Miscellaneous Pathogenic Bacteria

Mycoplasma/ Eaton’s Agent

Mycoplasma is the most common cause of walking pneumonia and atypical community-acquired pneumonia.

The Cold agglutination test is +ve with mycoplasma. Mycoplasma lacks a Cell wall, but its cell membrane contains sterols.

Pluto Pneumonia Like Organism (PPLO) agar shows fried egg colonies.

Diene’s Stain is used to stain mycoplasma.

Mycoplasma is the Smallest bacteria that can pass through bacterial filters. NAAT (Nucleic acid amplification testing) is the most sensitive test.

Pulmonary Symptoms Caused by Mycoplasma

• The most common cause of walking pneumonia.
• The most common cause of atypical community-acquired pneumonia.
• Associated with cold agglutinin disease - AIHA (IgM - Mycoplasma).

Extrapulmonary Symptoms Caused by Mycoplasma

• Meningitis.
• Encephalitis
• GBS
• Steven Johnson’s Syndrome
• Carditis

Treatment of Mycoplasma-Caused Infections

The drug Of Choice for mycoplasma is Macrolides.

The Bacters

The bacters includes

• Campylobacter
• Helicobacter

The bacters are spiral rods which are Catalase and Oxidase Positive..

Campylobacter

C.jejuni is found in areas with high temperatures or tropical climates. It is a food-borne infection caused by the Ingestion of contaminated poultry. It causes Water and Washroom related Diarrheal disease. It can cause CNS manifestations like GBS due to the presence of serotype O19. The incubation period is 1-7 days.

Intestinal infection caused by Campylobacter

• Implemented diarrhea.
• Abdominal pain
• Fever
• Pseudo appendicitis (due to more pain)
• Loose stools to bloody diarrhea (self-limiting).

Extraintestinal caused by Campylobacter

Extraintestinal infections are caused by C. Fetus. The clinical features are Bacteremia, sepsis, meningitis, and vascular infections.

Lab Diagnosis Of Campylobacter

The microcopy of Campylobacter shows Gram -ve, Gullwing-shaped bacteria, which shows Darting motility or shooting star motility.

The Stool Sample shows Fecal leukocytes or pus cells. On Selective media, Effuse droplet-like colonies are seen.

Treatment Of Campylobacter

• Symptomatic treatment
• Chronic/ Severe: Azithromycin

Helicobacter Pylori

Helicobacter pylori is catalase, oxidase and Urease +ve. The Virulence factors of Helicobacter pylori are:

• Vac A - Vacuolating cytotoxin A
• Cag A – Cytotoxin-associated gene A (encodes for type IV secretion system).

Pathogenicity of Helicobacter Pylori

• Route of infectionFeco-oral
• Risk factors: Poor hygiene, overcrowding
• Site of infection: Antrum

Diseases

• Inflammation related.
  • Chronic Gastritis B.
  • Peptic ulcer disease
• Cancerous
  • Adenocarcinoma.
  • MALToma (marginal zone lymphoma).

Protective Role of H.Pylori

• A - Adenocarcinoma of the esophagus
• B - Barrett’s esophagus
• G - GERD
• Analysis - Asthma (understudy).

Lab Diagnosis

Invasive tests

• Biopsy (Antrum).
• Microscopy (COPS).
  • Gram -ve spiral-shaped organism
• Stains
  • Warthin Starry Silver stain (black color H.pylori) - Best
  • Steiner Silver stain
  • Modified Giemsa stain - Less time-consuming.
• Non-invasive tests
  • IgM/ IgG ELISA
  • Capro antigen.
  • Urea breath test - Sensitive (urease +ve).
  • Biochemical reactions: Urease + Catalase + Oxidase
  • CLO test (to differentiate from Campylobacter, also called Campylobacter-like organisms).
  • Culture-Specific
    • Skirrow/ campy BAP/ butzler.

Treatment Of Helicobacter Pylori

• OCA - Omeprazole + Clarithromycin + Amoxicillin x 14 days
• OBM - Omeprazole + Bismuth Salicylate + Metronidazole x 14 days
• OBTM - Omeprazole + Bismuth Salicylate + Tetracycline + Metronidazole x 14 days

Gardnerella Vaginalis

It is responsible for causing Bacterial vaginosis. Bacterial vaginosis is diagnosed by taking a discharge sample from the patient. A PAP smear is performed, where Clue Cells can be seen.

Diagnosis of Bacterial vaginosis is made by Amsel’s Criteria.

• pH: > 4.5
• Whiff test: Discharge + 10% KOH → Fishy odor
• Clue cells

The treatment of Bacterial Vaginosis is Metronidazole

Pasteurella Multocida

It is a Gram-negative bacteria. The main clinical features of the disease are:

• Dog/ cat bite
• Local site inflammation - Swelling, tenderness, pus
• Tenosynovitis
• Osteomyelitis
• Septicemia

The treatment of Pasteurella Multcida is Beta lactams

Legionella Pneumophila

Legionella Pneumophila Causes Legionellosis it also causes legionnaires disease (pulmonary form) which can show clinical features such as

• Pontiac fever (non-pulmonary form). 
• Mild fever.
• Myalgia.
• Nonproductive cough.
• Respiratory failure.

Risk factors of legionellosis

• Smoking
• Alcohol
• Hospitalizations
• Immunodeficiency

Infection route: Aerosols (AC)

Incubation Period: 2-10 days

Lab Diagnosis

• Specimen: Sputum/ Bronchial washing
• M/E: Gram -ve coccobacilli.
• Stains: Silver impregnation stain - Black color
• Culture: BCYE agar (Buffered Charcoal Yeast Extract) - Black color.
• Serology: ELISA

Treatment: Macrolides

Klebsiella Granulomatis

• Other name: Calymmatobacterium granulomatis
• Pathogenicity: Donovanosis/ granuloma inguinale
• Incubation period: 1-2 weeks
• CF: Painless papule (genitalia) → Ulcer → Chronic
• Microscopy
  • Donovan bodies are seen on wright Giemsa stain
  • Safety pin appearance/ bipolar stain.
• Treatment: Tetracycline.

Erysipelothrix 

It is a Non-Motile, Non-Sporing, and Non-Capsulated organism

Lab diagnosis of Erysipelothrix is done by Tellurite medium/ tinsdale medium. The Treatment is by Penicillin (resistant to vancomycin).

Acinetobacter Baumanii

Acinebactor baumanii is a Non-fermenter. It is Present in hospital environments. It Leads to

• Opportunistic nosocomial infections
• VAP - Ventilator acquired pneumonia.
• Bloodstream infections
• Post catheter UTIs 

Francisella Tularensis

Francisella tularensis causes Tularemia. It is a Zoonotic infection. It is similar to plague.

• Route of tularemia infection
  • Contact with animal.
  • Aerosols inhalation
• Clinica features of tularemia infection
  • Ulceroglandular tularemia (most common).
  • Pulmonary tularemia.
  • Oropharyngeal tularemia
• Used as a Category-A bioterrorism agent.
• Culture
  • Francisella Tularensis is Difficult to culture
  • PCR is best.
  • Gram -ve coccobacilli
    • Catalase +ve
    • Oxidase -ve
• Treatment: Gentamicin

Frequently Asked Questions

Q: What is the treatment for Bacterial Vaginalis infection?

Answer: Metronidazole.

Q: Which antibiotic is given as a treatment for Tularemia?

Answer: Gentamicin

Q: What is the treatment for legionella?

Answer: Macrolides

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