Inhalational Anthrax Case Study Quiz

Gram-positive Bacilli (Aerobic, Anaerobic) & Intracellular Bacteria Infections & Fever

• Gram-positive bacilli (aerobic and anaerobic) and intracellular bacteria are discussed in relation to infections and fever.
• Different bacterial species are highlighted.
• A case study of a 45-year-old male presenting with symptoms, including fever, fatigue, shortness of breath, and abdominal pain, following a camping trip, is provided.

Disclosures

• No disclosures were included in the presentation.

Treaty Land Acknowledgement

• Acknowledgment of the territories of various Indigenous groups on which the Memorial University campuses are situated.
• Respect for the histories and cultures of the Beothuk, Mi'kmaq, Innu, and Inuit peoples is explicitly stated.

Case Study

• A 45-year-old male presented 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 where he drank untreated stream water.
• He had consumed unpasteurized cheese.
• He presented with mild diarrhea, productive cough, and scant yellow sputum.

Differential Diagnosis

• A list of possible gram-positive bacilli includes Bacillus anthracis, Clostridioides difficile, Bacteroides fragilis, Nocardia spp., Actinomyces spp., Listeria spp. and Legionella pneumophilia.

Objectives

• Distinguishing key characteristics of various bacterial species of aerobic gram-positive bacilli, anaerobic bacteria (mainly gram-positive bacilli), and intracellular organisms (certain species of Chlamydia, Legionella, and Spirochetes).
• Predicting bacterial identity from clinical and/or diagnostic findings relevant to specific species: Bacillus anthracis, Lactobacillus species, Clostridioides difficile, Bacteroides species, Nocardia species, Actinomyces israelii, Listeria species, Chlamydia trachomatis, and Legionella species.
• Understanding the characteristics of each species regarding epidemiology, pathogenesis, disease manifestations, diagnostic procedures, first-line treatment, and public health response.

Gram-What?

• Gram staining is the initial examination of a specimen (bacteria) to determine if it is a gram-positive or gram-negative bacteria.
• The Gram stain process involves steps like treating with crystal violet, iodine, alcohol, and safranin.

Gram Morphologies

• Different bacterial shapes (coccus, rod, and spiral) are presented visually.
• Examples of bacteria in each shape category are provided.

Aerobic GPB

• The presentation highlights common aerobic gram-positive bacilli, such as Bacillus spp., Listeria spp., Corynebacterium spp., and Lactobacillus spp.
• It specifies Bacillus anthracis as a relevant species to consider in some scenarios except this case study, further distinguishing it from other Bacillus species.

Bacillus spp.

• Epidemiology: Worldwide distribution, often linked to environmental contamination, but Bacillus anthracis is more associated with Central/South America and Asia, and requires exposure to reservoirs.
• Pathogenesis: Opportunistic, can produce various toxins (e.g., Enterotoxin, Lethal and Edema toxins). Disruption of signaling pathways.
• Clinical Disease: The presentation details the different manifestations (cutaneous, inhalational, and gastrointestinal) of Bacillus anthracis infections.

Bacillus spp. - Clinical Disease

• Cutaneous - most common - includes symptoms like painless papule that forms a dark eschar.
• Inhalational - rare but has high mortality during bioterrorism attacks.
• Gastrointestinal - rare.

Bacillus spp. - Diagnosis

• Gram stain (bacilli, large, boxcar, spores)
• Morphology of different Bacillus species may include large 'Medusa head' shape, tenacious, or beta-hemolytic forms.

Bacillus spp. - Therapy

• Intravenous treatment with penicillin followed by Ciprofloxacin for Bacillus cereus.
• Vaccination for Bacillus anthracis is not available for most Bacillus species.

Listeria monocytogenes

• Epidemiology: Worldwide, L. monocytogenes is the most common species.
• Transmission: Contaminated food ingestion or trans-placental transmission for pregnant women and newborns.
• Pathogenesis: Opportunistic pathogens. They produce toxins and virulence factors (e.g. capsule, flagella, internalins, listeriolysin O). Cause symptoms such as fever and watery diarrhoea.
• Clinical Disease: Presentation of self-limited febrile gastroenteritis or invasive diseases such as during pregnancy (3rd trimester), and in neonates.

Listeria monocytogenes - Diagnosis

• Gram stain - Bacilli, small, faint straining.
• Morphology - small and beta-hemolytic.
• Biochemicals - Catalase positive, Oxidase-negative, with tumbling or umbrella motility.

Listeria monocytogenes - Therapy

• Intravenous treatment with Ceftriaxone.
• First-line medications include Penicillin or Ampicillin.
• Vaccination is not available.

Corynebacterium spp. - Epidemiology

• Worldwide prevalence.
• Normal flora in the respiratory tract, GI tract, and/or vaginal tract.
• Transmission of Corynebacterium diphtheria can occur through droplets and/or raw milk consumption.

Corynebacterium spp. - Pathogenesis

• Opportunistic.
• Toxins and virulence factors (biofilms, pili, and exotoxins) are involved in pathogenesis, except for the C diphtheriae group.

Corynebacterium spp. - Clinical Disease

• C. diphtheria group - respiratory tract infections, sore throat with pseudomembrane ('bull neck'), and potential neurological symptoms.
• C, urealycium - Chronic UTI in elderly patients with struvite crystals in urine.
• Cutaneous and ulcerative lesions may also be associated.

Corynebacterium spp. - Diagnosis

• Gram stain — bacilli, has palisades and/or clubbed morphology.
• Biochemicals – Catalase positive; Non-motile for C. diphtheriae and Motile for other species.
• Toxin production detection may be necessary using special testing (PCR).

Corynebacterium spp. - Therapy

• Intravenous treatment with Penicillin, Macrolides, TMP-SMX.
• First line of treatment is Erythromycin and IgG antitoxin.
• Tdap vaccination (Tetanus, Diphtheria and Pertussis) is indicated for younger patients.

Question 1

• The question is about the most common type of anthrax infection, and the answer is cutaneous anthrax.

Listeria monocytogenes - Clinical Disease

• Self-limited febrile gastroenteritis includes fever and watery diarrhoea.
• Invasive disease during pregnancy, in the third trimester, is severe and lethal in neonates.
• Early onset or late onset trans-placental infection can lead to pneumonia and/or sepsis.

Listeria monocytogenes - Diagnosis

• Gram stain — Bacilli, small, faint staining.
• Morphology — Small, beta-hemolytic.
• Biochemicals — Catalase positive, Oxidase negative, exhibits motility with the tumbling or umbrella phenomenon.

Listeria monocytogenes - Therapy

• Intravenous therapy for infection includes Ceftriaxone.
• First-line treatment usually includes Penicillin or Ampicillin.
• No vaccination exists.

Nocardia spp.

• Epidemiology:Worldwide. Nocardia species are usually in individuals of male gender and immunocompromised individuals. Soil and water are typical sources.
• Pathogenesis:Opportunistic. Low tropism for neuronal tissue. Grow within macrophages and form biofilms.
• Clinical Disease: Pulmonary disease with symptoms of fever, flu-like symptoms, chronic/relapsing brochopneumonia and abscess formation. Systemic infection leading to brain lesion and high mortality rates. Cutaneous and lymphocutaneous forms are also observed.
• Diagnosis: Gram stain - branching/beaded morphology. AFB smear is typically positive (similar to Tuberculosis).

Nocardia spp - Therapy

• IV Penicillin and/or TMP-SMX are standard for infections.
• No vaccination exists.

Anaerobic Bacteria

• Presents variations in Gram-positive and Gram-negative cocci and bacilli.
• Includes a range of bacteria, including Clostridia, Bacteroides, Fusobacterium, and Prevotella species, and other bacteria.

Clostridium spp.

• Epidemiology:Worldwide.
• Pathogenesis:Opportunistic pathogens that can cause various diseases through the production of toxins, including those related to food-borne illnesses, but most importantly include Tetanus, Botulism, and Necrotizing Enteritis, Gas Gangrene, and food poisoning.
• Clinical Disease: Characterizing symptoms as diarrhea, muscle spasms and/or paralysis.

Clostridioides difficile

• Epidemiology:Worldwide.
• Pathogenesis:Opportunistic pathogens that cause diarrhea via production of toxins (A and B).
• Clinical Disease: Common in individuals undergoing antibiotics, resulting in diarrhea.
• Diagnosis:Detecting toxins A and B; stool Samples are used to identify the causative agents.

Clostridioides difficile - Therapy

• Supportive treatment for diarrhea.
• Metronidazole, Vancomycin is the first line therapy for most cases, however, other antibiotic options can be utilized as required.
• No vaccine exists.

Corynebacterium spp. - Diagnosis

• Gram stain—bacilli, has palisades and/or clubbed morphology.
• Biochemicals –Catalase positive; Non-motile for C. diphtheriae and Motile for other species.

 
- Toxin production detection may be necessary using special testing (PCR).

Corynebacterium spp. - Therapy

• Intravenous treatment with Penicillin, Macrolides, TMP-SMX.
• First line of treatment is Erythromycin and IgG antitoxin.
• Tdap vaccination (Tetanus, Diphtheria and Pertussis) is indicated for younger patients.

Question 2

• The correct answer to the question about the antibiotic not covering Listeria monocytogenes is Ampicillin.

Question 3

• This question is about C. difficile and the best answer is oral Metronidazole (the patient was experiencing systemic symptoms).

C. tetani - Tetanus (Clinical Disease and Therapy)

• Epidemiology: Worldwide, often seen in developing countries
• Pathogenesis: Potent neurotoxin (tetanospasmin or TeNT). Causes muscle spasms and paralysis. Blocking inhibitory neurotransmitters (GABA) is a crucial step in the pathogenesis.
• Diagnosis: Gram stain findings. Media used — anaerobic. Stool, serum, foods and/or body fluids used for PCR samples.
• Therapy: Intravenous administration of aminoglycosides. Debridement is essential. Tdap (tetanus, diphtheria, pertussis) is important for vaccination.

C. botulinum - Botulism

• Epidemiology:Worldwide, sporadic transmission routes are foodborne, injection (intravenous or intramuscular), or wound contamination.
• Pathogenesis:Opportunistic. Neurotoxic.
• Clinical Disease: Characterized by sudden flaccid paralysis.

C. botulinum - Diagnosis

• Gram Stain - bacilli, large, common spores.
• Media — anaerobic.
• GOLD standard — Toxin Detection and PCR using mouse lethality assays to kill 50% of mice within 96 hours with the toxin using stool, serum, foods and body fluids.

C. botulinum - Therapy

• Intravenous administration of aminoglycosides, ventilatory support, and toxin-specific antitoxin.
• No vaccine is available.

C. perfringens

• Epidemiology:Worldwide, predominantly sporadic. Routes of transmission include foodborne and/or wound contamination.
• Pathogenesis:Opportunistic. 5 types of toxins produced by C. perfringens.
• Clinical Disease: Range of clinical presentations. Food poisoning is most common (mild diarrhea following ingestion of preformed toxin).
• Diagnosis: Gram stain—bacilli, large spore formation is common. Only grows on anaerobic media. Confirmation culture.
• Therapy: Aminoglycosides and appropriate antibiotics (Penicillin or Clindamycin). Surgery for Gas Gangrene cases.
• Vaccination is not available.

Question 4

• The correct response is Beta toxin is the C. perfringens toxin responsible for the symptoms.

Cutibacterium spp.

• Epidemiology: Worldwide. Very often a component of normal flora in the skin.
• Pathogenesis:Opportunistic. Produces toxins, biofilms, lipases, and proteases.
• Clinical Disease: Acne, as well as chronic infections in immunocompromised individuals. Can be part of other conditions such as shoulder revisions.

Cutibacterium spp - Diagnosis

• Gram stain—small, usually takes 1-2 days for growth,
• Media–Aerobic & anaerobic, slow growing around 5-7 days,
• Morphology–small, granular bacteria, non hemolytic.
• Serology & antigen testing typically not used.

Cutibacterium spp - Therapy

• Intravenous administration of Metronidazole and Tetracycline, Macrolides or Penicillin (as first line treatment)
• No vaccine is available.

Actinomyces spp

• Epidemiology:Worldwide. Associated with poor hygiene in individuals, especially those with certain infections.
• Pathogenesis:Opportunistic.
• Clinical Disease: Oral and respiratory tract infections.Cervicofacial infections that include Lumpy Jaw. Thoracic, Peritoneum and brain abscesses. Actinomycetoma-similar to nocardia.
• Diagnosis:Gram stain — slender, filamentous morphology in culture. Sulphur granules or Splendore-Hoeppli phenomenon are important to observe under the microscope for diagnosis.
• Therapy: Metronidazole is an intravenous administration, often supplemented with High dose Penicillin.
• Vaccination is not available.

Bacteroides spp

• Epidemiology:Worldwide. Component of normal flora in the GI tract, oral cavity and vaginal tract.
• Pathogenesis:Opportunistic, producing endotoxins (LPS), and beta-lactamases.
• Clinical Disease: Abdominal infections (most common species causing). Bacteremia, abscess formations, and SSTIs.
• Diagnosis: Gram stain—Bacilli, pleomorphic, typically small and grey, non-hemolytic.
• Therapy: Intravenous administration of penicillin, ampicillin, and/or Metronidazole.
• Vaccination is not available.

Fusobacterium spp.

• Epidemiology:Globally distributed, commonly found as normal flora in the upper respiratory, GI and female Genital tracts.
• Pathogenesis:Opportunistic. The main virulence factor is Leukotoxin (F. necrophorum).
• Clinical Disease: F. nucleatum is the most common species, producing oral, dental, and bite infections, often associated with Pharyngotonsillitis (in children), and Lemierre's disease.

Fusobacterium spp. - Diagnosis

• Gram stain-Bacilli, pleomorphic, tapered ends.
• Morphology—Small, grey, non-hemolytic.

Fusobacterium spp. - Therapy

• Intravenous administration of Metronidazole.
• No vaccine is available.

Chlamydia spp.

• Epidemiology:Worldwide.
• Pathogenesis:Biphasic life cycle. LPS, lack of a cell wall makes them unique.
• Clinical Disease: May be asymptomatic (as a sexually transmitted infection or through other means). Oculogenital, conjunctivitis, Reiter's syndrome, trachoma, lymphogranuloma venereum (LGV), and psittacosis presentations are seen. C. pneumonia is identified as a contributor to atypical pneumonia or CAP.
• Diagnosis:Gram stain is negative. Media used for growth is typically intracellular.
• Therapy: Azithromycin, Doxycycline are the first-line antibiotics most commonly utilized.
• Vaccination is not available.

Legionella pneumophilia

• Epidemiology: Worldwide. Normal flora is not confirmed as a significant factor.
• Pathogenesis: Linked to contaminated water systems. Most common source of outbreaks in hospitals.
• Clinical Disease: Presents with pneumonia-like illness or typical pneumonia manifestations.
• Diagnosis: typically use serology or antigen tests in urine to identify the causative agent.
• Therapy:Azithromycin is a common first line of treatment.
• Vaccination is not available.

Spirochetes

• Epidemiology:Worldwide, though prevalence may vary depending on region and specific spirochetal species. Treponema pallidum causes disease or significant illness in regions, and/or individuals.
• Pathogenesis:Treponema pallidum (Syphilis) has a typical 5-stage progression. Borrelia burgdorferi (Lyme Disease) involves tick transmission. Leptospira interrogans (Leptospirosis) involves exposure to rat urine.
• Clinical Disease: Various clinical manifestations. Treponema pallidum (syphilis) involves progression from primary to secondary to latent to tertiary stages with various manifestations. Borrelia burgdorferi (Lyme Disease) commonly includes rash, diffuse joint pain. Leptospira interrogans (Leptospirosis) involves acute, febrile illnesses, and multi-organ failure.
• Diagnosis: Serological testing is commonly performed for most spirochetes. PCR.
• Therapy:Treatment strategies vary based on the specific spirochete and stage of disease. Penicillin is crucial for Treponema pallidum (syphilis). Doxycycline is the most common treatment for Borrelia burgdorferi (Lyme Disease). Penicillin may be crucial in severe cases.

Question 5

• The correct response to the question is b. Actinomyces israelii.

Question 6

• The correct response to the question is a. Doxycycline. It is the first-line treatment for Lyme disease caused by Borrelia burgdorferi.