Microbiology Flashcards
The antiviral which is given to untreated pregnant women with HIV to prevent vertical transmission of the virus during childbirth.
Nevirapine/Zidovudine
An immunomodulatory therapy used in the treatment of hepatitis B.
Preffered Treatment of Hep B
Immunonodulator: interferon alpha Nucleos(t)ide analogues
Inhibitors of viral polymerase – Entecavir (no resistance),Lamivudine, Adefovir dipivoxil, Telbivudine
Inhibitor of reverse transcriptase – Tenofovir
Preferred 1st line treatment choice: o Entecavir, PegINF alpha 2a, and tenofovir
An antiviral currently used to prevent and treat Influenza in the elderly and which has the potential to be used to prevent Avian influenza.
Neuraminidase inhibitors: Oseltamivir (Tamiflu)
The final metabolite of the antiviral used to treat Herpes Simplex
Aciclovir triphosphate Aciclovir diphosphate and triphosphate are the product of cellular tyrosine kinase
An antiviral which can be used in aerosol form to prevent respiratory syncytial virus (broncholitis) in children with heart and lung disease
Ribivarin
Ribavirin is a prodrug, which when metabolized resembles purine RNA nucleotides.
It is a guanosine (ribonucleic) analog used to stop viral RNA synthesis and viral mRNA capping, thus, it is a nucleoside inhibitor.
Drug used to treat CMV infections.
CMV (and EBV, HHV-6). Nucleoside analogue.
Treat CMV – Congenital, immunocompromised, pregnancy, HIV Remember what CMV does? – RCHEAP (Retinitis/colitis/hepatitis/encephalitis/pneumonits.
Sight-threatening CMV retinitis in severely immunocompromised people
CMV pneumonitis in bone marrow transplant recipients
Prevention of CMV disease in bone marrow and solid organ transplant recipients
Confirmed CMV retinitis in people with AIDS (intravitreal implant)
Ganciclovir -guanosine analgue
SE: BM suppression
If CMV resistant to ganciclovir (or severe side effects), then use:
Pyrophosphate analogue, inhibits nucleic acid synthesis without requiring activation. Also used as propylaxis post organ transplant.
Foscarnet
blocks viral DNA extension through activation by viral thymidine kinase (TK) present in HSV
aciclyovir
An antiviral which can be used in aerosol form to prevent respiratory syncytial virus in children with heart and lung disease
Ribivarin
Direct antiviral effect + upregulates expression of MHC on cell surfaces
Interferon alpha - Hep B
Nucleoside phosphonate, it is mainly used for Rx in CMV retinitis.
Often used in treatment of non-herpes viral infections in the opportunistic post-transplant setting: Eg: BK virus for BK nephropathy/BK cystitis/Adenovirus/PML (JC virus)
Cidofovir
Which option is the product of the action of viral tyrosine kinase on aciclovir?
Aciclovir monophosphate
Which option inhibits the action of viral DNA polymerase?
Aciclovir triphosphate
The synthetic nucleoside analogue ganciclovir is the drug of choice against which infective virus?
Cytomegalovirus
Ribavirin, a synthetic nucleoside that acts as an RNA polymerase inhibitor, is similar in structure to which of the options given above
Guanosine analogue
Valaciclovir, a prodrug of aciclovir, is used to treat patients with which viral disease in the list, above?
Varicella-zoster virus
HSV – genital, oral, encephalitis, disseminated If you get herpes you need to.
Act Acyclovir
Very Valaciclovir
Fast! Famciclovir
Used for the treatment of severe, resistant herpes infections or CMV secondary treatment
Foscarnet
The treatment of choice for CMV-induced hepatitis
gancyclovir
A drug that is effective against influenza A but not influenza B
Amantadine
A purine nucleoside analogue that selects specifically for thymidine kinase
Aciclovir
A nucleoside analogue which is NRTI inhibitor
Part of HAART
(NRTI, PI, NNRI)
What is it used for?
zidovudine:
Neonatal antiretroviral therapy
zidovudine is usually administered orally to the neonate if maternal viral load is <50 copies/ml. Otherwise triple ART should be used. Therapy should be continued for 4-6 weeks.
general NRTI side-effects: peripheral neuropathy
zidovudine: anaemia, myopathy, black nail
The drug mechanisms which acts by stopping post-translational cleaving of polyproteins by inhibiting proteases= protease inhibitor, used in HIV
What are its side effects?
Indinavir
indinavir: renal stones, asymptomatic hyperbilirubinaemia
side-effects: diabetes, hyperlipidaemia, buffalo hump, central obesity, P450 enzyme inhibition
The drug which can be delivered by inhalation to treat both influenza A and B.
Zanamivir ZA i ZB
Zanamivir (Relenza)
inhaled medication*
also a neuraminidase inhibitor
may induce bronchospasm in asthmatics
The following groups are particularly at risk of influenza:
patients with chronic illnesses and those on immunosuppressants
pregnant women
young children under 5 years old
The drug which works by attenuating or preventing rabies or hepatitis, following a known exposure but before the onset of signs and symptoms.
Human Specific Immunoglobulin
Targets M2 ion channel. BUT single AA mutation (S31N) in M2 = resistance
Amantadine (Influenza A only) –
A 37yr old American business man staying in a hotel presents with a headache, myalgia and a dry cough. He is also suffering with nausea, diarrhoea and abdominal pain. On examination he is tachypnoeic and has a pyrexia of 39ºC. Blood tests reveal lymphopenia and hyponatraemia.
L. pneumophila
A 19yr old medical student who lives in residential halls presents with a one week history of headache, malaise, shortness of breath and a cough. Her WBC is not raised but tests reveal the presence of cold agglutinins.
Dry cough, new infiltrates on CXR, dyspnoea and target shaped lesions on the palms. No recent history of herpes.
M. pneumoniae
systemic symptoms, joint pain, cold agglutinin test, erythema multiforme.
Risk SJS, AIHA
A 30yr old lady presents with a three week history of tiredness, malaise, cough and weight loss. She feels her condition has worsened in the past week and she now also suffers from a fever and haemoptysis. In addition she complains of a “tender lump” in her supraclavicular region. Chest x-ray demonstrates nodular shadowing of the right upper zone.
M. tuberculosis
A forty year old ornithologist presents with malaise, muscular pains and a cough. On examination he has a fever and several distinctive rose spots on his abdomen. Chest x-ray reveals a diffuse pneumonia.
C.pistacii
Cystic Fibrosis
Pseudomonas aeruginosa, Burkholderia cepacia (v. high mortality)
Staphylococcus aureus
Pseudomonas aeruginosa
Burkholderia cepacia*
Aspergillus
HIV associated infections
P. Jiroveci (PCP), TB, Cryptococcus neoformans
An 80 year old clown appears at the GP having been discharged from hospital for a complicated bowel resection with a stint in the ITU. He has a cough and fever and is prescribed a macrolide antibiotic because he is penicillin allergic.
What is macrolide mechanism of action:
MSSA
Macrolides (see Table: Macrolides) are antibiotics that are primarily bacteriostatic; by binding to the 50S subunit of the ribosome, they inhibit bacterial protein synthesis
A 55 year old female clown, recovering from a cold, is found to have a CAVITITING lesion on CXR and a productive cough.
MSSA or MRSA
An 18 year old trainee clown is being seen in the cystic fibrosis clinic and is found to be colonised with a particularly persistent organism.
Burkholderia cepacia
Assoc. w/ smoking
The most common bacterial organisms that cause infective exacerbations of COPD are
Haemophilus influenzae (most common cause)
Streptococcus pneumoniae
M. Catarrhalis
The previous day he had a fever, headache and malaise but has now subsided.
5 year old boy comes to the GP and shows you small pustules over his face, scalp and trunk, which have progressed from small macules in a matter of hours.
chicken pox
Virology showed the presence of Varicella Zoster Virus.
A 21 year old man came to hospital complaining of severe headache, fever, malaise and a Sore Throat. On examination he showed cervical Lymphadenopathy, especially the posterior cervical nodes, and Splenomegaly.
Peripheral blood tests showed the presence of lymphocytosis with atypical mononuclear cells.
haemolytic anaemia secondary to cold agglutins (IgM)
Glandulaer Fever HSV4Diagnosis
heterophil antibody test (Monospot test) - NICE guidelines suggest FBC and Monospot in the second week of the illness to confirm a diagnosis of glandular fever.
Management is supportive and includes:
rest during the early stages, drink plenty of fluid, avoid alcohol
simple analgesia for any aches or pains
consensus guidance in the UK is to avoid playing contact sports for 8 weeks after having glandular fever to reduce the risk of splenic rupture
On your elective in central Africa a 7 year old child comes to your clinic with a large mass on his jaw. You take a biopsy of the lump, which shows EBV positive large cell lymphoma B cells. Histology shows a starry sky appearance (isolated histiocytes on a background of abnormal lymphoblasts). Genetic testing shows the presence of a 14q/8q translocation. The consultant suggests treating with cyclophosphamide and a single dose leads to a spectacular remission.
.
Burkitt’s lymphoma
Shingles
varicela zoster
chiken pox in children
3/7 fever, then transient rash. Abx often prescribed for fever then rash is often
blamed on pencillin and child branded penicillin allergic. Most common cause of febrile convulsions. Latent in monocytes/lymphocytes. Can
cause pneumonitis, hepatitis, encephalitis in BMT
Diagnosis
Treatment
Causes roseola infantum (=exanthum subitum, Sixth disease).
Roseola infantum (also known as exanthem subitum, occasionally sixth disease) is a common disease of infancy caused by the human herpes virus 6 (HHV6).
It has an incubation period of 5-15 days and typically affects children aged 6 months to 2 years.
Features
- high fever: lasting a few days, followed by a
- maculopapular rash
- febrile convulsions occur in around 10-15%
- diarrhoea and cough are also commonly seen
Diagnosis – Blood PCR
Rx – Ganciclovir, foscarnet or cidofovir
Other possible consequences of HHV6 infection
aseptic meningitis
hepatitis
Herpetic keratitis — unilateral/bilateral conjunctivitis + pre-auricular LNs Acute retinal necrosis if immunocompotent, if immunosuppressed:
Progressive Outer Retinal Necrosis (PORN) (also caused by VZV, EBV, CMV)
Keratitis: Keratitis describes inflammation of the cornea. There are a variety of causes:
Features
red eye: pain and erythema
photophobia
foreign body, gritty sensation
hypopyon may be seen
HSV1 and HSV2
Herpes Simplex Type 1 complication
Primary stomatitis
Cytomegalovirus Complication
Pneumotitis
Herpes Simplex Type 2 Complication
Neonatal Infection Associated with Vaginal Delivery
Infection associated with Kaposi’s sarcoma
Human Herpes Virus 8
Kaposi’s sarcoma
caused by HHV-8 (human herpes virus 8)
presents as purple papules or plaques on the skin or mucosa
(e.g. gastrointestinal and respiratory tract)
skin lesions may later ulcerate
respiratory involvement may cause massive haemoptysis and pleural effusion
radiotherapy + resection
Human Herpes virus 6
Exanthem Subitum Roseola Infantum
The 6th disease
Prodorome of fever
Tratment: gancyclovir
It has an incubation period of 5-15 days and typically affects children aged 6 months to 2 years.
Features high fever: lasting a few days, followed by a maculopapular rash
febrile convulsions occur in around 10-15%
diarrhoea and cough are also commonly seen
Other possible consequences of HHV6 infection:
aseptic meningitis
hepatitis
Fever + submandibular lymphadenopathy. + vesicles
Symptoms include sudden fever with sore throat, headache, loss of appetite, and often neck pain. Within two days of onset an average of four or five (but sometimes up to twenty) 1 to 2 mm diameter grayish lumps form and develop into vesicles with red surrounds, and over 24 hours these become shallow ulcers, rarely larger than 5 mm diameter, that heal in one to seven days
Most commonly affects infants and young children
Typically occurs during the summer
Herpangina (Coxsackie A)
Although it has been known to occur in eighteen-year-olds, whose manifestations are usually limited to a transient rash (“exanthem”) that occurs following a fever of about three days’ duration.
Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7),
Roseola is a disease of children, generally under two years old.
Pneumonitis after a bone marrow transplant
CMV
Acute necrotising encephalitis
HSV1
Blistering rash in dermatomal distribution
shingels
Alpha herpes viruses: neurotropic
Beta herpes viruses: epitheliotropic
Gamma herpes viruses: Lymphotropic
what does it mean
). Alpha herpes viruses: neurotropic Beta herpes viruses: epitheliotropic Gamma herpes viruses: Lymphotropic
Candida infection
A 37-year-old woman with a past history of intravenous drug use presents to her GP for her methadone prescription. On examination they note pale rigid lesions on the side of her tongue. Alongside her methadone the GP prescribes aciclovir.
which virus causes it?
hairy leukoplakia
EBV causes post-transplant lymphoproliferative disease where control of proliferation of
latently infected B cells is lost.
In HIV patients; oral hairy leukoplakia and lymphomas. Tx:
Reduce immunosuppression + Rituximab (anti-CD20 mAb
In addition to CD4+ T-lymphocyte counts, HIV monitoring is typically assessed through which measurement?
Viral load
HIV seroconversion is symptomatic in 60-80% of patients and typically presents as a glandular fever type illness. Increased symptomatic severity is associated with poorer long term prognosis. It typically occurs 3-12 weeks after infection
Features:
sore throat
lymphadenopathy
malaise, myalgia, arthralgia
diarrhoea
maculopapular rash
mouth ulcers
rarely meningoencephalitis
Diagnosis:
- antibodies to HIV may not be present
- HIV PCR and p24 antigen tests can confirm diagnosis
HIV antibody test
- most common and accurate test
- usually consists of both a screening ELISA (Enzyme Linked Immuno-Sorbent Assay) test and a confirmatory Western Blot Assay
- most people develop antibodies to HIV at 4-6 weeks but 99% do by 3 months
p24 antigen test
- usually positive from about 1 week to 3 - 4 weeks after infection with HIV
- sometimes used as an additional screening test in blood banks
Which of the above is a naturally occurring cytokine that is able to inhibit HIV fusion to CD4+ T-lymphocytes?
MIP-1alpha
Which viral protein is responsible for the binding or fusion of HIV to human CD4+ T-lymphocytes?
gp120
CD4 molecule is receptor for HIV.
The virus binds via gp120 (initial binding)
and
gp41 (conformational change) – on CD4+ T cells
Most strains use CCR5 and CXCR4 chemokine co-receptors (on macrophages)
Vaccine given at 12 – 18 months to prevent otitis media, parotitis, and cataracts in patients.
MMR
An immunocompromised HIV positive patient should not receive this vaccine.
BCG
Haemophiliacs and patients in receipt of regular blood transfusions should be vaccinated against this virus.
Hep B
Toxoid given as part of ‘triple’ vaccine during first year of life to prevent cardinal features of the disease: muscle spasms and rigidity.
Tetanus
Vaccine recommended for high risk patients with chronic respiratory diseases, but contraindicated in patients hypersensitive to eggs.
Influenza
MRSA, C.Diff
Glycopeptides - Vancomycin, Teicoplanin
35 year old household wife presents with an infected insect bite.
In the past she has been treated with Penicillin and responded with facial swelling and acute shortness of breath.
Erthyromycin
Patient with an abdominal collection that contains gram –ve anaerobes, what david is saying ….
Metronidazole
56 year old male with endocarditis caused by VRE.
Gram +ve, MRSA + VRE
Vancomycin-resistant enterococci (VRE)
Linezolid
Oxazolidinones
Gram negative sepsis
Inhibit protein synthesis Aminoglycosides Gentamicin
C.difficile colitis where metronidazole has failed
Vancomycin
Severe systemic infection before cause has been identified
CeFURoxime
Atypical pneumonia caused by Legionella in individuals with penicillin allergy
Erythromycin
Long-term prophylactic treatment for post-splenectomy patients
Penicillin V
A 75 yr old lady develops severe wound infection following hip replacement. MRSA is isolated from the wound.
vancomycin
The following antibiotics are commonly used in the treatment of MRSA infections:
vancomycin + teicoplanin
linezolid
An 82 yr old gentleman, living at home, develops severe dyspnoea with a productive cough and fever. His PaO2 has fallen below 8kPa, and he is becoming confused.
B.
cefuroxime & clarithromycin
A 6 month old child whose father has just been diagnosed with tuberculosis.
isoniazid
A 12 yr old boy requests treatment for widespread impetigo. He developed an urticarial rash 3 yrs ago when he was given penicillin V.
Erythromycin
Eye drops
Bacterial conjuctivitis
Chloramphenicol
Gram-negative curved rod, whose toxin affects adenyl cyclase. Its major cause of death is shock, metabolic acidosis and renal failure.
D.
Vibrio cholera
This microbes affects mainly the distal colon, producing acute mucosal inflammation and erosion. It is spread by person-to-person contact, and its clinical features include fever, pain, diarrhoea and dysentery.
Shigella
This microbe affects the ileum, appendix and colon. Its peyer patch invasion leads to mesenteric lymph node enlargement with necrotising granulomas. Complication can include peritonitis, pharyngitis and pericarditis.
Yersinia
undergoes multiplication in Peyer’s patches following invasion of human epithelial cells and penetration of the mucosa which occurs in the ileum. Complications include diarrhoea, mesenteric adenitis, mesenteric ileitis, or acute pseudoappendicitis, reactive arthritis and erythema nodosum
Yersinia enterocolitica
Ingestion of ………… cysts is followed by excystation in the small bowel and trophozite colonisation of the small colon.
The trophozyte may then encyst and be excreted in faeces or it may invade the intestinal mucosal barrier, thereby gaining access to the circulation.
Complications include amoebic colitis, liver abscesses, pleuropulmonary amoebiasis and cerebral amoebiasis.
Entamoeba histiolytica
A 40 year old female, who is a ex-smoker, who has recently returned from a holiday in India, comes to A+E complaining of severe abdominal cramps and bloody diarrhoea. She mentions that her mother suffered from similar symptoms in the past.
Ulcerative Collitis
A 34 year old female returned from Indonesia two weeks ago. She complains of diarrhoea, abdominal pain, weight loss, nausea and vomiting for the past few days. She has no fever. Investigation reveals steatorrhoea and stools appear to contain numerous cysts.
- *Giardiasis is** caused by the flagellate protozoan Giardia lamblia.
- *Features**
often asymptomatic: lethargy, bloating, abdominal pain non-bloody diarrhoea
chronic diarrhoea, malabsorption and lactose intolerance can occur
stool microscopy for trophozoite and cysts are classically negative, therefore duodenal fluid aspirates or ‘string tests’ (fluid absorbed onto swallowed string) are sometimes needed
Treatment is with metronidazole
Giardasis
Drinking unpastuerised milk, food eg: poultry
Prodrome of headache and fever, abdo cramps, bloody (foulsmelling)
diarrhoea
Curved, S-shaped, Microaerophilic, Oxidase +ve, motile,
sensitive to nalidixic acid (first quinolone).
Assoc with Guillain-Barre, reactive arthritis (Reiter’s)
TreatmenT:
C.Jejuni
Erythromycin or Cirp
Following a trip to Brazil MSM, a patient develops bloody diarrhoea, with a high fever, sweating and on examination the patient is found to have RUQ pain
(RUQ pain due to liver abscess)
Chronic weight loss +
Entamoeba Histolytica
Following a barbeque, a 41 year old develops watery diarrhoea and vomiting. On retrospect, he wondered whether he should have had that dodgy looking shish kebab…
Multiplies in Peyers patches, 3% carriers (in gallbladder)
Slow onset fever + CONSTIPATION, relative bradycardia
Splenomegaly and rose spots, anaemia and leukopaenia
Salmonella
A 40 year old homosexual man develops severe flatulence, accompanied by bloating and explosive diarrhoea.
Giardia Lamblia
Mrs A became ill at about midnight after eating chicken wings for lunch at a summer BBQ. Mrs A complained of nausea, vomiting and non-bloody diarrhoea. Her symptoms resolved 3 days later.
Salmonella
Mr S became ill with nausea, vomiting and watery diarrhoea about 4 hours after eating some ham at a conference buffet lunch. Mr B’s illness was attributed to a heat stable, preformed toxin in the ham. His symptoms resolved within 24hours.
S.aureus
Mr C complained of fever and severe (>10 bowel movements/day) diarrhoea after looking after his neighbours dogs for a few days. Laboratory analysis of Mr C’s stools found the causative organism to be a S-shaped microaerophillic bacteria.
Campylobacter
Miss D initially complained of a dry mouth and visual disturbance a few days after ingesting some home canned produce. She sought medical attention after she began to experience bilateral descending paralysis. Miss A later died from respiratory failure.
Clostridium botulinum
. If there was laceration and lots of blisters on the foot
Trichophyton interdigitale.
normally associated with GROIN infections,
E floccusum
A 45 year old female presents with fever. O/E she is pyrexial, has hepatosplenomegaly, lymphadenopathy and a severely swollen eyelid. She returned from Guatemala 2 days ago.
Chagas
