Community Acquired Infections Flashcards
(71 cards)
1
Q
Difference between cellulitis and erysipelas
A
Cellulitis:
- s progenies, s aureus
- involves deep subcutaneous tissue (lower half of dermis)
- legs
- indistinct margins
Erysipelas
- S pyogenes
- upper subcutaneous tissue and lymphatic vessels (upper half of dermis)
- common site: face bridge, cheeks
- well defined margins
- self limiting
2
Q
SSTIs
- complications
- causes of recurrence
A
Cx: abscess, pyomyositis, OM
Recurrent: edema
- venous insufficiency
- lymphedema
- hypoalbuminemia
- poorly controlled DM/ immunosuppression
3
Q
Difference between Hospital acquired and community acquired MRSA
where do you get Ca-MRSA
how to tx
A
HA
- panton valentine leukocydine (PVL) absent
- staph chromosomal cassette (SCCmec) I-III
- bacteremia, OM, IE
- resistant to most abx
CA
- PVL present (hallmark!)
- SCCmec IV/V
- SSTI, nec pneumonia, severe sepsis
- susceptible to non beta lactam abx (>2 agents)
from athletes, MSM, military recruits, IVDU, long term care facility residents (close proximity)
tx:
susceptible to non beta lactam abx (>2 agents)
4
Q
Difference between Necrotising fasciitis T1 and T2
A
T1
- RF: DM, PVD
- Organism: polymicrobial (mixed aerobic/ anaerobic)
T2
- RF: young, previously well, blunt trauma, injection, chicken pox
- Bug: mono microbial (S progenies, S aureus)
5
Q
Gas gangrene
- RF and bug
A
RF: trauma, bowel sx, septic abortion (O&G)
Org: clostridium perfringens
6
Q
Mgx of SSTI
- tx of cellulitis
- tx of nec fasc
- duration
A
- elevate
- tx underlying RF (tinea, lymphedema, chronic venous insufficiency)
mild cellulitis:
- PO cloxacillin, cephalexin
- clindamycin (if severe pen allergy)
mod cellulitis:
- IV cloxacillin, IV cefazolin or IV vancomycin (if severe pen allergy)
Necrotising fasciitis:
- IV penicillin, IV clindamycin, IV ceftazidime, IV immunoglobulins, surgical debridgement
Duration: 5-10days or till clinical resolution
7
Q
S/S of pneumonia
A
fever, chills, cough, pleuritic chest pain, dyspnea
sputum
- mucopurulent (bacteria)
- rust coloured (strep)
- watery (atypical)
GI
AMS
8
Q
Approach to acute CAP
A
- risk stratify: CURB65, ATS guidelines, PSI
- microbiological diagnosis
- empiric and targeted tx
- watch for complications
9
Q
Risk stratification of CAP
A
CURB65:
confusion, urea>7, RR>30, BP<90/60, age >65
- >2: hospitalisation
- >3: severe CAP: ICU
PSI
ATS guidelines (severe = 1 major or 3 minor)
- major criteria
- mechanical ventilation
- septic shock req vasopressors - minor criteria
- confusion
- urea >7
- RR >30
- low BP req aggressive fluid resuscitation/ lactate>4
- leucopenia WBC<4
- multilobar involvement on CXR
- PaO2/FiO2<250 or req venturi mask 40% to maintain SpO2 >95%
10
Q
Causes of pneumonia
A
- Typical
- s pneumo (urinary ag)
- h flu
- m catarrhalis
- burkholderia pseudomallei (serology)
- k pneumoniae
- s aureus post resp viral infx - Atypical
- mycoplasma pneumo (PCR)
- chlamydophilia pneumo
- legionella pneumophillia (urine ag) - Resp virus (resp multiplex)
- mTB
11
Q
S/s of atypical pneumonia
A
- gradual onset
- dry cough
- extrapulmonary symptoms/ signs
> cold agglutinin induced hemolysis
> encephalitis, transverse myelitis
> erythema multiforme
> hypoNa
> diarrhea
wbc may be normal
12
Q
Empiric tx of CAP
- duration of tx
A
MILD - PO augmentin MOD - IV augmentin + PO clarithromycin SEVERE - IV augmetin PLUS - IV ceftazidime (meliodosis cover) PLUS - PO azithromycin (legionella) fluid resus (lactate guided)
If influenza: early oseltemivir within 48 hours of symptom onset
mild/mod:7 days
severe:14 days
IV to oral: no fever for 24 hours, able to take orally, stable vitals
13
Q
Targeted tx of CAP
- when to oralise
- duration
A
based on culture results
- oralise if afebrile for 24h, no absorption issues, good oral intake, stable vitals
- duration: mild (5-7d), severe(10-14d)
follow up CXR 7-12w after tx TRO malignancy
vaccinate
14
Q
How to differentiate complicated effusion/ empyema from uncomplicated effusion
- tx
A
complicated/ empyema:
- WBC>10k
- LDH>200
- Protein>3
- Glucose<60
- pH<7.2
- culture positive
- appearance: cloudy/purulent
tx:
- uncx: abx
- cx: abx + tube thoracotomy
- empyema: abx + sx drainage
15
Q
Vaccinations for asplenic pt
A
- pneumococcus
- H flu
- N meningitides
- influenza
16
Q
Meliondosis
- RF
- S/S
- Tx/ Mgx
A
RF: DM, alcoholism, chronic renal dz, chronic lung dz
HOPC: pneumonia, visceral abscesses (any part of body)
TX:
- drain abscess
- induction: IV ceftazidime or meropenem if severe (4-6w)
- maintenance: PO bactrim or augmentin/ doxycycline (3mth)
- notify MOH
17
Q
Causes of chronic pulmonary syndrome (symptoms >3w)
A
Atypical pneumonia: mycoplasma, chlamydia, legionella
Mycobacteria: TB, non tuberculous
Fungal: cryptococcus, histoplasma
Lung abscesses
Non infective: cancer, ILD, wegener, drugs
18
Q
Clinical presentation of CNS infx
A
meningitis triad: fever, neck stiffness, AMS
others: headache, N&V, seizures, CN palsies, rash
19
Q
how long to isolate N meningitides
A
droplet precautions for N meningitides till 24 hours post appropriate Rx
20
Q
when to image before LP (risk of coning)
A
- immunocompromised state (HIV, transplant)
- hx of CNS dz (mass, stroke, focal infection)
- new onset seizures within 1 w
- papilledema
- AMS
- focal neuro déficit
- age > 60
21
Q
Differentials for lymphocytic CSF result from LP
- how to differentiate
- how to confirm diagnosis
A
glucose and protein
- TB > AFB smear, culture, TB molecular - Fungal > india ink, CSF crypt ag - Viral > PCR - Cancer > cytology/ flow
22
Q
Causes of neutrophilic pleocytosis on CSF
A
bacterial: S pneumoniae, N meningitides, H influenzae
23
Q
Causes of lymphocytic pleocytosis on CSF
A
INFECTIVE
- viral: HSV, VZV, HIV, enterovirus, mumps, CMV, EBV, JE
- bac: TB, listeria, leptospirosis, syphillis, rickettsia
- fungal: cryptococcus, histoplasmosis, coccidioidomycosis
NON INFECTIVE
- malignant: lymphoma, leukemia, leptomeningeal
- drugs: NSAIDs, sulphonamides, tetracyclines
- autoimmune: behcet, SLE, vasculitis, sarcoidosis, NMDA encephalitis
24
Q
MRI results in CNS infection
- temporal enhancement
- basal meningitis
- rhombencephalitis
A
- temp: HSV
- basal: TB
- rhomb (brain stem): listeria
25
Empiric tx of meningitis
1. IV ceftriaxone 2g 12 H + vancomycin 15mg/kg 12H
2. IV ampicillin 2g 4H (for listeria)
3. Steroids: dexamethasone 0.15mg/kg 6H for 4 days: reduces neuro deficits, hearing loss esp in pneumococcus
26
How to tx HSV encephalitis
IV acyclovir 10mg/kg Q8h
27
TB tx duration
Pul TB: 6-9months
Osteoarticular TB: 9months
Meningeal TB: 12 months
28
Tx of TB meningitis and SE
when to intervene for SE
RIPE + pyridoxine (B6) + steroids (prevent compression and tamponade for heart from paradoxical rx with tx)
Rifampicin: hepatitis, rash, haemolytic anemia, thrombocytopenia, CYP450 inducer (may dec levels of concomitant meds - cause tissue rejection in tranplant pt),
Isoniazid: peripheral neuro, hepatitis, rash
Pyrazinamide: hepatitis, high rate level/ arthralgia, rash
Ethambutol: retrobulbar neuritis
INTERVENE if
- 3x ULN of LFT (symptomatic), 5x if asymptomatic: staggered rechallenge
- severe rash: stop and rechallenge
29
Post exposure prophylaxis for meningococcal disease
- who is at risk
- what drugs and considerations
Risk: household contact, direct exposure to oral secretions, childcare centre contacts
Abx:
- ciprofloxacin PO: not for kids, pregnant
- rifampicin PO: avoid in 1st T, children ok
- ceftriaxone IM: ok for both kids and pregnancy
30
What is considered complicated UTI
- male
- systemic symptoms: fever, chill/rigors
- functional/ metabolic or anatomical conditions that predispose to more cx/ tx failure
- calculi
- urinary tract tumors
- obstruction
- catheter
- neurogenic bladder
- pregnancy
- diabetes
- immunosuppression
- renal insufficiency
31
Bugs for UTI
```
e coli
klebsiella
proteus
citrobacter
s saprophyticus
enterococcus
```
32
role of imaging in UTI
- severely ill
- persistent fever/ bacreremia with no response after 48 hours of antibiotics
look for abscesses/ pyonephrosis which may need decompression/ drainage
- complicated UTI (e.g. stone)
- obstruction
33
What is the tx of
- cystitis
- pyelonephritis
- prostatitis
- abscess
cystitis
- beta lactam 5-7d
- ciprofloxacin/ cotrimoxazole 3d
pyelonephritis
- ciprofloxacin or cotrimoxazole 7d
- beta lactam 10-14d
- aminoglycosides 7-10d
prostatitis
acute: 2-6w
chronic: 6w-3m
abscess: drainage plus targeted abx till resolution of abscess/ improvement of CRP
34
when should I admit for pyelonephritis
- sepsis, unstable, hypovolemic
- ongoing N&V
- possible resistant org, no suitable oral options
- frail
- male
- immunocompromised
- poor psychosocial support
35
When do you give cystitis prophylaxis
- what to give
- duration
- other mgx
```
FOR recurrent cystitis
young women:
- >3 culture pos epi/ yr
post menopausal:
- >3 culture pos + symptomatic UTI/ yr or >2 in 6 months
```
cover for enterobacteriaceae, enterococcus, s saprophyticus
- TMP-SMX daily or 3x/w OR
- trimethoprim once daily OR
- cephalexin daily OR
- single dose nitrofurantoin after intercourse
give counselling: hydration, urination after sex, perineal hygiene
36
Causes of recurrent UTI
```
congenital anomalies
stones
tumors
neurogenic bladder
catheter/ prosthesis
inadequate tx or persistent source (e.g. prostatitis)
```
37
When do you tx asymptomatic bacteriuria
- pregnant women
| - going for invasive genitourinary procedures associated with mucosal bleeding (TURP)
38
Norovirus
- how they present
- special feature
- diagnosis
- myalgia, malaise, headache
- GE symptoms
- low grade fever
low infectivity dose, highly transmissible (food, water, air)
novovirus PCR
39
Causes of persistent fever
- wrong bug
- source control (abscess)
- dosing of abx incorrect
- penetration into correction site
- non infective cause/ alt diagnosis
40
Mgx of vibrio cholera
- oral rehydration therapy
- ciprofloxacin or tetracycline
- notify MOH within 24h
(endotoxin)
41
Causes of acute diarrhea
- viral: norovirus, rotavirus
| - bac: campylobacter, salmonella, shigella, enterotoxigenic eccoli, vibrio, c diff
42
Causes of chronic diarrhea (>30d)
parasitic: giardia, entamoeba histolytica, cryptosporidium, cyclospora, Isospora, microsporidia
43
Causes of watery diarrhea
- norovirus
- other enteric virus: rotavirus, adenovirus, astrovirus
- clostridium perfringens
- Enterotoxigenic E coli
- Listeria
- Giardia
- Cryptosporidium
- Cyclospora
44
Causes of inflammatory diarrhea (fever, mucoid, bloody)
- non typhoidal salmonella
- campylobacter
- shigella
- EHEC
- Yersinia
- Vibrio parahemolyticus
- Entamoeba histolytica
45
Which patients do you treat for diarrhea
if severe symptoms
- high fever
- bloody diarrhea
- profuse diarrhea >6x/day
- hypovolemia
- severe ab pain
- duration >1w
if immunocompromised/ elderly>65yo
46
Cx of GE
post infectious syndromes
- GBS (campylobacter)
- Reactive arthritis (campylobacter, Yersinia)
- HUS/ TTP (EHEC Ecoli, shigella)
- Irritable bowel syndrome
- Lactose intolerance
47
differentials for N&V + diarrhea other than GE
- subacute IO
- spurious diarrhea
- drugs: laxatives
- change of diet
- colonic cancer
- IBD
- malabsorption states
- metabolic: hyperthyroidism, carcinonoid
- underlying HIV
48
Manifestations of S aureus bacteremia
```
Disseminated infection
- endocarditis
- septic thrombophlebitis
Deep localised
- OM
- Septic arthritis
- Other deep abscesses
```
49
Manifestations of S aureus
```
localising
- abscesses
- bacteremia: disseminated, deep localised
toxins
- scalded skin syndrome
- staphylococcal scarlet fever
- toxic shock syndrome
- food poisoning
```
50
Approach to S aureus bacteremia
| - duration of abx
- ID review
- IV cloxacillin/ cefazolin
- look for metastatic manifestations: echo 5-7d after bacteremia onset, joint tap/ wash out, MRI spine
- source control: debride, drain, remove prosthesis
- clearance cultures every 24-48 hours
- decide if complicated:
> persistent fever/ bacteremia at 48-72 h despite appropriate abx and source control
> IE
> indwelling devices (heart vales, grafts)
> met complications
duration:
- uncx: 14 d from neg cultures
- cx: 4-6w
51
Abx for MRSA
| - what to monitor in mgx
vancomycin
alt: daptomycin, linezolid, ceftaroline (5th gen), clindamycin, TMP-SMX
monitor pre4th dose vancomycin trough levels (keep around 15-20)
52
RF for endocarditis
- pre existing heart conditions
- IVDU
- poor dentition
- age >60
- males
- prosthesis/ valves/ lines/ previous cardiac surgery
- history of IE
53
Bugs causing IE
NATIVE VALVE
- Acute: s aureus, s pneumo, n meningitidis
- Subacute: viridians, streptococci, E faecalis, HACEK
IV DRUG USER: S aureus, S epidermidis, Gram neg rods, yeast
PROSTHETIC VALVE
- early: s epidermis, s aureus
- late: viridians, strep, s aureus, s epidermidis
- Q fever
54
Causes of culture negative IE
- Coxiella burnetii (Q fever)
- Bartonella spp
- Tropheryma whipplei
- Brucella spp
- Chlamydophilia pneumoniae/ psittaci
- Fungi: aspergillus
- Mycobacterium chimaera (heater cooler machine in open heart sx), TB, M bovis
- legionella
- mycoplasma
- Non infective e.g. APS
- HACEK
prior antibiotic administration
non infective endocarditis
55
What does HACEK stand for
```
haemophilus aphrophilus
actinobacillus spp
cardiobacterium hominis
eikenella corrodens
kingella spp
```
56
How to diagnose infective endocarditis
Modified duke critiera
2major, 1M +3m or 5minor
Major
- micro-org consistent with IE from persistently positive blood cultures: at least 2 +ve cultures drawn 12h apart
(s viridian, s bovis, HACEK, s aureus, enterococci)
- evidence of endocardial involvement (TEE)
Minor
- risk factors (IVDU, heart conditions)
- fever >38
- vascular phenomena: arterial emboli, septic pul infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, janeway lesions
- immunological phenomena: GN, osler nodes, roth spots, RF
- microbiological evidence
57
Empiric tx for IE (if native valve)
IV penicillin +
IV cloxacillin +
IV gentamicin
58
Indications for early valvular sx in IE
1 Heart failure: refractory APO or cardiogenic shock, persistent heart failure with poor hemodynamic tolerance
2 Valve dehiscence/ rupture, conduction defects, paravalvular abscess
3 Uncontrolled infection: persistent bacteremia infection >1w
4 prevention of embolisation: persistent/ enlarging vegetation/ large vegetation on mitral valve
5 prosthetic valves esp with HF, abscess, persistent fever
6 fungal organism
59
What antibiotic can cover e coli, klebsiella, proteus
what to change to if need to also cover chlamydia trachomatis
abx: Ciprofloxacin
(note klebsiella naturally resistant against ampicillin)
ceftriaxone + doxycycline (covers chlamydia - little cell wall)
60
What is Light's criteria
Pleural fluid is an exudate if any one of the following is fulfilled
- pleural protein/ serum protein > 0.5
- pleural LDH/ serum LDH >0.6
- pleural LDH>2/3 upper limit of lab normal value for serum LDH
61
what tests to send for severe CAP (req ICU)
blood cultures
legionella and pneumococcus urinary antigen tests
sputum cultures
62
Abx for pseudomonas
1. aminoglycosides - gentamicin, amikacin)
2. carbapenem - imipenem, meropenem
3. cephalosporins - ceftazidime, cefepime, 4. fluroquinolones (ciprofloxacin, levofloxacin)
5. Penicillin w beta lactase inhibitors (piptazo)
6. monobactam - aztreonam
63
What are factors that are associated with failure of non surgical tx of DM foot
- More severe signs of infection (necrosis/ gangrene
- Lower transcutaneous oxygen tension (peripheral vascular dz)
- High serum creatinine
- Pyrexia (>38.5)
64
how to tx cellulitis
- bed rest, limb elevation
- analgesia
- tx RF: tine, lymphedema
- antibiotic
mild: PO cloxacillin 5-7d/ if pen allergy: PO cefalexin/ PO clindamycin
severe: IV cloxacillin/ cefazolin
if pen allergy: IV vancomycin
65
mgx for necrotising fasciitis
```
PO clindamycin
IV ceftazidime
IV penicillin
IVIG
urgent sx review and debridement
order MRI
```
66
how to do you assess penicillin allergy
| - what alt antibiotics to give
most common allergy: maculopapular rash
serious allergy:
- anaphylaxis
- angioedema
- SJS, TEN
- hypersensitivity
cross reactivity with other beta-lactams (10%)
if mild rash, cephalosporin or other beta lactase can be used, and observe for rash
if severe allergy, avoid all beta-lactams
67
What is the empiric tx for infective endocarditis
- native valve
- prosthetic valve
- IV drug user
native:
- IV penicillin + IV cloxacillin + IV gentamicin
prosthetic:
- IV vancomycin + IV gentamicin + rifampicin
IV drug user
- IV cloxacillin + IV gentamicin
68
What antibiotics for MSSA
Cloxacillin/ Flucloxacillin
Cefazolin/ Cephalexin
With beta-lactamase inhibitor: Augmentin, Unasyn
Erythromycin/ clindamycin (Pen allergy)
vancomycin is inferior with higher rates of failure and relapse
69
Indications for surgery in PVE
- signs or symptoms of heart failure due to valve dysfunction
- uncontrolled infection (abscess, relapse of PVE, fungal, MDR org)
- prevention of embolism
70
Indications for surgery in native valve endocarditis
- organism: fungal
- vegetation: persistent, >10mm on anterior leaflet, >1 embolic events during first 2 w on antimicrobial therapy, increase in size
- valvular dysfunction: acute aortic or mitral insufficiency with signs of ventricular failure. heart failure unresponsive to medical therapy
- valve perforation/ rupture:
perivalvular extension, valvular dehiscence, rupture, fistula, new heart block, large abscess or extension despite appropriate antimicrobial therapy
71
who needs IE antimicrobial prophylaxis
- prosthetic heart valves/ materials in cardiac valve repair
- prior IE
- unrepaired cyanotic congenital heart disease/ partially repaired (residual shunts, regurg)
- valve regurgitation due to abnormal valves in transplanted heart
