Week 13 - Microbiology II Flashcards
Fever
An increase in hypothalamic setpoints:
- pyrogeniccytokines → increased prostaglandin e2 → signals Hypothalamic set range increase → leads to fever
Fever symptoms
1 decreased cutaneous blood flow = perception of chills
2. Shivering to generate heat to match rapid rise in setpoint.
3. Thermogenesis from brown fat
Fever range.
Practical →
38 C
monitor closely 37.7 -39.9
suggested –>
AM temperature > 37.2 C
PM temperature >37.8 C
Febrile Neutropenia
Fever and Neutropenia
- Fever – >38.3 C x1 orally or > 38 C for over 1 hr
- Neutropenia - low neutrophil count
- ANC <500 cells/mm3
- ANC <1000 cells/mm3 with predicted decr to <500 cells/mm3
- typically occurs in patients undergoing chemotherapy (suppressed WBC) . neutrophils fall low –> patient cant fight infection
Fever of unknown origin
- > 38.3C
- no cause after initial standard investigations
- not applicable to:
- immunocompromised patients
- nosocomial acquisition
- returned travelers
- children
(groups with other potential differentials and sets of causes than a healthy person in community)
3 Parameters of risk for BBV transmission
Healthcare setting
- Risk in type of percutaneous injury
- Risk of the contaminated instrument or HCW /patient’s blood contacting the other person’s blood
- Susceptibility of individual exposed
the 3s
Risk of BBV transmission
HIV, HCV, HBV - patient to healtcare worker
- HIV - 1in 300
- HCV - 1 in 30
- HBV - 1 in 3
Risk of BBV transmission
HIV, HCV HBV - HC worker to patient
- HIV - 1 in 42000
- HCV - 1 in 1750
- HBV - 1 in 420
Reflects the amount of circulating virus in the blood
Risk of injury
- long complicated surgery - greater risk of sustaining injury while operating on the patient
- expertise is a factor
- compliance with Infection Prevention and Control practices
- Experience or training level (students more likely)
Risk of Transmission
- nature of injury (deep vs superficial)
- Frequency of injury ( those performing exposure prone procedures)
- Volume of blood (volume of virus in the blood) present during exposure
- viral load (amount of Virus ciruclating in the person)
- fitness of the virus (virus infectivity)
- suceptibility of exposed individual (no vaccine for HIV or HCV)
Risk of Percutaneous Exposure to BBV
- Deep intramuscular injury
- visible blood on sharp device
- meedle used to enter blood vesel
- HCW or source patient with terminal AIDS or HEP with high viral load
- Lack of PEP
Managing exposure to BBV
- Assess type of exposure/injury
- Assess status of source patient and HCW (are they carrying the virus and how much in the blood)
- Assess Vaccination and Immume status of HCW and patient
- Assess Overall Health status (underlying health concern, medication, allergy)
HBV Exposure Management
- someone exposed and not immune -> give HBV immuge globulin (HBIG) gives instant antibodies as protection
- get HBV vaccine for long term protection
- timeline is 72 hours post incident
HCV Exposure Management
- no vaccine for prophylaxis
- regualr followup and monitoring, especially if symptoms develop
- early treatment increases chances of clearing virus
HIV Exposure Management
Risk of infection after:
a. percutaneous exposure - 0.3 %
b. mucus membrane exposure - 0.1%
c. skin exposure - <0.1%
- antiviral therapy is used in combination for prophylaxis post exposure - reduses risk by 80%
- prophylaxis should be taken ideally within 2 hours, up to 72 hours.
- combination theraphy for 4 weeks
- expensive
- side effects - nausea, fatigue, headache, vomiting
- apply first aid to injury site (make sure immunizations are up to date and given.)
-
BBV Exposure HCW/Patient Followup
- baseline bloodwork for HIV HBV HCV
- want to know if theyre immune
- BAseline Liver Function tests (LFTs) - if giving prophylaxis want to make sure liver works properly
- baseline viral load - chance of transmitting
- council HCW/patient on the risk, potential risks/benefits or PEP, follow up about 2degree transmission
- followup testing (6, 12, 24 weeks)
- monitoring for side effects/toxicity
Exposure Prone Procedures
invasive procedures with higher than average risk that injury to HCW may lead to exposure of patient’s open tissues to the blood or body fluid of the healthcare worker (dental procedures, surgery)
Parasite
An organism deriving nutrients from another organism (host) at the expense of the host
Host
Organism that harbors the parasite
3 Types of Hosts
- **Definitive host **- the host where the parasite is in its adult stage (complete sexual reproduction) ex. malaria - mosquito is the definitive host
- Intermediate Host - host organism where the parasite is in its larval stage or complete asexual cycle of development. ex. malaria - humans
- Accidental Host - the host organism not normally infected by the parasite
Classification of parasites
- Protozoa - unicellular
- Helminths - worms
- Arthropods - invertebrates
Protozoa
divided into Amoebae, flagellates (incl. kinetoplastid flagellates) cilliates and apicomplexans
- differentiated by locomotion
- amoebae - pseodopodia
- flagellated - flagella
- cilliates - cilia
- apicomplexans - no external organelles for locomotion, use microtubules for small moving
Protozoa - Ameobae
locomotion - pseodopodia
- divided into free living or facultative
-** free-living** - can live in the environment without a host
- ex nigleria fowleri aka braineating disease
-** facultative** behave as a parasite but do not rely on host to complete life cycle
- organisms here mostly non pathogenic except entomeoba histolytica (can cause gastro symptoms or ameobic liver abscess
Protozoa - Flagellates
Locomotion - flagella
- can be pathogenic or non pathogenic
- wellknown examples :
- Giardia lamblia - gastroint issues
- Trichomonas vaginalis - sexually transmitted disease
- Kinetoplastic flagellates
- Trypanosomes - cause human African Trypanosomiasis or African Sleeping sickness
- American illness call Chagas
- Leishamania spp. - cause cutaneous and visceral or organ disease
- both new world and old world species
