Infectious Diseases Flashcards
Define sepsis
Life-threatening organ dysfunction causes by a dysregulated host response to infection
Define septic shock
Subset of sepsis with profound circulatory and metabolic abnormalities
- associated with greater mortality
Sepsis red flags
RR > 25
New need for > 40% O2 to keep saturations over 91%
- 87% in COPD
Systolic BP < 91 mmHg or fall of 40 from normal
HR > 130 bpm
No urine output for 16hrs or < 10ml/hr
New onset delirium
Responds only to voice or pain/unresponsive
Non-blanching rash / mottled / ashen / cyanotic
Neutropenia or chemotherapy in last 6 weeks
Time frame for sepsis 6
1 hour
Features of sepsis 6
Oxygen - sats > 94% Take blood cultures Give IV antibiotics - meropenem IV 1g stat Fluid challenge - 500mls Hartmann's or 0.9% saline over 15 mins Measure lactate - blood gas Measure urine output - hourly fluid balance chart
Common organisms of skin/soft tissue infection and antibiotics used
Staphylococci, staph. aureus - Flucloxacillin
Coagulase negative staph - often fluclox/penicillin resistant
Streptococci - Benzylpenicillin/Fluclox
MRSA - Glycopeptide ( Vancomycin, Teicoplanin)
Penicillin allergy
- Doxycycline (tetracycline)
- Meropenem (carbapenem)
- Ceftriaxone (cephalosporin)
Common organisms of musculo-skeltal infection and antibiotics used
Diabetic foot - mixed infections - Pseudomonas sp, Enterobacteriacae - Broad spec penicillin - Tazocin - Carbapenem TB - quadruple therapy
Common organisms of respiratory infection and antibiotics used
Streptococci ( S. pneumoniae) - Amoxicillin (penicillin) - Erythromycin, Clarithromycin (macrolide) H. influenzae - Co-amoxiclav (amoxicllin + clavulinic acid) Atypical (Legionella, Mycoplasma) - Doxycycline - Levofloxacin (fluroquinolone) Rhinovirus/adenovirus/enterovirus - no specific treatment Influenza - Osletamivir
Common organisms of diarrhoea/enterocolitis infection and antibiotics used
Virus (rotavirus, adenovirus)
- no specific treatment
Enterobacteriacae (Campylobacter, Shigella, E.Coli
- usually nil
- if severe:
- Ciprofloxacin
- Clarithromycin, Azithromycin
Salmonella spp. (S.typhi/parathyphi)
- Ceftriaxone/Azithromycin
C.difficle
- PO Metronidazole/VancomycinCommon organisms of visceral infection/ peritonitis and antibiotics used
Enterobacteriacae - Co-amoxicillin or Ciprofloxacin or Gentamicin - Metronidazole (anaerobic cover) If severe/penicillin allergy - Carbapenem
Common organisms of GU tract infection and antibiotics used
Enterobacteriacae - E.coli, Klebsiella sp, Proteus sp - mild infection = PO Trimethoprim / Nitrofurantoin / Co-amoxicillin - mod-severe infection = IV Co-amoxiclav / PO Ciproflaxacin Pseudomonas aerogenosa - Ciprofloxacillin - Gentamicin - Tazocin ESBL/resistant organisms - Carbapenem Gonorrhoea (Neiseria gonorrhoea) - IM/IV Ceftriaxone Chlamydia trachomatis - Azithromycin
Common organisms of CNS infection and antibiotics used
S. pneumoniae - IV Ceftriaxone N. meningitidis / H. influenzae - IV Ceftriaxone Listeria - age >55 / immunocompromised = high dose IV amoxicillin Penecillin allergy - Meropenem Herpes simplex virus (encephalitis) - IV Aciclovir
Common organisms of endocarditis and antibiotics used
S. viridans group - Benzylpenicillin +/- Gentamicin Enterococci (E.facealis) - Amoxicilin +/- Gentamicin Staph. aures (IV drug users) - Flucoxacillin +/- Gentamicin +/- Rifampicin Culture negative endocarditis - Ceftriaxone MRSA / penicillin allergy / penecillin resistant - Vancomycin
Common organisms of line infection and antibiotics used
Staphylococci, staph. aureus - Flucloxacillin Coagulase negative staph - often fluclox/penicillin resistant Streptococci - Benzylpenicillin/Fluclox MRSA - Vancomycin Penicillin allergy - Doxycycline (tetracycline) - Meropenem (carbapenem) - Ceftriaxone (cephalosporin)
Common organisms of hospital inquired infection and antibiotics used
Enterobacteriacae (E.coli, Klebsiella spp) - Co-amoxiclav Pseudomonas spp - Ciprofloxacin - Gentamicin C.difficile - Metronidazole - Vancomycin Multi-drug resistant - Tazocin - Carbapenem
Presentation of travel-related illness
Febrile GI symptoms - diarrhoea - vomiting Jaundice Reticuloendothelial change - lymphadenopathy - hepatosplenomegaly Respiratory symptoms - cough - SOB Rash
Featuers of travel history
Geographic region within last 12 months Dates and duration of stay - incubation period Onset and nature of signs/symptoms Types of accomodation - rural vs urban Recrational activities and expsoures - insects - malaria, rickettsia - animals - biets, ticks - freshwater lakes and streams - schistosomiasis - well/canal - leptospirosis Food and water drunk - faecal-oral transfer Sexual history - HIV, Hep B/C PMH and immunosuppression
Infections develop within 0-10 days of travel
Dengue Rickettsia Viral - infectious mononucleosis GI - bacteria - amoeba
Infections that develop within 10-21 days of foreign travel
Malaria
Typhoid
Primary HIV
Infections that develop > 21 days of foreign travel
Malaria Chronic bacterial infections - brucella - coxiella - endocarditis - bone and joint infections TB Parasitic infections - helminths - protozoa
What does a pulse rate slow for the degree of fever suggest?
Typhoid fever
Skin changes in infection post foreign travel
Maculopapular rash - dengue fever - leptospirosis - rickettsia - infectious mononucleosis (EBV, CMV) - childhood viruses (rubella, parvovirus B19) - primary HIV infection Rose spots on chest/abdomen - typhoid fever Black nectrotic ulcer with erythematous margins - tick exposure Petechiae, ecchymoses or haemorrhagic lesions - dengue fever - meningococcaemia - viral haemorrhagic fever
What does conjunctival suffusion suggest?
Leptospirosis
What does splenomegaly post foreign travel suggest?
Mononucleosis Maleria Visceral leishmaniasis Typhoid fever Brucellosis
What does altered mental state in fever suggest?
Meningo-encephalitis Post travel - cerebral malaria - Japanese encephalitis - West Nile Viral encephalitis Common infective causes - N. meningitis - Strep. pneumonia - Herpes simplex virus
Investigations in post foreign travel infections
Complete blood count
LFTs
U+Es and electrolytes
Malaria smears +/- antigen dipstick - 3 times over 24-48hrs
Blood cultures - x2
Urinalysis +/- urine culture
Stool culture +/- stool for ova, cysts and parasites (OCP)
CXR
HIV, Hep B/C, Syphillis (treponema) serology
Acute serology tube to be saved in lab
Cause of malaria
Blood protozoa transmitted by night-biting Anopheles mosquitoes Plasmodium species - P. falciparum - most serious - P. vivax - P. ovale - mostly SE Asia
Presentation of malaria
Abrupt onset of rigors followed by high fevers, malaise, severe headache and myalgia, vague abdominal pain, N+V
Diarrhoea
Jaundice and hepatosplenogmegaly
Bloods
- anaemia, thrombocytopenia, leukopenia, abonormal LFTs
Complications of untreated P. falciparum
Hypoglycaemia Renal failure Pulmonary oedema Neurologic deterioration Death
Presentation of typhoid fever
Sustained fever Anorexia Vague abdominal discomfort Constipation or diarrhoea Dry cough
Findings on examination for typhoid fever
Pulse-temperature dissociation
Hepatosplenomegaly
Rose spots
Labatory findings for typhoid fever
Non-specific
- leuocpenia
- lymphopenia
- raised CRP
Diagnosis and treatment of typhoid fever
Isolation of organism in cultures of blood, stool, urine, bone marrow or duodenal aspiraties
IV Ceftriaxone 2g OD
- once sensitivities known PO Ciprofloxacin 500mg BD or PO Azithromycin 500mg OD
PUO
Pyrexia of unknown origin
Definition of PUO
Temperature > 38 on multiple occasions
Illness > 3 weeks duration
No diagnosis despite > 1 week worth of inpatient investigation
Common causes of PUO
Infective - TB - abscess - infective endocarditis - brucellosis Autoimmune/connective tissue - adult onset Stills disease - temporal arteritis Neoplastic - leukamias - lymphomas - renal cell carcinoma Other - drugs - emboli - hyperthyroidism - adrenal insufficiency
Management of PUO
Establish diagnosis
Do no start empirical antibiotics/steriods/anti-fungals without speaking to senior
Rhematology/haematology review
Stable patients managed in outpatients following period of observation in hospital
Epidemiology of Tuberculosis
Caused by mycobacterium tuberculosis
Endemic in many parts of Asia, Africa, South America and Eastern Europe
Pathogenesis of TB
Transmitted by aerosol inhalation - causes pulmonary infection - haematogenosus spread to body Initial infection can be asymptomatic - can be latent for many years Lifetime reactivation risk is 10-15% - usually due to immunosuppression, advancing age or HIV infection
Classification of TB
Active
- classified by affected site - pulmonary, pericardial. abdominal, miliary
Latent
- asymptomatic
- identified by screening - CSR and interferon gamma
What does QuantiFERON test involve
Assess amount of interferon gamma relased by T cells when they are exposed to proteins found of mycobacteria - pre-exposed cells release more interferon
Does not differentiate between active and latent TB
Patients with immunosuppression may not release interferon gamma causing false negatives
What does T-spot test involve
Lymphocytes isolated and tested directly
Postive test does not mean patient has active TB
What does TB screening involve
Used in asymptomatic patients with risk factors for latent TB
- immigrants from high prevalence countries
- healthcare workers
- HIV positive patients
- patients starting immunosuppression
Treatment of latent TB
3 months rifampicin and isoniazid or 6 months rifampicin alone
- balance reduced risk of reactiviation and risk of hepatotoxicity
Common symptoms of TB
Non-resolving cough
Unexplained persistent fever (low or high grade)
Drenching night sweats
Weight loss
Common signs of TB
Clubbing Cachexia Lymphadenopathy Hepto/splenomegaly Erythema nodosum Crepitations or bronchial breathing Pericardial rub
Imaging for TB
CXR - mediastinal lymphadenopathy - cavitating pneumonia - pleural effusion CT - lymphadenopathy - lesions in viscera MRI - leptomeningeal enhancement in TB meningitis
Investigations for TB
Culturing bacteria
- 6 weeks so ATT usually started after samples taken
Pulmonary TB
- sputum samples or induced sputum
- seen on microscopy = smear positive - high bacterial load and high infectivity so start ATT immediately
Meningeal TB
- lumbar puncture for TB culture and TB PCR
Lymph node TB
- core biopsy of lymph node
Pericardial TB
- pericardiocentesis - but often not practical
GI TB
- colonscopy and bowel biopsy / USS guided omentum biopsy
Histological appearance of TB
Caseating/necrotising granulomatous inflammation
Paradoxical reaction in TB
Increase in inflammation as bacteria die -> woresening symptoms
- usually occurs at start of treatment
If TB is affecting sites where additional swelling cannot be tolerated
Features of TB meningitis
1% of TB patients
All patients with millary TB should have lumbar puncture to exclude TB meningitis
- shows high protein, low glucose and lymphocytosis
MRI shows leptomeningeal enhancement
12 month treatment with steriods
Symptoms of TB meningitis
Varied Personality change Headache Meningitic Coma
Features of pericardial TB
Result in pericardial effusion and tamponade
Signs include pericardial rub or kussmauls sign
6 months treatment - steroids at start
Features of Miliary TB
Characteristic appearance on CXR/CT
Widespread and found in multiple sites
Neuroimaging and lumbar puncture to exclude CNS involvement
ATT started as soon as determined whether CNS involvement
Multi Drug Resistant TB
Consider in - patients who have had incomplete treatment for TB previously - patients from abroad Treatment based on sensitivities Infection control paramount - negative pressure room
Standard ATT treatment for TB
2 months - Rifampicin - Isoniazid - Ethambutol - Pyrazinamide - plus pyridoxine (vitamin b) 4 months - Rifampicin - Isoniazid - plus pyridoxine (vitamin b)
Side effects of TB treatment
Rifampicin - urine/tears turn orange - drug induced hepatitis + Isoniazid - peripheral neuropathy - reduced by pyridoxine - colour blindness - drug induced hepatitis ++ Ethambutol - optic neuropathy/reduced visual acuity Pyrazinamide - drug induced hepatitis +++
Monitoring for TB treatment
Measure baseline LFTs and visual acuity
Monitior LFTs
- if deranged stop treatment and gradually reintroduce drugs once normalised
- liver friendly regime - amikacin, levofloxacin and ethambutol for 24 months
Screening for bacterial STIs performed in
All patients who are already know to have a sexually transmitted/transmissible infection
All patients who request testing
Any patient identified as high risk of STI from history
Tests for asymptomatic patients STI
First pass urine (men)
Vulvo-vaginal swab
Pharyngeal swab
Rectal swab
Additional tests for symptomatic STI patients
Urethral / vaginal / anal discharge - charcoal swab for Gonococcal culture
- Posterior fornix for Trichomonas vaginalis and Candida culture
Oral/genital ulceration - for HSV 1 and 2 PCR
Conjunctivitis
Baseline investigations for all new HIV diagnoses
Confirmatory HIV test
CD4 count
HIV viral load
HIV resistance profile
HLA B*5701 status
Serology for syphilis, hepatitis A, B, C
Toxoplasma IgG, measles IgG, varicella IgG, rubella IgG
FBC, U&Es, LFTs, bone profile, lipid profile
Schistosoma serology - if spent >1 month in sub-Saharan Africa
Cervial cytology - annually
HIV patients with low CD4 counts
Susceptible to infection
CD4 < 200
- Co-trimoxazole 480mg PO OD - primary prophylaxis against PCP
CD4 < 50
- Azithromycin 1250mg PO once weekly - MAI
- opthalmology with dilated fundoscopy - evidence of intra-ocular infections such as CMV retinitis
Vaccinations for those with HIV
Hepatitis B
Pneumococcus
Annual influenza
