Infectious conditions Flashcards

1
Q

What is an abscess?

A

Collection of pus built up within tissue over time, associated with Bacteria

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2
Q

What causes an abscess?

A

Most common sites: Axillae, Anus, Vagina (Bartholin’s abscess), pilonidal and tooth (dental) and groin
Incisional abscesses occur secondary to surgical incision
Caused by obstruction of sebaceous glands or sweat glands, or inflammation of hair follicles, or through minor skin breaks
Caused by bacteria - usually MRSA

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3
Q

What are the Risk Factors for Abscesses?

A

Immunocompromised i.e. steroid use, AIDS, IV drug use

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4
Q

What are the signs and symptoms for abscesses?

A

Tender, soft swelling filled with pus
Warm to touch
Surrounded by erythema
May have fever and rigors

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5
Q

What investigations are done for Abscess?

A

Usually clinical

Can use Ultrasound scan

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6
Q

How do you manage abscesses?

A

Drain pus from the abscess

  • Skin: Cut top of skin and allows pus to drain w/ local anaesthetics, if deep put a small piece of gauze
  • In the body: Prescribe Abx
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7
Q

What are the complications of abscesses?

A

Skin abscesses would normally burst on to skin and let out pus after enlarging and becoming more painful
If in body, very serious

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8
Q

What is Behcet’s disease?

A

Systemic vasculitis, most commonly seen in Turkey and israel.
Causes skin and mucosal lesions, uveitis, major arterial and venous vessel disease, and GI and Neurological manifestations

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9
Q

What causes Behcet’s disease?

A

Unknown cause
Associated with HLA-B51
Small vessel ANCA negative vasculitis

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10
Q

What are the Risk factors for Behcet’s disease?

A

Age 20-40 years
Family history
Genetic predisposition

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11
Q

What are the signs and symptoms of Behcet’s disease?

A
Tiredness
Malaise
Muscle pains
Transient fevers
Headaches
Oral ulceration
Genital ulceration
Eye disease
Uveitis
Arthritis
Vasculitis
Myo/pericarditis
CNS symptoms
Colitis
Skin lesions (e.g. Erythema nodosum)
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12
Q

What is the classic triad of Behcet’s disease?

A

Oral ulceration
Genital ulceration
Eye disease

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13
Q

What are the investigations for Behcet’s disease?

A

Pathergy testing - SC skin prick performed using a 21-gauge needle & observed formation of a papule / pustule 48 hrs later (positive in 60%)
Rheumatoid factor - Negative
ANA - Negative
Anti-neutralising cytoplasmic ABs - negative

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14
Q

What is Encephalitis?

A

Inflammation of brain parenchyma associated with neurological dysfunction such as: altered state of consciousness, seizures, personality changes, cranial nerve palsies, speech problems and motor and sensory deficits.

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15
Q

What are the viral causes of encephalitis?

A
Herpes simplex virus, EBV, VZV
Enteroviruses (Enterovirus-71, coxsackievirus, poliovirus)
Parechovirus
Flavivirus
Bunyavirus
Togavirus
Paramyxovirus
Others: Mumps, HIV, Rabies, Measles, Adenovirus, Hep C, Rotavirus, Parvovirus B19
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16
Q

What are the non-viral causes of encephalitis?

A
Bacterial meningitis
TB
Malaria
Listeria
Lyme disease
Legionella
Leptospirosis
Aspergillosis
Cryptococcus
Schistosomiasis
Typhus
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17
Q

What are the signs and symptoms for encephalitis?

A
Bizarre encephalopathic behaviour
Decreased GCS or Coma
Fever
Headache
Focal neurological signs
Seizures
History of travel / animal bite
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18
Q

What are the investigations for Encephalitis?

A

Culture
Serum for viral PCR
Toxoplasma IgM tire
Malaria film
Contrast-enhanced CT (B/L temporal lobe involvement suggests HSV encephalitis.)
Lumbar puncture (Raised CSF protein and lymphocytes, and decreased glucose)
EEG (diffuse abnormalities confirm diagnosis)

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19
Q

What is HIV?

A

Infection with the human immunodeficiency virus

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20
Q

What causes HIV?

A

Infects and replicates primarily in human CD4+ T cells and macrophages
Reverse transcriptase incorporates HIV genetic material into host genome
Leads to dissemination of HIB, cell death adn eventually T cell depletion

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21
Q

How is HIV transmitted?

A
Sexual intercourse
Bodily fluids (Blood transfusion/organ transplantation)
Vertical transmission
Breast milk
Needles
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22
Q

What are the Risk factors for HIV?

A
IV drug users
Unprotected intercourse
Percutaneous needle stick injury
High maternal viral load
HSV-2 infection
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23
Q

What are the 3 phases of HIV?

A

Seroconversion (Self-limiting)
Early/asymptomatic
AIDS

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24
Q

What are the signs and symptoms of seroconversion?

A
Fever
Night sweats
Generalised lymphadenopathy
Sore throat
Oral ulcers
Rash
Myalgia
Headache
Encephalitis
Diarrhoea
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25
What are the signs and symptoms of Early/asymptomatic disease?
Apparently well with progression of symptoms from serconversion
26
What are the signs and symptoms of AIDS?
Syndrome of secondary diseases due to immunodeficiency?
27
What are the AIDS defining conditions?
``` PCP Kaposi's sarcoma Oesophageal candidiasis Salmonella septicaemia Burkitt's lymphoma Immunoblastic lymphoma Primary brain lymphoma ```
28
What investigations are done for HIV?
``` Serum ELISA (positive) Serum HIV rapid test (Positive) HIV non-invasive tests (Positive) Serum western blot Serum HIV DNA PCR Serum p24 antigen Serum viral load Drug resistance Investigations for AIDS defining conditions ```
29
What is infectious mononucleosis?
Known as glandular fever Clinical syndrome most commonly caused by EBV Other causes a lot less common. Called mononucleosis syndrome when non-EBV pathology
30
What causes infectious mononucleosis?
EBV aka Human Herpes virus 4 - 80-90% of IM cases Mononucleosis syndrome may be caused by: Herpes virus 6, CMV, HSV-1 and rarely strep Pyogenes, toxoplasma gondii, HIV-1, adenovirus May be caused by a connective tissue disorders, malignancy and drug reactions
31
What are the symptoms of infectious mononucleosis?
``` Malaise Fever Rash Yellowing of skin Muscle pains ```
32
What are the signs of infectious mononucleosis?
Splenomegaly Hepatomegaly Cervical or generalised lymphadenopathy Pharyngitis
33
What are the investigations for Infectious mononucleosis?
FBC (lymphocytosis, atypical lymphocytes) Heterophile antibodies (Positive) but is non-specific EBV-specified antibodies (positive for: VCA-IgM, VCA-IgG, EA, EBV, EBNA) Real-time PCR Throat swabs CT of abdomen Ultrasonography of abdomen (splenomegaly)
34
What is the management for infectious mononucleosis?
-All patients: Supportive care (paracetamol or ibuprofen) - With upper airway obstruction or haemolytic anamia: Corticosteroid (prednisolone) - With thrombocytopenia: Corticosteroids or IV immunoglobulin (prednisolone or methylprednisolone or dexamethasone or normal immunoglobulin human)
35
What are the complications of Infectious mononucleosis?
``` Antibiotic induced rash Splenic rupture Neurological complication Chronic active EBV infection AI diseases, non-haematological Malignancy Fatigue Acute acalculous cholecystitis Renal complications ```
36
What is malaria?
Infection with plasmodium protozoan 5 types of plasmodium Transmitted by an infected female anopheles mosquito but may be transmitted by blood transfusion of organ transplantation
37
What are the 5 types of plasmodium?
``` Mosquitos Know Our Vital Fear Plasmodium Malariae Plasmodium Knowlesi Plasmodium Ovale Plasmodium Vivax Plasmodium Falciparum (most serious) ```
38
What causes malaria?
Protozoa grow in red cells Gametocytes taken up when another mosquito feeds, an develops into sporozites in the gut of the mosquito Then move to salivary gland to be transmitted next bite
39
What is the life cycle of malarian protozoa?
Injection of sporozites into blood stream by mosquito Invasion and replication in hepatocytes to form merozites Released into blood and enters RBCs Replicate in RBCs and develop ring forms, and then trophozites RBC's rupture and release merozites, which reinfects other RBC's Trophozites form merozites and gametocytes
40
Which populations have immunity to malaria?
Sickle cell trait/disease G6PD deficiency Pyruvate kinase deficiency Thalassemia
41
What are the Risk factors for malaria?
``` Low socioeconomic status Travel/live in endemic area Immunocompromised Pregnancy <5 or old age ```
42
What are the symptoms of malaria?
``` Can be up to 1 year Cyclical symptoms: High fever Flu-like symptoms Severe sweating Shivering cold/rigors Cerebral symptoms: Headache Disorientation Coma ```
43
What are the signs of malaria?
Pyrexia Anaemia (Haemolytic) Jaundice Hepatosplenomegaly
44
What are the investigations for malaria?
``` Giemsa thick and thin blood smears - Thick (Parasitaemia) - Thin (Type of parasite) FBC (thrombocytopenia, anaemia) U&Es (Impaired renal funciton) LFTs (Slightly raised) ABG (Acidosis in severe disease) Urinalysis (Slightly raised proteins) ```
45
What is Meningitis?
Inflammation of leptomeninges and underlying subarachnoid cerebrospinal fluid. Inflammation may be caused by infection with viruses, bacteria, other micro-organisms or non-infective causes. Viral meningitis more common and more benign than bacterial.
46
What causes viral meningitis?
``` Human enterovirus most common cause 5 subgenres (Coxsackieviruses, echoviruses, polioviruses, herpes, mumps) ```
47
What causes bacterial meningitis?
Haemophilus influenzae B (was most common) Streptococcus pneumoniae (18%) Neisseria meningitides (14%) HiB only children, rest in both! Listeria monocytogenes in immunocompromised patients In neonates, E.coli and Streptococcus agalactiae common causes
48
What are the less common causes of meningitis?
Fungal: Cryptococcus (AIDS defining disease) Other: Aseptic meningitis Mollaret's meningitis (recurrent benign lymphocytic meningitis)
49
What are the risk factors for viral meningitis?
``` Infant and younger children Young adults Older people Summer and autumn Exposure to mosquito or tick vector Unvaccinated for mumps Use of swimming pools and ponds Immunosuppression Exposure to rodents ```
50
What are the risk factors for bacterial meningitis?
``` =5 or 65= Crowding Exposure to pathogens Non-immunised infants Immunodeficiency Cancer Asplenia/hyposplenic state Cranial anatomical defects Cochlear implants Contiguous infectoin ```
51
What are the early symptoms of meningitis?
Severe headache Leg pain Cold hands and feet Abnormal skin
52
What are the later symptoms of meningitis?
``` Neck stiffness Photophobia Kernig's sign Fever Irritability/altered mental state Reduced consciousness Vomiting Children: High pitched crying/fits, Hypothermia, irritability, poor feeding Petechial rash - non-blanching ```
53
What are the signs of meningism?
``` Photophobia Neck stiffness Kernig's sign Brudzinski's sign Pyrexia Tachycardia Hypotension Skin Rash Altered mental state ```
54
What is Kernig's sign?
Hip and knee at 90 degree angle, further extension of knee has resistance
55
What is Brudzinski's sign?
Flexion of hips and knees when neck is flexed hurts
56
When thinking of meningism, a detailed history is needed. | What do you need to take note of exposure for? And what organism causes meningism?
Rodents (Lymphocytic choriomeningitis virus) Ticks (Lyme borrelia, rocky mountain spotted fever) Mosquitos (West nile virus) Sexual activity (HSV-2, HIV, syphilis) Travel
57
What investigations are done for Viral meningitis?
``` LP: CSF microscopy (Raised WBC) CSF Gram stain (Negative) CSF Bacterial culture (Negative) CSF protein (Normal or raised) CSF glucose (May be low) CT/MRI head (unremarkable) ```
58
What investigations are done for bacterial meningitis?
CSF cell count and differential (polymorphonuclear pleocytosis) CSF protein (Raised) CSF glucose (Low) CSF gram stain (positive) CSF culture (Specific bacteria) FBC and differentials (Leukocytosis, anaemia, thrombocytopenia) CRP (High)
59
What is the management of viral meningitis?
Initially antibiotics + Dexamethasone IV Confirmed viral agent: - Other than HSV, Varicella zoster or CMV: Supportive care - HSV or Varicella zoster: Acyclovir > Foscarnet - CMV: Ganciclovir > Foscarnet Recurrent: Recurrent benign lymphocytic meningitis (mollaret meningitis) most commonly caused by HSV-2
60
What is the initial management for bacterial meningitis?
Immunocompetent: = 1month old: Empirical ABx (ampicillin & Cefotaxime) + supportive therapy >1month or <50: Vancomycin and ceftriaxone + supportive + dexamethasone >/=50: Ampicillin & Vancomycin and ceftriaxone) with supportive therapy
61
What is the management for Bacterial meningitis?
Antibiotics per causative organism + supportive therapy + Dexamethasone (if >1 month of age)
62
What are the complications of meningitis?
``` Septicaemia Shock DIC Renal failure Seizues Peripheral gangrene Cerebral oedema Cranial nerve lesions Cerebral venous thrombosis Hydrocephalus Waterhouse-friderichsen syndrome ```
63
What is Necrotising fasciitis?
Life-threatening subcutaneous soft-tissue infection that may extend to the deep fascia, but not underlying muscle tissue. Aerobic, anaerobic or mixed floral causative organisms
64
What are the 2 types of necrotising fasciitis?
Type 1: Polymicrobial infection with an anaerobe e.g. bacteroides or peptostreptococcus and a facultative anaerobe e.g. enterobacteriaceae or non-group A streptococcus Type 2: Monomicrobial infection with streptococcus pyogenes or more rarely: Aeromonas hydrophilia (fresh water expoure), vibrio vulnificus (salt water exposure)
65
What are the risk factors for necrotising fasciitis?
``` Inpatient contact with index case Varicella zoster infection Cutaneous injury, surgery, trauma Non-traumatic skin lesions IV drug use Chronic illness Immunosuppresson NSAID use Varicella zoster infection in children Alcohol abuse, chronic liver or renal disease, diabetes ```
66
What are the signs and symptoms of Necrotising fasciitis?
Typically over a few days but can progress more rapidly in some cases e.g. Vibrio spp. and A. Hydrophila can be fatal in 48 ``` Changes day to day! Overall: Anaesthesia / severe pain Fever Palpitations Nausea and vomiting Delirium Crepitus Vesciles or bullae Grey discolouration of skin Oedema or induration Location of lesion ```
67
How do the signs and symptoms present in the first 2 days?
Local pain, swelling and erythema - mimics cellulitis or erysipelas - necrotising depp and not visible Severe constant pain, out of proportion Margins poorly defined, tender beyond visible area. No Abx respons Lymphangitis rarely seen Systemic illness - malaise, tachycardia +/- fever and dehydration - WORST theyve felt
68
What are the signs and symptoms day 2-4?
Tense oedema extending beyond erythema Bullae, indicating skin ischaemia Discoloured, progress to grey necrosed skin which breaks down SC tissues have wooden-hard feel. Fascial planes and muscles not palpable Crepitus due to gas Goes from intense tenderness to painless as nerves are destroyed Broad erythematous tract along route of infection as it advances If open wound, can separate layers of fascia
69
What are the signs and symptoms day 4-5?
Hypotension and septic shock develop Patient becomes confused and apathetic Fournier's gangrene: Rapidly progressive form of infective NF of the perineal, genital or perianal regions, leading to thrombosis of the small SC vessels and necrosis of the overlying skin
70
What are the investigations for Necrotising fasciitis?
``` FBC (Abnormally high or low WCC) U&Es (Possible decreased sodium, raised urea and creatinine) CRP (Raised) CK (Raised) Lactate (Raised) ABG (Hypoxaemia, acidosis) ```
71
What is Neutropenic sepsis?
Development of sepsis in a patient with Neutropenia
72
What conditions define neutropenic sepsis?
Temperature >38 sustained over an hour Neutrophil count <0.5 Temperature may be masked by anti-pyretic medications/steroids
73
What causes Neutropenic sepsis?
``` Drugs Infections Autoimmune Bone marrow failure B12/folate deficiency Congenital (rare) ```
74
What drugs cause neutropenic sepsis?
- Cytotoxic chemotherapy - Haematopoietic stem cell transplant - Immunosupportive drugs (Azathioprine/methotrexate/sulfasalazine/infliximab)
75
What infections cause neutropenic sepsis?
HIV/Influenza/CMV/EBV | TB/Shigella
76
What AI conditions cause neutropenic sepsi?
Crohn's Rheumatoid arthritis SLE
77
What Risk factors are there for Neutropenic spesis?
``` Age >65 Albumin <35 Preexisting organ dysfunctino Pre-treatment haemoglobin Full-dose intensity chemotherapy Low first-cycle neutrophil count (<0.5) Haematological malignancies Concurrent radiotherapy Prior episodes of neutropenia following chemo Female sex ECOG PS > 1 Advanced stage disease Prior chemo Corticosteroids ```
78
What are the signs and symptoms of Neutropenic sepsis?
``` Pyrexia Infective endocarditis symptoms (Tachycardia, hypotension, N&V) Mucositis, oral ulcers Lymphadenopathy Skin rashed ```
79
What are the investigations for neutropenic sepsis?
FBC (neutrophils <0.5) Temperature >/= 38.0 Blood cultures (Identify causative agents)
80
Whats important to know about Neutropenic fever?
Often those with neutropenic fever have pneumonia without cough or SOB