16 - Infectious Diseases including Travel Infections Flashcards
What is antimicrobial stewardship?
Process of persuading prescribers to use evidence-based prescribing to prevent antibiotic overuse and therefore prevent antibiotic resistance
Preserves future effectiveness of antibiotics
What are some of the steps in antimicrobial stewardship for every prescriber?
- Prescribe the most appropriate dose, for the shortest time to be effective and the most appropriate route, with the narrowest spectrum abx
- Take microbiological samples before prescribing antibiotic and review prescription when get the results
- Consider delayed prescribing for self-limiting conditions
- Explain to patients why antibiotics might do them more harm than good
- Avoid repeat antibiotic prescriptions within 6 months
What scenarios do the AMS team review?
- Set local antimicrobial guidelines and review regularly
- Review patient safety events
- Ensure antibiotic pack sizes are appropriate for course length
What is the 10 point approach to a patient with a suspected infection?
- What is the evidence for the infection?
- How severe is it?
- Any patient factors to consider?
- Which organ system is infected?
- What is the likely microorganism?
- Which anti-microbial therapy is best?
- Which route of administration is best?
- Any other treatment needed?
- Any risk of transmitting to others?
- How do we follow up and achieve discharge?
What are some causes of immunosuppression?
- HIV
- Immunosuppressive drugs e.g steroids, chemo
- Primary immunodeficiency
- Age
- Malnutrition
- Malignancy
- Asplenism
What do you need to consider with vaccinating immunosuppressed patients?
- Cannot have live vaccines as can develop disseminated disease
- Try to give inactivated vacines two weeks before immunosuppressive therapy as poor antibody response when immunosuppressed
- Need to be offered flu and pneumovax
How are nosocomial infections managed?
- Identify: e.g screening of MRSA
- Protect: isolate multiantibiotic resistant microbes, highly transmissable diseases or hgih risk groups
- Treat: using local guidelines
- Prevent: modify risk factors e.g improve nutrition, remove catheters, clean hands
What are the preventative measures used in hospital to stop infection spreading?
- Hand washing/gelling (wash for C.Diff)
- Bare below elbows and tie back hair
- Scrubs in highly infectous areas
- PPE
- Aseptic techniques
- Clean environment
What is the difference between standard isolation and respiratory isolation?
Respiratory:
- Negative pressure room if AGP or room with door closed at all times if NAGP
- Respiratory precautions sign on door
- Gown, gloves, face shield and mask/FFP3
- Dispose of waste in the room
- Hand hygeine after glove removal
- Limit movement to other departments and visitors
What are the most common organisms causing infection in the following systems and what antibiotics are used to treat them:
- Skin/Soft tissue
- MSK
- Respiratory
- Skin: Staph Aureus, Coagulase negative Staph (S.Epidermidis), Group A Strep (S.Pyogenes), MRSA
- MSK: same as above, Pseudomonas for diabetic foot, TB)
- Respiratory: S.Pneumoniae, H. Influenzae, Legionella, Mycoplasma, Rhinovirus, Adenovirus, Influenza
What are the most common organisms causing infection in the gastrointestinal system and what antibiotics are used to treat them?
Diarrhoea: Rotavirus, Adenovirus, Campylobacter, C.Diff, Salmonella
Peritonitis: Enterobacteriacae
What are the most common organisms causing infection in the following systems and what antibiotics are used to treat them:
- Genitourinary Tract
- CNS
- Endocarditis
GU: Enterobacteriacae, P.Aeruginosa, N.Gonnorrhea, C.Trachomatis
CNS: S.Pneumonia, N.Meningitidis, HSV, TB, Listeria (>55 or immunocompromised)
Endocarditis: Strep Viridans, Enterococci, S.Aureus, MRSA
What are the most common organisms causing infection in the following systems and what antibiotics are used to treat them:
- Line infections
- Hospital acquired
- Sepsis
What is the gram stain of the following:
- S.Aureus
- S.Epidermidis
- C.Diff
- S.Pneumoniae
- S.Pyigenes
- H.Pylori
- Salmonella
- Campylobacter
- Pseudomonas Aeruginosa
- H.Influenzae
What are some examples of common parasites?
- Protozoa: malaria, entamoeba histolytica, giardia lamblia
- Hyatid disease
- Schistosomiasis
What are some examples of notifiable diseases?
- Mumps
- Measles
- Food poisoning
- Malria
- SARS
- TB
- Tetanus
- Whooping cough
What are some bacteria that are encapsulated?
- N.Meningitidis
- H.Influenzae
- S.Pneumoniae
These are destroyed in spleen so sickle cell or after splenectomy need prophylactic vaccinations as higher risk of infection from these
What is the definition of the following:
- Endotoxin
- Exotoxin
- Enterotoxin
Endotoxin: LPS complex on outer membrane of gram negative bacteria that can activate complement and trigger inflammatory response
Exotoxin: toxin secreted by bacteria that works at different site to bacterial growth
Enterotoxin: exotoxin that targets the gut e.g C.Diff
How can antibiotics be grouped by their actions?
Affect:
- Cell wall synthesis
- Nucleic Acid synthesis
- Protein synthesis
What are the two different categories of antibiotic resistance and give some examples of each?
Intrinsic: due to structural characteristics e.g vancomycin cannot outer membrane of gram negative bacteria
Acquired: bacteria have evolved via mutation due to selection pressue from antibiotic use (including agricultural antibiotics)
What are some examples of antibiotics that inhibit cell wall synthesis?
Beta lactams: penicillins, carbapenems, cephalosporins
Non beta lactams: glycopeptides
What is Tazocin?
Piperacillin + Tazobactam
(beta lactam + betalactamase inhibitor)
What are the indications for the following antibiotics:
- Benzylpenicillin (Penicillin G)
- Phenoxymethylpenicillin (Penicillin V)
- Co-Amoxiclav
- Tazocin
- Flucloxacillin
- Vancomycin
- Cetriaxone
Penicillin G: usually gram positive such as streptococci (chest, endocarditis, cellulitis), meningococcus
Penicillin V: prophylaxis after splenectomy, rheumatic heart disease
Co-Amoxiclav: chest, pyelonephritis, cellulitis, bone
Tazocin: broad spectrum gram positive and negative, neutropenic sepsis, nosocomial infection
Flucloxacillin: staphylococcus e.g skin, bone, post viral pneumonia
Vancomycin: complicated gram positive e.g MRSA, oral for C.Diff
Ceftriaxone: meningococcus
What are some examples of antibiotics that inhibit protein synthesis?
- Aminoglycosides
- Macrolides
- Tetracyclines
- Fusidic acid
- Chloramphenicol
What are the indications for the following antibiotics and what are some side effects:
- Gentamicin/Tobramycin
- Azithromycin/Clarithromycin/Erythromycin
- Tetracycline/Doxycycline
What are some examples of antibiotics that inhibit nucleic acid synthesis?
- Folate synthesis inhibitors: trimethoprim
- Fluoroquinolones: ciprofloxacin, levofloxacin
- Metronidazole
- Rifampicin
What are the indications for the following antibiotics and what are the side effects:
- Trimethoprim
- Ciprofloxacin
- Metronidazole
- Rifampacin
Which antibiotics have a risk of the following:
- Long QT
- C.Diff
- Nephrotoxic
- Ototoxic
Long QT: macrolides, fluoroquinolones, azole antifungals
C.Diff: cephalosporins, fluoroquinolones, clindamycin, amoxicillin, ampicillin
Nephrotoxic: aminoglycosides, glycopeptides (vancomycin, gentamicin)
Ototoxic: gentamicin/tobramycin (aminoglycosides)
How are staphylococcal organisms classified and what are some infections that they cause?
Gram positive and coagulase +ve/-ve
S.Epidermidis (coag -ve): less virulent and usually only infection if immunosuppressed or foreign material e.g prosthetic joint, heart valve, catheter, IV line
S.Aureus (coag +ve): toxic shock, cellulitis, impetigo, endocarditis, mastitis, septic arthritis
How are staphylococcal infections treated?
- Usually penicillins
- If MRSA use vancomycin
How are streptococcal organisms classified and what are some infections they cause?
Gram Positive, Haemolytic a/b/y, Lancefield Group
S.Pyogenes (B Haemolytic Group A): tonsillitis, scarlet fever, pneumonia, necrotising fascitis
S.Pneumoniae: otitis media, meningitis, pneumonia
S.Viridans: endocarditis from dental origin
What are some examples of gram positive bacilli?
- C.Diff
- C.Botulinum
- Listeria
What are some examples of gram negative cocci and bacilli ?
Cocci
- N.Meningitidis
- Moraxhella Catarrhalis
Bacilli
- P.Aeruginosa
- E.Coli
- Klebsiella Pneumoniae
- Haemophillus influenzae
- Whooping cough/Bordetella Pertussis
What is the definition of sepsis and septic shock?
Sepsis is dysregulated immune response to an infection leading to life threatening organ dysfunction
Septic Shock is a subset of sepsis with profound circulatory, cellular and metabolic abnormalities with greater risk of mortality than sepsis
How is the risk of sepsis stratified?
LEARN RED FLAGS!!
What is included in the sepsis 6?
What are the most common manifestations of travel related illness?
- Fever
- GI symptons (N+V, Diarrhoea)
- Jaundice
- Lymphadenopathy
- Hepatosplenomegaly
- Respiratory symptoms (SOB, Cough)
What are the most common infections acquired from travel in the following areas:
- Subsaharan Africa
- South East Asia
- South and Central Asia
- South America
- Malaria
- Dengue fever
- Typhoid (enteric) fever
Do not forget community acquired infections that may not be related to travel!!!
How do you take a travel history for a suspected travel-related infection?
Who, What, Where, When, How
- Geographic region and when (<10, 10-21, >21)
- Type of accomodation
- Time of onset of symptoms (incubation period)
- Recreational activities e.g freshwater lakes, game parks, farms, caves
- Food and water
- Sexual history
- Unwell contacts
- Travel vaccinations
- Any healthcare exposure
What are some travel related infections with a long (>21 days) incubation period?
- Malaria
- TB
- Viral hepatitis
- Infective endocarditis
- Schistosomiasis
Rashes are common in travel-related infections. What differentials would you think of with the following rashes:
- Maculopapular
- Petechiae or Purpuric
- Necrotic ulcer with erythematous borders
- Rose spots on chest/abdomen
Maculopapular: dengue, EBV, primary HIV, leptospirosis, CMV, rubella, parvovirus B19
Purpuric: dengue, meningococcal infection, viral haemorraghic fever
Necrotic ulcer: rickettsia from tick bit, anthrax
Rose spots: Typhoid fever
What investigations should you do in a returning traveller with fever? (remembering always isolating them first and excluding VHF)
- FBC: lymphopenia with viruses, eosinophillia with parasites, low platelets in malaria, dengue, HIV, sepsis
- Malaria blood smears x 3 and rapid diagnostic testing
- Blood cultures x 2 before antibiotics
- LFTs
- U+Es
- Urinalysis dipstick and culture
- Stool culure (cysts, ova, parasites)
- Serology/PCR
- CXR
- HIV, HepB/C, Syphillis serology
What organism causes malaria?
- Plasmodium Falciparum/P.Ovale/P.Vivax
- Parasite spread by Anopheles mosquito
- Common in Sub-Saharan Africa
- P.Falciparum incubation of 7 days-4 weels, Others can be up to a year
What is the life cycle of malaria?
- Sporozites transferred to blood of human from mosquito
- Sporozites travel to liver where they mature then rupture and go into RBCs
- In RBCs merozites form larger trophozites which rupture the RBCs (haemolysis)
What is the presentation and examination findings of a patient with malaria?
Presentation: (Non-Specific)
- Cyclical rigors and fever
- Jaundice
- Malaise
- Severe headache
- N+V
- Vague abdominal pain
- Myalgia
Examination: Jaundice, confusion, fever, hepatosplenomegaly
Malaria should be considered in all patients with a fever and recent travel history. (P.Falciparum incubation of 6 days and occurs within 3 months of travel)
What investigations are done to diagnose malaria?
3x thin and thick blood smear PLUS Rapid diagnostic test of parasite antigen
FBC: anaemia, thrombocytopenia, leukopenia
LFTs: deranged
Glucose: hypoglycaemia
Clotting: DIC
Urinalysis: check for AKI
Head CT: if CNS symptoms
CXR
What defines severe falciparum malaria?
Increased risk of severe malaria with increased age and elevated serum lactate
What is the issue with leaving P.Falciparum infection untreated?
- Hypoglycaemia
- Renal failure due to AKI
- Pulmonary oedema
- Neurological deterioration
- Metabolic acidosis
How is uncomplicated falciparum malaria treated?
1st Line:
- Artemisinin combination therapies (ACT) such as Artemether-Lumefantrine PO
- Take with high fat food to increase absorption
2nd Line:
- Oral quinine sulfate plus doxycycline (or clindamycine)
How is severe falciparum malaria treated?
IMMEDIATE URGENT TREATMENT AND TREAT IN HDU
1st Line:
- Artesunate IV (need to do G6PDH screen before due to risk of haemolysis)
- Followed by full course of oral ACT therapy
2nd Line:
- Quinine IV
Monitor glucose every 4 hours, Hb, clotting, electrolytes, creatinine and daily parasite counts
What are some of the adverse effects of quinine?
- Long QT
- Hypoglycaemia
- Vertigo
- Tinnitus
- Deafness
How is non-falciparum malaria treated?
- Chloroquine PO
- If P.Vivax/P.Ovale then give Primaquine too to clear liver hypnozites. Check for G6PD
How is malaria prevented?
- Prevent bites: cover up, insect repellent with high DEET, mosquito nets
- Vector control: destroy breeding sites (standing water), sterile male mosquito release
- Chemoprophylaxis: usually chloroquine or doxycycline
What are the symptoms of enteric (typhoid) fever?
- Sustained stepwise fever
- Relative bradycardia
- Fatigue
- Headache
- Anorexia
- Vague abdominal pain
- Constipation
- Dry cough
- Rose spots
What might you find on examination of a patient with typhoid fever?
- Pulse-temperature dissociation (relative bradycardia)
- Hepatosplenomegaly
- Rose spots
What are some complications of typhoid fever?
- Intestinal haemorraghe/Perforation
- Myocarditis
- Pneumonia
- DIC
- CNS involvement e.g meningitis, encephalitis, fits
- Eye complications e.g uveitis, corneal ulcer
What investigations should you do to diagnose typhoid fever?
- FBC: leucopenia, lymphopenia, raised CRP
- Blood cultures: TAKE TWO!!
- Stool cultures
- Urine cultures
- Bone marrow cultures
- Duodenal aspirates
How is enteric fever treated?
- IV Ceftriaxone
- When sensitivities are back switch to PO Azithromycin or PO meropenem
- Antipyretics
- Good nutrition and IV fluids
- If CNS involvement add dexamethasone
What is the basis of the vaccine for enteric fever?
- Oral or IM
- Live so do not give in pregnancy or immunosupprision
- 3 years protection
- No protection agaisnt paratyphoid
What is the definition of pyrexia of unkown origin? (PUO)
Temperature over 38 degrees with no identified cause for over 3 weeks or >3 outpatient visits, despite 1 weeks worth of inpatient investigation
What are the different types of PUO?
Nosocomial PUO: patient hospitalised >48h with no infection on admission
Immunodeficient PUO: Pyrexia in patient with neutrophils <500/ul
HIV PUO: Pyrexia in HIV lasting 3d as in patient or >4 weeks as outpatient
What are some common causes of PUO?
Infective: TB, infective endocarditis, abscesses
Autoimmune: temporal arteritis, SLE, Wegener’s granulamotosis
Neoplastic: leukaemia, lymphoma, renal cell carcinoma
Other: drugs, VTE, hyperthyroidism, adrenal insufficiency
What investigations should you do for patients with PUO?
Bloods: FBC, U+Es, LFTs, Bone profile, CRP, clotting, TFTs, multiple sets of blood cultures, LDH, ferritin, B12, folate, immunoglobulins, RF, ANA, dsDNA, pANCA, cANCA, C3, C4
Microbiology: HIV, HepB/C, Syphillis, MSU, sputum cultures, Malaria films, atypical pneumonia screen, CMV/EBV,
Imaging: CXR, CT thorax/abdo/pelvis, transthoracic echo, PET scan, MR spine/head
Biopsy: check for MC+S/TB/histology on all (bone marrow, lymph nodes, abscesses, liver)
How is PUO managed?
- Do not give empirical antibiotics/steroids/antifungals without specialist input
- Rheumatology/Haematology referral
- Keep front sheet in notes of tests been done
- Stable patients can be managed as outpatients
- If no diagnosis despite prolonged investigation, good prognosis
Dengue viruses are spread by the Aedes mosquito. How will a patient with dengue fever present?
Incubation of 3-14 days
- Fever up to 40
- N+V
- Headache
- Retroorbital pain
- Myalgia
- Arthralgia
What are some warning signs that dengue fever is turning severe, and what does severe dengue fever involve?
Dengue Haemorraghic Fever/Dengue Shock Syndrome
Warning signs: abdominal pain, persistent vomiting, mucosal bleeding, hepatosplenomegaly
Severe: shock, respiratory distress, severe bleeding, organ involvement
How is dengue fever diagnosed?
- PCR for virus/ELISA for antigens during first 5 days of fever
- IgM/IgG after first 5 days
- Low WBC and platelets
How is dengue fever treated?
Supportively:
- IV fluids with careful fluid balance due to risk of plasma bleed
- IV crystalloid if severe disease
- Avoid NSAIDs
- Monitor via haematocrit
What diseases can the following organissm spread:
- Mosquitos
- Ticks
- Bugs/Flies
- Snails
Lyme disease is spread by ticks. What is the presentation of this disease?
Early Localised (3-30d after bite): erythema migrans, pain, pruitis, lymphadenopathy, fever, malaise, headache
Early Disseminated (Weeks to months): borrelial lymphocytoma on earlobes, nipples, genitals; lymphocytic meningitis, ataxia, facial/cranial nerve palsy, acute onset 2nd/3rd degree heart block
Late Disseminated (months to year): lyme arthritis, focal inflammation then atrophic skin
What is the organism causing Lyme disease and how is it diagnosed?
Borrelia Burgdoferi (spirochete bacteria)
Diagnosis:
- Can be clinical with erythema migrans and known exposure
- Borrelia culture or PCR
- IgG/IgM serology after a few weeks
What is the definition of Viral Haemorraghic Fever, and what are some causative organisms?
Severe multiorgan disease is which the endothelium is damaged and homeostasis impaired. Haemorraghe complicates the disease course
Causes: ebola, dengue, yellow dever
What does Plasmodium Falciparum look like on blood smear?
Headphone shaped parasites in RBCs
Why does dengue only cause a severe infection on the second time a person is infected?
When there is a reinfection with a different serotype there is an antibody dependent effect which causes the illness
What are some infections caught from fresh water lakes?
- Schistosomiasis
- Leptosporodisis
What are some causes of traveller’s diarrhoea and how is it treated?
What is the definition of dysentry?
Infectious gastroenteritis with bloody diarrhoea
