Infections Flashcards
What type of bacteria commonly cause septic arthritis?
Gram Positives (S.pyogenes, Group G Strept, Pneumococcus)
Gram negative (H.inflenzae, Kingella, N.meningitidis)
What bacteria commonly cause prosthetic joint infections?
CoNS
S.aureus
Gram negative bacilli
Streptococci
Define virulence in terms of organisms
Ability of an organism to infect
Why are prosthetic joints more likely to develop sepsis?
Require fewer bacteria than soft tissue to establish sepsis
Avascular - protected from circulating immunological defences and most Abx
Cement can inhibit phagocytosis and lymphocytic/complement function
Biofilms can easily develop on metal
What Abx should be given prophylactically prior to joint replacement surgery?
Cephalosporin
When should prophylactic cephalosporin be given prior to joint replacement surgery?
30-60 mins prior to skin incision
What is the cut off as to whether a joint prothesis is salvageable following infection?
30 days post op
What is the surgical management of an acute joint prothesis infection?
Debride
Antibiotics
Implant
Retained
Following an acute joint prothesis infection, how long are Abx required for?
4-6 weeks IV
What Abx are useful for managing a prosthetic joint infection post surgery?
Rifampicin
Ciprofloxacin
Define osteomyelitis
Progressive infection of bone characterised by new bone formation and loss of the integrity of the bone
What type of bacteria commonly cause osteomyelitis?
Anaerobes
Describe the management of osteomyelitis
Surgical debridement
May require 4-6week IV Abx
Describe vertebral discitis
Infection of the disc space and adjacent vertebral end plates
Can be very destructive
Deformity
Spinal cord instability –> cord compression, paraplegia, disability
Define neutropenia
<0.5 x 10^9/L or <1.0 x 10&9/L and falling
What gene is defective in chronic granulomatous disease?
Gene which encodes for NADPH oxidase in neutrophils
What are the effects of chronic granulomatous disease?
Deficient production of oxygen radicals
Defective intracellular killing
Recurrent bacterial and fungal infections
What is the life expectancy for people with chronic granulomatous disease?
40 (due to prophylaxis Abx)
Give 3 causes of cellular immunity suppression
DiGeorge Syndrome
Malignant lymphoma
Cytotoxic chemotherapy
Infections
Give 3 examples of immunosuppressive drugs
Corticosteroids Cyclosporins Tacrolimus Alemtuzumab Rituximab
What condition results in mature B cells not being produced?
Bruton agammaglobinuaemia
In what type of leukaemia, is humoral immunity preserved?
Acute leukaemia
What will intensive radiotherapy and chemotherapy result in?
Hypoglubinaemia
What is the immunological function of the spleen?
Splenic macrophages eliminate non-opsonised microbes eg encapsulated bacteria
Site of primary immunoglobulin response
If the spleen is defective, what infections are a person at a greater risk of developing?
S. pneumoniae
Haemophilius influnezae type B
Neisseria meningitidis
What immunoglobulin is found in sweat glands?
IgA
Define impaired nutritional status
<75% ideal body weight OR rapid weight loss
AND
Hypoalbuminaemia
If a patient has an impaired nutritional status, what is the effects in terms of their infection risk?
Too few B and T cells
Increased risk of infections
Describe pneumocystis jerovecii
Fungal infection
Causes a severe lung infection following transplant
Describe aspergillus
Causes infections in patients who have febrile neutropenia or who have had chemotherapy
Treat with Abc then add in anti-fungal on d3
Describe the clinical importance of recognising a cancer patient with febrile neutropenia
Medical emergency
Cancer patient + temperature –> infection until proven otherwise
Do blood cultures
Bloodstream infections are most troublesome –> systemic infection
Define SIRS
Sweats Chills Rigors Malaise Tachypnoea (>20/min) Tachycardia (>90bpm) Hypotensive
Define sepsis
Evidence of infection and organ dysfunction
2 or more:
Hypotensive
Confusion
Tachypnoea >22/min
Define septic shock
Sepsis induced hypotension (SBP <90mmHg or reduced by >40mmHg from baseline) requiring inotropic support or hypotension which is unresponsive to adequate fluid resuscitation
Define neutropenic sepsis (febrile neutropenia)
Neutrophil count of <0.5 (or <1 if recent chemo) + fever/hypothermia or SIRS or SEPSIS/SEPTIC SHOCK
What scoring system can be used to assess the severity of sepsis?
NEWS
In what time frame should SEPSIS 6 be implemented in a patient with sepsis?
1 hour
What is SEPSIS 6?
- Blood cultures
- Urine output
- Serial lactates
- High flow O2
- IV fluid resuscitation
- IV ABx
If a patient is septic, and a skin or soft tissue infection is suspected, what Abx should be added?
Vancomycin
If a patient is septic and considered to have an atypical pneumonia, what Abx should be added?
Clarithromycin
What bacteria causes gonorrhoea?
Neisseria gonorrhoea
Describe Neisseria gonorrhoea
Gram negative intracellular diplococci
What symptoms are typically present in a male with gonorrhoea?
Anterior urethritis
Purulent urethral discharge
Dysuria
What symptoms are typically present in a female with gonorrhoea?
Increased vaginal discharge
Dysuria
Post-coital/intra-menstrual bleeding
Lower abdominal pain
Describe how gonorrhoea infections are diagnosed
Urethral gram stain (sample from within urethra)
Uses the NAAT test
Males = urine sample ± rectal/throat swab
Females = vulvovaginal swab
Combine with testing for chlamydia
What systemic condition is associated with disseminated gonorrhoea?
Reactive arthritis
Describe the management of gonorrhoea
Ceftriaxone 500mg IM
Azithromycin 1g
Partner notification
What bacteria often co-exists with chlamydia trochomatis?
Mycoplasma genitalium
What is the major clinical effect of chlamydia infections?
Mostly asymptomatic (80% F’ 50% M)
Delays in treatment
16% of women develop PID (tubal infertility, ectopic pregnancy, chronic pelvic pain)
What symptoms are typically present in males with chlamydia?
Anterior urethritis
Purulent discharge
Dysuria
What symptoms are typically present in females with chlamydia?
Increased vaginal discharge
Dysuria
Post-coital/inter-menstrual bleeding
Lower abdominal pain
How is chlamydia diagnosed?
NAAT test
M: first void urine samples
F: vulvovaginal swab
How is chlamydia treated?
Doxycycline 100mg BD for 1 week
Azithromycin 1g oral stat + 500mg od for 2 days
What causes Lymphogranuloma venereum (LGV)?
Invasive serovars L1 L2 L3 of Chlamydia trochomatis
What population are more likely to develop Lymphogranuloma venereum (LGV?)
MSM esp if have HIV
Frequently associated with other STIs and Hep C
Describe the clinical stages of Lymphogranuloma venereum (LGV)
Transient - painless papule (shallow ulcer) at site of inoculation 3-30d post exposure
Proctitis - rectal pain, mucupurulent discharge, rectal bleeding, constipation, tenesmus + systemic symptoms
Chronic inflammatory response –> fistulae, strictures, granulomatous fibrosis (mimics Crohn’s disease)
What is the management of Lymphogranuloma venereum (LGV)?
Doxycycline 100mg BD for 21 days
What bacteria causes Syphilis?
Treponema pallidum (a motile spirochaete)
Describe primary syphilis
Around 21d post exposure, a papule develops at site of inoculation –> ulcerates –> painless, firm ulcer (chancre)
Painless regional lymphadenopathy
Chancre heals in 2-6 weeks
Describe secondary syphilis
Constitutional symptoms appear 6-10wks post primary lesion
Fever, sore throat, malaise, arthralgia (due to septicaemia)
What are the common signs associated with secondary syphilis?
Widespread skin rash (non-itchy, maculopapular, coppery colour)
Generalised lymphadenopathy
Condylomata lata - moist wart like plaques found in the perianal area and other moist sites
How is syphilis diagnosed?
IgG and IgM detected using treponemal enzyme immunoassay
Describe tertiary syphilis
Develops in 1/3 of people with untreated latent syphilis
Commonly involves the bones, but can involve any organ
Describe the treatment of syphilis
Penicillin injections
Doxycycline if have penicillin allergy
Repeat bloods 3/12
Give examples of bacterial STIs
Chlamydia
Gonorrhoea
Lymphogranulosa venerum
Syphilis
What HPV strains cause genital warts?
6 and 11
What causes the risk of developing genital warts following exposure to HSV to increase?
Smoking
Pregnancy
Immunocompromised
Gardasil protects against which strains of HPV?
6, 11, 16 18
How can genital warts be treated?
Topical podophyllotoxin (2x daily for 3 consecutive days of the week)
Ablative treatment
Imiquimod
Describe the virus that causes molluscs contagiosum
Large DNA Pox virus
Describe the papule associated with molluscs contagiosum infections
Small, benign, smooth papules with central umblication
What are the two types of herpes simplex virus?
HSV 1 and 2
Describe primary infection of HSV
First time infected with either HSV1/2
Multiple painful, shallow ulcers
Tender inguinal lymphadenopathy
Systemic symptoms of viraemia - fever, malaise, headaches
Describe non-primary infection of HSV
Previously infected with HSV1/2 then acquire the other
A degree of cross-protection –> milder illness
Describe recurrent infection of HSV
Reactivation of previous HSV1/2 infection
HSV2 reactivation occurs more commonly than HSV1 reactivation
How is HSV diagnosed?
PCR - distinguishes between HSV1/2
Describe the treatment of HSV
Primary infection = aciclovir 400mg TDS for 5 days
Recurrence = aciclovir 800mg TDS for 2 days
Suppression = aciclovir 400mg BD 6-12 months
What is the leading cause of meningitis in children?
N.meningitidis
What is the leading cause of meningitis in adults?
S.pneumoniae
What is leading cause of meningitis in children between 3 months and 6 years?
H.influenzae
In what population of people, does listeria need to be considered as a potential cause of meningitis?
Over 60s
Immunocompromised
What bacteria, that can cause meningitis, is described as being a gram positive bacilli?
Listeria
What bacteria, that can cause meningitis, is described as being a gram positive diplococci?
S.pneumoniae
What bacteria, that can cause meningitis, is described as being a gram negative diplococci?
N.meningitidis
What are risk factors for developing pneumococcal meningitis?
>60yrs Immunosuppression Alcohol dependency Middle ear infection Previous head trauma Surgery
What CSF results are associated with bacterial meningitis?
Raised neutrophils
Low glucose
High proteins
What CSF results are associated with viral meningitis?
Raised neutrophils
High proteins
Normal glucose
What Abx should be given pre-hospital if a patient is suspected of having meningitis?
Benzyl penicillin
Ceftriaxone
Chloramphenicol
Describe the immediate management of a patient with meningitis
ABC
Blood cultures
Abx + dexamethasone
LP (CT if needed)
What Abx should be given to a patient with meningitis?
Ceftriaxone Amoxicillin Benzyl penicillin \+ Vancomycin (pneumococcus meningitis) \+ Gentamicin (listerosis)
Why are patients with meningitis given dexamethasone?
Prevents complications such as deafness/hydrocephalus
Given at the start of Abx therapy (continue for 4 days)
If a patient has meningitis, who needs to be informed?
Public Health
What Abx should be given as prophylaxis to close contacts of a patients with meningitis?
Ciprofloxacin
Once a patient has recovered from meningitis, what test do they require?
Audiology hearing test
What viruses commonly cause the common cold?
Rhinovirus
Coronavirus
What virus causes acute bronchitis?
RSV
What virus causes pharyngitis?
Adenovirus
What virus causes bronchiolitis?
RSV
What virus causes croup?
Parainfluenza virus
What viruses causes pneumonia?
Influenza
RSV
How can you differentiate as to whether pharyngitis is more likely to be viral or bacterial?
Nasal symptoms = viral
No nasal symptoms = bacterial
What virus causes glandular fever?
EBV
Describe croup
Seal like barking cough
Caused by parainfluenza virus especially 1+3
Supportive treatment
Describe bronchiolitis
Lower respiratory tract infection of young children
Wheeze and tachycardia
7-10d duration, cough persists up to 3 weeks
RSV is the most common cause
Most children infected by 2 (re-infection is common but less severe)
Describe RSV
Affects immunocompromised, adults with chronic lung disease, elderly
What is Ribivirin? What side effects are associated with it? When is it used?
Broad spectrum antiviral
Anaemia, abdominal pain, depression/suicidal thoughts
Given to high risk children (pre-term, <6months, oxygen requirement under 2s, cardiopulmonary disease in under 2s)
What influenza viruses cases flu?
Influenza virus A-C
Give complications associated with flu
Acute otitis media Sinusitis Secondary bacterial pneumonia Exacerbation of underlying disease Dehydration
What causes epidemics of flu?
Antigenic drift
What causes pandemics of flu?
Antigenic shifts