Infection Flashcards
Cellulitis
severe inflammation of dermal and subcutaneous layers of the skin
Candidiasis
Candida albicans and other Candida species
infections have various manifestations, depending on the site and the degree of immune-incompetence of the patient.
Oral candidiasis (thrush)
yeast Candida albicans and other Candida species
raised, white plaques on the oral mucosa, tongue, or gums. The plaques can become confluent and ulcerated and spread to the throat
treated topically with nystatin or clotrimazole
Vaginal candidiasis
yeast Candida albicans and other Candida species
itching and burning pain of the vulva and vagina, accompanied by a white discharge.
treated topically with nystatin or clotrimazole
Pneumonia
- Definition
- Pathenogenesis
- Clinical features
Pneumonia is infection of the terminal air sacs (“alveoli”) and tissue of the lung.
Pneumococci, characteristically in pairs (diplococci), multiply rapidly in alveolar spaces and induce extensive oedema =incite an acute inflammatory
response in which neutrophils and congestion are prominent. As the inflammatory process progresses, macrophages replace the neutrophils and ingest debris. The
process usually resolves.
fever, malaise, tachypnea (increased respiratory rate),
and tachycardia, cough
Pneumonia
- Definition
- Pathenogenesis
- Clinical features
Pneumonia is infection of the terminal air sacs (“alveoli”) and tissue of the lung.
Pneumococci, characteristically in pairs (diplococci), multiply rapidly in alveolar spaces and induce extensive oedema =incite an acute inflammatory
response in which neutrophils and congestion are prominent. As the inflammatory process progresses, macrophages replace the neutrophils and ingest debris. The process usually resolves.
fever, malaise, tachypnea (increased respiratory rate),
and tachycardia, cough
Community-Acquired Pneumonia
pneumonia (infection of the lung parenchyma seen on chest X-ray) which develops outside the hospital
2 years old+: S.pneumoniae
Under 2 years old: Respiratory syncytial virus (RSV)
No causative agent is found in up to 40% of patients with CAP.
X ray patterns of acute pneumonia
Lobar pneumonia is pulmonary consolidation demarcated by border of lung segment or lobe.
Bronchopneumonia is seen as patchy consolidation around the larger airways
Interstitial pneumonia is demonstrated by fine areas of shadowing in the lung fields and there is usually no sputum production at presentation. It is usually seen in mycoplasma, legionella, and viral pneumonia
Meningitis
Meningitis is inflammation of the meningeal lining of the brain and spine.
A patient will have:
General features of an infection such as fever, increased pulse rate
Symptoms and signs due to inflammation of the meninges:
a. headache
b. photophobia (difficulty looking at bright lights)
c. vomiting
d. neck stiffness on flexion of the neck
e. irritable (progressing to reduced level of consciousness)
f. Other findings dependent on severity (e.g. sepsis) or complications.
Sepsis
a syndrome of life-threatening organ dysfunction caused by a dysregulated host response to infection. It is usually caused by a bacterial infection.
Septic shock: subset of sepsis where particularly profound circulatory, cellular and metabolic abnormalities substantially increase mortality.
Causative agents depend on the syndrome, host and clinical context. Gram-negative infections account for an increasingly large proportion of cases,
particularly of healthcare-associated infections
Common presenting syndromes include pneumonia, intra-abdominal and urinary sepsis, and skin and soft tissue infections.
Management and treatment: prompt recognition, early appropriate
antimicrobial therapy and supportive treatment- Sepsis 6 bundle
Neisseria meningitidis infection
Neisseria meningitidis is a Gram negative diplococcus that may be found within polymorphonuclear leukocytes (neutrophils)
Rates of meningococcal disease are highest for young children and increase again
for adolescents and young adults.
Neisseria meningitidis causes both meningitis and septicaemia. They can occur
together or separately.
Septicaemia
the bacteria in the blood
Neisseria meningitidis in the blood triggers an intense host immune response.
- Fever:
- Sepsis: reduced level of consciousness, tachycardia, low blood pressure, poor peripheral circulation,
reduced urine output.
- Disseminated Intravascular Coagulation (DIC)
- Non-blanching Rash (30-75% pts)
Management: Early recognition Early administration of antibiotics. Urgent investigation Supportive care, often in an intensive care unit to manage organ dysfunction and DIC. Notify Public Health Prevention
Treatment: ceftriaxone
Disseminated Intravascular Coagulation (DIC)
syndrome of widespread intravascular activation of coagulation.
Clostridioides difficile infection
gram-positive, anaerobic, spore-forming bacillus that is
responsible for the development of antibiotic-associated diarrhoea and colitis
(bowel inflammation).
Spore (faecal-oral) transmission
The diagnosis of C. difficile colitis should be suspected in any patient with
diarrhoea who has received antibiotics within the previous 3 months, has been
recently hospitalised, and/or has an occurrence of diarrhoea within 48 hours or more after hospitalisation
CDI clinical picture can vary from the asymptomatic carrier state to life-threatening colitis
Treatment:
-Asymptomatic carriers: No necessary treatment
-Mild, antibiotic-associated diarrhoea without fever, abdominal pain, or
leucocytosis: Cessation of antibiotic(s) may be the only treatment
necessary
-Mild to moderate diarrhoea or colitis: Metronidazole (P.O or IV)
or vancomycin (oral) for 10 days
-Severe or complicated disease: Vancomycin is considered to produce faster symptom resolution and fewer treatment failures than metronidazole; in
fulminant cases, combined therapy with IV metronidazole and
oral vancomycin may be considered
MRSA
a type of Staphylococcus aureus that is resistant to most beta-lactam antibiotics, antistaphylococcal penicillins (e.g., methicillin, oxacillin), and
cephalosporins.
Skin to skin transmission
Treatment:
Norovirus
a small, non-enveloped single stranded RNA virus that is a major cause of acute gastroenteritis outbreaks.
There is no specific treatment available so
treatment consists of supportive measures.
Transmission is mainly faecal-oral and also thought to be respiratory. Can be spread following ingestion of contaminated food, direct person-to-person contact or through contact with contaminated surfaces.
HIV
Retrovirus that infects cells with CD4 surface receptor. It destroys the cell, causes inflammation and spreads to/infects to more cells
Clinical features: oral candidiasis, Kaposi’s sacroma, PCP
Transmission: contact of infected bodily fluids with mucosal tissue/blood/broken skin
Treatments: anti-retroviral drugs
Malaria
One of the most common and deadly infections
Vector transmission: female Anopheles mosquito
Presentation: headache, fever, fatigue, pain, chill, pallor, sweating, dry cough, splenomegaly, nausea, vomiting] bite marks, low BP, high HR (110bpm)
Treatment dependant of species:
P. faciparum= artesunate, quinine + doxycycline
P. vivax, ovale, malariae = chloroquine,
Endocarditis
Formation of vegetation that binds to valves or mural endocardium. Aberrant flow predisposes to a collection of fibrin, platelets and scant inflammatory cells
Clinical features of Endocarditis
Fever
Heart murmur
Other cardiac complications
Embolic features: These are small bits of the vegetation (or biofilm) that become loose and travel to small capillaries where they can block the
capillary or cause local infection at that site.
e.g Janeway lesions, splinter haemorrhages, roth spots in the eye, oslers nodes
Chicken pox/shingles
Chicken pox: varicella
Shingles: Herpes zoster
Presentation: fever, malaise, headache, and abdominal pain. The exanthem begins on the scalp, face, or trunk as erythematous macules, which evolve into virus-containing vesicles that begin to crust over after about 48 hours
Treatment: acyclovir
Examples of disease caused by healthcare infection viruses
blood borne viruses (hepatitis B, C, HIV)
norovirus
influenza
chickenpox
Examples of disease caused by healthcare infection bacteria
Staph aures including MRSA Clostridium difficle Escherichia coli, Klebsiella pneumoniae Pseudomonas aeruginosa Mycobacterium tuberculosis
Describe the role of E.coli in health and disease
Gra m-negative rods, typically lactose-fermenting, facultatively anaerobic
normal part of large bowel microbiota
Possibly protects against invasion by pathogenic species
Can cause:
intestinal infections
toxin-mediated disease
extra-intestinal infections
disease is linked to the presence of virulence factors, frequently restricted to specific E.coli strains
Hepatitis B
Inflammation of the liver
Chronic: persistence of HBsAg after 6 months
Double-stranded eveloped DNA virus
Transmission: vertical (75% cases globally), sexual contact, drug injection, needlestick injuries
Presentation: jaundice, fatigue, abdominal pain, anorexia/nausea/vomiting, arthralgia
Treatment: no cure, life-long anti-virals
Vaccine available
Pharyngitis
Streptococcus pyogenes
• Peak incidence 5-15 years • Droplet spread • Association with overcrowding • Untreated patients develop M protein specific antibody
Clinical features Abrupt onset sore throat Malaise, fever, headache Lymphoid hyperplasia Tonsillopharyngeal exudates Throat swab -> Group A strep
Scarlet fever
Due to infection with streptococcal pyrogenic exotoxin strain of S.pyogenes • Local or haematogenous spread • High fever, sepsis, arthritis, jaundice
Typhoid and paratyphoid (enteric fever)
Systemic disease
Salmonella typhi, Salmonella paratyphi= rod shaped Gram-negative bacteria
Faecal-oral transmission from contaminated food/water
-poor sanitation, limited access to clean water
Presentation: fever headache, abdominal discomfort, dry cough, relative bradycardia
Treatment: fluoroquinolones (increasing resistance), IV ceftriaxone or azithormycin for 7-14days Vaccine available (50-75% effective)
Dengue fever
commonest arbovirus
Vector transmission: Aedes aegytpo
Presentation: first infection ranges from asymptomatic to non-specific febrile illness
