Lectures 2124 Clinical case studies in Infectious diseases

1
Lectures 21-24Clinical case studies in
Infectious diseases

• Aims
• To review case studies relating to
• Wound infections
• UTI
• RTIs
• Refer Black Chapters 19 and 20

2
Wound infections

• Overview
• Source of post operative or trauma infections may
  be endogenous or exogenous
• Trauma usually involves Mos in the immediate
  vicinity or introduced by penetrating item
• Greatest risks intraoperative inoculation and/or
  exogenous contamination
• SSWI incidence is about 1-3, but increases up to
  10 in colonic surgery

3
Wound infections

• Organisms likely to be involved determined by
  factors such as
• Site of trauma/surgery
• In surgery contamination often occurs during
  procedure
• Duration of procedure
• Organ system involved

4
Wound infections

• Diagnosis
• Not difficult
• Patients often febrile elevated WBC
• Wound erythematous, discharge, swollen
• Sometimes difficult to differentiate colonisation
  vs infection
• Gram stain very helpful

5
Wound infections

• Clues to diagnosis
• Visual inspection- may indicate severity but not
  cause
• Pus
• Smell
• Palpation (gas eg AnO bacteria?)

6
SS Wound infections

• Risk for post operative wound infection are
  categorised according to risk
• Clean interventions
• (least risk with no breach of aseptic technique
  eg hernia repair)
• Clean/contaminated
• Moderate risk eg oral surgery

7
SS Wound infections

• Contaminated
• (significant risk due to nature of intervention
  eg colon resection)
• Dirty
• (major risk which is evident -eg entry into
  purulent material, soiled untreated trauma wound,
  eg rupture appendices and associated peritonitis)

8
SS Wound infections

• Clean interventions
• Primarily skin borne microbes
• Eg S.aureus S.pyogenes
• Can lead to cellulitis
• Patient underlying illness and predisposition
  needs to be accounted
• eg 1. immunocompromised/suppressed
• eg 2 Diabetics can have infections of decubitous
  ulcers colonized by enterococci enterobacteria

9
SS wound infections

• Prophylaxis/empirical treatment
• Depending on patient status and underlying
  condition
• Simple cellulitis some options include
• benzylpenicillin flucloxacillin
• Oral amoxicillin clavulanic acid
• IV if warranted eg gentamicin amoxil
  metronidazole

10
SS wound infections

• Dirty or increased risk
• Main risks are S.aureus, Gram negative bacteria,
  enterococci and anaerobes
• In serious cases IV gentamicin amoxil
  metronidazole (substitute ceftazidime if renally
  impaired)

11
CASE STUDY

• 43 yo Female patient presented to AE following
  MCA. Trauma sustained to lower limbs with
  complicated compound fracture to R.tibia. The
  wound had penetrated the skin was soiled. At
  surgery a pin was placed to stabilise the femur.
• Patient was given IV amoxil cefotaxime
  metronidazole for 7 days and then placed on oral
  flucloxacillin-wound appeared to be healing
• After 3 weeks the wound showed evidence of
  cellulitis.
• Fever was absent BC remained negative

12
CASE study Wound infection

• Questions?
• Was the original treatment reasonable
• What is the likely origin of the cellulitis?
• What would be a reasonable treatment regimen for
  the cellulitis
• What , if any further steps should be taken

13
Analysis

• The absence of internal organ injury particularly
  spleen trauma obviates need for pneumococcal
  vaccine
• Soiled nature of wound increases risk for G
  infections AnO in particular
• Treatment regimen covers enterococci, staphs,
  streps, coliforms and AnO- but not pseudomonas
• Wound healing suggest regime effective

14
analysis

• Followup oral flucloxacillin reasonable as staph
  is a problem on orthopaedic patients
• Cellulitis is a problem- difficult to diagnose,
  therapy is often empirical
• External pin added problem as they may become
  colonised
• In the face of flucloxacillin possible MRSA- may
  need to consider vancomycin
• Follow ups C-reactive protein, wound status,
  removal of invasive devices ASAP
• Epilogue patient had MRSA IC action?

15
UTIs

• UTIs are a major cause of female presentation for
  medical attention (101 males)
• Bacteruria is the presence of bacteria in urine
• Pure (predominant) growth of bacteria gt100,000 mL
  presence of pyuria is considered significant
• Variations to this (eg /- pyuria) may make
  interpretation difficult
• May be resolved by obtaining 2nd sample

16
UTIs

• UTIs may involve
• Bladder (cystitis)
• Kidney pelvis (pyelitis)
• Kidney parenchyma (pyelonephritis)
• Urethra (urethritis)

17
UTIs

• Presentation
• Can be asymptomatic (few)
• Generally associated with
• Dysuria
• loin pain
• /- haematuria
• Pyelonephritis usually more sever malaise,
  rigours, tenderness and fever

18
UTIs

• Mains causal agents
• E.coli 60-90
• S.saphrophyticus more common in sexually active
  women
• Less cases due to coliforms, pseudomonads, and
  other staph sp (depends on patient status)
• Catheterisation single major predisposing factor
• UTIs most common nosocomial infection

19
UTIs

• Treatment
• Depends on severity, patient status history
• Acute uncomplicated usually ORAL X
• Eg Trimethoprim, nitrofurantoin,
  amoxil/clavulanic acid
• Recurrent /complicated may require parenteral X
• Eg gentamicin, cefotaxime
• Best to modify X regime once MO identified (MCC
  completed)

20
UTIs

• Special patient groups may need more attention
  especially in selecting empirical therapy
• Eg para/quadraplegic patients
• These patients often suffer with multi antibiotic
  resistant bacteria

21
UTI case study

• 28 yo female presents at AE complaining of
  urinary frequency, loin pain, dysuria
  haematuria
• Patient is afebrile, no evidence of vaginal
  inflammation/discharge
• MSU taken and lab request for MCS
• Patient prescribed 5 day course oral amoxil
  clavulanic acid 500mg TDS
• Patient recommended to see GP if no improvement
  in 72hrs or w/I 7 days to review case

22
Case study contin...

• Pathology examination
• gt100,000 polymorphs
• gt100,000 pure S.saprophyticus
• Sensitivity
• Sflucloxacillin, trimethoprim, norfloxacin
• R amoxil, nitrofurantoin
• Patient reported to GP indicated recovery after 3
  days X

23
UTIs

• What is the likely diagnosis?
• Was the X regimen reasonable?

24
UTIs

• Analysis
• The symptoms as described are consistent with UTI
  and probably cystitis
• No evidence of discharge, unlikely to be a common
  STD
• Absence of fever, rigours and general malaise not
  indicative of renal involvement (although loin
  pain more consistent with nephritis)

25
UTIs

• Analysis contin
• Patient report to GP indicates empirical X was
  appropriate
• Initial examination indicated acute uncomplicated
  UTI probably w/o nephritis
• Amoxil/clavulanic acid empirical X is not
  uncommon due to majority of UTIs caused by
  E.coli- but the X also effective against
  S.saprophyticus and other less common causes