Microbiology 2 Flashcards
(350 cards)
what is infection?
process of foreign organisms invading and multiplying in or on a host
- infectious diseases are the main cause of morbidity and mortality in man, especially in areas where they’re associated with poverty and overcrowding
what has reduced the prevalence of infectious disease in the developed world?
- increasing prosperity, universal immunisation and antibiotics
- HIV, vCJD, avian influenza and pandemic H1N1 influenza have emerged
what is increased global morbidity being caused by?
- enforced (war, civil unrest and natural disaster)
- voluntary (tourism and economic benefit)
what is the epidemiology of HIV/AIDS?
- first description of AIDS in 1981
- identification of the causative organism in 1984
- 20 million deaths
- 33 million people living with it
- Sub-Saharan Africa is most seriously affected
- infection rates rising exponentially in Eastern Europe and parts of central Asia
- 33% of 15 year olds in high-prevalence countries in Africa will die
- demographics of the epidemic are influenced by social, behavioural, cultural and political factors
what is HAART? what is its effect on morbidity/mortality of HIV/AIDS?
highly active antiretroviral therapy
- reduced mortality for those who can access care
- a quarter of those who need treatment are on it
- for each individual starting therapy, there are two new infections
what are the largest groups of people living with HIV in the UK?
- men who have sex with men (MSM)
- culturally diverse heterosexual populations from sub-Saharan Africa
what percent of people diagnosed with HIV in the UK are women?
30%
what is the most common cause of HIV-related morbidity and mortality in the UK?
- 1/4 of those with HIV in the UK are undiagnosed and unaware of their infection
- leads to late diagnosis, poorer clinical outcomes and onward transmission
- late diagnosis is most common cause
what are the clinical settings in which all patients should be offered HIV testing?
- GUM/sexual health clinics
- antenatal services
- termination of pregnancy services
- drug dependency programmes
- healthcare services for TB, hepB, hepC and lymphoma
what are people in whom HIV testing is recommended?
- all patients diagnosed with an STI
- sexual partners of men and women known to be HIV positive
- men who have disclosed sexual contact with other men
- female sexual contacts of MSM
- IV drug users
- men and women from a country of high HIV prevalence (>1%)
- men and women who have sex with people from countries of high HIV prevalence
- patients presenting for healthcare where HIV enters the differential diagnosis
what are HIV-associated indicator respiratory conditions?
TB, pneumocystitis, bacterial pneumonia, aspergillosis
what are HIV-associated indicator neurological conditions?
- cerebral toxoplasmosis
- primary cerebral lymphoma
- cryptococcal meningitis
- progressive multifocal leucoencephalopathy
- aseptic meningitis/encephalitis
- cerebral abscess
- space-occupying lesion of unknown cause
- Guillain-Barre syndrome
- transverse myelitis
- peripheral neuropathy
- dementia
what are HIV-associated indicator dermatological conditions?
- Kaposi’s sarcoma
- severe/recalcitrant seborrhoeic dermatitis
- severe/recalcitrant psoriasis
- multidermatomal/recurrent herpes zoster
what are HIV-associated indicator gastroenterological conditions?
- peristent cryptosporidiosis
- oral candidiasis
- oral hairy leukoplakia
- chronic diarrhoea of unknown cause
- weight loss of unknown cause
- Salmonella, Shigella, Campylobacter
- hepB and hepC
what are HIV-associated indicator oncological conditions?
- non-Hodgkin’s lymphoma
- anal cancer
- anal intraeptihelial dysplasia
- lung cancer
- seminoma
- head and neck cancer
- Hodgkin’s lymphoma
- Castleman’s disease
what are HIV-associated indicator gynaecological conditions?
- cervical cancer
- vaginal intraepithelial neoplasia
- cervical intraepithelial neoplasia, grade 2 or above
what are HIV-associated indicator haematological conditions?
any unexplained blood dyscrasia including thrombocytopenia, neutropenia and lymphopenia
what are HIV-associated indicator opthalmological conditions?
- cytomegalovirus retinitis
- infective retinal diseases including herpesviruses and toxoplasma
- any unexplained retinopathy
what are HIV-associated indicator ENT conditions?
- lymphadenopathy of unknown cause
- chronic parotitis
- lymphoepithelial parotid cysts
what are HIV-associated indicator miscellaneous conditions?
- mononucleosis-like syndrome
- pyrexia of unknown origin
- any lymphadenopathy of unknown cause
- any STI
what are routes of acquisition of HIV?
majority of infections are transmitted via semen, cervical secretions and blood
- sexual intercourse (vaginal and anal)
- mother to child (transplacental, perinatal, breast feeding)
- contaminated blood, blood products and organ donations
- contaminated needles (IV drug misuse, injections, needle-stick injuries)
what are features of sexual intercourse as a route of acquisition of HIV?
- heterosexual intercourse accounts for the vast majority of infections and co-existent STIs, especially those causing genital ulceration
- passage of HIV is more efficient from men to women and to the receptive partner in anal intercourse, than vice versa
- in the UK, sex between men accounts for over half the infections reported
- in Central and sub-Saharan Africa, the epidemic has always been heterosexual and more than half the infected adults are women
- South-east Asia and India are having an explosive epidemic, driven by heterosexual intercourse and a high incidence of other STIs
what are features of mother-to-child acquisition of HIV?
- transplacental, perinatal, breast feeding
- increased vertical transmission is associated with advanced disease in the mother, maternal viral load, prolonged and premature rupture of membranes and chorioamnionitis
- transmission can occur in utero
- most infections occur perinatally
- breast-feeding doubles the risk of vertical transmission
- in the developed world, interventions to reduce vertical transmission, e.g. use of antiretroviral agents and avoidance of breast feeding, has reduced number of infected children
what is HIV?
human immune deficiency virus
- belongs to the lentivirus group of the retrovirus family
- two types: HIV-1 and HIV-2