Bacterial Infection Diagnosis And Treatment

Introduction

Definition of bacterial infections

Bacterial infections are the combination of the presence of bacteria and inflammation or systemic dysfunction. Infections can be caused by pathogens that are transmitted through air, water, food, or living vectors, and can occur at any site, subsequently leading to severe disease and even death.^1,2 Therefore, early and accurate diagnosis and effective treatment are crucial in significantly reducing bacterial infection morbidity. This article will discuss the types of bacterial infections, how they are diagnosed and treated, and how to prevent future infections.

Types of bacterial infections

Common bacterial infections

Bacterial Infections can manifest in various ways, affecting different parts of the human body such as the skin, respiratory system, urinary system and gastrointestinal tract.³ Bacterial infections in these various systems lead to a range of symptoms and complications. Some of the most common bacterial infections include:

1. Respiratory infections – e.g., upper respiratory tract infections  (URTIs)⁴  
2. Skin infections – e.g., cellulitis
3. Gastrointestinal infections – e.g., salmonella infection
4. Urinary tract infections – e.g., urinary tract infections (UTIs)
5. Bloodstream infections – e.g., sepsis

Some of the least common Less common bacterial infections include:

1. Lyme disease
2. Tuberculosis

Diagnosis of bacterial infections

Accurate diagnosis of bacterial infection is crucial to prevent unnecessary antibiotic use and to identify the appropriate therapeutic approach.⁷ A detailed clinical evaluation, including history and physical examination, is the first step in the diagnostic process. Although these evaluations have positive and negative aspects, they are rarely used on their own, often used in combination with other tests. Clinical testing is usually the next step and these results can be used to direct bedside and laboratory testing, with the likelihood of a diagnosis changing with each new piece of information.⁷ 

Clinical assessment

Overall, single clinical criteria are neither sensitive enough nor specific for bacterial infection, and further testing is typically required to aid in the diagnosis.⁷ Combining elements from the physical examination and patient history can help to produce useful case definitions, for example, doctors use diagnostic algorithms to identify bacterial meningitis involving blood tests, lumbar punctures, and clinical features alongside a patient's history.⁸ Case definitions are usually created with a high sensitivity and a low specificity to remove patients who don’t meet the criteria for having the condition. 

Bedside tests

• One useful example of a bedside test that can help with bacterial infection diagnosis is the urine dipstick test, which identifies the urine pH and the presence of any blood.  
• To diagnose female sexually transmitted infections, wet prep microscopy is another often utilised bedside technique. 
• When confirming gonococcal arthritis by finding Gram-negative diplococci in a joint aspirate, a bedside Gram stain can be of great assistance.⁷ 
• Gram-staining can also be used to quickly diagnose meningococcemia from a skin scrape or a petechial rash. 

Unfortunately, although these bedside tests are inexpensive and require little training, these examinations are not conducted very often.⁷

Laboratory tests

Numerous laboratory tests fall into two categories: indirect non-culture-based or direct culture-based tests. Direct non-culture-based tests generally identify an antigen from an organism or a serological reaction to that antigen. These tests vary in their performance characteristics but are generally specific for a particular bacterial infection in the correct clinical setting. Modern microbiology is built on culture-based assays, which are also typically used as the benchmark for comparing other diagnostic procedures. Nevertheless, in actual practice, cultures are rarely utilised to establish a preliminary diagnosis of bacterial infection. 

Nucleic acid amplification tests (NAATs) can also be used. NAATs provide the greatest advantage in terms of turnaround time as they can be performed directly on clinical specimens, such as stool samples.⁷ 

Below is a list of some laboratory tests that can be conducted:⁶

1. Blood tests
   1. Complete blood count (CBC)
   2. Blood cultures
2. Urine tests
   1. Urinalysis
   2. Urine cultures
3. Swabs and Cultures
   1. Throat swabs
   2. Wound cultures
4. Imaging Studies
   1. X-rays
   2. CT scans

Treatment of bacterial infections

Antibiotic therapy

Selecting appropriate antibiotics is crucial to the treatment process. Based on the patient's medical history and the type of bacterial infection the patient has, the healthcare provider will select the most effective antibiotic, with the mechanisms of action and side effects being evaluated. During the selection, antibiotic resistance will be taken into consideration as antibiotic-bacterial resistance is a growing threat and the patterns of occurrence need to be observed. To fully eradicate the infection, the healthcare provider will proceed to advise the patient on how long they should complete the treatment while taking into account the type of antibiotic, and the severity of the infection.⁹ 

Alternative therapies and supportive care

Probiotics, found in yoghurt and supplements, may help to support the immune system and prevent infections, however, more research is needed to understand how they work.¹⁰ Some combination treatments including immunotherapy and antibiotics may occasionally be used to boost or alter the immune system to improve the body's capacity to fight the infection.¹¹ Common treatment methods such as pain medication may be used to alleviate symptoms such as fever or muscle aches. One of the most common treatment options is to allow the body's natural healing process to take place through rest and consuming a balanced diet.

Antibiotic resistance

Antibiotic resistance poses a serious threat to global health, leading to rising numbers of infections caused by multidrug-resistant and pan-resistant bacteria with increases in morbidity and mortality.¹²  This resistance can be caused by several factors including the overuse/misuse of antibiotics. For instance, when patients are prescribed antibiotics and don't complete the course, this allows the bacteria to develop resistance to the antibiotics. This resistance to antibiotics affects both the healthcare system and individuals, causing difficulties in treatment and longer hospital stays with increased complications and high mortality.¹³ To combat the resistance, programs have been put in place to promote the appropriate use of antibiotics in the healthcare system, along with educating medical professionals on the importance of antibiotic supervision. Educating the public on antibiotic resistance and encouraging patients to adhere to the prescription guidelines and complete courses will also help combat antibiotic resistance.¹⁴

Prevention of bacterial infections

Preventative medicine has been shown to drastically reduce the rate of morbidity of several diseases in the form of vaccines.¹⁵ Vaccines have previously been developed to target extracellular bacteria, however, it is rare to find vaccines against intracellular bacteria.¹⁶ Thus only leaving other preventative measures including practising hygiene, through hand washing and food safety.¹⁷ However in a healthcare setting, infection control is crucial and can be implemented through sterilisation techniques and isolation precautions which can help prevent the transmission of infectious agents and improve patient safety.^18,19

Summary

In order to identify bacterial infections, clinicians have to often undertake laboratory evaluations and bedside testing but also take into account various clinical symptoms. Understanding the various tests available and their application is crucial in enhancing patient outcomes and ensuring appropriate antibiotic prescribing. However, further research needs to be conducted to help understand and better prevent and treat bacterial infections.