Infections

Question 1

What are the typical and atypical bacteria causing CAP?

Answer 1

Typical: streptococcus pneumoniae, haemophilus influenzae, moraxalla catarrhalis
Atypical: legionalla pneumophila, mycoplasma pneumoniae, chlamydophila pneumoniae

Question 2

What are the common and uncommon viruses causing CAP?

Answer 2

Common: influenza viruses (A,B,C)
RSV

Uncommon
Measles virus
Avain influenza
MERS

Question 3

In the initial dx of CAP what needs to be assessed?

Answer 3

 local endemicity of pulmonary tuberculosis
 host factors like immunocompromised status
 risk factors for atypical or emerging pathogens (FTOCC, i.e. fever, travel, occupation, cluster and contact)
 Early isolation of patients with suspected or confirmed air-borne pathogens if indicated

Question 4

What is empirical treatment for outpatient CAP?

Answer 4

PO Amoxicillin-clavulanate (beta-lactam with beta-lactamase inhibitor) ± macrolide OR doxycycline

Question 5

What is empirical treatment for outpatient CAP?

Answer 5

 PO/IV Amoxicillin-clavulanate ± macrolide OR doxycycline
 Alternatives: IV ceftriaxone, cefotaxime ± macrolide OR doxycycline
 Anti-pseudomonal antibiotics (e.g. IV piperacillin-tazobactam, cefepime) ± macrolide OR doxycycline for those with chronic lung condition like bronchiectasis
 Consider oseltamivir (especially during influenza season)

Question 6

What is the major and minor criteria for admitting severe pneumonia patients into hospital?
What is the treatment?

Answer 6

1 in 3 major criteria OR 2 in 6 minor criteria:
 Major criteria: need of mechanical ventilation, septic shock, acute renal failure;
 Minor criteria: multi-lobar involvement, mental confusion, respiratory rate >30 bpm, PaO2/FiO2 <250, SBP <90 mmHg/ DBP <60 mmHg, serum urea level >7 mmol/L)
 IV piperacillin-tazobactam or ceftriaxone or cefepime ± macrolide OR doxycycline
 Consider oseltamivir (especially during influenza season)

Question 7

What the organisms causing HAP with onset <4 days after admission with no previous antibiotics?
What is the empirical antibiotics?

Answer 7

S. pneumoniae, H.influenzae, M. catarrhalis, S. aureus
Empirical antibiotics: IV/PO amoxicillin-clavualante or IV ceftriaxone

Question 8

What the organisms causing HAP with onset <4 days after admission + recieved antibiotics?
What is the empirical antibiotics?

Answer 8

MRSA, P. aeruginosa, Acinetobacter spp, klebsiella spp, enterobacter spp
IV piperacillin-tazobactam/IV cefipime/IV meropenem/imipneme +vancomycin if at risk of MRSA infection

Question 9

Who is notified in TB case:

Answer 9

Notified to DH, particularly once the case is put on treatment
If patient happens to be a health care worker or working in other relevant occupations with increased risk of exposure to TB, notification to the Labor department is required under the occupational safety and health ordinance.

Question 10

What is the treatment for uncomplicated TB cases?

Answer 10

– 6 months in total
 2 HRZ + (E or S)7 / 4HR7 (When Rx started in hospital or when 3x/week regimen not tolerated)
 2 HRZ + (E or S)7 / 4 HR3
 2 HRZ + (E or S)3 / 4HR3 (Government Chest Clinic regimen)

Question 11

What is the treatment for retreatment cases of TB?

Answer 11

9 months in total
 3 (or 4) HRZES7 / 6 (or 5) HR  E7

Question 12

What are the drug dosages for TB treatment?

Answer 12

Question 13

What are adverse reactions to 1st line anti TB treatment?

Answer 13

Question 14

If suspicious of CNS infection what Ix should be done?

Answer 14

2. Watch out for signs of ↑ ICP and do urgent CT brain before LP. If LP is contraindicated, likely to be delayed or fails, empirical antibiotics
   can be started after taking blood cultures
3. CSF analysis: cell count, protein, glucose (simultaneous blood
   sugar), gram stain, culture, AFB (smear and C/ST), Cryptococcus (India ink smear, Ag and culture), viral studies. Do not wait for C/ST results before starting Rx
4. Other Ix: CBP, RFT, LFT, CXR, EEG, XR skull, sinuses and mastoid
5. Look for any predisposing factors: sinusitis, endocarditis, otitis
   media, skull fracture, immunocompromised state, etc

Question 15

What is the CSF findings in meningitis for viral, bacterial TB/cryptococcal?

Answer 15

Question 16

What is initial impericial antimicobial regimens for bacterial, brain abscess, tb, crypotoccal meningitis and viral encephalitis?

Answer 16

Question 17

What is dexamethasone given for CNS infections?

Answer 17

 Consider dexamethasone in patients with TB meningitis (0.3 to 0.4 mg/kg/day for two weeks, then 0.2 mg/kg/day week 3, then 0.1 mg/kg/day week 4, then taper 1 mg off the daily dose each week) or brain abscess with significant cerebral oedema.
 Dexamethasone (0.15 mg/kg q6h for 2-4 days with the first dose administered 10-20 min before, or at least concomitant with, the first dose of antimicrobial therapy) in adults with suspected or proven pneumococcal meningitis
 Prophylactic anti-convulsant may be considered in cerebral abscess & subdural empyema

Question 18

How long is treatment for brain abscess and meningitis?

Answer 18

 Duration of Rx for brain abscess 6–8 weeks
 Duration of Rx for meningitis:  7 days for H. influenzae, 10–14 days for S. pneumoniae, 14–21 days for L. monocytogenes and S. agalactiae, and 21 days for Gram negative bacilli.
DO NOT change to oral therapy.

Question 19

What is the common pathogens causing acute uncomplicated cystitis, what is management and antibiotic therapy?

Answer 19

Common pathogen: E.coli, S. saprophyticus, group B streptococcus
General management: analgesics, encourage oral fluid intake

Antibiotics (generally for 7 days): amoxicillin-clavualnate, nitrofurantoin (avoided in patients with creatinine clearance <30mL/min)

Question 20

What is the common pathogens causing acute uncomplicated cystitis, what is management and antibiotic therapy?

Answer 20

Common pathogen: E.coli, S. saprophyticus, group B streptococcus
General management: analgesics, encourage oral fluid intake

Antibiotics (generally for 7 days): amoxicillin-clavualnate, nitrofurantoin (avoided in patients with creatinine clearance <30mL/min)

Question 21

What is the common pathogens causing acute pyelonephritis, what is management and antibiotic therapy?

Answer 21

Common pathogen: E.coli and other gram negative bacilli
Management: analgesics, antipyreetic, fluid resuscitation and/or inotropic support for severe cases
Empirical antibiotics: IV amoxicillin or clavulanate/IV piperacillin-tazobactam/IV meropenem (for severe or rapidly deteriorating cases)

Review antibiotics regimen when culture results are available, and to complete antibiotics course of 14 days

Question 22

What are the pathogen causes of secretory diarrhea (non inflammatory enteritis)?

Answer 22

Commonly caused by salmonellosis
Norovirus: pronounced vomiting
Cholera classically presents as acute painless profuse rice water diarrhea without blood or mucus

Question 23

What are the pathogen causes of invasive diarrhea (inflammatory enteritis)?

Answer 23

Presents as dysenteric syndrome i.e. transient diarrhea followed by abd colic, tenesmus, fever, blood and mucus in stool
Commonly caused by shigellosis (bacillary dysentery), non-cholera vibrios (Vibrio parahaemolyticus and Plesiomonas shigelloides) and occasionally Entamoeba histolytica (amoebic dysentery).

Question 24

What is the cause of typhoid and paratyphoid fever?
What features in CBC?

Answer 24

• Caused by Salmonella typhi (typhoid fever) and Salmonella paratyphi (paratyphoid fever)
• Suspect in patient of high fever with relative bradycardia, ↓platelet, N to ↓WCC, no localized focus of infection.
  Rose spots

Question 25

What is the result of clostridium difficile infection?
What risk factors are there?

Answer 25

Commonly caused by hospital acquired diarrhoea
Presentation can range from mild diarrhoea to pseudomembranous coliits (PMC). Fulminant colitis can result in toxic megacolon and death
Most common risk factor is exposure to broad spectrum antibiotics (esp 3rd gen cephalosporins, fluoroquinolones and clindamycin).
Other risk factors: old age, prolonged hospitalization, antineoplastic chemotherapy, proton- pump inhibitors (PPIs), gastrointestinal surgery and procedures & severe underlying disease.

Question 26

What systemic complication associated with E.coli O157H7, campylobacter enteritis, non polioenteroviruses?

Answer 26

E.coli O157H7: haemolytic uraemic syndrome
Campylobacter enteritis: Guillain-Barre syndrome
Non polioenteroviruses: Hand foot mouth disease, myocarditis, encephalitis

Question 27

What is the management for enteric fever?

Answer 27

Dx by clinical features and positive culture from bone marrow aspirate, blood/stool. Widal serology is neither sensitive for specific
Fluoroquinolones e.g. ciprofloeacin 500mg BDpo, can be given for susceptible isolates, 5-7 days for uncomplicated cases and 10-14 days for severe cases
Fluoroquinolone resistant strains (which are common in southeast asian region), 3rd gen cephalosporin e.g. ceftriaxone 2gm q24h IV for 10-14 days, or azithromycin 500mg daily po can be used.

Question 28

What is the management for febrile dysentery, campylobacter enteritis?

Answer 28

Febrile dysentery: ciprofloxacin 500mgBD po, or azithromycin 500mg daily po or ceftriaxone 1-2gm q24h, for 3-5 days can be considered

Prevalence of fluoroquinolones resistance among campylobacter, shigella and salmonella isolates has been rising.
For confirmed or suspected campylobacter enteritis, macrolide (azithromycin or clarithromycin) is preferred if antibiotics is indicated.

Cases of chloera, antibiotics can hasten rate of recovery. Treatment options include single dose of doxycycline 300mg po, or azithromycin 1gm po, or ciprofloxacin 1 gm po.

Question 29

How to dx C. difficile infection?
What is the management of clostridium difficile infection?

Answer 29

Detection of C. difficile toxin or PCR in stool
Discontinuation of inciting and unnecessary antimicrobial therapy
Oral metronidazole 500mg TDS for 1-14 days (most mild cases)
Oral vancomycin 125mg 4x a day for 10-14 days (for patients who fail to respond, or not tolerate metronidazole, or for severe cases)
Oral vancomycin + IV metronidazole, or intracolonic vancomycin for patients with severe ileus.
Fulminant colitis, surgery may be needed.
For repeated relapse give oral vancomycin

Other treatment options include rifaximin, faecal microbiota transplant.

Question 30

What are the investigations for acute cholangitis?

Answer 30

CBP, LFT, RFT
PT, aPTT, glucose
Blood culture
Abd USG

Question 31

What is the management of acute cholangitis?
Mild- moderate/severe cases
How long is treatment?

Answer 31

Active resuscitation and monitor vital signs
IV antibiotics for mild to moderate cases: amoxicillin-clavulanate (augmentin), cefuroxime + metronidazole. If penicillin allergy, levofloxacin + metronidazole. IV can be switched to oral for completion of therapy if clinically stable
IV antibiotics for severe cases: piperacillin-tazobactam (tazocin), carbapenems, 3rd ceph or levofloxacin + metronifazole
Duration of treatment: 4-7 days unless difficult to achieve biliary decompression
Early decompression of biliary obstruction by ERCP or PTBD

Question 32

How do you prepare a patient for ERCP to manage acute cholangitis?
What are the indications for ERCP?
Manamgent for post ERCP?

Answer 32

Indications for emergency ERCP: increasing pain and guarding in epigastrium or RUQ, hypotension despite resuscitation, high fever (>39C), mental confusion (indicator of poor outcome)
Correct coagulopathy
Fast patient

Watch out for post ERCP complications including post ERCP pancreatitis, perforation and bleeding

Care for patients who have nasobiliary or percutaneous (PTBD) drainage of obstructed biloiary tract
Check I/O chart (including NB drain) daily
Check hydration status, RFT, HCO3- and correct fluid and electrolyte derangement as necessary

Question 33

What is the diagnostic criteria for spontaneous bacterial peritonitis?
What Ix necessary?
What pathogens?

Answer 33

Diagnostic criteria: ascitic fluid WCC >500/mm3 or neutrophil >250/mm3
Diagnostic paracentesis. Send ascitic fluid for CBC (EDTA bottle), bacterial culture, cytology. Perform blood culture
Pathogens: E.coli, klebsiella sp, strept. pneumoniae, enterococci

Question 34

What is the empirical treatment of spontaneous bacterial peritonitis?

Answer 34

IV ceftriaxone 2gm q24h or IVI cefotaxime 2gm q8h (q4h if life threatning)
May consider reassessment by repeating paracentesis 48 hours lateer.
Duration of treatment 5-10 days
Consider IV albumin 1.5gm/kg at diagnosis and 1gm/kg on day 3, especially in patients with renal impairment

Watch out for hepatic encephalopathy
Prophylactic antibiotics may be considered for recurrent spontaneous bacterial peritonitis (SBP)
Ciprofloxacin 500mg daily po
Norfloxacin 400mg daily po
Septrin 960mg daily po

Question 35

How to do history and physical examination for skin and soft tissue infection (SSTI) and staphylococcal infection?

Answer 35

Question 36

What are signs and symptoms of necrotizing fasciitis?

Answer 36

Excruciating pain and presence fo systemic toxicity out of proportion to the local findings
SKin breakdown with bullae and drank cutaneous gangrene ca be seen

Question 37

What is organisms causing necrotizing fasciitis following exposure to freshwater, seawater or seafood. What antibiotics given?

Answer 37

Pathogen: aeromonas spp, vibrio.vulnificus
Antibiotics: IV levofloxacin + IV amoxicillin clavulanate

Question 38

What is organisms causing necrotizing fasciitis following intraabd, gynaecological or perineal surgery. What antibiotics given?

Answer 38

Pathogens: polymicrobial, enterobacteriacea, streptococci, anaerobes
Antibiotics: imipenem or meropenem

Question 39

What is organisms causing necrotizing fasciitis following exposure to cuts, abrasion, recent chickenpox, IVDU, healthy adults. What antibiotics given?

Answer 39

Pathogen: group A streptococcus
Antibiotics: IV penicillin G 4 megaunits Q4h +
IV linezolid 600mg Q12H
IVIG for streptococcal toxic shock syndrome (1g/kg on day 1, 0.5kg on day 2 and 3)

Question 40

What is the clinical criteria for septic shock?

Answer 40

Alternatively: 2 or more of qSOFA criteria:
1. Altered mentation
2. Systolic BP <100mmHg
3. Respiratory rate >22/min

Clinical criteria: sepsis and persistent hypotension requiring vasopressors to maintain MAP >65mmHg and serum lactate level >2mmol/L despite adequate volume resuscitation

Question 41

What is the principles of management for septic shock?

Answer 41

Hour 1 bundle
1. Measure lactate level. Remeasure if initial lactate is >2mmol/L
2. Obtain blood cultures (and appropriate microbiologic cultures) prior to administration of antibiotics
3. Administer broad spectrum antimicrobials: choice based on suspected primary site of infection and risk factors for drug resistsant pathogens
4. Begin 30ml/kg crystallodi for hypotension or lactate >4mmol/L
5. Apply vasopressors (noradrenaline, dopamine) if patient is hypotensive during or after fluid resuscitation to maintain MAP >65mmHg

Source control: e.g. removal of indwelling devives, drainage of abscess
Proper ventilatory management with low tidal volume in patients with ARDS
Target blood glucose level <10mmol/L

Question 42

What is the diagnostic criterai for febrile neutropenia?
What is the antibiotics given?

Answer 42

Question 43

What is the assessment and Ix for neutropenic fever?

Answer 43

 Complete history and physical exam to identify infectious foci
 Lab: CBC with differential counts, LRFT, LDH, CaPO4
 Sepsis work-up: blood cultures (with a set collected from each lumen simultaneously if CVC present and 1 peripheral site), other cultures, e.g. urine, sputum, respiratory virus panels, CSF, stool, etc. if clinically indicated
 Imaging: CXR ± other imaging modalities if clinically indicated

Question 44

What is the assessment done for risk of complications of severe infeciton in neutropenic fever?

Answer 44

Patients with any of the following features are considered as high risk:
1. Anticipated prolonged (>7 days duration) and profound neutropenia
(ANC <100 cells/mm3 following cytotoxic chemotherapy)
2. Significant medical co-morbidities, e.g.
a. Haemodynamic instability
b. New pulmonary infiltrates / hypoxaemia / known COPD
c. New onset abdominal symptoms e.g. pain, vomiting
d. Change in mental state
e. Advanced age
f. Uncontrolled or progressive malignancies
g. Oral and gastrointestinal mucositis
h. Intravascular catheter infection
i. Hepatic or renal insufficiency
j. Inpatient status at time of development of fever
k. Allogeneic HCT
l. History of infection / colonization with MDRO, e.g. MRSA,
VRE, ESBL, etc.
3. Multinational Association for Supportive Care in Cancer Risk-
Index (MASCC) Score < 21:

Question 45

Malaria