Hospital-acquired pneumonia: causes, diagnosis and treatment in the UK

Pneumonia is inflammation of the lungs, usually caused by an infection. The NHS says it is usually caused by a bacterial or viral infection and that babies, older people, and people with heart or lung conditions are at risk of getting seriously ill. NICE explains that pneumonia is an infection of the tiny air sacs in the lungs, which makes it hard for the lungs to work properly.

Most pneumonia is caught outside hospital, which NICE calls community-acquired pneumonia. The group discussed here begins after admission. In the NICE guideline, hospital-acquired pneumonia means pneumonia that develops 48 hours or more after admission and was not already incubating when the person came in, and it also includes people who present with pneumonia but have been discharged within the previous 7 to 10 days. The UK guideline uses the term hospital-acquired pneumonia, and this page covers the same group under the older label "healthcare-associated pneumonia".

NICE notes that, for the purposes of its guideline, ventilator-associated pneumonia, which occurs in someone on mechanical ventilation, is excluded from the definition.

NICE's patient information says the main symptom of pneumonia is usually a new cough along with at least one other symptom, such as bringing up yellow or green phlegm, fever, breathlessness or difficulty breathing, chest discomfort or pain, or confusion. The NHS adds a high temperature, aching body, tiredness, loss of appetite, wheezing and, in older people, confusion, which it describes as common.

In hospital, where a person may already be unwell with something else, a new chest infection can be easy to miss. A change in breathing, a rising temperature, new confusion or a need for more oxygen are the sort of signs that nursing and medical staff look for. If you are an inpatient, or you or a relative are recently home from hospital, tell staff straight away about a new cough, breathlessness or chest pain.

• A new cough, with or without yellow or green phlegm.

• Fever or feeling hot, cold or shivery.

• Breathlessness or fast breathing.

• Chest pain, especially when breathing in or coughing.

• New confusion or unusual drowsiness, particularly in older people.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have a cough, are coughing up yellow or green mucus, have chest pain that comes and goes or happens when breathing or coughing, or feel short of breath. It says to call 999 or go to A&E if you are struggling to breathe, have pale, blue or blotchy skin, lips or tongue, are coughing up blood, or suddenly feel confused. This matters after a hospital stay because NICE's definition includes pneumonia that presents within 7 to 10 days of discharge.

The NHS says pneumonia is usually caused by a bacterial or viral infection and can also follow something getting into the lungs, such as water or food, which is called aspiration pneumonia. In hospital people are often already unwell with another illness or recovering from an operation, and reduced movement, a weak cough or swallowing difficulties can make it harder to clear the lungs. The bacteria involved may also differ from those that cause pneumonia in the community.

NICE says antibiotic choice should take account of how many days into the admission symptoms began and local antimicrobial resistance data, which reflects that ward-based organisms can be harder to treat. The guideline also asks teams to take a sample so the specific bacteria can be identified.

NICE patient information says healthcare practitioners usually diagnose pneumonia by asking about symptoms and examining the chest, and that if you are in hospital a chest X-ray is usually carried out to confirm the diagnosis. Blood tests are also used. For people with hospital-acquired pneumonia, NICE recommends sending a sample such as sputum, a nasopharyngeal swab or a tracheal aspirate for microbiological testing.

NICE uses scoring tools to judge severity in hospital. The CURB65 score gives one point each for confusion, raised blood urea, a raised breathing rate, low blood pressure and age 65 or over, and helps estimate the risk of death and the level of care needed.

NICE recommends offering antibiotics to people with hospital-acquired pneumonia, starting as soon as possible after the diagnosis is established and within 4 hours of clinical suspicion if symptoms start in hospital. The choice of antibiotic depends on how severe the illness is, whether the person is at higher risk of resistant bacteria, allergies and local resistance patterns. For non-severe illness and no higher risk of resistance, NICE lists oral co-amoxiclav as first line for 5 days then review, with alternatives such as doxycycline for people with penicillin allergy.

Antibiotics may be given into a vein at first. NICE says that if intravenous antibiotics are given they should be reviewed by 48 hours and, if possible, switched to oral antibiotics to complete the course. It recommends reviewing treatment after a total of 5 days and considering stopping if the person is clinically stable. The NHS says that in hospital people are usually given antibiotics and sometimes steroids, may be given oxygen, and may have a chest X-ray and blood tests.

NICE patient information explains that for people admitted with community-acquired pneumonia an extra corticosteroid or high-flow nasal oxygen may be offered if needed. Those options are described for that group, and the treating team will decide what applies to a particular person with a hospital-acquired infection. Taking antibiotics can cause side effects such as diarrhoea and feeling sick, and NICE says healthcare practitioners should explain this.

The NHS says that most people with pneumonia get better in 2 to 4 weeks depending on symptoms, although tiredness can linger. It advises resting, drinking plenty of fluids, taking paracetamol or ibuprofen if you have been told you can, not smoking, and finishing any antibiotics you are given at home.

NICE does not recommend routine follow-up chest X-rays for people discharged after pneumonia, but advises considering one at 6 weeks for people with risk factors for lung cancer or other underlying respiratory disease, such as smoking or being over 50, or with persisting or worsening symptoms or unexplained weight loss.

Prevention in hospital relies on good hand hygiene, early mobilisation after surgery, careful swallowing assessment and clean equipment. Vaccination against pneumococcus, flu, RSV and COVID-19 is recommended for eligible groups, according to the NHS, and stopping smoking reduces the chance of getting pneumonia.

Hospital-acquired pneumonia is managed by the team already looking after the patient, whether in an NHS or independent hospital, and it often lengthens the stay. The principles of testing and antibiotic choice follow the same national guidance, and local microbiology teams advise on resistant organisms.