Dehydration and Nutrition: Infection Risk in Aged Care

When we talk about infection prevention in aged care, the conversation usually turns to hand hygiene, PPE, and environmental cleaning. These are non-negotiable. But there is another risk factor that quietly underpins almost every outbreak of infection, and it is one we can address every single day. Dehydration and poor nutrition are not just clinical complications, they are infection risks. In residential aged care facilities (RACFs), they are far more common than most teams realise.

Understanding the relationship between what residents eat and drink and how well their bodies fight infection is one of the most practical steps an aged care team can take to reduce the infection burden and to meet the expectations of the Strengthened Aged Care Quality Standards.

The physiology of ageing works against adequate hydration and nutrition. Thirst perception declines with age, so residents may not feel thirsty even when they are significantly dehydrated. Kidney function declines, making it harder to concentrate urine and conserve fluid. Appetite decreases as metabolism slows and sensory experiences such as taste and smell become less acute.

Add to this the complexity of aged care: polypharmacy can suppress appetite or cause nausea; cognitive decline - including dementia - can impair the ability to recognise hunger or thirst; dysphagia can make eating and drinking uncomfortable or unsafe; and the demands of shift-based care can mean that meal and fluid monitoring falls through the cracks.

Malnutrition and dehydration are endemic in residential aged care. Australian studies consistently report malnutrition rates of 30–50% among RACF residents, with dehydration at similarly high levels. These are not outliers. They are the baseline.

Dehydration does not just affect how a resident feels; it directly compromises the body's ability to prevent and fight infection.

The most well-established link is with urinary tract infections (UTIs). When fluid intake is insufficient, urine becomes concentrated, and bacteria are not effectively flushed from the bladder. This creates ideal conditions for bacterial colonisation of the urinary tract. UTIs are the most reported infection in Australian RACFs, and dehydration is one of the most modifiable contributing factors.

Beyond UTIs, dehydration compromises mucosal defences throughout the body. The mouth, airways, and gastrointestinal tract rely on adequate moisture to maintain the mucous membranes that form a physical barrier against pathogens. A dry oral environment, for instance, can increase the bacterial load in the mouth, contributing to aspiration pneumonia, which remains a leading cause of infection-related hospitalisation and death among aged care residents.
Dehydration also compromises skin integrity. Dehydrated skin is more fragile, more prone to breakdown, and slower to heal, creating entry points for infection that would otherwise be absent.

Nutrition and immune function are inseparable. The immune system is metabolically demanding - producing antibodies, mounting inflammatory responses and, repairing tissue all require adequate protein, micronutrients, and energy.

When residents are malnourished, the immune response is dulled. White blood cell production declines, wound healing slows, and the gut microbiome - a critical component of immune defence - becomes disrupted. Vitamin and mineral deficiencies, particularly of vitamins A, C, D, and E, zinc, and selenium, further reduce the body's capacity to respond to pathogens.

The consequences are concrete: malnourished residents are more likely to develop infections, to experience complications when they do, and to have prolonged recovery times. For a resident already managing multiple chronic conditions, this can be the difference between a manageable illness and a life-threatening one.

There is also an important bidirectional relationship to keep in mind: infection worsens nutritional status. During acute infection, the body’s energy and protein demands rise sharply, precisely when residents are least likely to eat and drink well. If not actively interrupted, this cycle drives rapid functional decline.

The infections most consistently associated with inadequate hydration and nutrition in aged care are:

• Urinary tract infections are directly linked to low fluid intake, concentrated urine, and reduced bladder flushing
• Aspiration pneumonia - associated with dehydration-related oral dryness, dysphagia, and reduced immune function
• Skin and wound infections - driven by skin fragility from dehydration and impaired healing from malnutrition
• Gastrointestinal infections - linked to a compromised gut mucosal barrier and a disrupted microbiome
• Respiratory infections - exacerbated by dry mucous membranes and a weakened immune response

During winter or outbreak periods, these risks compound quickly. A resident who is already nutritionally depleted and mildly dehydrated enters an influenza or gastroenteritis outbreak significantly vulnerable and compromised.

This is where daily care practice becomes infection prevention practice. The two are not separate.

Structured fluid rounds - offered regularly, not just at mealtimes - are among the most effective interventions to improve hydration. Residents who are cognitively impaired or have reduced thirst perception need staff to offer them fluids consistently. Offering preferred drinks, varying temperature and flavour, and using appropriate cups or thickened fluids for residents with dysphagia all support better intake.

Nutrition screening and monitoring are equally important. Weighing residents regularly, documenting dietary intake, and escalating concerns to a dietitian early - rather than waiting until significant weight loss has occurred - make a real difference to outcomes.

Documentation matters here, too. Fluid balance charts, food intake records, and weight monitoring data are not merely administrative tasks. They serve as an early warning system for deterioration in a resident's health. Under Standard 5 of the Strengthened Aged Care Quality Standards (effective 1 November 2025), facilities must demonstrate that clinical care - including nutrition and hydration - is person-centred, evidence-based, and continuously monitored.

Mealtime assistance training for care staff, referral pathways for speech pathologists and dietitians, and facility-wide policies to support adequate nutritional intake are all part of a comprehensive infection prevention approach.

The Strengthened Aged Care Quality Standards, effective from 1 November 2025, make explicit what has long been understood in clinical practice: nutrition and hydration are fundamental to residents' safety and wellbeing.

Standard 5 (Clinical Care) requires facilities to identify and respond to clinical deterioration, including nutritional and hydration needs, in a timely and person-centred manner. This includes systems for screening for malnutrition, monitoring fluid intake, and involving allied health professionals in care planning.

Standard 1 (The Person) reinforces that residents have a right to food and drink that meets their individual needs, preferences, and cultural backgrounds; not just minimum nutritional thresholds. Meeting the standard means going beyond adequacy to genuine responsiveness.

For IPC Leads and facility managers, this presents an opportunity to align infection prevention strategy with everyday care practices. When teams view hydration rounds and nutritional monitoring as infection-prevention activities rather than simple comfort measures, these tasks take on greater clinical importance.

Dehydration and malnutrition are not inevitable in aged care. They are modifiable risks, and when we address them effectively, we reduce infection rates, reduce hospitalisations, and improve residents' quality of life.

Infection prevention does not begin and end at the alcohol rub dispenser. It starts with the glass of water you offer a resident at morning tea and the extra ten minutes spent encouraging a reluctant eater at lunch. Those moments are clinical. They matter.

IPS - Infection Prevention Services. Lead your staff and residents to a healthier future.

If your team needs support to build a culture of infection prevention that links clinical care to IPC practice, IPS can help. Speak with us about our infection prevention training and support services for aged care - tailored to your facility, team, and residents at: support@infectioncontrol.care

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