Genus staphylococcus
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This document provides information on the genus Staphylococcus. It discusses the morphology, classification, virulence factors, and diseases caused by Staphylococcus species. Some key points include: - Staphylococcus is a genus of gram-positive bacteria that forms grapelike clusters and includes major human pathogens. - Important virulence factors include toxins like alpha toxin, enterotoxins, and exfoliative toxins. Enzymes and surface proteins also contribute to pathogenesis. - Major diseases caused by coagulase-positive Staphylococcus include mastitis, tick pyemia, exudative dermatitis, and botryomycosis in various animal
Genus staphylococcus
- 1. Genus STAPHYLOCOCCUS Dr Ravi Kant Agrawal, MVSc, PhD Senior Scientist (Veterinary Microbiology) Food Microbiology Laboratory Division of Livestock Products Technology ICAR-Indian Veterinary Research Institute Izatnagar 243122 (UP) India
- 2. Introduction Staphyloccocci - Greek “staphyle” (bunch of grapes) and “Kokkos” = berry, meaning bacteria occurring in grapelike clusters or berry. >40 species are known Occur as commensal on skin and mucous membrane Natural habitat: Nostril and skin (Present on the skin and mucus membrane) Include major human pathogen • Some act as opportunistic pathogens causing pyogenic infections. • Hardy organisms surviving many non- physiologic conditions
- 3. History Robert Koch (1878)- first to see staphylococci in pus specimen Louis Pasteur (1880)- first to cultivate in liquid medium Sir Alexander Ongston (1881)- named the bacteria as “Staphylococcus”
- 4. Morphology & Biochemical Characteristics Gram-positive cocci, 0.5-1.5 µm in diameter Occur characteristically in group, also singly and in pairs Form irregular grapelike clusters (since divide in 3 planes) Non-motile Non- spore forming Catalase positive Oxidase negative Few strains are capsulated Mostly aerobic or facultative anaerobic (02 species S. anaerobius and S. saccharolyticus are anaerobic and catalase negative) Grow in media containing 10% NaCl at temp 18 to 400 C Coagulase positive S. aureus, S. intermedius, and coagulase variable S. hyicus are important pathogens of domestic animals. Coagulase negative staphylococci are low virulence, some occasionally cause disease in humans and animals.
- 5. Classification Family: Micrococcaceae • G. Staphylococcus (facultative anaerobic) • G. Micrococcus (only aerobic) • G. Stomatococcus (facultative anaerobic) • G. Planococcus (only aerobic)
- 6. Classification S. albus , S. aureus , S. citrus on Nutrient Agar • Based on pigment production: S. aureus : golden-yellow pigmented colonies S. albus : white colonies S. citrus : lemon yellow colonies • Based on pathogenecity: Pathogenic: i.e. S. aureus Opportunistic pathogens: S. epidermidis, S. saprophyticus Non-pathogenic: S. albus, S. citrus, S. hominis etc. • Based on coagulase production: Coagulase positive: S. aureus Coagulase negative: S. epidermidis, S. saprophyticus
- 7. Usual Habitat Staphylococci occur worldwide as commensals on skin of animals and man. Also found on mucous membrane of upper respiratory tract and lower urogenital tract and as transients in digestive tract. They are stable in the environment. Some staphylococcal species exhibit affinity for particular animal species. Transfer of S. aureus between animals and man is limited.
- 9. Antigenic structure • Capsule • Peptidoglycan • Teichoic acid • Protein A
- 10. Structure CAPSULE loose fitting polysaccharide layer (slime layer) protects bacteria by inhibiting chemotaxis and phagocytosis facilitates adherence of bacteria to catheters and synthetic materials PEPTIDOGLYCAN half of the cell wall consist of layers of glycan chains with alternating subunits of N – acetylmuramic acid and N- acetylglucosamine has endotoxin like activity
- 11. Structure..... TEICHOIC ACID Phosphate containing polymers bound to peptidoglycan layer or to cytoplasmic membrane - mediates the attachment of staphylococcus to mucosal surfaces S. aureus: Ribitol teichoic acid with N- acetylglucosamine (Polysaccharide A) S. epidermidis: Glycerol teichoic acid with glucosyl residues (polysaccharide B)
- 12. Structure..... PROTEIN A Covalently linked to peptidoglycan Has affinity to Fc region of Immunoglobulins Blocks opsonization and phagocytosis
- 13. Structure..... COAGULASE Bound coagulase or Clumping factor binds fibrinogen, convert to insoluble fibrin causing staphylococcus to clump Other SURFACE PROTEINS Collagen, Elastin, fibrinogen and fibronectin binding proteins CYTOPLASMIC MEMBRANE Osmotic barrier for the cell and provides an anchorage for the biosynthetic and respiratory enzyme
- 14. MSCRAMMs Microbial Surface Component Recognizing Adhesive Matrix Molecules – include Fibronectin-binding protein Collagen-binding protein Interacting with host cells S. aureus colonizes the skin of mammals S. aureus infections often begin at some breach in the epithelial barrier MSCRAMMs enhance the bacterial attachment to host cells
- 15. Virulence Factors in Staphylococci
- 20. Toxins A. 5 Cytolytic or membrane damaging toxins 1. Alpha hemolysin 2. Beta hemolysin 3. Gamma hemolysin 4. Delta hemolysin 5. Panton Valentine leucocidin B. 2 Exfoliative toxins C. Toxic Shock Syndrome Toxin (TSST-1) D. >23 Enterotoxins
- 21. Cytotoxins Alpha toxin – disrupts the smooth muscle in blood vessels toxic to erythrocytes, hepatocytes, platelets, cultivated cells integrates to host cell membrane - pores - efflux of K and influx of Na, Ca - osmotic swelling - cell lysis septic shock Beta Toxin Sphingomyelinase C Specific for sphingomyelin and lysophosphatidylcholine Toxic to RBC, WBC, Macrophage and fibroblast Catalyze hydrolysis of membrane phospholipids in susceptible cells Tissue destruction and abscess formation Delta toxin disrupts cell membrane toxic to variety of cells Lyse neutrophils - release of lysosomal enzymes - damage surrounding tissues
- 22. Cytotoxins.... Gamma toxin and Panton Valentine leucocidin Both damage membrane of susceptible cells Lyse nuetrophils and macrophages Cell lysis is mediated by pore formation Cause necrotizing skin infection PVL - potent leukotoxicity
- 23. Exfoliative toxin • ETA - heat stable • ETB – heat labile • Serine protease • Exposure - splitting of desmosomes or intercellular bridges in the stratum granulosum epidermis and causes its separation from underlying tissue, resulting in a blistering and exfoliating disease of skin • Common in neonates – ETA and ETB binds to GM4 like glycolipids present in neonates
- 24. TSST-1 • Formerly pyrogenic exotoxin C and entertoxin F • Induce cytokine release from macrophage and T lymphocytes • heat & proteolysis resistant • Superantigens • Penetrate mucosal barrier • Increase sensitivity to endotoxin • Produce leakage of endothelial cells • All S. aureus responsible for menstruation-associated TSS produce TSST-1 • 50 % of the strains responsible for other forms of TSS produce TSST-1
- 25. Enterotoxins • >23 types - till date • Stable to heating, resistant to hydrolysis • Enterotoxin A – most commonly associated with disease • Enterotoxin C and D- contaminated milk products • Enterotoxin B - Pseudomembranous colitis • Superantigens
- 26. Staphylococcal Enzymes convert fibrinogen react with globulin plasma factor to form insoluble fibrin staphylothrombin Clumping factor Cause formation of fibrin layer around abscess protecting staphylococcus from phagocytosis Coagulase Bound Free
- 27. Staphylococcal enzymes • Catalase: catalyze the conversion of toxic hydrogen peroxide to water and oxygen • Hyalurodinase: hydrolyzes hyaluronic acid in acellular matrix of connective tissue - spread • Fibrinolysin: Also k/a staphylokinase Dissolve fibrin clot- aid in bacterial spreading • Lipases: Lipases hydrolyse lipid to ensure survival in sebaceous areas of the body • DNase: • Penicillinase: Plasmid mediated • Fatty acid modifying enzyme (FAME): antibacterial lipid- prolonged bacterial survival
- 28. Pathogenesis • Staphylococci are pyogenic bacteria, they often cause suppurative infections. • Minor trauma or immunosuppression may predispose to development of infection. • Adhere to damaged skin, mucosa or tissue surfaces – At these sites, they evade defence mechanisms of the host, colonize and cause tissue damage • Structural features including capsular polysacchrade, peptidoglycan, teichoic acid and protein A interfere with opsonization. • Cell wall proteins may bind to fibronectin, collagen, elastin and fibrinogen may facilitate bacterial attachment to tissues. • Production of coagulase is important virulence factor. • Other virulence factors including enzymes also play important role. • S. aureus produces disease by – Multiplying in tissues – Liberating toxins, – Stimulating inflammation
- 29. Predisposing Factors Leading to S. aureus Infections Skin damage: burns, cuts, sutures Reduced Chemotaxis: burns, diabetes, cancer Reduced Phagocytosis: diabetes, complement deficiency, immunoglobulin deficiency, genetic defect in phagocytes Age: very young or very old
- 30. Clinical Infections: in Animals Since staphylococci occur as both commensal of skin and mucous membrane and as environmental contaminants, infections can be either endogenous or exogenous in origin. Many infections are opportunistic and associated with trauma, immunosuppression, inter-current parasitic or fungal infections, allergic conditions or endocrine or metabolic disturbances. COAGULASE POSITIVE STAPHYLOCOCCI ARE RESPONSIBLE FOR MOST OF THE INFECTIONS. COAGULASE NEGATIVE STAPHYLOCOCCI ARE ALSO CAPABLE OF CAUSING DISEASE IN ANIMALS. Important staphylococcal diseases include mastitis, tick pyaemia, exudative dermatitis, botryomycosis and pyoderma.
- 31. Diseases in Animals by Coagulase positive Staphylococci Species Hosts Clinical Conditions Staphylococcus aureus Cattle Mastitis, Udder Impetigo Sheep Mastitis, Tick Pyaemia (Lambs), Dermatitis, Benign Folliculitis (Lambs) Goat Mastitis, Dermatitis Pigs Botryomycosis of mammary glands, Impetigo of mammary glands Horses Botryomycosis of spermatic cord (Scirrhous cord), Mastitis Dogs, Cats Suppurative conditions similar to those caused by S. intermedius Poultry Bumblefoot, Omphalitis in chicks, Arthritis and Septicaemia in turkeys
- 32. Species Hosts Clinical Conditions Staphylococcus intermedius Dogs, Pyometra, endometritis, cystitis, otitis externa and other suppurative conditions Cats Varous pyogenic infections Cattle Mastitis (Rare) S. hyicus (50% are CoPS) Pigs Exudative dermatitis (Greasy Pig disease) Cattle Mastitis (Rare) S. aureus ssp anaerobius Sheep Lymphadenitis S. delphini Dolphins Suppurative skin lesions S. Schleferi S. schleiferi ssp. coagulans (cf. S. schleiferi ssp. schleiferi is CN) Dogs Otitis externa S. pseudintermedius S. lutrae Diseases in Animals by Coagulase positive Staphylococci
- 33. Staphylococcal mastitis Staphylococcal mastitis, mostly caused by S. aureus, is a common form of bovine mastitis, worldwide. It may be subclinical, acute or chronic. The majority of infections are subclinical. Peracute and gangrenous forms are associated with severe systemic reactions and can be life threatening. In gangrenous mastitis, the affected quarter, which becomes cold and blue black, eventually sloughs. Tissue necrosis is attributed to alpha-toxin which causes contraction and necrosis of smooth muscles in blood vessel walls, impeding blood flow in the affected quarter. In addition, this toxin causes release of lysosomal enzymes from leucocytes.
- 34. Tick Pyaemia Tick pyaemia is an infection of lambs by S. aureus. Infection is confined to hill grazing regions where there are suitable habitats for the ticks Ixodes ricinus. Ixodes ricinus is a vector for the Rickettsial agent of tick-borne fever, Ehrlichia phagocytophila, which can cause immunosuppression in lambs and may predispose to staphylococcal infection. Lambs carry S. aureus on their skin and nasal mucosa and infection occurs through minor skin trauma including tick bites. Tick pyaemia is characterized either by septicemia and rapid death or by localized abscess formation in many organs. Clinical manifestations include arthritis, posterior paresis and ill thrift. The condition can be of considerable economic importance on some farms where up to 30% of lambs between 2 and 10 weeks of age can be affected in spring and early summer.
- 35. Exudative dermatitis (Greasy Pig Disease) This disease is caused by S. hyicus. Occurs worldwide in sucklers and weaned pigs up to 3 months of age. It is highly contagious and characterized by widespread excessive sebaceous secretion, exfoliation and exudation on the skin surface. Affected pigs, which are anorexic, depressed and febrile, have an extensive, non-pruritic dermatitis with greasy exudate. Piglets under 03 weeks of age may die within 24 to 48 hours. Morbidity range from 20-100%, and morality rates can reach 90% in severely affected litters. S. hyicus can be isolated from the vaginal mucosa and skin of healthy sows. The organisms probably enters the skin of young pigs through minor abrasions such as bite wounds. Predisposing stress factors include agalactia in the sow, intercurrent infections and weaning stress.
- 36. Botryomycosis Botryomycosis; also known as bacterial pseudomycosis is a rare chronic suppurative granulomatous bacterial infection that affects the skin, and sometimes the viscera, often caused by S. aureus. Botryomycosis has been known to affect humans, horses, cattle, swine, dogs and cats. It can occur within a few weeks of castration in the horse due to the infection of the stump of the spermatic cord (scirrhous cord). Botryomycosis can also occur in mammary tissues of the sows. The lesion is composed of a mass of fibrous tissue containing foci of pus and sinus tracts. The disease was originally discovered by Otto Bollinger (1843– 1909) in 1870, and its name was coined by Sebastiano Rivolta (1832–1893) in 1884. The name refers to its grape-like granules (Gr. botryo = grapes) and the mistakenly implied fungal etiology (Gr. mykes = fungus). In 1919 the bacterial origin of the infection was discovered.
- 37. Bumblefoot in Poultry Bumblefoot is an infection caused by the Staphylococcus which enters the chicken’s system through a cut, scratch, injury. The infection creates an abscess full of pus. It affects all species of poultry and occurs worldwide.
- 38. Staphylococcal infections of dogs and cats Staphylococcus intermedius is commonly isolated from pyometra, otitis externa and other suppurative conditions including mastitis, endometritis, cystitis, osteomyelitis and wound infections. Occasionally, similar suppurative conditions are caused by S. aureus.
- 39. DISEASES – In human • Due to direct effect of organism – Local lesions of skin – Deep abscesses – Systemic infections • Toxin mediated – Food poisoning – Toxic shock syndrome – Scalded skin syndrome
- 40. Clinical Syndromes- in humans 1. Cutaneous infections – Folliculitis – Boils/furuncles – Carbuncle – Impetigo – Wound infections 1. Deep infections – Osteomyelitis – Periostitis – endocarditis 1. Exfoliative diseases (SSSS) 2. Toxin shock syndrome 3. Staphylococcal food intoxication
- 41. 1) Cutaneous Infections • Folliculitis: It is inflammation of the hair follicles. • A small red bump or pimple develops at infection sites of hair follicle. • Sty: A sty is folliculitis affecting one or more hair follicles on the edge of the upper or lower eyelid.
- 42. Cutaneous Infections (contd....) Furuncle/boils: • Furuncle is deep seated infection, originating from folliculitis, (if infection extends from follicle to neighbouring tissue) • Causes redness, swelling, severe pain • Commonly found on the neck, armpit and groin regions Carbuncle: • Carbuncle is an aggregation of infected furuncles. • Carbuncles may form large abscesses. • It is a large area of redness, swelling and pain, punctuated by several sites of drainage pus. •
- 43. Cutaneous Infections(contd....) Impetigo: • a very superficial skin infection common in children, usually produces blisters or sores on the face, neck, hands, and diaper area. • It is characterized by watery bristles, which become pustules and then honey coloured crust impetigo with vesicles, pustules, and sharply demarcated regions of honey-colored crusts.
- 44. 2) Deep Infections Osteomyelitis: Inflammation of bone • Bacteria can get to the bone – Via bloodstream – Following an injury Clinical features: pain, swelling, deformity, defective healing, in some case pus flow, Diagnosis: X-ray, MRI, bone aspirates
- 45. Deep Infections (contd....) Periostitis: inflammation of periosteum • Clinical features: fever, localised pain, leucocytosis • Diagnosis: needle aspiration of subperiosteal fluid
- 46. Deep Infections(....contd) • Endocarditis: It is an inflammation of the inner layer of the heart, the endocardium • Endocarditis occurs when bacteria enter bloodstream, travel to heart, and lodge on abnormal heart valves or damaged heart tissue.
- 47. 3) Exfoliative Disease • Exfoliate - scaling off tissues in layers • It is a skin disease in which outer layer of epidermis gets separated from the underlying tissues. • Exfoliative toxin produced by S. aureus is responsible for this. • Also known as ‘Staphylococcal skin scalded syndrome’ SSSS • Previously called dermatitis exfoliativa, pemphigus neonatorum, Lyell’s disease and Ritter’s disease • Epidermal toxin produced by S. aureus at skin and is carried by bloodstream to epidermis, where it causes a split in a cellular layer i.e., this toxin separates outer layer of epidermis from underlying tissue splitting of desmosomes or intercellular bridges in the stratum granulosum epidermis and causes its separation from underlying tissue, resulting in a blistering and exfoliating disease of skin
- 48. Types of SSSS: Severe form Milder form In new born - Ritter’s disease - Pemphigus neonatorum In older patients - Toxic epidermal - Bullous necrolysis impetigo Toxic epidermal necrolysis Ritter’s disease Bullous impetigo Pemphigus neonatorum
- 49. 4) Toxic Shock Syndrome • Caused when Toxin shock syndrome toxin (TSST) liberated by S. aureus enters bloodstream • It is fatal multisystem disease presenting with fever, hypotension, myalgia, vomiting, diarrhoea, mucosal hyperemia and erythematous rash which desquamates subsequently.
- 51. 5) Staphylococcal Food Poisoning • Caused when consuming food in which S. aureus has multiplied and formed enterotoxins. • It usually occurs when preformed toxin is ingested with contaminated food. • Enterotoxin is responsible for manifestations of staphylococcal food poisoning. • > 23 types of enterotoxin are currently known, named A-E and G- w. • The toxin acts directly on the autonomic nervous system to cause the illness, rather than gut mucosa • Symptoms: Nausea, Vomiting, Severe abdominal cramp, Diarrhoea, Sweating, Headache etc. • The common food items responsible are - milk and milk products, meat, fish and ice cream. • Source of infection- food handler who is a carrier. • Incubation period- 2 to 6 hours. • The illness is usually self limited, with recovery in a day or so.
- 52. Laboratory Diagnosis A. Bacteriological Investigation: • Specimens: – Pus: from wound or abscess or burns – Nasal Swab: from suspected carrier – Food: to diagnose staphylococcal intoxication – Blood: to diagnose endocarditis and bacteremia – Sputum: to diagnose lower respiratory tract infection – Milk: To detect mastitis
- 53. STAPHYLOCOCCI Gram’s Stain: • These are spherical cocci. • Approximately 1 μm in diameter. • Arranged characteristically in grape like clusters. • They are non motile and non sporing. • A few strains possess capsules.
- 54. CULTURE Media used: i) Non selective media: Nutrient agar, Blood agar, MacConkey’s agar. ii) Selective media: Mannitol salt agar Baired Parker agar Ludlam’s medium Salt-milk agar,
- 55. Cultural Characteristics I. On nutrient agar- The colonies are large, circular, convex, smooth, shiny, opaque and easily emulsifiable. Most strains produce golden yellow pigments. II.On MacConkey’s agar- The colonies are small & pink in colour. III.On blood agar- Most strains produce β- haemolytic colonies.
- 56. Double zone of hemolysis Outer zone: incomplete hemolysis (Alpha) Inner zone: complete hemolysis (beta-hemolysis) Double zone hemolysis by S. aureus. S. intermedius and S. pseudintermdedius also produce double-zone hemolysis
- 57. Laboratory Diagnosis (contd....) • Culture and isolation: – Specimens are cultured on BA plate and are incubated @ 37 °C for 24 hours – After incubation, BA plate is observed for significant bacterial growth (> 2mm in diameter) – Then, Gram-staining is performed of the isolated organisms – Then, sub-cultured on NA plate for further biochemical tests • Tube coagulase test: – i. Mix 0.5ml of human plasma with 0.1 ml of an overnight broth culture of S. aureus – ii. Incubate the mix in a water bath @ 37°C for 3-6 hours – Result: plasma clots and doesn’t flow if the tube is inverted
- 58. Culture • Aerobes and facultative anaerobes • Optimum temp. for growth= 37°C • Optimum pH for growth= 7.4-7.5 • On Nutrient agar, – golden yellow and opaque colonies with smooth glistening surface, 1-2 mm in diameter (max. pigment production@22 °C) • On Blood agar, – golden yellow colonies, surrounded by a clear zone of hemolysis (beta-hemolysis), esp. when incubated in sheep or rabbit blood agar in atmosphere of 20% CO2 • On MacConkey agar, – Smaller colonies than those on NA (0.1-0.5 mm) and are pink coloured due to lactose fermentation • On Mannitol salt agar, – S. aureus ferments mannitol and appear as yellow colonies – MSA is a useful selective medium for recovering S. aureus from faecal specimens, when investigating food poisoning
- 59. Biochemical Properties • Catalase test: positive • Oxidase test- negative • Coagulase test= positive • Sugar Fermentation tests: Ferment glucose, lactose, maltose, sucrose and mannitol, with production of acid but no gas Mannitol fermentation carries diagnosis significance • Indole test= negative • MR test= positive • VP test= positive • Urease test= positive • Hydrolyse gelatin • Reduces nitrate to nitrite • Phospahatase= positive • DNase test= positive • Gelatin liquefaction test- Positive. • Produces Lipase • Produces Phosphatase • Produces Thermostable nuclease.
- 60. Differentiation of Staphylococcus species Species Colony Colour Hemolysis on sheep blood ager Tusbe coagulase test Slide Coagulase test Acetoin Producti on Maltose utilizatio n S. aureus Golden yellow + + + + + S. intermedius White + + V - + S. hyicus White V V - - - S. aureus ssp anaerobius White + + - - NA S. Delphini White + + - - NA S. Schleferi White + + - + NA
- 61. Species Catalase Coagulase Mannitol Novobiocin S. aureus positive positive positive sensitive S. epidermidis positive negative negative sensitive S. saphrophyticus positive negative negative resistant Properties of Staphylococcus species
- 62. Differentiation of Gram Positivi Cocci Organism Gram Staining Catalase Production Coagulase Production Oxidase O-F test Bacitracin Sensitivity (0.04U) Staphylococci Irregular clusters + + - F R Streptococci and Enterococci Chains - - - F R Micrococci Packets of four + - + O S
- 63. Treatment • Antibiotic susceptibility testing should be done before treatment. • Drug resistance is common. • Benzyl penicillin is the most effective antibiotic, if the strain is sensitive. • Cloxacillin or Methicillin is used against beta-lactamase producing strains. • Methicillin Resistant Staphylococcus aureus (MRSA) strains have become common, now. • Vancomycin is used in treatment of infections with MRSA strains. • Vancomycin resistance is very rare – so far • MRSA were considered to be Hospital-acquired • But, Community-acquired cases now (CA MRSA) • Methicillin-resistant S. epidermidis - MRSE • VRSA= vancomycin resistant Staphylococcus aureus • VISA= vancomycin intermediate Saphylococcus aureus
- 64. Prevention
- 65. Schematic Diagram for Identifying Staphylococcal Species
- 66. Summary Micrococcaceae Staph. aureus Staph. Epidermidis Staph. saprophyticus Micrococcus Colony Morphology Opaque, smooth, raised, entire, white- golden(cream) Opaque, smooth, raised, entire, gray- white Opaque, smooth, raised, entire, butyrous, glossy, white- yellow Opaque, smooth, raised, white, bright yellow Hemolysis Most are beta hemolytic Non-hemolytic Non-hemolytic Non-hemolytic Gram morphology GPC in clusters, pairs, short chains or singly GPC in clusters, pairs, short chains or singly GPC in clusters, pairs, short chains or singly GPC in pairs and tetrads Catalase Pos Pos Pos Pos Glucose fermentation Fermenter Fermenter Fermenter Oxidizer Modified Oxidase Neg Neg Neg Pos Bacitracin susceptibility (Taxo A 0.04U) Resistant Resistant Resistant Sensitive Coagulase Production (tube) Pos Neg Neg N/A Clumping factor (slide or latex Coagulase test) Pos Neg Neg Neg
- 67. Thanks Acknowledgement: All the material/presentations available online on the subject are duly acknowledged. Disclaimer: The author bear no responsibility with regard to the source and authenticity of the content. Questions???
Editor's Notes
- #66: When it comes times to perform your unknowns, this diagnostic schema should be helpful to determine the organism that you have. The flowchart starts with identification of the gram stain result.. Gram positive, then depending on the reactions you get for each time, it will direct you to the answer! Hopefully….
- #67: I have included the summary chart for you to use while studying. Please note, there are some tests which we did not discuss. I have added them for you to have for the registry exam.