Resistant Bacterial Infections

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