Infection - Travel related + microbial Flashcards
Why are travellers vulnerable to infection?
More likely to take risks when away from home
Different epidemiology of some diseases
Stress of travel
What are the infections related to water?
Schistosomiasis Leptospirosis Liver Flukes Strongyloidiasis Hookworms Guinea Worms
What is the vector for malaria?
Female anopheles mosquito
What is the life cycle of malaria?
Mosquito bites human
Sporozoites go to liver + form merozoites
These enter red blood cells + make gametocytes in blood cells
Digested where gametocytes merge in mosquito and have more sporozoites
What are the species of malaria?
Plasmodium falciparum (potentially severe) Plasmodium vivax Plasmodium ovale Plasmodium malariae Plasmodium knowlesi
What are the symptoms of malaria?
Fever Rigors Aching bones Abdo pain Headache Dysuria Frequency Sore throat Cough
What are the signs of malaria?
Splenomegaly
Hepatomegaly
Mild jaundice
What are the complications of malaria?
Cerebral malaria (encephalopathy) Blackwater fever Pulmonary oedema Jaundice Severe anaemia Algid malaria (gram negative septicaemia)
How do you diagnose malaria?
Blood films
Quantitive buffy coat (centrifugion + UV micropscopy)
Rapid antigen tests (optimal + parasight-F)
What are the types of blood films used in malaria?
Giemsa
Fields stain
What determines complicated malaria?
1+ of: Impaired consciousness Hypoglycaemia Parasite count >2% Haemoglobin <8mg/dl Spontaneous bleeding Haemoglobinuria Renal impairment Pulmonary oedema Shock
What drugs are used for uncomplciated p. falcoparum malaria?
Riamet 3 days
Eurastesim 3 days
Malarone 3 days
Quinine 7 days
How do you treat complicated/sever p/ falciparum malaria?
IV artesunate –unliscenced
IV quinine + doxycyline
What are the causes of typhoid fever?
Salmonella typhi
Salmonella paratyphi
What are the predisposing factors for typhoid fever?
Poor sanitation
Unclean drinking water
What is the incubation period for typhoid fever?
1-4 weeks
What are the clinical features found in first week of typhoid fever?
Fever Headaches Abdo discomfort Constipation Dry cough Relative brachycardia Neutrophillia Confusion
What are the clinical features found in second week of typhoid fever?
Fever peaks at 7-10 days Rose spots Diarrhoea Tachycardia Neutropenia
What are the complications possible in the third week of typhoid fever?
Intestinal bleeding
Perforation
Peritonism
Metastatic infections
What percentage of people relapse with typhoid fever (in 4th week)?
10-15%
How do you diagnose typhoid fever?
Clinical - evolution of features
Laboratory
Culture blood, urine + stool
Culture bone marrow
How do you treat typhoid?
Oral azithromycin - uncomplicated
IV ceftrixone or convern with reabsorption
What countires are most at risk of dengue fever?
Central belt (south america, africa, south asia
How is dengue fever transmitted?
Via mosquitoes
What is the presentation of dengue fever?
Sudden fever + headache (retro-orbital pain)
Severe myalgia + arthralgia
Macular/maculopapular rash
Haemorrhagic signs (petechia, purpura, positive tourniquet test)
How do you diagnose dengue fever?
Lab tests - PCR, serology Clinically - thrombocytopenia Leucopenia Elevated transaminases Positive tourniquet test
How do you treat/manage dengue fever?
No specific agents to treat, managing complications
PREVENTION - avoid bites + vaccine
What organisms are responsible for schistosomiasis?
S. Haematobium
S. Mansoni
S. Japonicum
Freshwater snails
What are the types of schistosmiasis?
Hepatic/intestinal
Urinary
What i the demography od dengue fever?
Central belt - Africa, south America, Asia
What is the life cycle of schistosomiasis?
Eggs hatch, releasing miracidia
These penetrate snail tissue
Cercaria released by snail into water (free swimming)
Loses tail when penetrate human skin
Migrate into portal blood in liver + mature
Released by urine/faeces
What are the clinical features in the first day of schistosomiasis?
Swimmer’s itch 1st few hours but clear
Invasive stage after 24 hours (cough, abdo discomfort, splenomegaly, eosinophilla)
What complication can develop from schistosomiasis from 15-20 days?
Katayama fever
What are the clinical features of katayama fever?
Fever Urticaria Lymphadenopathy Splenomegally Diarrhoea Eosinophilia
What is the acute disease phase of Schistosomiasis?
Eggs are deposited into bowel or bladder
How do you diagnose Schistosomiasis?
Antibody test
Clinical features
Ova in stools/urine
Rectal snip
How do you treat schistosomiasis?
praziquantel 2 doses 6 hrs apart (20mg/KG)
Prednisolone if severe
What are the clinical features of rickettsiosis?
Abrupt onset of swining fever Heache Confusion Endovasculitis Rash Bleeding
How do you diagnose rickettsiosis?
Clinical features + serology
How do you manage rickettsiosis?
Tetracycline
How is rickettsiosis spread?
Via tick typhus
How do you manage viral haemorrhagic fever?
Rule out common severe infections first
Isolation in high security infection unit
Supportive treatment
What is responsible for the zika virus?
Flavivirus
Transmitted via Aedes mosquitoes, sexual contact + blood
What are the clinical features of the zika virus?
None or mild symptoms
Headaches, conjunctivitis, , joint pains
Can cause guillian barre
What is the treatment for zika virus?
No antivirals, just supportive
What travel related infections have a rash?
Typhoid
Typhus
Dengue
What travel related infections have jaundice?
Hepatitis
Malaria
Yellow fever
What travel related infections have abnormal lymph nodes?
Leishmania
Trypanosmoiasis
What travel related infections have abnormal liver signs?
Malaria
Typhoid
Amoebic abscess
What travel related infections have abnormal spleen signs?
Visceral leishmaniasis
Typhoid
Malaria
What are the main targets for anti-viral agents?
Stages in the life cycle - most intracellular
As viralstatic and not viralcidal, they aime to inhibit more viral functions than host functions
What are the types of viral treatment?
Prohylaxis - prevention
Pre-emptive - infected but no symptoms
Overt disease
Supression therapy - to keep viral load low
When do you use an antiviral in herpres simplex?
If mucocutaneous (oral, genital etc)
Encephalitis
Immuno compromisied
When do you use antivirals in chickenpox?
Neonates
Immunocompromised
Pregnant
When do you use antivirals in shingles?
Elderly/immunocompromised
Only immunocomptetnt host if within 72 hours of onset
What antivirals are used for HSV/VZV? (herpes/chickenpox)
Acicilovir (oral, IV eye oinment or topical)
Valacicilovir - oral
What is the MOA for aciclovir?
Converted to ACVMP by virus
ACVMP converted to ACV-TP by host
This competitively inhibits HSV-specific DNA polymerase
Prevents further DNA synthesis without affecting normal processes
When do you treat CMV infections?
Only life threatening as significant toxcitity
Eg HIV - colitis + retinitis
Transplant recpients - penumonitis
What agents are used in CMV?
Ganciclovir (IV
Valganciclovir - oral
Cidofovir IV
What antivirals are used in chronic hepatitis B
Pegylated interferon alpha
Neculoside analogues
Tenofovir, adefovir, entecavir etc
What antivirals are given for chronic hep C?
Pegylated interferon alpha + ribavirin
Sometimes protease inhibitor on top
Elvolving field
When do you test for viral resistance to antivirals?
After 7 days in immunocomprimised if no response
What agents cause soft tissue infections?
Streptoccous pyogenes
Staph A
Strep group C/G
E coli
Pseudoaeruginosa
Clostridium sp.
What bacterium cause pneumonia?
Strep pneumonia Haemphilius influenzae Staph A Klebsiella pneumonia Moraxella catarrhalis Mycoplasma pneumonia Legionella pneumoia Chlamydia pneumonia
When are bactericidal and bacteristatic indicated?
Cidal - when need to kill organims quickly
E.g mengitis, endocarditis, neutropenia
Static - toxin mediated disease
What are the common side effects from antibiotics?
GI - nausea/vommiting/diarrhoea C. diff Candida Liver toxicity Renal toxciity Neurological problems Haemalogical
What drugs cause candida?
Broad spectrum antibiotics
Cephlasporins
What drugs cause liver damage/problems?
All drugs, but especially tetracyclines + TB drugs
More likely if pre-exisitng disease
What drugs cause renal damage?
Gentamicin
Vancomycin
More likely if pre-exisiting disease
What drugs cause adverse neurological effects?
Ototoxcity - gentamcin/vancomycin
Optic nuropathy - ethanbutol (TB)
Convulsions/encephalopathy - penicillins, cephlasporin
Peripheral neuropathy - isoniazid (TB), metronidazole
What are the adverse haemtological effects caused by some antibiotics?
Marrow-toxcity Megoblastic anemia (co-trimoxazole)
What are the classes of antimicrobials?
b lactams (penicillins + cephlasporins) Aminoglycacides Macrolides Quinolones Glycopeptides Antifungals Antivirals
Which drugs act to inhbit cell wall syntheiss?
B lactams + glycopeptides (vancomycin + teicoplanin)
Which drugs act to inhibt protein syntehsis?
Aminoglycosides (gentamicin)
Macrolides (clairthromycin)
Tetracylcines (doxyxycline)
Ozazolidinoes (linezolid)
Which drugs act to inhibit nucleic acid synthesis?
Trimetroprim
Sulfonamides (sulfamethoxazole)
Quinolones (ciprofloxacin
What are the different penicillins?
Benzylpenicillin Amoxicillin Fluclocacilin Co-amoxiclav Piperacillin
When do you use benzylpenicillin?
Bacteria:
Streptococci
Neisseria
Spirochetes
Infections: Soft tissue Pneumococcal Menigiococcal Gonorrhoa Syphilis
When do you use amoxicillin?
Broad spectrum
Infections:
UTI
RTI
When do you use flucloxacillin?
Staphylococci - main uses Staph A
When do you use co-amoxiclav?
Braod spectrum - includes anerobes
Infections UTI RTI Soft tissue Surgical wound infections
When do you use piperacillin/tazobactam?
Broad spectrum incl pseudomonas, anaerobes
Infections - neutropenic sepsis
What are the types of cephlasporins
1st gen - cefradine
2nd gen - Cefuroxine
3rd gen - Ceftriaxone, ceftazidime
When do you use cefradine?
Broad spectrum
Used in UTI + spft tissue infection
When do you use cefuroxime?
Broad spectrum
UTIs
RTIs
Surgical prophylaxis
When do you use ceftriaxone?
Broad spectrum - very good against gram negative bacilli
Hospital infections + bacteraemia
Pneumonia
Abdo sepsis
When do you use ceftazidime?
Broad spectrum, useful against gram neg bacilli + pseudomonas
Pseudomonal infections in hospital + CF
When do you use aminoglycosides?
(eg gentamicin)
Gram-neg bacilli
For serious gram-negative infections
Ie bacteraemia
Endocarditis
Neutropenic sepsis
What are the types of macroolides?
Clarithromycin
Erythromycin
Azithromycin
When do you use clarithromycin? (and erythromycin)
Bacteria: Streptococci Staphylococci Myoplasma Chlamyia Legionella
Infections:
Resp infection
Soft tissue infection
When do you use azithromycin?
Good for gram negative (haemophilus, chlamydia)
Used for chlamydia
What are the types of quinolones?
Ciprofloxacin
Levofloxacin
When do you use ciprofloxacin?
Gram negative bacilli
Includes pseudomonas
Used in complicated UTIs
Complicated hospital acquired pneumnia
When do you use levofloxacin?
Active against staph/strepococci + [neumococcus
Mycoplasma
Chlamydia
Legionella
2nd/3rd line for penumonia
When do you use glycopeptides?
Gram positive bacteria only
MRSA
Allergy to penicillin
What are some other antibiotics?
Trimethoprim Co-trimoxazole Clindamycin Tetracycline Rifampicin Meropenem Metronidazole Linezolid Daptomycin Tigecycline
When do you use trimpthropin
UTIs
MRSA
