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MBBS - Year 1 > Microbiology - Infection and Immunity > Flashcards

Microbiology - Infection and Immunity Flashcards

1
Q

Prophylaxis

A

Treatment given, or action taken to prevent disease

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2
Q

HCAI

A 
Healthcare-associated Infections
MRSA 
C. difficile 
ESBL 
Surgal site infections
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3
Q

MRSA as a HCAI

A 
Indwelling catheters (urinary, PEG’s etc)
Poor hygiene (handwashing, etc)
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4
Q

C. difficile as a HCAI

A

Antibiotics
Proton pump inhibitors
Poor hygiene

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5
Q

ESBL as a HCAI

A

Urinary catheters

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6
Q

Surgical site infections

A

Gram -ve bacteria
MRSA
Group A streptococcus
Anaerobes

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7
Q

How do we prevent HCAI

A 
Operating theatre air quality 
Vaccination
Post exposure prophylaxis 
Surveillance - outbreak investigation 
Standardisation 
ANTT
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8
Q

ANTT

A

Aseptic no touch technique

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9
Q

Why do we need to prevent HCAI

A

To reduce morbidity and mortality which may result from sepsis
To reduce the length of stay in hosp
To reduce the economic burden
To reduce the risk of surgical procedure
Patients w/ HCAI’s are 7x more likely to die as inpatients

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10
Q

Factors associated w/ infection

A

The micro-organisms
The host
The environment
Treatment: previous and current

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11
Q

Preventing airborne transmission

A

Place the infected patients in source isolation

Protect the vulnerable patients by use of filtered air, negative pressure (TB)

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12
Q

Preventing direct contact

A

Patients w/ microorganisms that pose a risk for others (e.g. MRSA, Vancomycin-resistant enterococci, Clostridium difficile, Norovirus) are placed in source-isolation
Aseptic technique, hand hygiene etc

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13
Q

Environmental hygiene

A

Decontamination of contaminated equipment or medical devices
Safe disposal of hosp waste
Screening of suspects carriage (patient) and immunisation (staff)

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14
Q

Enhancing resistance to infection

A

Vaccination
Optimising nutrition
Other factors e.g. body temp

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15
Q

Infection transmission route (HCAI)

A 
Person to person spread 
Direct contact (skin to skin)
Faecal-oral 
Airborne/ droplet 
Blood to blood 
Environment or person spread - indirect
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16
Q

Factors to consider for surgical antibiotic prophylaxis

A

Type of wound
Most likely pathogens
Antimicrobial factors

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17
Q

Type of wound - Abx prophylaxis

A

Clean
Clean/ contaminated, has opportunity to become contaminated as is in close proximity to a contaminated area
Dirty – contaminated, purulent (filled w/ pus)

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18
Q

Colonisation vs infection

A

Microorganisms existing in the body but don’t invade tissue or cause detectable (clinical) damage vs when microorganisms begin to invade the body tissues and cause detectable (clinical) damage

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19
Q

Examples of clean surgeries

A 
Cardiac/ vascular 
Breast 
Orthapaedic 
Dialysis access 
Neurologic
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20
Q

Most likely pathogen in clean surgeries

A

Staphylococcus aureus,

S. aureus, Cogaulase -ve

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21
Q

Examples of clean/contaminated surgeries

A

Burn
Head and neck
GI
GU

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22
Q

Most likely pathogen in clean/contaminated surgeries

A

Coagulase -ve staphylococci

Psuedomonas aeruginosa

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23
Q

Example of dirty surgeries

A

Ruptured viscera

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24
Q

Most likely pathogen in a dirty surgery

A

Streptococci
S. aureus
Anareobes
Enterococci

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25
Routes of delivery for Abx
``` Oral - time for conc to peak IV - injection or infusion Intramuscular Local PK/PD characteristics ```
26
Patient related factors to HCAI
4 hr mark is very critical ``` Host resistance Age Malnutrition Hypovolemia Obesity Diabetes Steroids Other immunosuppressants ```
27
Host resistance in patient related factors
Healing response Local wound characteristics Operative characteristics
28
Hypovolemia
Poor tissue perfusion
29
Procedure related factors
Some procedures are riskier than others depending on entry of tract Pre-existent sepsis (local or distant) Poor skin preparation, incl shaving Nonviable tissue in wound Hematoma Foreign material, incl drains and sutures Dead space
30
Golden standard sample to send to microbiology
Bone sequestrae | Pus is better than swabs
31
Most septic part of body
Bone
32
Main presentation of infections
``` Fever Chills and sweats Change in cough or a new cough Sore throat or mouth sore Shortness of breath Nasal congestion Stiff neck Dysuria Unusual vaginal discharge Increased urination D + V Pain in the abdomen or rectum Redness, soreness or swelling New onset of pain ```
33
Localised signs of infection
Rubor (redness) Tumor (swelling) Calor (heat) Dolor (pain)
34
Classification of skin and soft tissue infections
Superficial Moderate Deep
35
Respiratory infections
Sore throat, about 70% of acute sore throats are caused by viruses A lab diagnosis is not generally necessary for pharyngitis or tonsilitis
36
Cause of pneumonia or LRTI
Viruses in winter, and bacteria in summer (70%)
37
LRTI vs URTI
Usually more severe than infections of the URT and choice of appropriate antimicrobial therapy is important and be life saving
38
Symptoms of pneumonia and LRTI
``` Fever, sweating and/or chills Cough, often severe, that produces phlegm Shortness of breath Difficulty breathing Nausea and vomiting Muscle aches ```
39
Rash
Manifestation of infection that's generalised in the skin
40
UTI
Bacterial infection usually acquired by ascending route from the urethra to the bladder May proceed to kidney or bloodstream ---> septicaemia
41
Most common cause of ascending UTI
Gram -ve rod E. coli
42
Bacteria causing infections of GI tract
E. coli Salmonella Campylobacter
43
Viruses causing infections of GI tract
Rotavirus | Norovirus
44
Abdominal infections
Usually polymicrobial | Usually result in an intra-abdominal abscess or secondary peritonitis, may be generalised or localised (phlgemon)
45
Symptoms of abdominal infections
``` Abdominal pain or tenderness Bloating or distention Fever Nausea + vomiting Loss of appetite Thirst Inability to pass stool or gas Fatigue ```
46
Viral hepatitis
Viruses directly targets the liver from A-E Diff aetiologies e.g. non-infectious multisystemic conditions, infectious agents (hepatotropic viruses) and drug toxicity
47
Obstetrics and neonatal infections
Congenital Perinatal Postnatal
48
Congenital infections
Maternal ---> microorganisms enter the blood, establish infection in placental ----> foetal infection
49
Intrauterine infections in pregnant women
May result in death of the foetus or congenital malformations
50
When will a foetus survive despite a congenital infection
In relatively non-cytopathic virus or when controlled by mother’s IgG response but may still be born w/ malformations or other pathological changes
51
Perinatal infections
Maternal blood: passage down infected birth canal e.g. herpes simplex
52
How do postnatal infections
``` Milk Blood Saliva contact Infected umbilical stump Meconium ----> sepsis ```
53
CNS infections
Usually blood -borne or infectious agents invading via peripheral nerves
54
Clinical feature of meningitis - bacterial
Clinical features incl a haemorrhagic skin rash w/ petechiae
55
Incubation period of bacterial meningitis
1-3 days | Sudden onset of sore throat, fever, irritability, neck stiffness
56
Pathogens causing bacterial meningitis
Haemophilus influenzae Streptococuus Pneumoniae Neisseria meningitides
57
Treatment for bacterial meningitis
Ceftriaxone - cephalosporin 2-4g daily by IV infusion or IV injection or deep intramuscular injection
58
Viral meningitis
Most common type of meningitis Milder disease than bacterial meningitis, w/ headache, fever and photophobia but less neck stiffness CSF is clear
59
Tetanus
Cl. tetani toxin is carried to CNS in peripheral nerve axons
60
Spores carrying tetanus
Widespread in soil and originate from fences of domestic animals Spores enter wound and if necrotic tissue or the presence of a foreign body permits local and anaerobic growth ---> tetanospasmin is produced
61
FUO
Fever of Unknown Origin
62
Common causes of FUO
``` Bacterial infections Viral infections Malignancy Automimmue Miscellaneous ```
63
Bacterial infections causing FUO
OM, abscess, infective endocarditis, typhoid fever
64
Viral infections causing FUO
EBV Enterovirus Adenovirus
65
Malignancy causing FUO
Leukaemia Lymphoma Neuroblastoma
66
Autoimmune conditions causing FUO
SLE | IBD
67
Miscellaneous conditions causing FUO
Kawasaki disease Drug fever Periodic fever
68
Causes of infective endocarditis
Native valves are usually infected by oral streptococci and staphylococci
69
Bacterial endocarditis signs
FROM JANE ``` Fever Roth spot Oster nodes Murmur Janeway lesions Anaemia Nail bed haemorrhage Emboli ```
70
When should sepsis be treated
Within 1 hr w/ Abx
71
Blood clotting
Disseminated intravascular coagulation
72
Sepsis 3
Low systolic pressure (<100 mmHg) Increased respiratory rate (>22 breaths/ min) Altered mental state
73
Body sites that are usually sterile
``` Blood and bone marrow Cerebrospinal fluid Serous fluids Tissues Lower respiratory tract Bladder ```
74
Body sites that have normal commensal organisms
``` Mouth, nose and upper respiratory tract Skin Gastrointestinal tract Female genital tract Urethra ```
75
Main 3 factors leading to infection
Host Environment Pathogen factors
76
Koch's postulates
The microbe must be present in every case of the disease. The microbe must be isolated from the diseased host and grown in pure culture. The disease must be reproduced when a pure culture is introduced into a non-diseased-susceptible host. The microbe must be recoverable from an experimentally infected host.
77
Functions of toxins
Promote bacterial survival by killing cells of the defence system Killing other cells Disabling tissue function,
78
Exotoxins
Substances produced by bacteria with a variety of functions
79
Nerve stimulating toxins
Staphylococcal enterotoxins act on gut nerves, which signal to the brain to cause vomiting
80
Toxins as super antigens
Activating many T lymphocytes, with the release of many cytokines, especially tumour necrosis factor (TNF), causing shock
81
Endotoxins
Produced by Gram -ve bacteria | Stimulate macrophages to release cytokines, TNF and IL1
82
How can HCAI be acquired
``` Exogenous source (e.g. from another patient – cross-infection) Endogenous source (i.e. another site within the patient – self- or auto-infection). ```
83
Reducing risks of post-operative infections
Preoperative stay minimised Any infections treated before Operations kept to minimum w/ good air flow - laminar air flow Adequate debridement
84
Reducing the risk of infection in surgery
``` Abx and prophylaxis Foot flow – minimising coming in and out People in theatre Air flow directed away from pt Scrubbing and hand washing Reduce contamination n Sterile environment ```

MBBS - Year 1 (93 decks)

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