MT 6320 Clinical Bacteriology PDF

[MT 6320] CLINICAL BACTERIOLOGY (LEC/LAB) 3DMT | AY 2023-2024 UNIT #3.3: Aerobic Gram-Positive Bacilli Gram stain of bacillus OUTLINE...

[MT 6320] CLINICAL BACTERIOLOGY (LEC/LAB) 3DMT | AY 2023-2024 UNIT #3.3: Aerobic Gram-Positive Bacilli Gram stain of bacillus OUTLINE A. Bacillus a. Bacillus anthracis b. Bacillus cereus B. Corynebacterium a. Corynebacterium diphtheriae C. Listeria monocytogenes D. Erysipelothrix rhusiopathiae E. Actinomycetes F. Nocardia sp. Spore stained with Malachite green BACILLUS SPORE-FORMING NONBRANCHING CATALASE POSITIVE BACILLI G(+) sporeforming bacilli Aerobic or facultative anaerobes Catalase (+) Motile SBA Common laboratory contaminant LABORATORY DIAGNOSIS Bacillus anthracis Specimen B. anthracis: blood, lung tissue, CSF VIRULENCE FACTORS Glutamic acid capsule SBA, PEA Protein exotoxin: Protein antigen, edema factor, lethal Colonies: nonhemolytic, gray, raised Culture factor w/irregular curled margin & whirling projections “medusa head” Causative agent of Anthrax ○ Associated w/ cattle, hides, goat hairs Bamboo fishing poles appearance with ○ Occupational hazard (Woolsorter’s disease endospores and Ragpicker’s disease) ○ Spores are located at the center ○ Humans: get infected by direct contact Microscopy Square ends GS: G(+) w/infected animals: fibers, wool, hair G(V): violet rods Fulton Schaeffer: red-veg cells; FORMS OF ANTHRAX green-spore Most common but least severe form S/S: lesion forms on the site of Medusa head Tenacious consistency inoculation that develops into black Cutaneous eschar MOT: Wounds are contaminated with spores Woolsorter’s disease or Ragpicker’s disease S/S: Initial, mild fever, malaise, Inhalation/ fatigue Pulmonary Sudden severe phase: respiratory distress; more severe can lead to death S/S: Abdominal pain, nausea, anorexia Gastrointestinal Higher fatality compared to cutaneous MOT: Ingestion of spores Associated with drug users Injectional “Skin popping” IDENTIFICATION anthrax MOT: Direct injection of spores into Catalase (+) tissues Nonhemolytic Nonmotile Cutaneous anthrax skin infection ○ Wet mount preparation / hanging drop method ○ SIM Transparent (nonmotile) Turbid (motile) Encapsulated ○ India ink stain Direct Fluorescent Antibody Assay Nucleic Acid Amplification Test AST: Penicillin; Gentamycin, Erythromycin, chloramphenicol PAGE 1 MT 6320 (LEC/LAB) 3DMT | AY 2023-2024 CORYNEBACTERIUM NONSPOREFORMING NONBRANCHING CATALASE POSITIVE BACILLI G(+) bacilli that are pleomorphic ○ May appear club-shaped, Chinese character, picket fence ○ Diphtheroid appearance: club-shaped, coryneform Facultative anaerobe, catalase (+) Non-motile, non-encapsulated, non-sporeforming A - Catalase Positive C - India Ink stain Widely distributed in the environment: soil, water B - nonmotile D - String of pearl String of pearl reaction Gram stain of B. anthracistaken from a medium containing Corynebacterium diphtheriae 0.05 –0.5 units of Penicillin. (1000x) Klebs Loeffler’s Bacillus VIRULENCE FACTORS Bacillus cereus Most virulent sp (toxin-producing) “Fried rice poisoning” Diphtheria toxin (tox gene) – lysogenic B-phage Common cause of food poisoning and opportunistic Infects humans – Diphtheria infection Spores: resist pasteurization CLINICAL INFECTIONS SBA – aerobic Isolated from human nasopharynx; not a normal flora Beta-hemolytic MOT: person to person exposure to respiratory Motile droplets, direct contact to cutaneous lesions Found in the environment: soil, water Nonspecific S/S Mild sore throat, Low-grade fever, Morphologically and metaboillically same with B. body malaise anthracis, but grown aerobically in SBA ○ Abdominal pain, cough, difficulty in breathing, fatigue Drugs: Penicillin, Erythromycin Respiratory diphtheria & cutaneous diphtheria DIPHTHERIA FORMS Acute, contagious Site of infection: tonsils, pharynx ○ Often accompanied with high grade fever Production of toxin Respiratory form ○ Leading to respiratory obstruction ○ Toxin can damage heart, 2 FORMS OF FOOD POISONING kidneys peripheral nerves Diarrhea Emeti ○ Death due to cardiac failure Ingestion of meat Common in the tropics products, poultry, Ingestion of fried Systemic complications are less Implicated food vegetables, sauces, or boiled rice Cutaneous form common pasta Nonhealing ulcers Incubation period Longer (8-16 hrs) Shorter (1-6 hrs) ○ Specially if patient is diabetic Diarrhea More common Less common Vomiting Less common More common Response when fed Diarrhea Vomiting to Rhesus monkey Eye infection Meningitis Nongastrointestinal infections Treatment: ○ Vancomycin ○ Clindamycin PAGE 2 MT 6320 (LEC/LAB) 3DMT | AY 2023-2024 LABORATORY DIAGNOSIS Nasopharyngeal and throat swabs, Specimen skin/wound lesions Highly pleomorphic Presence of Babes-Ernst granules / metachromatic granules / volutin granules ○ Presence of nutrient reserves Most frequently isolated sp GS: G(+) pleomorphic bacilli from humans Stained by methylene blue C. amycolatum Normal flora skin –metachromatic stain Associated w/ prosthetic joint infection Microscopy Associated w/ nosocomial infections Most common cause of C. jeikeium Corynbacterium-associated prosthetic valve endocarditis in adults Produces diphtheria-like toxin Dsc: humans: diphtheria-like Methylene blue stain C. ulcerans infection CAP, CTBA, Tinsdalemedium Cattle: mastitis (mammary gland) C. xerosis Opportunistic infection C. urealyticum Associated w/ UTI Culture Rare cause of lymphadenitis in C. pseudotuberculosis humans following contact w/ infected livestock Normal flora skin, mucus C. psudodiphtheriticum membrane Cause RTI, endocarditis Colony types of Corynebacterium diphtheriae Listeria monocytogenes NONSPOREFORMING NONBRANCHING CATALASE POSITIVE BACILLI G(+) coccobacillus in singles, chains, palisade Aerobic, Facultative anaerobe Catalase (+), motile Recovered from environment: soil, water, sewage, fecal matter, animal products like raw milk Isolated from crustaceans, flies, ticks, domestic animals TEST FOR TOXIGENICITY Disease: Listeriosis ELISA MOT: ingestion of contaminated meat, poultry, Immunochromatographic assay coleslaw PCR ○ Contaminated meat has putrid odor and change in meat’s color Infection of neonates, pregnant, immunocompromised ○ Pregnant S/S: flu-like illness leading to spontaneous abortion and stillborn Elek Test ○ Fetus: granulomatosis infantiseptica ○ Newborn: meningitis, sepsis ○ Immunocompromised: CNS infection, endocarditis VIRULENCE FACTOR Elek plate for Demonstration of Toxin Listeriolysin O Dismutase Scheck’s Toxigenicity Test Catalase Phospholipase C Test Results to swelling Superoxide Protein p60 PAGE 3 MT 6320 (LEC/LAB) 3DMT | AY 2023-2024 LABORATORY DIAGNOSIS Erysipelothrix rhusiopathiae Specimen Blood, CSF, swab of lesions NONSPOREFORMING May be mistaken for group NONBRANCHING GS CATALASE NEGATIVE BACILLI B-Streptococcus, Corynebacterium BAP, CAP, nutrient agar, and broth BHI, G(+) bacilli thioglycolate Catalase (-) ○ 30 –35C Nonspore forming Culture Pleomorphic ○ 4C (cold enrichment) ○ Colonies: small, round, translucent Aerobic/facultative anaerobe ○ Beta hemolytic Veterinary infection and occupational hazard (meat, Inverted Christmas tree or umbrella poultry, fish handling) SIM Scratches pattern at room temperature Wet mount Tumbling motility Cuts and skin Arrow head-shaped zone of (+) CAMP CLINICAL INFECTIONS beta-hemolysis at the junction of the two Reaction Disease: Erysipeloid organisms ○ Localized skin infection ○ Painful lesions seen on hands or fingers PATHOGENICITY TEST Ocular test of Anton Rabbit/guinea pig – installation of culture on Erysipeloid conjunctival sac (+) result: Keratoconjunctivitis within 24hrs LABORATORY DIAGNOSIS Tissue biopsy or aspirates from skin Specimen lesions Microscopy Thin, G(+), V-form Culture BAP, CAP, nutrient broth Catalase (-), nitrate (-), VP (-), urease (-) Nonmotile, nonhemolytic Identification H2S positive Test tube brush growth on gelatin at 22C Inverted tree or umbrella Tumbling motility pattern motility Actinomycetes Branching or Partially Acid Fast Aerobic Actinomycetes Species: Nocardia, Streptomyces, Actinomadura, CAMP TEST Rhodococcus, Gordonia, Tsukamurella, Trophery mawhipplei ○ Trophery mawhipplei Causative agent of whipple disease - rare bacterial infection that affects joints and digestive system Nocardia sp. G(+) bacilli Conventional CAMP test with L. monocytogenes showing block Thin branching filaments (beads) hemolysis on the junction of the organism Staphylococcus “Partially acid-fast” aureus. 48-72 hours growth - weeks Species of Nocardia: Depending on the culture conditions, L. ○ N.asteroides monocytogenes can resemble Streptococcus when ○ N.brasiliensis found in the coccoid form and Corynebacterium when ○ N.caviae the bacillus forms prevail. Soil, water, humans Organisms are not usually seen on CSF smear. Catalase (+) Sabouraud’s Dextrose Agar (SDA) 10% CO2 ○ Bumpy, velvety, yellow-orange colonies PAGE 4 MT 6320 (LEC/LAB) 3DMT | AY 2023-2024 CLINICAL INFECTIONS Inhalation / airborne Pulmonary Nocardia asteroids complex Infection Chronic, confluent bronchopneumonia Inoculation of the skin or subcutaneous tissue Chronic granulomatous of the skin, Cutaneous subcutaneous tissue Infection On outdoor activities Nocardia brasiliensis Actinomycotic mycetoma / eumycotic mycetoma LABORATORY DIAGNOSIS May be mistaken for Gram(+) cocci; Beads so not touch each other Microscopy Filamentous branching isolate –partially Acid-fast Wet mount Presence of granules on cutaneous tissue Grows on common nonselective medium Culture Grow at 22C –37C May take longer incubation period Resistant to Penicillin Treatment Susceptible to Sulfonamides PAGE 5