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Septic arthritis - causative organism
19 - 30yo commonest is Neisseria gonnorhoea, the arthritis occurs after an asymptomatic period. Take a sexual history in a young person with a single inflammed joint!
Gram Negative Bacteria
- Do not retain crystal violet as outer membrane prevents it getting in
- Retain safranin (red)
- Have 2 membranes:
- 1. cytoplasmic membrane
- ------ thin peptidoglycan layer
- ----- periplasmic space
- 2. outer membrane containing LPS and porins
- LPS includes lipid A, a core polysaccharide and the O Ag
Gram Negative Bacteria
- more antibody resistant (impenetrable wall)
- pathogenesis may be associated with cell envelope especially LPS (endotoxin) layer- LPS --> cytokines --> inflammation
- don't sporulate (except Coxiella burnetii)
Retain crystal violet after washing
- salmonella typhi (G-)
- salmonella paratyphi
21d or less
stepwise temperature increase, malaria has been excluded, abdo symptoms, relative bradycardia (expect heart rate to increase by 15bpm for each degress above 37ish so tachycardia expected if pyrexial. 80 - 90 therefore = bradycardia).
"= 2 - 3mm pale pink spots, mainly on torso
"pea soup" diarrhoea or constipation.
blood and stool cultures diagnostic. EXCLUDE MALARIA.
GI perforation, bleeding
2 - 6 weeks
flu-like prodrome (2 weeks), icteric hepatitis (2 weeks - 3 months). May be asymptomatic in <5yo
faecal-oral (sometimes sexual, especially in MSM)
moratlity ~1-%, increased in >40yo, CLD, HepB or C or EtOH
- Investigations:1. hepatitic biochemistry (high AST/ALT, BR, mildly high ALP)
- 2. IgM anti-HAV using EIA
symptom control, rest, hydration, outpatient care. May give Ig or HAV vaccine to contacts.
Biochemisty of Acute Viral Hepatitis
ALT and AST 500 - 10,000 IU/L in first few weeks
BR 30 - 100 umol/L, conj and unconj and bilirubinuria
PT 1 - 5 seconds prolonged. (>5s suggests impending hepatic failure)
global majority acquired vertically. Efficient sexual transmission.
10% get chronic HBV (antigen + for >6mo), typically asymptomatic until cirrhosis and decompensated liver disease - ascites, jaundice, varices, confusion, cachexia, death.
- Clinical: asymptomatic in children and immunosuppressed. ~30% icteric, can --> fulminant hepatitis, cirrhosis, and hepatocellular cancer.
- 1% get fulminant hepatitis - decompensated liver disease, 50% mortality.
10% with cirrhosis --> Ca (enlagring liver, weight loss, death).
- 1. hepatitic biochemistry when acute (high AST/ALT, BR, mildly high ALP) OR mildly high AST/ALT when chronic
- 2. Worsening LFT and PT if cirrhosis or Ca
- 3. Serology - sAg proves infection. e and c are also useful and DNA is the most sensitive assay. NB. some mutations give HBeAg negative active infection (pre-core mutations).
symptom control, fluids, rest. Lamivudine, adeofovir, inteferon. Liver transplant (if cirrhosis/Ca).
Hepatitis B Serology
sAb = antibodies against the surface - positive with any exposure, incluidng infection and vaccination
eAb = antibodies against the core - positive in anyone who has had replicating virus in them - infected, chronic, carrier, and had previously but now cleared.
sAg = surface antigen - positive if currently have virus or recently vaccinated
eAg = core antigen - positive if currently replicating virus in the system - infected and infectious
HBV-DNA = DNA of the virus, positive if currently replicating virus in the system - infected and infectious
Hepatitis D (delta)
RNA virus, only occurs as co-infection with HBV
sexual, IVDU. Acquired with acute HBV or as superinfection during chronis HBV. (May get two acute bouts of virus.)
3 - 7 weeks
- Clinical: 10x more likely to be fulminant, 80% fatal.
- When + acute HBV: severe icteric hepatitis (--> chronic in 80%). More rapid progression to cirrhosis and Ca.
serum anti-HDV (antigen and RNA tests also possible)
no effective antivirals. HBV vaccination and protective behaviour.
Transmission: IVDU, vertical (esp is HIV coinfection), some sexual (esp if HIV)
Incubation: 150 days
Clinical: ~20% are icteric, mainly asymptomatic. Fulminant rare unless HAV superinfection. 80% --> chronic HCV. ~20% develop cirrhosis 20 years later. 5% develop Ca 20 - 30 years later. Cirrhosis more likely and more rapid with HIV, HBV or EtOH.
Investigations: Ab assays (may be negative for first 9 months). ELISA for screening, RIBA for confirmation. PCR.
Management: no vaccine. Education and prevention. Vaccinate for HAV and HBV. pegylated inteferon injections + 6 - 12mo of ribavirin is curative for 50% (expensive).
- gram negative
- obligate intracellular cocci
- 3 human biovars:
- -- Ab, B, Ba, C = trachoma in the eyes
- -- D - K = STI cervicitis, urethritis, PID, neonatal pneumonia and conjunctivitis
- -- L1 - L3 = LGV
Symptoms of Chlamydia
- post-coital bleeding
- dysuria (especially in men)
- mucopurulent discharge in men
- pelvic pain
- cobble-stone appearance of cervix
- 50% women and 80% men aysmptomatic
- 2 week incubation
Sequelae of Chlamydia
- salpingitis, PID
- subsequent ectopic pregnancy
- perihepatitis (if ascends into abdomen)
- conjunctivitis (neonatorum)
- Reiter's disease
ascending chlamydia enters the abdomenal cavity and causes perihepatitis??
Diagnosis of Chlamydia
- urine antigen detection
- vaginal swab culture
Management of Chlamydia
- contact tracing
Lymphogranuloma Venerum (LGV)
- Chlamydia trachomatis
- L1, L2, L2a or L3
- infects lymphatics then monocytes
- commoner in MSM
- commoner in HIV infection
- primary stage: painless ulcer
- secondary: buboes and lymphangitis
- tertiary: fibrosis and long-term oedema
LGV - Primary Stage
- painless genital ulcer 3 - 12 days after infection
- self-resolving, often goes unnoticed
- 10% get Erythema Nodosum
LGV Secondary Stage
- 10 - 30 days after primary stage
- unilateral buboes - inflammed LN in groin
- lymphangitis, e.g. dorsal penis (cord-like)
- proctitis or proctocolitis
- cervicitis, perimetritis, salpingitis
- fever, malaise, anorexia
- painful enlarged inguinal LN
- inflammation --> thin skin, fixation
- progress to: necrosis, flutuant/suppurative LN, abscess, fistula, stricture, sinus tract, fibrosis obstructing lymphatics, chronic oedema
Symptoms of Proctitis
(distal 10 - 12cm)
- anorectal pain
- rectal discharge
Symptoms of Proctocolitis
(>12cm from anus)
- anorectal pain
- rectal discharge
- abdominal cramps
- Plasmodium: falciparum (deadliest), vivax, ovale, malariae
- Falciparum has most cases in UK and increasing.
- Malaria is 22% of the cases of fever in the returning traveller in the UK
subsaharan African (incl Ghana, Nigeria, Kenya), India, Southeast Asia, Central America and the northern part of South America
Clinical differentials may include:
- Clinical: fevers and rigors (acute phase response), flu-like syndrome, cough, diarrhoea, jaundice
- NB. not typically rash or lymphadenopathy
flu, URTI, gastroenteritis, hepatitis
- - blood film: thick blood film shows plasmodium, thin film shows subtype. 3 may be needed 24 h apart. Not diagnostic if patient is on semi-immunosuppressant levels of antimalarials.
- see "ring form" of RBC containing small parasite that has an eosinophilic nucleus, basophillic cytoplasm and a vacuole in the middle. Classify parasitaemia as % of the RBC on the film containing parasites.
- lyssa virus
- an enveloped ssRNA with negative sense
- family: rhabdoviridae
Transmitted by bats, monkeys, cattle
travels up peripheral nerves, incubation depends on distance to travel
Rabies - Signs and Symptoms
Early: malaise, headache, fever (early encephalitis)
Mid: acute pain, violent movements, slight or partial paralysis, mania, depression, hydrophobia, hypersalivation, paranoia, hallucinations. Sometimes inflammation of spinal cord → transverse myelitis.
Late: mania, lethargy, confusion, coma, renal failure
Rabies - Investigation and Management
hx, examine animal which bit, Negri inclusion bodies
(eosinophilic, sharp outlines in cytoplasm of neurons, they are proteins produced by the virus)
- Management: 1. Thoroughly wash wound (reduces number of viral particles) - iodine or alcohol, or flush mucus membranes with water
- 2. If no pre-exposure vaccine: Human Rabies Immunoglobulin (1 dose) <20U/kg - around bite as much as possible, the rest as deep IM in
- distant site
- 3. rabies vaccine (4 doses over 14 days) PEP within 10 days can be up to 100% effective.
BUT rabies is usually fatal (respiratory insufficiency) once neuro symptoms begin.
Enzyme-linked immunosorbent assay
- 1. Sample Ag applied to surface
- 2. Ab-enzyme complex to this Ag applied
- 3. Enzyme's substrate is added
- flagellated protazoan
- invades superficial epithelium of urogenital tract
Symptoms of Trichomonas Infection (females)
- offensive, frothy, greeny-grey discharge
- strawberry cervix (punctate erythema)
- (asymptomatic in males)
Management of Trichomonas Vaginalis
- gram negative diplococcus
- infects mucosal surface of genito-urinary tract, rectum and pharynx
- typically asymptomatic
Complications of Gonnorrhoea
- Bartholin's abscess
- salpingitis +/- irreversible tubal damage
Symptoms of Gonorrhoea (males)
- mucopurulent discharge 3 - 5d after exposure
- meatal oedema
- (females usually symptomatic)
Disseminated Gonnococcal Infection
- <1% cases
- vasculitic rash
- managed with antibiotics (culture for sensitivity)
- mixed anaerobic flora
- may include Gardnerella vaginalis, Mycoplasma hominis
- creamy grey discharge
- fishy odour
- no itching
- risk of preterm delivery and late miscarriage if present in pregnancy