The organisms below were isolated and demonstrated antimicrobial sensitivities as listed.

Enterococcus faecalis

Drug

Sensitivity

Ampicillin

R

Chlorampenicol

R

Ciproflxacin

R

Erythromycin

R

Gentamicin

R

Nitrofurantoin

R

Cotrimoxazole

R

Teicoplanin

R

Vancomycin

R

Klebsiella pneumoniae

Drug

MIC (µg/ml)

Cefpodoxime

≥ 2

Ceftazidime

≥ 2

Aztreonam

≥ 2

Cefotaxime

≥ 2

Ceftriaxone

≥ 2

a)     What is the significance of these results?

b)    List 1 appropriate antimicrobial in each case.

c)     List   the   strategies   available   to   reduce   the   development   of   these organisms in ICUs.

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College Answer

Van A VRE
Linezolid, Daptomycin, (Tigecycline, Quinupristin-dalfopristin)

ESBL
Carbapenem     (imipenem,     meropenem,     and     perhaps     ertapenem),      Colistin, Aminoglycosides, Ciprofloxacin

c)     List   the   strategies   available   to   reduce   the   development   of   these organisms in ICUs.

Strategies to improve the efficacy and utilization of antimicrobial therapy
•    Antibiotic evaluation committees
•    Protocols and guidelines to promote appropriate antimicrobial utilization
•    Hospital formulary restrictions of broad-spectrum agents
•    Substitution of narrow-spectrum antibiotics (such as first generation cephalosporins and aminoglycosides)
•    Mandatory consultations with infectious diseases specialists
•    Antibiotic cycling by regularly cycling different antimicrobial classes

Infection control measures
•    Handwashing   compliance:   Alcohol-based   hand   wash   is  more   effective   than traditional soap and water in cleansing hands of bacteria
•    Barrier precautions with gloves and gowns
•     Isolation
•    Surveillance for multidrug-resistant bacteria for the early identification and control
•    Monitoring   and   disseminating   the   incidence   and   prevalence   of   isolation   of multidrug-resistant bacteria
•    Limiting LOS and invasive devices (idc / ett/  vascular)

Discussion

a) The Enterococcus is a VRE, and the Klebsiella possesses a β-lactamase which seems to lyse extended spectrum cephalosporins, which makes it an ESBL organism.

b) The Enterococcus can be managed with teicoplanin, linezolid, tigecycline or daptomycin.

The Klebsiella may still be sensitive to carbapenems and it may still be somewhat susceptible to extended spectrum β-lactams (such as Tazocin), but if all else fails there are always amikacin and colistin up your sleeve.

c) Strategies for the prevention and spread of multi-resistant organisms?

A CICM trainee should be able to issue forth a torrential stream of evidence-based antibiotic stewardship strategies and infection control protocols.

Prevent emergence of antibiotic resistance:

  • Limit use of broad-spectrum agents
  • Limit use of multiple antibiotics
  • Use narrow-spectrum agents whenever sensitivities are available
  • Rationalise duration of antibiotics to prevent over-long courses
  • Invitation to infectious diseases physicians to take part in antibiotic decisionmaking
  • Antibiotic class cycling

According to a 2011 review, antimicrobial stewardship interventions beyond 6 months were associated with reductions in antimicrobial resistance rates, which suggests that the above strategies can be rapidly effective.

Prevent cross-contamination:

  • Screening of patients during their ICU stay
  • Introduction of alcohol-based hand rub
  • Single rooms for infected patients
  • Explicit signs identifying MRSA-infected rooms
  • Wearing gloves and gowns when entering patient rooms

References

Gniadkowski, M. "Evolution and epidemiology of extended‐spectrum β-lactamases (ESBLs) and ESBL‐producing microorganisms." Clinical microbiology and infection 7.11 (2001): 597-608.

Huskins, W. Charles, et al. "Intervention to reduce transmission of resistant bacteria in intensive care." New England Journal of Medicine 364.15 (2011): 1407-1418.

Kollef, Marin H., and Victoria J. Fraser. "Antibiotic resistance in the intensive care unit." Annals of internal medicine 134.4 (2001): 298-314.

Kaki, Reham, et al. "Impact of antimicrobial stewardship in critical care: a systematic review." Journal of antimicrobial chemotherapy 66.6 (2011): 1223-1230.