Microbiology Flashcards
How do you diagnose malaria?
History, antigen testing, blood films to see what species, PCR
Secondary immunodeficiency
Due to an underlying disease state eg. cancer or diabetes. Or a treatment for disease eg. chemo/radiotherapy. Common.
How do inhibitors of folate synthesis work?
Inhibition of folate metabolism pathway leads to impaired nucleotide synthesis and therefore impaired DNA replication.
What antibiotics do you treat mycoplasma pneumoniae with?
Can’t treat with beta-lactams since bacteria doesn’t have a cell wall. Need to treat with intracellular antibiotics like macrolides, tetracyclines and quinolones.
What does selective media do?
Used in diagnosis of GI infection. Suppresses growth of background flora while allowing growth of the pathogen.
What antibiotics target the 50S ribosomal subunit?
- Macrolides
- Clindamycin
- Chloramphenicol
When is vancomycin given orally?
Only in the treatment of C. diff. Normally given as IV.
Name two beta-lactamase inhibitors and say how they work
1) Clavulanic acid. 2) Tazobactam. The inhibit beta-lactamases produced by bacteria. This greatly broadens the spectrum of penicillins against gram -ves and S. aureus.
Name two causes of primary immunodeficieny
1) DiGeorge Syndrome (cellular immunity)
2) Bruton agammaglobulinaemia (Humoral immunity)
Rhinovirus
Picornaviridae virus. ssRNA. RV-A, RV-B and RV-C. >100 types. Cause of common cold.
What is neutropaenia?
Abnormally low levels of neutrohils <0.5x10^9/L or <1.0x10^9/L and falling. Predisposes person to infection risk.
Name the macrolide antibiotics
- Erythromycin
- Clarithromycin
- Azithromycin
Empirical therapy
Best (educated) guess therapy based on clinical/epidemiological acumen. Used when therapy cannot wait for culture.
Diarrhoea
Abnormal frequency and/or fluid stool. Usually indicates small bowel disease. Causes fluid and electrolyte loss. Severity varies widely from mild self-limiting to severe/fatal (due to virulence of organism and degree of compromise of the host)
Name some risk factors for STIs
- unprotected sex
- young age 15-24 y.o.
- multiple partners
- sex workers
- urban areas
- illicit drug and alcohol abuse
OHPAT
outpatient and home parenteral antimicrobial treatment
Monobactams
Only member is Aztreonam. IV. No cross reactivity with penicillins so can be given to those with a penicillin allergy (except anaphylaxis).
What are the 4 plasmodium species responsible for human malaria?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Which two bacteria can lead to Guillain-Barre syndrome?
- Mycoplasma pneumoniae
- Campylobacter
What is Vertebral discitis?
Infection of a disc space and adjacent vertebral end plates.
MoA of beta lactam anitbiotics.
They inhibit cross-linking of cell wall peptidoglycan. Causes lysis of the bacteria-bactericidal.
What are the top 3 types of illnesses that travellers get?
1) Gastrointestinal disease
2) Febrile illness
3) Dermatological
Resection arthroplasty
Taking the diseased joint out and putting in an artificial one.
Bronchiolitis
Lower respiratory tract infection of young children-common cause of hospitalisation. Causes wheezing and tachycardia. RSV is the most common cause.
HIV PEPSE
HIV post exposure prophylaxis after sexual exposure
What are the uses of Chloramphenicol?
- Topical therapy to eyes.
- Bacterial meningitis with beta-lactam allergy.
Norovirus
Non-enveloped, single stranded RNA virus. Can cause viral gastronenteritis. Can affect all ages. Very small infectious dose (10-100 virions).
What are risk factors for joint infection in primary arthroplasty?
RA, DM, poor nutritional status, obesity, concurrent UTI, steroids, malignancy.
What virus is the most common cause of Croup?
Parainfluenza virus
What is Trimethoprim used to treat?
Uncomplicated UTI
What is erysipelas?
Erysipelas is a superficial form of cellulitis, a potentially serious bacterial infection affecting the skin.
Erysipelas affects the upper dermis and extends into the superficial cutaneous lymphatics. It is also known as St. Anthony’s fire, with reference to the intense rash associated with it.
What are the symptoms of ‘typical’ pneumonia?
Abrupt onset-cough, fever, pleuritic chest pain.
What is DAIR and what does it relate to?
DAIR= Debride, antibiotics and implant retained. Relates to joint infection. If infection occurs less than 30 days since insertion of prothesis then it is still functional, debridement and washout can occur of joint then 4-6 weeks of IV antibiotics started.
What is the incubation period of plasmodium falciparum?
7-14 days
Guided antibiotic therapy
Depends on identifying cause of infection and selecting agent based on sensitivity testing.
What is an influenza pandemic?
Worldwide epidemics of a newly emerged strain of influenza. Few people have immunity to the new virus, this allows it to spread widely and cause more serious illness.
Name two Quinolones
Ciprofloxacin and Levofloxacin
What type of HPV causes genital warts?
Type 6 and 11
Which drug can cause Red Man Syndrome and what is it?
Vancomycin if injected too quickly. It is an anaphylactoid reaction (similar clinical picture to anaphylaxis but not IgE mediated). Very rare nowadays.
What interactions does Rifampicin have?
It is a potent CYP450 enzyme inducer. Most drugs that undergo hepatic metabolism affected.
What is Gentamicin highly effective against?
E. Coli and other coliforms as well as pseudomonas.
Plasmodium Ovale
Usually West Africa, persistent liver infection, can relapse. No drug resistance.
Pneumococcal
Gram-positive diplococci.
What drug interactions does macrolide have?
- Simvastation (temporarily stop it)
- Atorvastatin
- Warfarin
What are the side effects of aminoglycosides eg. Gentamicin?
- Nephrotoxicity
- Ototoxicity
- Neuromuscular blockade
What is ‘antibiotic spectrum’?
Spectrum refers to the range of bacterial species effectively treated by the antibiotic.
Why should you avoid Tetracyclines in pregnant women and children?
Can lead to bone abnormalities and tooth discolouration.
What microorganisms cause ‘typical’ pneumonia?
Streptococcus pneumniae, Haemophilus influenzae, Moraxella catharralis.
What virus is the most common cause of Pneumonia?
Influenza
Plasmodium vivax
Worldwide but most commonly the Asian subcontinent. Persistent liver infection, can result in relapse months after initial infection, some Chloroquine resistance in SE Asia.
What is Palivizumab used for?
A prophylactic monoclonal antibody used to treat RSV. Given IM monthly. Can reduce hospitalisations of high risk infants by 45%.
STEC infection
Shiga toxin producing E. Coli infection
What are the barriers to GI infection in the large intestine?
Epithelial turnover and normal flora.
What are the barriers to GI infection in the stomach?
Acid pH
How do you diagnose legionella pneumophila?
With a urinary antigen test.
Why must malarial prophylaxis drugs need to be taken still when you are back from travels?
As the malaria parasites could be in the pre-erthyrocytic stage in the liver.
What are the side effects of Chloramphenicol?
It is very toxic, can lead to bone marrow suppression, aplastic anaemia and optic neuritis.
Arthrosis
A joint
Cephalosporins
Good activity against gram positive and gram negative. Less susceptible to beta-lactamases than penicillin. Multiple generations of cephalosporins.
What are the side effects of metronidazole?
Causes an unpleasant reaction with alcohol and can cause peripheral neuropathy with long term use.
What is ‘pleocytosis’?
The presence of an abnormally large number of lymphocytes in the cerebrospinal fluid.
What is neutropaenic fever?
Neutropenic fever is a single oral temperature of 38.3º C (101º F) or a temperature of greater than 38.0º C ( 100.4º F) sustained for more than 1 hour in a patient with neutropenia. Infection until proven otherwise.
Anopheline mosquito
Transmits malaria. Dusk until dawn.
Broad spectrum antibiotics
Antibiotics that are active against a wide range of bacteria.
Treat most causes of infection but also have a substantial effect on colonising bacteria.
What are the barriers to GI infection in the small intestine?
Mucous, bile, secretory IgA, lymphoid tissue (Peye’r patches), epithelial turnover, normal gut flora.
Benzyl-penicillin
Highly active against streptococci. Most other disease causing bacteria are resistant. Narrow spectrum.
Arthrodesis
Fusing two bones together
What is viral gastroenteritis?
Inflammation of the stomach and intestine caused by virus(es). Children under 5, old people, immunocompromised people.
What are the two indications for using Rifampicin?
1) Tuberculosis (in combination therapy).
2) In addition to another antibiotic in serious gram +ve infection (esp. S. Aureus).
What is the incubation period of plasmodium vivax?
12-17 days
What are the treatments for enteric fever?
Quinolones, Cephalosporins and Azithromycin.
What is a Ghon’s complex?
A lesion seen in the lung that is caused by tuberculosis. The lesions consist of a calcified focus of infection and an associated lymph node.
What is an ‘undetectable’ viral load when talking about HIV?
Below 40 copies/ml. Below 10,000 is low, above 100,00 is high.
Croup
A commonly encountered childhood infectious syndrome that has a distinctive cough. Treatment is supportive. Mainly caused by parainfluenza virus.
What is chronic granulomatous disease?
An X-linked inherited disorder with deficiency in the gene coding for NADPH oxidase- deficient production of oxygen radicals and intracellular killing leading to recurrent bacterial and fungal infections. Inflammatory response with widespread granuloma formation.
What are the adverse effects associated with macrolides?
- Diarrhoea and vomiting
- QT prolongation
- Hearing loss with long term use.
What are the barriers to GI infection in the mouth?
Lysozyme
What is an epidemic?
Infectious disease spread rapidly to many people eg. 2003 severe acute respiratory syndrome (SARS). Caused by antigenic drift.
Pharyngitis
Sore throat and pharyngeal inflammation. Viral infections in 25-45% of cases. Not just caused by respiratory viruses.
What are the contra- indications to lumbar puncture in bacterial meningitis?
If it will delay antibiotic therapy or if on CT scan there is evidence of cerebral oedema or mass effect.
What factors affect the severity of diarrhoea?
1) Virulence of causative organism.
2) Degree of compromise of the host.
What are the 6 diarrhoeagenic groups of E. Coli?
1) Enteropathogenic E. Coli (EPEC)
2) Enterotoxigenic E. Coli (ETEC)
3) Enterohaemorrhagic E. Coli (EHEC)
4) Enteroinvasive E. COli (EIEC)
5) Entero-aggregative E. Coli (EAEC)
6) Diffuse aggregative E. Coli (DAEC)
Arhtroplasty
Putting in an artificial joint.
What is HAART?
Highly Active Anti Retroviral Treatment (for HIV). A triple therapy of 2 nucleosides and 1 drug from another class (hit HIV at different parts of its replication cycle).
What is a PJI?
Prosthetic joint infection.
What is Stevens-Johnson syndrome?
Type IV hypersensitivty reaction to pencillin. S-J syndrome is a rare, serious disorder of your skin and mucous membranes. It’s usually a reaction to a medication or an infection. Often, it begins with flu-like symptoms, followed by a painful red or purplish rash that spreads and blisters. Then the top layer of the affected skin dies, sheds and then heals.
Stevens-Johnson syndrome is a medical emergency that usually requires hospitalization.
Aedes mosquito
Transmits Dengue and Yellow fever. A day biter.
What is the CURB65 score?
Used for clinical assessment of pneumonia.
C-Confusion
U-urea >7
R-Respiratory rate > or equal to 30
B-BP, diastolic <60 or systolic <90
65-Age over 65 years.
Multilobular consolidation on CXR and/or hypoxia on room air.
What antibiotics target the 30S ribosomal subunit?
- Aminoglycosides eg. gentamicin
- Tetracyclines eg. Doxycycline
What is the incubation period of plasmodium malaria?
18-40 days (>1yr)
What is faecal-oral GI transmission route?
Any means by which infectious organisms from human/animal faeces gain access to GIT of another susceptible host.
Carbapenems
eg. Meropenem. Ultra-broad spectrum antibiotics. No activity against MRSA. Resistant to beta-lactamases.
Define bacterial intoxication (poisoning)
Bacterial pathogens grow in food and produce toxins eg. S. Aureus. Bacillus cereus. Relative short incubation time because of preformed toxin in food.
Why do negative cultures not necessarily exclude infection?
1) Bacteria may have been present in small numbers and take a long time to grow.
2) Bacteria may have died in transit if there was a delay in reaching the lab or if it was a fastidious organism eg. anaerobes.
3) Antibiotics may have been given pre-op.
What are ‘rose spots’?
Red macules, 2-4mm in diameter occurring in patients with enteric fever.
What virus is the most common cause of acute bronchitis?
Respiratory syncytial virus
What antibiotic might you give to treat Chlamydia?
Azithromycin 1g oral as a single dose or doxycycline or erythromycin for longer.
What is osteomyelitis?
Progressive infection of bone characterised by death of bone and the formation of sequestra.
What micrororganisms cause ‘atypical’ pneumonia?
Mycoplasma pneumoniae, Legionella penumoniae, Chlamydophila pneumoniae
Chlamydophila psittaci.
What is the commonest cause of acute renal failure of children in the UK?
Enterohaemorrhagic E. Coli
Rotavirus
Double stranded, non-enveloped RNA virus. Stable in environment and fairly resistant to hand washing.Low infectious dose (10-100 virus particles).
What examination findings will there be in ‘typical’ pneumonia?
Consolidation seen on CXR, dull percussion, coarse crepitations, increased vocal resonance.
What are the common pathogens in septic arthritis?
- MSSA or MRSA
- Streptococci (S. pyogenes, Group G Strep, pneumococcus (commoner in children)).
What are beta-lactamases?
Beta-lactamases are enzymes commonly secreted by gram –ve (except staph. Aureus that is gram +ve) bacteria that break down beta lactam antibiotics. The beta lactamase causes high levels of resistance to beta lactam bacteria.
What are the two most common beta-lactam/ beta-lactamase inhibitor combinations?
1) Co-amoxiclav= amoxicillin and clavulanic acid.
2) Piperacillin/tazobactam.
Meropenem
Active against almost all gram positive and gram negative species. Resistance is rare except in MRSA. Broad spectrum.
What is a pandemic?
A global disease outbreak eg. HIV/AIDS, or influenza. Caused by antigenic shift.
What are the 3F’s of GI infection transmission?
1) Food-contamination (farm to fork) and cross contamination (distribution chain or domestic kitchen)
2) Fluids-water/contaminated juices etc.
3) Fingers- importance of washing hands after toileting and before and/after preparing or consuming food and drinks.
What is MacConkey’s agar used for?
A type of differential media. Lactose fermenting colonies eg. E.Coli are pink whereas non-lactose fermenting ones (eg. Shigella spp.) are colourless. This particular medium is made more selective by addition of bile salts.
Bactericidal antibiotic
Achieve sterilisation of the infected site by directly killing bacteria. Rapid lysis of bacteria can release of toxins and inflammatory material-can be a problem in meningitis.
Why do prosthetic joints require fewer bacteria than normal tissue joints to establish sepsis?
Avascular surface allows the survival of bacteria as it protects from circulating immunological defences and most antibiotics. Cement can inhibit phagocytosis and lymphocyte/complement function.
Gastroenteritis
Nausea, vomiting, diarrhoea and abdominal discomfort.
What is the incubation period of plasmodium ovale?
15-18 days
What virus is the most common cause of pharyngitis?
Adenovirus
What is the first choice antibiotic for a serious streptococcal infection?
Benzylpenicillin.
Flucloxacillin
Synthetic penicillin highly active against S. Aureus (not MRSA) and streptococci. No activity at all against gram negative. Can be given orally but nausea limits dose.
What are clostridium difficile spores resistant to?
Heat, drying, disinfection and alcohol.
Risk factors for pneumonia due to Strep. pneumoniae?
Alcohol, smoking, influenza, immunosuppression (HIV), airways disease.
Define bacterial infection
When bacterial pathogens develop in the gut after ingestion of contaminated food eg. Salmonella, Campylobacter. Incubation time of at least 8-12hr before symptoms develop.
What does enrichment broth do?
Used in diagnosis of GI infection. Contains nutrients that promote preferential growth of the pathogen?
The 4C’s of C. diff
1) Clindamycin
2) Co-amoxiclav
3) Cephalosporins
4) Ciprofloxacin
What is the causative organism in Gonorrhea?
Gran-negative diplococcus bacteria
What bacteria cause enteric fever?
Salmonella typhi and salmonella paratyphi. These have a human only reservoir.
Plasmodium malariae
Worldwide, 10% occur>1 year after infection, no dormant liver infection. No drug resistance.
What types of adenovirus cause D&V?
Types 40 and 41. Adenovirus is a double stranded DNA virus.
What does differential media do?
Distinguishes mixed micro-organisms on the same plate. Uses biochemical characteristics of micro-organisms growing in the presence of specific nutrients combined with an indicator that changes colour.
What viruses most commonly cause the ‘common cold’?
Rhinovirus and Coronavirus
Sources of Legionella pneumophila?
Environmental things such as soil and water.
What are ‘fomites’?
Objects or materials which are likely to carry infection, such as clothes, utensils, and furniture.
Type I hypersensitivity to penicillin
Relatively common, 0.7-4% of penicillin courses. Urticarial rash, anaphylaxis can occur.
Narrow spectrum antibiotics
Antibiotics that are active against a limited range of bacteria.
Useful only where the cause of the infection is well defined.
Vancomycin
Inhibits cell wall formation in gram +ves (no gram -ve effect). Not dependent on penicillin binding protein so effective against resistant organisms. Very large molecule so give IV. Long half life so loading doses usually given.
What is the Jarisch-Herxheimer reaction and what does it relate to?
Antibiotic treatment of syphilis causes a sepsis-like picture due to the release of toxins from treponemal bacterium breakdown, therefore steroids are administered beforehand to prevent this.
What is ‘mass effect’?
The effect of a growing mass that results in secondary pathological effects by pushing on or displacing surrounding tissue.
Mefloquine
Anti-malarial. Taken once weekly. Psychiatric side effects-vivid dreams to psychosis.
How can a faecal microbiota transplant by administered?
- Enema
- Transcolonic infusion
- Nasoduodenal or nasogastric infusion.
Doxycicline
Anti-malarial. Taken daily. Photosensitisation.
Prophylactic therapy
Preventing infection before it begins. Important in modern medicine eg. chemotherapy and before surgery.
Revision arthroplasty
Re-operating on an artificial joint
What are the features of Dengue Haemorrhagic Fever?
Occurs in <1% of infections. Leads to increased vascular permeability, thrombocytopenia, fever and bleeding.
What are the risk factors for joint infection in a revision arthroplasty?
Prior joint surgery, prolonged operating room time, pre-op infection (teeth, skin, UTI).
Benzylpenicillin
IV. Similar to original penicillin. First choice for serious stretococcal infection eg. erysipelas. Narrow spectrum agent. Also quite good against Neisseria.
HIV PrEP
HIV pre-exposure prophylaxis
SIRS
Systemic Inflammatory Response Syndrome. SIRS is 2 or more of:
- temperature >38oC or <36oC
- tachycardia >90bpm
- tachypnoea RR>20/min
- WBC >12x10^9/L
What types of HPV cause over 90% of cases of cervical cancer?
Types 16 and 18
What is the incubation period of enteric fever?
5-21 days depending on age, gastric acidity, immune status and infectious load.
What groups make up Beta-lactam antibiotics?
Penicillins, Cephalosporins, Carbapenams, Monobactams.
What is Miliary TB?
Widespread dissemination of Mycobacterium tuberculosis via hematogenous spread. Classic miliary TB is defined as milletlike (mean, 2 mm; range, 1-5 mm) seeding of TB bacilli in the lung, as evidenced on chest radiography.
Pseudo-arthrosis
Allowing two bones to articulate against one another but without a joint eg. Girdlestone
What are the toxicities associated with Quinolones?
- GI toxicity
- QT prolongation
- Tendonitis
What is the current drug regime for TB?
Rifampicin, Isonizid, Pyrazinamide and Ethambutol.
What antibiotic would you use to treat MRSA?
Vancomycin
Plasmodium falciparum
Worldwide distribution, most important cause of malaria and the main cause of sever malaria and nearly all fatalities, no dormant live infection, drug resistance +++.
What antibiotic would you give to someone with an gram positive toxin meditated disease like toxic shock syndrome?
Clindamycin as it is highly effective at stopping exotoxin production.
Amoxicillin
Semi-synthetic penicillin, good activity against gram negative organisms (resistance now common). Much more orally bioavailable than natural penicillins. Good against a wide range of infections, very good against streptococcus and enterococcus.
What are some possible complications of Chlamydia infection?
- PID- increases risk of ectopic pregnancy and infertility.
- Epididymitis
- Prostatitis
- Reactive arthritis
Bacteriostatic antibitoic
Suppresses growth but does not directly sterilise infected site. Requires additional factors to clear bacteria- immune mediated killing.
How many million cases of infectious intestinal disease are there a year in the UK?
17 million
What is the causative organisms in Syphilis?
Treponema pallidum
How do you treat syphilis?
Give Benzathine Benzylpenicillin 1.8g intramuscular injection as a single dose as well as prednisolone for 3 days (start 24 hours prior to pencilling administration).
What is Abacavir?
An HIV treatment- a nucleoside reverse transcriptase inhibitor. Causes hypersensitivity in 5-8% of patients. People with HLA-B*5701 allele are affected.
Primary immunodeficiency
Inherited. Exposure in utero to environmental factors. Rare.
Define severe nutritional deficiency
=<75% ideal body weight or rapid weight loss and hypoalbuminaemia
What are the risk factors for pneumococcal meningitis?
Age >60 years, immunosuppression, alcohol dependency, middle ear disease, previous head trauma or surgery. Splenectomy increased general risk of serious bacterial infections (particularly of encapsulated organisms).
Since the lower respiratory system is meant to be sterile, how does pneumonia infect the lungs?
1) Host defence defect
2) Large innoculum
3) Increased virulence
Which 2 of the 4 human causing malaria plasmodium species has a liver stage?
P. ovale and p. vivax. They must be treated additionally with primaquine to eradicate the liver stage of infection and prevent relapse.
What is the major cause of “travellers” diarrhoea?
Enterotoxigenic E. Coli
What drugs are in the standard short course therapy for tuberculosis?
- Isoniazid
- Rifampicin
- Pyrazinamide
- Ethambutol
What is the causative organism in Chlamydia?
Chlamydia trachomatis
Dysentery
Inflammatory disorder of the large bowel. Blood and pus in faeces. Pain, fever and abdominal cramps.
Enterocolitis
Inflammatory process affecting small and large bowel.
Name some viral haemorrhagic fevers
Lassa, Ebola, Rift valley fever, Dengue Haemorrhagic Fever, Yellow fever, Congo Crimean Heamorrhagic fever.
Name two non-lactose fermenting bacteria
1) Salmonella
2) Shigella
What is a Girdlestone procedure?
A ‘Girdlestone’ procedure is otherwise known as a resection arthroplasty of the hip. In summary, it involves removing part of the ball or head of the thigh bone (femur), thereby allowing it to fuse with the socket of the hip (acetabulum) in the straight leg position. The patient is left with a stiff, usually pain free hip and a straight leg that is unable to bend at the hip.
How do you treat septic arthritis?
Often 3 weeks IV antibiotics followed by 3 weeks oral. Monitor response by CRP and clinical.
What two antibiotics might you give for a lower UTI?
Trimethoprim or nitrofurantoin
What are the 4 types of necrotising fascitis?
I-Synergistic infection with anaerobes and aerobes. more common in elderly diabetic patients- broad spectrum required.
II-Group A Streptococci (S. pyogenes or occasionally s. aureus), mediated by toxin production.
III-Vibrio vulnificus-vafter trauma in sea water.
IV- Fungal
What are the 3 main risk factors for Clostridium difficile infection?
1) Aged over 65 years old.
2) Recent hospitalisation
3) Recent course of antibiotics
Which viruses cause a vesicular rash?
Herpes simplex virus 1/2, varicella zoster virus, enteroviruses.
What are the most common types of enterovirus to cause hand foot and mouth disease?
Coxsackievirus A16, A6, A10 and enterovirus 71.
When is Varicella virus contagious?
Causes chickenpox. Contagious from 48 hours before onset of rash until every lesion has crusted over.
What are immunocompromised patients at risk of in terms of varicella zoster virus?
- Bacterial infection of skin and soft tissues
- Disseminated varicella
- Haemorrhagic varicella
- VZV pneumonitis
- VZV encephalitis
What can be offered to immunocompromised patients who are negative for varicella zoster virus IgG?
Varicella zoster immunoglobulin (VZIG) can be given. Prepared from pooled plasma of non-UK donors (due to risk of transmission of vCJD) with suitably high titres of VZ antibody. Supply of VZIG is limited by availability of suitable donors and its use is restricted.
When is varicella zoster immunoglobulin prophylaxis recommended?
For individuals who fulfil all of the following criteria:
1) Significant exposure to chickenpox or herpes zoster
2) Clinical condition that increases risk of server varicella; immunocompromised, neonates and pregnant women.
3) No antibodies to varicella zoster virus.
What is the treatment of varicella zoster in immunocompromised individuals?
Aciclovir 10mg/kg IV every 8 hours.
What is aciclovir and what is its MOA?
An anti-viral. Nucleic acid analogue made from guanosine. Competitively inhibits viral DNA polymerase by causing DNA chain termination, preventing further viral DNA synthesis.
What is aciclovir crystalline nephropathy?
IV aciclovir can cause reversible nephrotoxicity in <5-10% of patients due to the precipitation of acicilovir crystals in the kidney. More common when aciclovir is given as a rapid infusion, in patients with dehydration and pre-existing renal impairment.
What is Lysozyme?
An enzyme present at mucosal surfaces that is active in breaking down to gram positive cell wall. Part of the innate immune system.
What is Lactoferrin?
Part of innate immune system. Protein found at mucosal surfaces that chelates iron and therefore reduces soluble iron in the GI/respiratory tract. Inhibits the growth of bacteria.
Class I MHC
Presents to CD8 T cells. Found on all nucleated cells. Presents intra-cellular antigen.
Class II MHC
Presents to CD4 T cells. Presents extra-cellular derived antigen (phagocytosed). Found on antigen presenting cells (dendritic cells, macrophages, B cells).
