Gram Positive Bacilli PDF

Gram-positive Bacilli (Aerobic, Anaerobic) & Intracellular Bacteria Infections & Fever Robert M. Taylor, PhD, FCCM (He/Him) Division Head (Interim), Microbiology - NL Health Services Clinical Microbiologist, Public Health Microbiology Laboratory Assistant Professor, Laborato...

Gram-positive Bacilli (Aerobic, Anaerobic) & Intracellular Bacteria Infections & Fever Robert M. Taylor, PhD, FCCM (He/Him) Division Head (Interim), Microbiology - NL Health Services Clinical Microbiologist, Public Health Microbiology Laboratory Assistant Professor, Laboratory Medicine, Memorial University Jan 9th 2025 1 Disclosures No disclosures… 2 Treaty Land Acknowledgment We acknowledge that the lands on which Memorial University’s campuses are situated are in the traditional territories of diverse Indigenous groups. We also acknowledge with respect the histories and cultures of the Beothuk [bee- oth-uck], Mi’kmaq [mee-gum-maq], Innu [in- new] and Inuit [in-new-eet] of this province. Demasduit (1796 – 1820), one of the last Beothuk woman from NL 3 Case A 45-year-old male presents to the emergency department with a 10-day history of fever, fatigue, shortness of breath, and abdominal pain. He recently returned from a camping trip in a rural area where he drank untreated stream water and unpasteurized cheese. He also reports mild diarrhea, which started 3 days after the trip, and a productive cough with scant yellow sputum for the past week. He denies rash, joint pain, or weight loss. Works as a landscaper, frequently exposed to soil. Physical Examination Vitals: Temperature 38.8°C, Heart Rate 110 bpm, Blood Pressure 118/75 mmHg, Respiratory Rate 22/min, O2 Saturation 94% on room air. Lungs: Crackles at the right lung base. Abdomen: Mild tenderness in the lower quadrants without rebound or guarding. Skin: No rash or lesions. Neurologic: No focal deficits. What’s on your differential (within realm of this seminar topic)? 4 Case What’s on your differential? So many things, but related to Gram-positive bacilli: Bacillus anthracis (Anthrax) Clostridioides difficile Bacteroides fragilis Nocardia spp. Actinomyces spp. Listeria spp. Legionella pneumophilia Etc. Etc. 5  = important to remember Objectives = question for fun Distinguish key characteristics among varying species of: Aerobic Gram-positive bacilli Anaerobic bacteria (mainly Gram-positive bacilli) Intracellular organisms (Chlamydia spp., Legionella spp., Spirochetes, etc.) Predict organism identity based on select clinical and/or diagnostic findings, for Bacillus anthracis, Lactobacillus spp., Clostridioides difficile, Bacteroides spp., Nocardia spp., Actinomyces israelii, Listeria spp., Chlamydia trachomatis, Legionella spp. Discover and learn about other important characteristics for each organism regarding; epidemiology, pathogenesis, disease manifestations, diagnostic techniques, first line treatment and public health response 6 Gram-what? The Gram stain is the first look ‘under the hood’ to see what is growing in a specimen 7 Gram morphologies Note: The shape is determined by the shape of its cell wall 8 Aerobic GPB contamination Bacillus spp.* sually linked to B. anthracis exceptthis Other Bacillus spp. Listeria spp.* L. monocytogenes Corynebacterium spp.* diphtheria C. diphtheria complex causes Other Corynebacterium spp. Lactobacillus spp.  Usually normal flora, beneficial especially in vaginal tract, opportunistic…Int R Vancomycin (most species) show Nocardia spp.* Rare may upon exams 9 Bacillus spp. Epidemiology Worldwide Normal flora?  Usually more associated with environment B. anthracis – common in mainly Central/South America, Asia Not in Canada requires exposure to reservoir Pathogenesis Opportunistic diarrhea i.e foodpoisoning Virulence: causes B. cereus – Enterotoxin (heat-stable), capsule B. anthracis – Lethal and Edema toxins, disrupt signaling pathways Other Bacillus spp. – Capsule, adhesions cause anthraxpresentation 10 Bacillus spp. Clinical Disease B. cereus Ingestion, inhalation, injury GI distress, diarrhea B. anthracis Cutaneous - most common (Painless puritic papule, forms dark eschar, low mortality, usually self-limited) Inhalational – rare, “Woolsorter’s disease”, bioterrorism with high mortalityVery GI – very rare, ingestion of undercooked meat fatal Other Bacillus spp. Usually, contamination, especially if ¼ blood cultures Rare: bacteremia, brain abscesses, ocular infections 11 Bacillus spp. Diagnosis Gram stain – Bacilli, large, boxcar, spores B. cereus definitely bacillus Morphology: seethis B. anthracis – large, ‘Medusa head’, tenacious, γ-hemolytic Other Bacillus spp. – large, β-hemolytic Biochemicals B. anthracis – Catalase POS, Non-motile, Pen S (native) Other Bacillus spp. - Catalase POS, Motile, Pen R (native) ‘tenacious’ Serology/Antigen available in special cases Therapy B. anthracis Int R – Penicillin (B. cereus) 1st line – Penicillin, Ciprofloxacin Vaccination  None, but post-exposure prophylaxis in Anthrax cases Care to lace basis 12 Question 1) What is the most common manifestation for Anthrax infection? 0a) Cutaneous b) Inhalational c) Gastrointestinal d) Systematic 13 Question 1) What is the most common manifestation for Anthrax infection? a) Cutaneous b) Inhalational c) Gastrointestinal d) Systematic 14 Listeria monocytogenes Prettymuchonlyone disease Epidemiology thatcauses Worldwide, 19 species but L. monocytogenes is MOST common Normal flora?  No, environment. Cheese! (also poultry, raw milk, smoked salmon) noton body surfaces Transmission – contaminated food ingestion, transplacental Link to several outbreaks Pathogenesis Opportunistic Virulence  Capsule, Flagella, internalins, listeriolysin O, surface proteins 15 Listeria monocytogenes Clinical Disease Self-limited febrile gastroenteritis Fever, watery diarrhea Invasive During pregnancy – 3rd trimester, severe for neonate Neonatal listeriosis - ~30% mortality Early onset – trans placental (pneumonia or sepsis) Late onset – during birth (meningitis) Mostconcerning Most common in neonates and elderly patients 16 Listeria monocytogenes Diagnosis Gram stain – Bacilli, small, faint staining littleas Morphology – Small, β-hemolytic Biochemicals – Catalase POS, Oxidase NEG, “Tumbling/Umbrella” motility instead Use MALDI TOF Therapy Int R – All Cephalosporins ex. Ceftriaxone 1st line – Penicillin or Ampicillin Vaccination  None CAMP 17 Corynebacterium spp. Epidemiology Worldwide C. diphtheria group – C. diphtheria, pseudotuberculosis, ulcerans Normal flora?  No Transmission of C. diphtheria – droplets, direct, raw milk consumption Pathogenesis Opportunistic, except C. diphtheria group Virulence Corynebacterium spp. – biofilms, pili, adhesions C. diphtheria group – Also a main exotoxin (2 fragments, A & B) Not ALL strains have toxin! 18 Corynebacterium spp. Clinical C. diphtheria group Respiratory tract Sore throat, pseudomembrane with ‘bull neck’ Can involve neurological symptoms Cutaneous Ulcerative lesion C. urealyticum Bull’s Neck Chronic UTI’s in elderly, usually IC- May see struvite crystals in urine If urea in urine linked to bacteria 19 Corynebacterium spp. Diagnosis Gram stain – Bacilli, palisades, clubbed Morphology – Small, grey Biochemicals – Catalase POS, NON-Motile For C. diphtheriae strains  need to confirm toxin production Using special testing (PCR) Therapy Int R – Penicillin, macrolides, TMP-SMX 1st line – Erythromycin + IgG antitoxin Vaccination  Tdap (Tetanus, Diphtheria, Pertussis) Usually a 2, 4, 6, 18 months, boosters at 4, 6 years and routine every 10 years after 20 Question 2) Which antibiotic will not cover Listeria monocytogenes? a) Ampicillin b) Penicillin c) Ceftriaxone d) Amoxicillin 21 Question 2) Which antibiotic will not cover Listeria monocytogenes? a) Ampicillin b) Penicillin c) Ceftriaxone d) Amoxicillin 22 Nocardia spp. Epidemiology Worldwide, usually male, IC- Normal flora?  No, in soil and water neuronal Pathogenesis specific for tissue Opportunistic liljo there Virulence  Generally low BUT tropism for neuronal tissue, biofilms, can grow within macrophages 23 Nocardia spp. Clinical Pulmonary Acute – non-specific, flu like…inflammatory response can lead to necrosis and abscess formation Chronic Relapsing brochopneumonia lungs can mon to braineyes Systematic Usually starts in Up to 50% pulmonary cases disseminate Pleural effusions, empyema Brain lesions (30% of patients), high mortality rate Cutaneous Primary – mild, may cause ulcerations Mycetoma – pustules, fever, chronic…N. brasilliensis most common species Lymphocutaneous – Sporotrichoid like rash THINK  Abscesses in Lungs AND Brain! 24 Nocardia spp. Diagnosis Gram stain – branching/beaded, AFB smear POS (like TB) Morphology – Small necklace like chains likely nocardia Biochemicals – Not usually done, not reliable Serology/Antigen not common treatasap to avoid spread Therapy Int R – Penicillin 1st line – TMP-SMX Vaccination  None 25 BCYE Anaerobic Bacteria Gram-positive cocci Gram-positive bacilli Peptostreptococcus spp. Clostridia* Finegoldia spp. C. difficile, C. perfringens, C. tetani, C. botulinum Parvimonas spp. Cutibacterium acnes* Actinomyces israelii* Gram-negative cocci Gram-negative bacilli Veillonella spp. Bacteroides fragilis* Fusobacterium nucleatum* Fusobacterium necrophorum* Prevotella spp. 26  Clostridia spp. There are >240 species but most important: Clostridioides difficile c Diff f Clostridium tetani  Tetanus C. botulinum  Botulism C. perfringens  Necrotizing Enteritis, Gas Gangrene, Food poisoning 27  Rising eightonarn Clostridioides difficile C. difficile ribotype -27 (North America, complicated organism increasing virulence) Epidemiology Worldwide! Fecal/Oral & Nosocomial spread ~30% of all Antibiotic associated diarrhea Depend on antibiotic You can be colonized with NO symptoms! used somemore Common in younger likelythanothers ages Pathogenesis Opportunistic pathogens…produce A LOT of Toxins NEED toxin production to be pathogenic! Toxin A Enterotoxin, activates macrophages Toxin B (most common) Cytotoxin, necrotizing action Toxin C “Binary toxin” Overproduction of A/B = more severe disease Found in hypervirulent strains 28 Clostridioides difficile Clinical Disease Diarrhea During/after Atx, up to 12 weeks later Antibiotics decrease levels of susceptible gut flora allowing C. difficile to overgrow Watery, Foul odour, Blood is rare Severe – toxic megacolon IF Atx stopped, reverts (30%) OR pseudomembrane colitis (PC, 60-70%) PC = intense inflammation of colon 29  Specimens Stool! Test of cure NOT accurate Reject with