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173 Cards in this Set
- Front
- Back
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Mention some roles of the micro lab (4)
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Diagnosis/confirmation of infection (microscopy, culture, PCR)
Abx sensitivity testing Identifying resistance Collecting epidemiological data |
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Anti-biotic vs. anti-microbial
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Originally, antibiotic referred to a naturally occurring compound, whereas anti-microbial was any compound. Now used interchangeably.
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True or false: penicillin is slowly eliminated by the kidneys?
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False. Benzylpen (pen G) especially is rapidly eliminated, and often given with probenecid to slow its elimination (competes for tubular secretion). Insoluble derivatives such as benzathine pen are slow release IM injections.
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Which GNBs is ampicillin effective against?
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E.coli, salmonella, shigella, Hemophilus influenzae
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Name two anti-staphylococcal penicillins.
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Flucloxicillin and methicillin
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What is the difference btw penicillinase and beta-lactamase?
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Beta-lactamase confers resistance to all beta-lactams, including cephalosporins.
Restore with clavulanate, tazobactam. |
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What are the anti-pseudomonal penicillins?
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Ticarcillin and piperacillin.
Similar in spectrum to fluoroquinolones. |
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What are the natural penicillins?
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Penicillin V (phenoxymethylpen ie oral) or penicillin G (benzylpen ie injected)
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What organisms are covered by 1st gen cephalosporins? Give an example.
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Gram+ cocci. Cefazolin.
similar spectrum to natural penicillins. |
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What ogranisms are covered by 3rd gen cephalosporins? Give an example.
What activity do they lack? |
Gram+ and gram- cover.
Ceftriaxone or cefotaxime. Lack good staphylococcal activity. |
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What are the extended spectrum penicillins?
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Ampicillin and amoxicillin
similar spectrum to 3rd gen cephalosporins |
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What useful extra activity did 4th generation cephalosporins get?
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Anti-pseudomonal activity
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What is the main coverage by macrolides?
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Gram+ and non-enterobacteriaciae gram- (eg legionella)
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Name some macrolides
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Clarithromycin, azithromycin, erythromycin
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What specific infections are macrolides useful for?
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Chlamydia (azithromycin)
Pneumonia: mycoplasma (clarithro), legionella (clarithro) |
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What is the MOA for macrolides?
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Bind 50S ribosomal subunit - prevent translation
buy AT 30, CELL at 50 the E is for erythromycin a macrolide |
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What is the MOA of fluoroquinolones?
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inhibit DNA gyrase (topo II) and topoisomerase IV
(bactericidal) |
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Name three agents which could be used for vancomycin resistant bugs?
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Linezolid - good lung penetration for MRSA pneumonia
Daptomycin - for MRSA skin infection Tigecycline - MRSA or VRE |
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Which antibiotics inhibit cell wall synthesis?
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Beta-lactams
Glycopeptides ie vancomycin Bacitracin Cycloserine |
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Name a monobactam
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aztreonam - active against aeroboic gram- only
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Which two amino acids make the beta-lactam ring
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valine and cysteine
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What are the main organisms penicillin is useful for?
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Grp A,C,G Streptococci
Pneumococcus Meningococcus (gram -) - too bulky to penetrate most gram- |
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What are the main organisms amp/amox are useful for?
Which one is oral? |
Gram+ covered by penicillin (strep, pneumococc) (also gram- meningo) and
E Coli, H influ, Salmonella amoxicillin is oral |
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What use is flucloxacillin?
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Mainly for non-MRSA staph
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What does co-amoxyclav cover?
Does it cover pseudomonas? |
broad spec - gram+ and gram- and some anaerobes; some staph activty;
No |
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Does piptazo cover pseudomonas?
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Yes; with similar spectrum to co-amoxyclav
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What percent of penicillin allergic pts will also react to a cephalosporin?
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10%
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Which two important bugs do third generation cephalosporins not cover?
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Staphylococci and pseudomonas
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What do fourth generations cover?
Name one |
Good gram- activity and pseudomonal activity
Cefepime, cefepirome |
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Which bugs are most cephalosporins not active against?
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anaerobes
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Name the useful activities of meropenem
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anaerobes, pseudomonas, streps; not MRSA
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What do glycopeptides bind to?
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acyl-D-alanyl-D-alanine
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What is the only oral use of vancomycin?
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clostridium difficile
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What are the main toxicities of vanc?
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NOT
Nephrotoxicity ototoxicity thromophlebitis also red man syndrome if bolus given |
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What are the side effects of quinolones?
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Seizures, photosensitivity, interaction with theophylline
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How does co-trimoxazole work?
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Inhibits two steps in folate metabolism, thereby preventing purine synthesis and thymidine synthesis
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What are the uses of trimethoprim?
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UTIs or as co-trimoxazole in PCP pneumonia
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How does rifampicin work?
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Prevents DNA-dep RNAP from transcribing DNA
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What use is rifamipicin?
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TB treatment (RIPE)
meningococcal prophylaxis staph |
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How does metronidazole work?
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DNA strand breaks by unknown mechanism
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What is metronidazole active against?
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Anaerobes and protozoans
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How do tetracyclines work?
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Prevent binding of tRNA to 30S ribosome
buy AT 30, CELL at 50 |
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Who are tetracyclines contraindicated in?
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Children and pregnant women
- act to chelate Ca ions thereby disrupting bone growth and discolouring teeth - use chloramphenicol in these pts |
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Name the new and old quinolones
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Old: ofloxacin, ciprofloxacin
New: moxi, levo, gati - new have poor pseudomonal, better gram+ activity |
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True or false, quinolones are useful for intracellular parasites
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True; can even be used for TB
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Who are quinolones contraindicated in?
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Children - incorporated into cartilage/bone
occasionally used in child CF pts |
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true or false rifampicin should be used in combination?
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true - resistance develops fast
(unless using as prophylaxis) |
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what is the mechanism of chloramphenicol?
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inhibits peptidyl-transferase reaction on ribosome (50S)
by AT 30, CELL at 50 |
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What is the major risk of chloramphenicol?
Why is it useful? |
Aplastic anemia
Good CSF and intracellular penetration (eg ricketsiae) |
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How do aminoglycosides work?
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Bind both ribosomal subunits (mainly 30S?) and cause misreading of code, defective protein synth
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What are the major toxicities of aminoglycosides?
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NOT
nephrotoxicity ototoxicity teratogenicity |
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What is the spectrum of aminoglycosides?
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good for gram- and synergistic with beta-lactams against gram+
no good for anaerobes (need O2 for uptake) |
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what particular case is clindamycin useful in?
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necrotizing fasciitis - switches off toxin production
- good for gram+ and anaerobic skin infections |
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how does linezolid work?
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binds 50S - prevents formation of 70S complex, thus preventing translation
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define significant bacteruria
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> 10^5/mL bacteria in an appropriately collected sample
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true or false: the entire genitourinary tract is sterile
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false: the distal urethra is colonized by skin/fecal flora
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Name the three cases where a UTI is considered complicated
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Lower UTI in men
Lower UTI in pregnant women Upper UTI (beyond bladder) |
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What is a lower UTI?
What is cystitis? |
Infection of the urethra +/- bladder, with NO sysmtemic symptoms
Cystitis is bladder inflammation |
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What is an uncomplicated UTI?
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Lower UTI in non-pregnant woman without anatomical abnormalities
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What is urethral syndrome?
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Symptoms of lower UTI with sterile urine culture; may be STI
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What is pyelonephritis?
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acute or chronic infection of the renal pelvis and collecting system
- flank pain, hematuria, WBC casts, evidence of lower UTI |
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in the first three months of life, which sex is more likely to get a UTI?
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males
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why do elderly men get UTIs?
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prostate enlargement (typically)
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what percent of females get a UTI over their lifetime?
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20%
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true or false: there are normally Ig molecules in the urine?
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true: secretory IgA protects from infection
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name some host defences to UTIs
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mechanical flushing by urine
low urinary pH IgA anti-biotic prostatic secretions lactobacilli colonization |
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name some risks for UTI
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catheterization
diabetes pregnancy urethral colonization by pathogens vesico-ureteric reflux obstruction, stones, external compression OCP or spermicide reduces lactobacilli colonization immunosuppression |
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what are the two routes for infection reaching the genitourinary tract?
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ascending - 95%
hematogenous - usually staph aureus or salmonella direct (fistula) |
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when does cystitis occur?
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usually due to chronic infection - see lymphos and plasma cells
- may lead to glandular metaplasia - subtypes: interstitial/eosinophilc/malakoplakia |
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true or false: schistosomiasis is a UTI
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false? sort of?; eggs may enter bladder and lead to granulomatous response, metaplasia and possibly SCC
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What is the commonest bug in UTIs?
Name some others |
E. coli - 50%
also: staph saprophyticus, proteus, klebsiella, enterococcus fecalis, pseudomonas occasionally staph aureus or epidermidis |
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List clinical presentation of acute PN
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Severe pain
Rigors Tender renal angle Fever Dysuria/frequency (may be absent) Vomiting Septicemia, shock |
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What part of GUT does a first-void urine specimen represent?
What about a midstream specimen? |
Urethra
Bladder |
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True or false: urine specimens should be gram stained
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False; this is not routine
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What defines a positive diagnosis of UTI?
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Bacterial count > 10^5 / mL of urine (significant bacteruria) - if symptoms, treat
There is a gray area around 10^4 where if pt is symptomatic, might be worth treating; should repeat sample |
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What is standard treatment for an uncomplicated UTI?
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3-day course of abx (trimethoprim, nalidixic acid, amp-gent, co-amoxyclav)
and increase fluid intake |
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Define acute pyelonephritis
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Acute inflammation of the parenchyma and pelvis of the kidney
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What are some complications of acute pyelonephritis?
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Pyonephrosis - dilating of collecting system as it fills with pus
Perinephric abscess - extensionof suppuration into surrounding tissue - may need drainage Papillary necrosis - areas of necrosis - may lead to: ARF |
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What are some risks for acute PN?
(similar for UTI) |
pregnancy
prostate enlargement anatomical defect obstruction/calculus/tumour |
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What is the commonest cause of chronic pyelonephritis?
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Anatomical defect combined with infection
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What is seen pathologically with chronic pyelonephritis?
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bilateral asymmetric scarring with blunted calyces
tubular atrophy, dilation and fill up with eosinophilic material -> thyroidization chronic inflammation |
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What significant complication may occur in the glomeruli due to chronic pyelonephritis?
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FSGS - leads to nephrotic proteinuria and progression to renal failure
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What is xanthogranulomatous PN ass'd with?
What can it mimic? |
Proteus infection or obstruction
Malignancy |
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What two critical microbiological tests should be done for acute PN?
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Urine specimen - culture, sens, microscopy (WBC casts)
Blood culture |
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What is the treatment for acute PN?
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Amp+gent IV would be a reasonable start
Must drain perinephric abscess if present (must do CT to see) |
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What predisposes to UTI in pregnancy?
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Poor urethral tone due to hormones
Urinary stasis due to compression by uterus |
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True or false: significant bacteruria in pregnant women should always be treated?
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True: even if asymptomatic, must treat -
risk of pyelonephritis is 20-30% if untreated also increased risk of spontaneous abortion or early labour |
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In children, besides treating a UTI, what else should be done?
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Investigations into anatomical abnormalities - KUB, IVP, renal US
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What is the commonest HCAI?
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UTI - biofilms form on catheters
UTI is in turn the commonest cause of GNB sepsis |
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Are UTIs usually monomicrobial or polymicrobial?
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Mono; except healthcare-acquired
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List some causes of sterile pyuria
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Use of abx following recent infection is commonest cause
TB, tumour, stones, brucellosis, chlamydia |
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What clinches the diagnosis of acute PN?
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WBC casts in urine (along with clinical picture)
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What is the commonest cause of gram negative sepsis?
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UTI
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What is the most frequent extra-pulmonary site for TB?
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Kidney - see granulomas in the cortex - can invade rest of GUT from here - HIV pts at high risk
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Symptoms of renal TB?
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Malaise
weight loss painless hematuria fever |
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What tests should you do if you suspect renal TB
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early morning urine for culture 3 days in a row - ZN not helpful (atypicl mycobacteria)
image kidney - IVP helpful mantoux test |
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What comes to mind if you find sterile pyuria, with no history of recent abx/UTI?
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TB
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What area of the kidney does renal TB preferentially infect?
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The cortex due to high oxygen tension
-- if imaging reveals multiple cortical nodules, suspect TB |
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Name three factors which might impair antibiotic penetration to a site
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Poor blood flow (eg heart valve)
Abscess (walled off) Foreign body (biofilm formation) Inflammation usually facilitates penetration (esp protein bound drugs) |
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What is the post-antibiotic effect? Which antibiotic class classically shows this?
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Persistent killing after limited exposure to ab.
aminoglycosides - this is beneficial because the toxicity is concentration dependent --> less frequent dosing req'd |
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What is time-dependent killing?
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Time spent with levels above MIC determines killing
- seen with penicillin --> requires frequent dosing |
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What is concentration-dependent killing?
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The higher the peak levels, the more killing
aminolgycosides, quinolones |
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How is metronidazole eliminated?
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In bile
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How are penicillins and cephalosporins eliminated?
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Tubular secretion
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What is the most important form of passive immunization?
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Maternal IgG in the post-natal period
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Name the sources which can be used for passive immunization
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Most blood/blood products contain Ig
Homologous pooled human antibody Homologous hyperimmune globulin (enriched with specific antibody) Heterologous hyperimmune sera (ie from other species) |
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What childhood illness often requires passive immunization?
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RSV
Either as RSV Ig or pavlizumab, a mouse monoclonal against RSV |
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Which vaccine is likely to require multiple doses, live or attenuated?
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Attenuated - does not evoke as strong a response often; mostly humoral, as opposed to cell-mediated
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Name three live and three attenuated vaccines
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Live: MMR, oral polio, yellow fever, flumist, BCG
Attenuated: polio, hep A, rabies, DaPT (acellular and toxoid), hep B, typhoid (Vi) |
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Name three polysaccharide vaccines
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Pneumococcus, meningococcus, Hib
(all conjugated) |
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Why is rubella immunized against, given its very low mortality?
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To avoid congenital rubella syndrome in babies
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What is a group 1 vs. a group 2 vaccine?
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Group 1 is recommended for all citizens; group 2 is for at risk groups
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Irish vaccine schedule?
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DaTP, IPV, Hib, MenC -- 2,4,6 months; 4-5 yrs
BCG - birth; 10-14 yrs MMR - 15 months; 11-12 yrs Td - leaving primary school |
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What vaccines are likely to be added to the Irish schedule soon?
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Pneumococcal; HepB
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What vaccines may adults need?
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Women - rubella if no MMR as child
Tetanus HBV, HAV, pneumococcal - high risk groups travelling - hep A, typhoid health workers - influenza, HBV, TB |
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What should be done if an immunization course is interrupted?
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Resume as normal; repeating not necessary generally
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What are contraindications to further vaccine doses?
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anaphylaxis
fever > 40.5 w/in 48 hrs prolonged unresponsiveness convuslions prolonged screaming (children) |
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True or false: Live vaccines should not be given during pregnancy, but some inactivated vaccines are safe
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True
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What should be done for an HBV+ women who gets pregnant?
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Mother should receive HBV vaccine +/- HBV hyperimmune globulin
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True or false: SSPE is fatal unless treated early
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False - it is always fatal
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What can be done to make polysaccharide vaccines more attractive to the immune system?
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Conjugation to toxoids
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True or false: acellular pertussis vaccine induces better long-term immunity than cellular pertussis
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True
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Which HPV subtypes are ass'd with anogenital warts
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Mainly 6,11
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Which subtypes of HPV are particularly ass'd with cervical cancer?
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16,18,31,33
(31,33 not covered by vaccine) |
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What percent of cervical cancers are caused by HPV subtypes not covered by the vaccine?
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30%
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How do other STIs facilitate the transmission of HIV?
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mucosal surface breaks
increased HIV secretion increased susceptible cells at site |
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How is syphilis diagnosed?
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Acute - darkfield microscopy
Also serology - RPR test (non-specific) - treponema EIA CSF serology |
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What treatment is appropriate for syphilis?
|
Procaine penicillin (slow release)
Amoxicillin Doxycycline |
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What is the Jarish-Herxheimer reaction?
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Massive release of antigen when bacteria (syphilis) die cause flare of symptoms - malaise, flu-like symptoms
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Besides the male and female genital tract, where else can gonorrhea infect?
|
Joints - septic arth
Pharynx Anorectal area |
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How is gonorrhea diagnosed?
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Microscopy, culture, PCR
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What treatments are appropriate for gonorrhea?
|
single dose IM Ceftriaxone (3rd gen ceph)
Spectinomycin (quite good) |
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Name some treatments for HPV
|
Cryotherapy
Imiquimod Laser ablation Surgery Electrocautery Podophyllotoxin Tricholroacetic acid |
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How do you diagnose gential herpes?
|
Viral culture
EM Type specific antibodies |
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What is the treatment for genital herpes?
|
Acyclovir
Valacyclovir Famcyclovir |
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Which infections does chlamydia cause?
|
Cervicitis
PID Urethritis Epididymitis Proctitis Reiter's syndrome (post-infxn) despite all this -- 70% asymptomatic |
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What are some risks related to PID?
|
Ectopic pregnancy
Infertility Chronic pelvic pain |
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How is chlamydia diagnosed?
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PCR or ligase chain reaction
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What is the treatment for chlamydia
|
Azithromycin - best - single dose
Doxycycline Erythromycin Ofloxacin |
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What type of organism is trichomonas vaginalis?
Is it sexually transmitted? |
Flagellated protozoan
Yes |
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Symptoms of trichomonas infection?
|
Vaginal discharge
Offensive odour Vulval itching |
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What particular risk is trichomonas?
|
In pregnancy - premature rupture of membrane
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Diagnosis of trichomonas?
|
Wet smear
Culture |
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Treatment of trichomonas?
What consideration must be made? |
Metronidazole (flagyl)
Need to treat partner too |
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What causes chancroid and who does it affect?
|
Hemophilus ducrei
90% Men |
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What 3 basic factors influence HCAI?
|
Microbes - different bugs
Environment - crowding, etc. Patient - very ill, etc. |
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What is the difference btw cleaning, disinfection and sterilization?
|
Cleaning - removal of some organsism
Disinfection - removal of significant amount of organisms Sterilzation - complete eradication of all microbes, incudling spores, but not including prions |
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True or false, ethylene oxide can be used in hospitals for sterilization?
|
True
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True or false: hypochlorite, ortho-phthaldehyde and chlorhexidine are effective sterilizaing agents
|
False - disinfection only
(same for alcohol and iodine) |
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What point in pregnancy is most susceptible to the damage caused by rubella infection?
|
First 8 weeks
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How is meningococcus commonly transmitted?
|
Respiratory droplets
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Which vaccines are allowed in pregnancy
|
Hep A
Hep B influenza tetanus toxoid |
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|
HDS
What BMI is overweight? Obese? |
BMI > 25 overweight
BMI > 30 obese |
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HDS
Obesity - what groups affected in Ireland? |
Highest in: Men, >35, low education/SES
1% increase in Irish adults/yr higher rates in 13-15 yr old girls |
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HDS
Key messages in obesity lecture |
1) a growing problem (faster in lower SES groups)
2) indicator of social/economic deprivation 3) may respond to educational interventions |
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HDS
What six responses to the obesity problem were outlined in the Obesity Taskforce Report? |
1) High government level commitment
2) Education 3) Social and community 4) Health sector 5) Food, commodities, production, supply 6) Physical environment |
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HDS
What is genetic epidemiology? |
Study of joint actions of genes and environmentla factors in causing disease and their pattern of inheritance
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HDS
Definition of a polymorphism? |
Genetic variant occurring at frequency of > 1% in population
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HDS
What does descripitive epidemiology allow us to study |
Disease characteristics - ie which populations does it affect
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HDS
What do familial aggregation studies attempt to find? |
Familial clustering of diseases and whether or not this could be due to genetics
- includes twin and adoption studies |
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HDS
What does segregation analysis show us? |
mode of inheritance
- dominant vs. recessive - reduced penetrance or variable expressivity |
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HDS
What does linkage analysis show us? |
location of disease susceptibility genes broadly - are there markers which tend to be co-inherited with gene of interest? - closer ones turn up more often - relation between loci
-- done within families |
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HDS
What use are association studies? |
For finding exact location of gene
- look for linkage disequilibrium - relation btw alleles -- done with populations |
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HDS
What is public policy? What is policy making? |
What gov'ts choose to do or not do about perceived problems
How gov'ts decide what to do |
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HDS
What are the four steps in policy making? |
1. agenda setting
2. policy formulation 3. implementation 4. re-evaluation |
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HDS
What are doctors roles in influencing public policy? |
1. leadership and advocacy
2. harnessing public opinion 3. evidence and authority 4. get debate message to mainstream 5. lobbying for legislative support |
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HDS
What are 7 stages in the planning cycle |
1. measurement/assessment of illness
2. cause of illness 3. measurement of effectiveness of interventions 4. assessment of efficiency 5. implementation of intervention 6. monitoring of activities 7. reassessment of illness to burden to determine impact |
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HDS
What is public health impact? |
burden of illness in terms of number of cases created by an environmental factor
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HDS
What are the four strategies which govern irish healthy policy? |
Equity
People-centredness Quality Accountability |
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HDS
What are margins |
cost-benefit thing
- the question is not will we provide a service, but how much or to what level of quality - addding or taking away a marginal amount is associated with a marginal cost |
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HDS
What factors make the health market imperfect? |
1. professional monopolies
2. information asymmetry 3. ability/inability to pay 4. externailities neglected (affects of other factors such as immunization protecting unimmunized people) |
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HDS
What are consequences of market failure? |
1. poor people left out
2. reliance on demand neglects externalities 3. governments must get involved to promote equity |
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HDS
Reasons why govt's should finance health services? |
1. ensure universal access
2. public accountability 3. control of demand and expenditure 4. ability to implement coherent national strategies |
