE Streptococcus pyogenes SCARLET EFVER 19  Streptococcus agalactiae Group B: β-Hemolytic ¨Catalase negative ¨ Found in vaginocervical tract in females ¨Urethral mucus membranes of males ¨GI tract ¨Endometritis in postpartum women ¨Leading cause of meningitis and septicemia in neonates See left: LATEX AGGLUTINATION TEST FOR GR A -Beta Hemo. Strep…………….. Positive test: Latex particles clump together (A) Rest are negative—No clumping!! http://www.nlm.nih.gov/medlineplus/ency/article/003334.htm TRX: Penicillin G & Ampicillin in most cases In Life threatening situations, an Aminoglycoside can be added (Amikacin, Genta etc.)  Micrococcus ¨ Gram-positive cocci that are 0.5 to 3.5µ in diameter Micrococcus luteus ¨ Arranged in tetrads or irregular clusters COLONIES ¨ Strict aerobes and can generally reduce nitrate ¨ M. Luteus oxidizes carbohydrates to CO2 and water ¨ Some micrococcus are pigmented bacteria; for example, M. luteus produces yellow colonies and M. roseus produces reddish colonies ¨ Although micrococcus rarely causes infections or problems in the body, those with compromised immune systems, such as with HIV +ve patients, micrococcus can cause skin infections 21  Gram Positive - Bacilli Anaerobic General Characteristics of Clostridial species ¨ C. tetani, C. botulinum, C. perfringens, C. difficile ¨ C. tetani- Tetanus; Lockjaw (soil, cuts, wounds etc.) ¨ C. botulinum- botulism (soil, fish, meat etc.) ¨ C. perfringens- Gas gangrene/myonecrosis (food borne) ¨ C. difficile (GI microflora) GI tract of children, can cause watery diarrhea ¨ Gram-positive, strictly anaerobic, spore-forming rods ¨ Motile and especially found in soil, sewage, aquatic settings ¨ Drumstick appearance (tetanus) ¨ A gram-stain is a good method for identifying Clostridium because the cell incorporates the dye while the spore DOES NOT stain. ¨ Clostridium shows optimum growth when plated on blood agar at human body temperatures. ¨ Prolific producers of exotoxins, enterotoxins 22  Clostridium tetani (tetanus) ¨ Causes tetanus (lockjaw) in humans ¨ Spores can be acquired from any type of skin trauma involving an infected device. ¨ In anaerobic environment, spores will germinate and eventually form active C. tetani cells. ¨ Releases an exotoxin called tetanospasmin. ¨ Transported from infected locus by retrograde neuronal flow or blood. Trx: Active immunization with Tetanus toxoid prevents tetanus; ATS: Anti tetanus serum; Penicillin-G, Clindamycin http://www.youtube.com/watch?v=zirt0Od05zg It’s called Achilles Piercing: Widely regarded as a myth, the Achilles Piercing is a self-inflicted act which the person pierces between the Achilles tendon and the ankle. Although extremely rare, it is real, and healed examples do exist. JUST FYI!!  Clostridium botulinum (Botulism) ¨ One of the most potent toxins in existence ¨ Cause of the deadly botulism food poisoning ¨ Clostridial spores can be airborne ¨ Spores can find their way into foods that will be placed in anaerobic Extremely toxic with a storage such as cans or jars human median lethal dose of 1.3–2.1 ng/kg IV ¨ Spores germinate and the bacteria release their potent toxin or IM and 10–13 ng/kg when inhaled. ¨ Patients will experience muscular paralysis as well as blurred vision. Trx: Antitoxin neutralizes unbound toxins; penicillin  Clostridium perfringens (Gas gangrene) ¨ Spores germinate- Cells proliferate ¨ Exotoxin is released ¨ Toxin causes myonecrosis ¨ The bacteria produce gas which leads to a bubbly deformation of the infected tissues. ¨ Capable of necrotizing intestinal tissues & can release an enterotoxin that may lead to severe diarrhea. Trx: Penicillin; Protein synthesis inhibitors; broad-spectrum works better; Exposing the wound to high oxygen concentration by placing the patient in a hyperbaric chamber.  CLOSTRIDIUM CLOSTRIDIUM PERFRINGENS TETANI Clostridium botulinum FYI: Clostridium botulinum is a heterogeneous gram-positive species that comprises four genetically and physiologically distinct groups of bacteria that share the ability to produce botulinum neurotoxin, the most poisonous toxin known to man, and the causative agent of botulism, a severe disease of humans and animals. The complete genome sequence of a representative of group I (proteolytic) C. botulinum. The genome consists of a chromosome (3,886,916 bp) and a plasmid (16,344 bp), which carry 3650 and 19 predicted genes, respectively. Consistent with the proteolytic phenotype of this strain, the genome harbors a large number of genes encoding secreted proteases and enzymes involved in uptake and metabolism of amino acids. Overall, the genome indicates that C. botulinum is adapted to a saprophytic lifestyle both in soil and aquatic environments. This pathogen relies on its toxin to rapidly kill a wide range of prey species, and to gain access to nutrient sources, it releases a large number of extracellular enzymes to soften and destroy. 27 JUST FYI!!  Actinomycetes ¨Fungus-like filamentous bacteria- forms branches (pleomorphic); High G+C content ¨Ex. Actinomyces israelii (*this is a genus of actinomycetes; anaerobic to microaerophillic). ¨Other Examples: Nocardia asteroides; Nocardia brasiliensis (aerobic- slow growth in anaerobic as well) ¨Gram +Ve with acid-fast beads; Commonly found in mouth, genital, and GI flora. Presence of intermediate- length mycolic acids in their cell wall & most strains possess the cord factor (trehalose 6-6' dimycolate)- considered a virulence factor. ¨Proliferation of the organisms, which is usually a result of trauma to the region of infection, can lead to actinomycosis. ¨Nocardia causes pulmonary infections- Nocardiosis. ¨Forms abscesses & swelling at the site of infection. Trx: For Actinomycetes- Penicillin G and Clindamycin, Erythromycin and Tetracyclins Trx: For Nocardia- TMP-SMX (Trimethoprim/Sulfomethoxazole)  Based on individual patient characteristics and medical conditions, determine alternative pharmacotherapeutic options by evaluating patient specific variables with regard to pathophysiology and anatomical characteristics (microbial or immunological). Propionibacterium species v Very common gram-positive anaerobes that are isolated in the laboratory. MILD v One particular species, P. acnes, is a usually harmless microbe that has pathogenic potential. v Primarily anaerobic but can grow in aerobic environment. v All members produce propionic acid as a major metabolic end-product; MED divided into 2 groups, a cutaneous group (which can cause acne) and a dairy group used in cheese production. v It has been linked to certain cases of endocarditis, wound infections, and abscesses. v Two other bacteria associated with acne vulgaris are: P. granulosum and S. epidermidis. HIGH Trx: Penicillins, Carbapenems & Clindamycin.  Gram positive Bacilli – Aerobic Bacillus anthracis ¨ Gram positive; Endospore forming rod ¨ Strict aerobes or aerotolerant anaerobes ¨ Causes anthrax in cows, sheep, goats and horses ¨ Humans contract via animal products/contaminated dusts (endospores) ¨ (i) Cutaneous infection (95% of human cases); ¨ (ii) inhalation-pulmonary anthrax (rare); ¨ (iii) GI anthrax (very rare) ¨ Produces unique capsule and two plasmid coded-extotoxins Other two pathogenic forms are: Bacillus cereus - RICE EATING RELATED FOOD POISONING. Bacillus polymyxa (polymyxin production) - is used in antibiotic production. Trx: ciprofloxacin, doxycycline and penicillin. Ciprofloxacin + Rifampin + Vanco is recommended for inhalation antrax!  Bacillus anthracis LEFT: OLDER COLONIES HAVE A GROUND GLASS APPEARANCE RIGHT: The rod-shaped Anthrax bacteria, Bacillus anthracis, the cause of anthrax. Magnification: x18,300 OBJ: Discuss the etiology, pathogenesis, morphology and clinical symptoms of selected bacterial infections of the musculoskeletal, nervous, endocrine, hematological, cardiopulmonary, gastrointestinal, respiratory, renal, and reproductive systems. Corynebacterium ¨ Causes life-threatening disease diphtheria ¨ A disease of the upper respiratory tract in humans ¨ Gram positive, anaerobic, nonmotile bacteria which are normally saprophytic and harmless to humans. ¨ An exception is the bacterium C. diphtheriae, which is a prolific toxin producer ¨ C. diphtheria is unique in its exotoxin formation. Corynebacterium diphtheriae colonies on blood agar. CDC. Trx: An antitoxin + a Penicillin Erythromycin; Clindamycin; Rifampin; Tetracycline. Prevention: Administration of DTaP vaccine. [Saprophyte defn.: Organisms especially a fungus or bacterium, that grows on and can derive its nourishment from dead or decaying organic matter.] Based on individual patient characteristics and medical conditions, determine alternative pharmacotherapeutic options by evaluating patient specific variables with regard to pathophysiology and anatomical characteristics (microbial or immunological). C. diptheriae TOP RIGHT- White patch of bacterial infection LEFT– False-colour transmission electron micrograph (TEM) of Corynebacterium diphtheria, showing a number of the Gram-positive, non-sporing, facultative aerobic bacilli (rod- shaped bacteria) which are the causative agents of diphtheria.  Listeria monocytogenes ¨ Gram-positive motile, rod-shaped non-spore former, Facultative anaerobe ¨ The only pathogenic species to human is L. monocytogenes. ¨ Listeriosis is mainly a food-borne illness caused by L. monocytogenes; Listeriosis can cause be inflammation of the brain. ¨ L. Monocytogenes has been implicated in several food poisoning epidemics. ¨ Normal inhabitant of the GI tract. ¨ Vomiting, nausea, and diarrhea are common ¨ Most vulnerable are pregnant women, newborns, elderly, and immunocompromised patients. ¨ Infections are associated with a high mortality rate, [Pregnant women are 20 times more likely than other healthy adults to get Listeriosis. About one-third of Listeriosis occurs during pregnancy.] Trx: Ampicillin alone or in combination with gentamicin (Aminoglycoside) remains the treatment of choice. TMP-SMX (Trimethoprim/Sulfomethoxazole) is also useful. 35  Gram positive Bacilli – Facultative Lactobacillus ¨ Non-spore-forming gram +ve ¨ Aerotolerant anaerobes ¨ Ferment glucose into lactose, hence the name lactobacillus. ¨ Most common application- dairy industry ¨ Human natural flora of the GI tract & vagina ¨ Because of their ability to derive lactic acid from glucose, these bacteria create an acidic environment which inhibits growth of many bacterial species which can lead to urogenital infections (ex. Human vagina) ¨ Generally harmless to humans, rarely inciting harmful infections or diseases. 36 Conclusions