Bacterial Infections In Older Adults

Introduction

As of 2016, 566 million people are equal to or above 65 years old.¹ Shockingly, infectious diseases, particularly bacterial infections, are the primary cause of one-third of deaths in older adults.² This vulnerability of older adults is a significant concern, with older adults being more prone to bacterial infections than younger adults.

What are bacteria and bacterial infections? 

Bacterial infections are caused by bacteria.³ Common bacterial infections include Urinary tract Infections (UTIs), pneumonia, sepsis, and food poisoning.³

Bacteria are tiny single-celled organisms that can be found everywhere on the planet.⁴ Most bacteria are not harmful, in fact, some are very beneficial for humans, but some can cause disease or an infection.⁴

Why are older adults prone to infection?

Older adults have a weakened immune system which makes them more vulnerable to diseases and infections.¹ This can be due to the natural ageing process or the presence of chronic conditions such as heart disease or diabetes 2. The symptoms are unusual (weakness, malaise, or confusion) compared to the more obvious symptoms (fever, chills) of infection in younger adults,² leading to delayed diagnosis and treatment. It is important to understand the infections to obtain better treatment.

This article discusses the risk factors, common bacterial infections, their diagnosis, treatment, and prevention.

What are the risk factors?

Age-related changes

The human immune system drastically changes after the age of 60.⁵ With increased age, immune functions progressively decrease, reducing the immune system’s ability to protect against infections.⁵ Chronic conditions such as COPD (Chronic obstructive pulmonary disease) and diabetes can increase the risk of infections. Older adults with COPD are more prone to pneumonia and respiratory infections.⁵ Urinary tract, skin tissue, and abdominal infections commonly occur in older adults with diabetes mellitus.⁶ Organ-specific physiological changes are also observed in older adults.⁶ For example, urothelial change in the urinary organ system can enhance the adherence of bacteria causing infections.⁶

Environmental and lifestyle factors

Older people in nursing homes and long-term care facilities share dining and therapeutic facilities.⁷ These residences are closely linked with hospitals, making them easier targets for acquiring infection, becoming reservoirs and sources of transmission to others.⁷ Susceptibility to infection is increased as the immune system is dysregulated in older adults due to factors including poor nutrition and poor personal hygiene.⁷

Medical interventions

Elderly patients who are prescribed immunosuppressants to treat autoimmune diseases such as rheumatoid arthritis are at higher risk of acquiring infection and increasing morbidity and mortality.⁸ Antibiotic resistance has been a significant threat worldwide, making it harder to treat bacterial infections in older adults.⁹

Common bacterial infections in older adults

Urinary tract infection (UTI)

In older adults, urinary tract infections (UTIs) are the leading cause of antibiotic use and morbidity.¹⁰ Studies have shown that hospital admissions have predominantly increased due to UTIs in the United Kingdom.¹¹ Urinary tract infections are caused by bacteria entering the urinary tract.

Causes¹²

• Poor bladder control leads to urinary retention
• Constipation
• Long term hospitalisation
• Malnutrition
• Inadequately controlled diabetes
• Vaginal atrophy
• Prostate hyperplasia
• Unhygienic living conditions

Symptoms¹³

• Urethral burning with urination
• Pelvic pain
• Fever
• Chills
• Frequent urination
• Lethargy
• An urgent need to urinate
• Decreased mobility
• Decreased appetite.

However, in older adults, classic symptoms of UTI may go unnoticed due to age-related issues such as dementia.¹³

Complications: 

The infection, if not treated, can spread to the kidney and bloodstream, leading to severe complications, including kidney damage and blood poisoning.¹⁴

Diagnostic tests for UTI¹⁵

• Urine culture
• Dipstick tests ( Urine analysis)
• Blood tests

Treatment¹⁵

UTIs are treated with Antibiotic therapy. A course of narrow-spectrum antibiotics for three days has been noted to be effective for uncomplicated UTIs (UTIs caused by less resistant bacteria). A course of broad-spectrum antibiotics for seven or more days is suggested for complicated UTIs (UTIs caused by resistant bacteria).

Prevention¹⁵

• Hydration
• Hygiene practices: proper cleaning after pooping (wipe from front to back) and regularly changing adult diapers to avoid bacterial growth.
• Maintaining bladder health by regular urination.
• Consuming probiotics
• Regular checkups and limiting the use of catheters

Respiratory infection: Pneumonia

Pneumonia is an extremely acute lower respiratory tract infection;¹⁶ it has been one of the leading causes of mortality in older adults.¹⁷

Symptoms: Pneumonia symptoms are atypical^17,18

• Fever and cough – Less severe / do not occur in older adults
• Heightened confusion
• Shortness of breath
• Rapid breathing
• Circulation problems with loss of blood pressure
• A very high fever or a very low temperature.

Complications

If pneumonia is not diagnosed and treated, it can lead to complications such as sepsis, lung abscess and respiratory failure;¹⁷ pneumonia can also cause complications that involve the heart, such as irregular heartbeat and heart failure.¹⁷

Diagnostic tests¹⁹

• Culture 
• Blood tests
• X-ray
• Pulse oximetry.

Treatment¹⁶

Antibiotic treatment is based on the severity of the infection, the type of bacteria causing it, and the bacteria’s resistance.

• For mild pneumonia, Macrolides such as Azithromycin, if resistance combination therapy is provided
• Beta-lactam antibiotics such as amoxicillin are given to patients with mild pneumonia in long-term healthcare facilities
• For moderate: Beta-lactam like ceftriaxone, cefotaxime, combination therapy with macrolide or respiratory fluoroquinolone if needed
• For severe: Antibiotics are provided the same as moderate but for the duration of 7-14 days

Prevention¹⁹

• Vaccination
• Good personal hygiene
• Maintaining health by consuming healthy food and regular physical activities
• Quitting bad habits such as smoking.

Skin and soft tissue Infection: Cellulitis

It is widespread for elderly people to have skin and soft tissue infections.²⁰ Cellulitis, which usually affects the legs, is the most common cutaneous infection in older people.²⁰ The bacteria can enter the skin through broken areas such as cuts.²⁰

Symptoms²¹

• The infected skin becomes hot, painful, and swollen
• Infected areas can have blisters
• Unwell and Flu-like symptoms
• Swollen and painful glands.

Complications²¹

Untreated cellulitis can spread the infection to other body parts, such as blood, muscles, and bones.

Diagnostic tests²²

Cellulitis can be diagnosed by observing the symptoms and the skin. In addition, a swab test may be taken. Blood tests might be necessary for treatment and to rule out the possibility of other infections.

Treatment²²

Initially, oral antibiotics are prescribed based on the signs and symptoms. If you do not respond to oral antibiotics and symptoms persist, antibiotics are provided into your veins.

Prevention²²

• Good personal hygiene
• Keep your skin clean and moisturised to avoid cuts and the entry of bacteria.

Gastrointestinal Infection: C. difficile infection

Older adults are 10 times more prone to infection caused by a bacteria called C. difficile. Misuse of antibiotics is one of the leading causes of acquiring this infection. The bacteria causes an infection in the colon.²³

Symptoms: Vary from moderate to severe²³

 Moderate:

• Watery diarrhoea – 3-4 times a day, for more days
• Belly cramp

Severe:

• Watery diarrhoea – 10-15 times in a day
• Fever
• Nausea
• Fast heart rate
• Blood or pus in the stool
• Loss of appetite
• Dehydration.

Complication

Loss of fluids and minerals due to diarrhoea can lead to severe dehydration, causing the blood pressure to drop and, in some cases, kidney failure.²³ One rare yet severe complication is toxic megacolon; due to the gas and stool, the colon might enlarge, and untreated, it might lead to a burst of the colon, which could be fatal.²³

Diagnostic tests²³

• Stool tests
• Colon exam
• Imaging tests: X-ray or CT scan.

Treatment²³

• Antibiotic therapy is the primary treatment: Vancomycin and Fidaxomicin are commonly used
• Surgery: In case of inflammation of the colon and toxic megacolon
• Antibody-based therapy
• Faecal microbiota transplant

Prevention²³

• Maintaining gut bacteria by consuming probiotics²⁴
• Reduction of inappropriate use of antibiotics

Summary 

Bacterial infections are becoming harder to treat for people of all ages due to increased antibiotic resistance. It is even more complex in older adults due to reduced immune capabilities.

Even though antibiotics are the primary treatment, mindful use is the major requirement to reduce the risk of bacterial resistance and, in turn, reduce severe hard-to-treat infections.

The cleanliness and sterilisation of hospitals and care facilities can reduce the facilitation of hospital-acquired bacterial infections in older adults. As symptoms are atypical,²⁵ routine body checkups and better care and nutrition can help to reduce the risk of severe bacterial infections.

In conclusion, bacterial infections in older adults can be treated effectively with early diagnosis, improved research, and better treatments, considering all the other factors associated with age.