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.