Toxic megacolon

Disease class: Megacolon

Definition

 

Causes

• Inflammatory bowel disease
• Ulcerative colitis
• Clostridium difficile colitis

 

Complications

• Colonic rupture 
• Bacteraemia
• Sepsis
• Septic shock

 

Investigations

• Abdominal radiograph (AXR)
• CT scan of abdomen and pelvis with bowel contrast (if possible)

 

Diagnostic tips

• Faecal loading can cause small areas of dilatation.
• It is normal for some segments of bowel to have a relatively large diameter. The "369 rule" refers to the approximate normal diameters of small bowel (up to 3cm), large bowel (up to 6cm), caecum + sigmoid colon (up to 9cm). 
• If the clinical history and physical examination support a diagnosis of toxic megacolon and the AXR may show abnormal dilation, it is worth discussing the AXR with a specialist colleague.
• If there is a strong suspicion of toxic megacolon, inform senior colleagues, request an arterial blood gas analysis, request an urgent abdominal radiograph (if not done already) and seek specialist advice immediately.

 

Treatment

Depends on severity and underlying cause

Conservative

• Watchful waiting

Medical

• Antibiotic therapy
• Clostridium difficile eradication therapy (e.g. oral vancomycin)

Surgical

• Pancolectomy

Megacolon

Disease class: Colonic diseases

Types

• Hirschsprung disease 
• megacolon, Toxic

A megacolon is a colon with a significantly increased diameter, usually throughout a large continuous segment of bowel.

 

Investigations

• Abdominal radiograph (AXR)
• CT scan of abdomen and pelvis with bowel contrast (if possible)

 

Diagnostic tips

• Faecal loading can cause small areas of dilatation.
• It is normal for some segments of bowel to have a relatively large diameter. The "369 rule" refers to the approximate normal diameters of small bowel (up to 3cm), large bowel (up to 6cm), caecum + sigmoid colon (up to 9cm).

Trench fever

Disease class: Bacterial infection 

Pathogens 

• Bartonella quintana

Psittacosis

Disease class: Bacterial infection 

Pathogens 

• Chlamydophila psittaci

Ehrlichiosis

Disease class: Bacterial infection 

Pathogens 

• Ehrlichia species

Diphtheria

Disease class: Bacterial infection 

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Pathogen

• Corynebacterium diphtheriae

Anthrax

Disease class: Bacterial infection 

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Pathogens

• Bacillus anthracis

Foodborne diseases

Disease class: Poisoning

Also known as

• Food poisoning

 

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

Typhus

Disease class: Bacterial infection 

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Etymology

• Greek : tûphos (τύφος) : hazy.
• This describes the state of mind of those infected.

 

Pathogens

• Orientia tsutsugamushi
• Rickettsia prowazekii
• Rickettsia typhi

 

Do not confuse with

• Typhoid
• Paratyphoid fever

Q fever

Disease class: Bacterial infection 

 

Pathogen

• Coxiella burnetii

Brucellosis

Disease class: Bacterial infection

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Also known as

• Undulant fever
• Undulating fever

 

Pathogen:

Brucella species

• Brucella abortus
• Brucella melitensis
• Brucella suis

 

Microbiology:

• Aerobic
• Gram-negative
• Coccobacilli
• Intracellular

Listeriosis

Disease class: Bacterial infection 

 

Pathogens

• Listeria monocytogenes

Pneumocystis pneumonia

Disease class: Pneumonia

Also known as

• Pneumocystis pneumonia 
• PCP 

Pathogen: 

• Pneumocystis jirovecii

Bacterial pneumonia

Disease class: Pneumonia

Types

• Chlamydial pneumonia
• pneumonia, Mycoplasma
• pneumonia, Pneumococcal
• pneumonia, Rickettsial
• pneumonia, Staphylococcal

 

[Medical microbiology] Introduction

Medical microbiologists study micro-organisms, particularly pathogens.
This is a pathology discipline.
There is significant overlap with infectiology. 

 

Etymology

Ancient Greek μικρός (mikrós) = small
Ancient Greek βίος (bíos) = bio-, life
Ancient Greek λογία (logia) = study

 

Responsibilities

• Giving advice on the best samples to collect to diagnose an infection, such as a swab, blood test or urine test.
• Working with scientists in the laboratory to discover what’s causing the infection.
• Giving advice about how to treat the infection before the cause has been identified, and after.
• Making sure antibiotics are prescribed and used appropriately, by advising on patient management and producing treatment guidelines for a variety of conditions.
• Promoting measures to prevent and control the spread of diseases.

 

Investigations

Legionellosis

 Disease class: Bacterial infection
Disease class: Respiratory tract infections

 

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Pathogens

• Legionella species

Common cold

Disease class: Respiratory tract infections

Also known as

• Acute coryza 

 

Symptoms

• Catarrh
• Rhinorrhoea
• Malaise
  
• Fatigue
  
• Cough
  
• Fever
• Muscle aches
  

 

Causes

• Over 200 known viral strains 
• Coronaviruses
  
• Rhinoviruses
  

Lemierre's syndrome

Disease class: Pharyngeal diseases

Also known as

• Septic phlebitis of the internal jugular vein
• Postanginal sepsis secondary to oropharyngeal infection
• Postanginal shock including sepsis
• Lemierre's disease
• Human necrobacillosis

 

Pathogens

• Fusobacterium necrophorum

 

[Medical microbiology] Investigations

Medical microbiology homepage

• Blood culture - Adults
• Helicobacter pylori stool antigen test
• Sputum culture
• Stool culture
• Urine culture

Whooping cough

Disease class: Bacterial disease

This is a notifiable disease. This means that all diagnosed cases must be reported to the national Public Health services.

 

Also known as 

• Pertussis 
• 100-day cough

Pathogen

• Bordetella pertussis