Day: March 17, 2024

Overview Upper respiratory tract infections (URTIs) are common self-limiting illnesses that present with coryzal symptoms. An upper respiratory tract infection (URTI) refers to inflammation of the mucosa of the nostrils, nasal cavity, mouth, throat (i.e. pharynx), and larynx that all constitute the upper respiratory tract. URTIs are very common and lead to symptoms of nasal stuffiness, runny nose, sneezing, sore throat, and cough. This collection of symptoms is often referred to as ‘coryza’. URTI is caused by a viral infection and there are numerous causative viruses including rhinovirus, adenovirus, and many others. URTI is colloquially known as the ‘common cold’ or more

Overview Sepsis is a dysregulated host response to infection leading to life-threatening organ dysfunction. Sepsis is a commonly encountered problem in the healthcare setting and a major cause of morbidity and mortality. In its most simplistic form, sepsis is organ dysfunction secondary to an infection. It is regarded as a dysregulated host response to infection that is associated with both clinical and biochemical abnormalities. It can be difficult to understand sepsis because the terminology used to define the condition has changed over the years and there is no universal agreement. In addition, in clinical practice, we see organ dysfunction in many systemic diseases.

Overview Sepsis is a dysregulated host response to infection leading to life-threatening organ dysfunction. Sepsis is a commonly encountered problem in the healthcare setting and a major cause of morbidity and mortality. In its most simplistic form, sepsis is organ dysfunction secondary to an infection. It is regarded as a dysregulated host response to infection that is associated with both clinical and biochemical abnormalities. It can be difficult to understand sepsis because the terminology used to define the condition has changed over the years and there is no universal agreement. In addition, in clinical practice, we see organ dysfunction in many systemic diseases.

Overview Meningitis refers to inflammation of the meninges, which are the outer membranes covering the brain and spinal cord. Meningitis broadly refers to inflammation of the meninges, which may be due to a number of infectious and non-infective aetiologies. The most devastating of these is bacterial meningitis, which is a life-threatening condition and one of the major causes of infection-related deaths worldwide. In these notes, we predominantly focus on bacterial meningitis. Epidemiology The annual incidence of bacterial meningitis in developed countries is estimated at 2-5 per 100,000 population. Further epidemiological data is dependent on the underlying aetiology. Meningitis has been reported to

Overview Malaria is a potentially life-threatening illness that is caused by the Plasmodium protozoa. Malaria is one of the most well known tropical diseases worldwide. In the UK, malaria is characterised by fever in travellers returning from endemic areas. Malaria is caused by the Plasmodium protozoa, which are transmitted to humans by Anopheles mosquitoes. These insects transmit the parasite following the bite of an infected female. There are five different types of Plasmodium protozoa that can cause malaria in humans. P. vivax P. falciparum P. ovale P. malariae P. knowlesi P. falciparum is associated with the most severe form of malaria, which can lead to multi-organ

Introduction Bacteria are prokaryotic (single-celled) microorganisms that are found in both human health and disease. Bacteria range in size from approximately 0.5-5.0 micrometers in length and different in morphology. Typical shapes of bacteria include spheres (i.e. cocci) and rods (i.e. bacilli) . The human body is colonised with trillions of bacteria in normal health. This collective is known as the human microbiota and is important for normal functioning. Bacteria are also the cause of many clinically relevant infections in humans. Cell wall structure The general structure of a bacterium includes the cell wall, cell membrane, capsule, flagella, fimbriae, nuclear material, cytoplasm and other intracellular components.

Introduction Bacteria are prokaryotic (single-celled) microorganisms that are found in both human health and disease. Bacteria range in size from approximately 0.5-5.0 micrometers in length and different in morphology. Typical shapes of bacteria include spheres (i.e. cocci) and rods (i.e. bacilli) . The human body is colonised with trillions of bacteria in normal health. This collective is known as the human microbiota and is important for normal functioning. Bacteria are also the cause of many clinically relevant infections in humans. Cell wall structure The general structure of a bacterium includes the cell wall, cell membrane, capsule, flagella, fimbriae, nuclear material, cytoplasm and other intracellular components. 

Overview Gastroenteritis is a diarrhoea and/or vomiting illness due to an enteric infection. Gastroenteritis is an acute transient diarrhoeal illness with or without vomiting due to an enteric infection that may be viral, bacterial or parasitic. Common additional symptoms include nausea, fever and abdominal pain. Worldwide, acute infective diarrhoea is a major cause of mortality, particularly in children under 5 years old. In resource-rich settings (e.g. UK), gastroenteritis is usually a self-limiting illness with symptomatic treatment only. There are several terms used to describe gastroenteritis illnesses: Diarrhoea: ≥ 3 loose/watery stools per day Acute diarrhoea: diarrhoea that lasts < 14 days Persistent or

Introduction Coronavirus disease 2019 is a respiratory disease caused by the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) emerged in 2019 in Wuhan, the capital of Hubei Province in China. On 8th December 2019, there were initial reports of an unusual pneumonia which following investigation was reported to the World Health Organisation (WHO) by the Chinese authorities on 31st December 2019. By January 2020, the causative organism of COVID-19 was identified as a novel coronavirus and termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Unfortunately, the virus spread significantly throughout the world and was declared a pandemic on

Overview Clostridium (now Clostridioides) difficile infection is one of the most well-recognised hospital-acquired infections. C. difficile (CD) is a gram-positive bacillus (rod-shaped), which is both spore-forming and toxin-producing. It is found in < 2% of healthy adults as a commensal organism within the bowel. This increases to 7% in patients within long-term care facilities and 3-26% among inpatient populations. There are two important strains of C. difficile: Toxigenic (70-90%): produce and release two exotoxins (A & B). Central to pathogenicity. Nontoxigenic (10-30%): cannot produce exotoxins. Colonises colon without causing disease. C. difficile infection (CDI) is an important hospital-acquired (nosocomial) infection that is responsible for 20-30% of

Overview Cellulitis is an acute bacterial infection of the skin. Cellulitis refers to an acute bacterial skin infection that affects both the dermis and subcutaneous tissue. It may occur anywhere on the body and ranges form a self-limiting infection to severe necrotising infection. Cellulitis is a very common condition. It can occur at any age, but is mostly seen in middle-aged to older adults and usually affects the lower limbs. Aetiology & pathophysiology Cellulitis is commonly caused by both Streptococcus and Staphylococcus species. Cellulitis occurs due to disruption of the skin barrier (e.g. cut, abrasion), which allows entry of microorganisms. Both Streptococcus and Staphylococcus are common skin commensal organisms that can enter