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C. difficile
This is a Gram-positive bacterium which colonises the gut in the absence of one’s commensal harmless bacteria.
The commensal flora in the gut can be killed due to the use of broad-spectrum antibiotics, leaving the individual vulnerable to a C. diff infection.
The bacteria make a toxin which leads to inflammation in the colon, causing pseudomembranous colitis.
It is a common hospital-acquired infection and can spread rapidly between patients.
Causes
Most commonly secondary to antibiotics beginning with the letter “C” like cephalosporins, clindamycin. Also associated with PPI use.
Symptoms
Diarrhoea, abdominal pain, fever
If severe, can lead to toxic megacolon (surgical emergency
Key tests
Blood tests show raised inflammatory markers (WCC, CRP)
Diagnostic test is Clostridium difficile toxin (CDT) in stool
C. diff antigen positivity shows exposure to bacteria, not necessarily current infection
Management
1st line is oral vancomycin. If this is not suitable, can also use fidaxomicin and/or metronidazole
CRE (Carbapenem-resistant Enterobacteriaceae)
CRE are Gram-negative bacteria that are resistant to carbapenems as they produce the enzyme carbapenemase which deactivates the antibiotics.
People can be colonised with CRE asymptomatically, but it causes infection when it enters blood or spreads locally.
CRE are more common in hospital patients who take long courses of antibiotics, require invasive ventilation or indwelling catheters.
Organisms
Resistant E. Coli
Klebsiella Pneumonia
Enterobacter aerogenes
Symptoms
Variety of illnesses e.g. wound infections, UTI, pneumonia
Key tests
Blood cultures, wound swabs
Management
Aim is to prevent infection as treatment options are limited
Antibiotics of use include fosfomycin, tigecycline and aminoglycosides
MRSA (Methicillin-resistant Staphylococcus Aureus)
This is a hospital-acquired infection due to the bacteria S. Aureus, which is resistant to the antibiotic methicillin.
It is common in hospital, prisons, and care homes, especially in people with open wounds and indwelling devices (e.g., catheter).
All patients awaiting elective surgery and those admitted are screened for MRSA.
Risk factors
Long course of antibiotics
Recent surgery
Catheters
Immunosuppressed
Symptoms
Most infections are localised to the skin and soft tissue, but can enter blood stream
Common presentation is small red bumps which develop into deep painful pus-filled boils, with associated fever and rash
Key test
Nasal swabs, swab of skin lesions and wounds sent for culture
Management
If asymptomatic, mupirocin cream (nose swab positive) or chlorhexidine (if on skin)
If symptomatic, antibiotic treatment e.g., vancomycin, teicoplanin or linezolid
VRE (Vancomycin resistant Enterococci)
This refers to a group of bacteria of the Enterococcus family resistant to vancomycin.
People can be colonised with VRE, but it causes infection when it enters the bloodstream or spreads locally.
Risk factors
Long course of cephalosporins, recent surgery, catheters, immunosuppressed
Symptoms
Variety of illnesses e.g. wound infections, UTI, bloodstream infections, endocarditis
Key tests
Blood cultures
Management
Newer antibiotics e.g. Linezolid, Quinupristin-dalfopristin
