The search for an environmental reservoir of
KPC-2-producing Citrobacter farmeri
Katie Cronin
CPE
Carbapenemase Producing Enterobacteriaceae
• Ambler classification:
A
KPC
B
NDM
IMP
VIM
C
D
OXA
blaKPC-2
Klebsiella pneumoniae carbapenemase
•
•
•
•
Very limited treatment options
High mortality rate (40-50%)
Ability to spread
Silent transmission
Melbourne Hospital Isolates
51 isolates:
- KPC-2 = 37
- NDM-5 = 5
- NDM-5, OXA-232 = 7
- OXA-181 = 1
- VIM-5 = 1
9
8
7
Clinical
Screening
O/S Travel
Citrobacter farmeri - KPC
6
5
4
3
2
1
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
0
2012
2013
2014
2015
2016
May
June
July
August
September
October
Patient
1
Patient
2
Patient
3
Patient
4
• Citrobacter farmeri harboring blaKPC-2 isolated
from 4 patients over a 6 month period
• Isolated from routine rectal screening swabs
• All patients had been admitted to the same four
bed room
• No clear line of transmission
• K. pneumoniae harbouring blaNDM-5 and
blaOXA-232 were detected in 2 of these patients
Citrobacter farmeri KPC
• Not previously reported in the literature
• All four C. farmeri isolates were the same by
whole genome sequencing
• Same transposon as K. pneumoniae-KPC
isolates
Citrobacter farmeri KPC
• Epidemiological link
– Admitted to the same room on the same ward
– However, cases spread over a 6 month period
• Are there patients that remain undetected by
routine screening?
• Is there an environmental reservoir?
• Previous extensive environmental screening
on this ward failed to detect CPE
Environmental Screening Methods
1.
2.
Ertapenem 10µg OR
Ceftazidime 30µg and
Vancomycin 30µg disks
Environmental Screening Methods
3.
4.
Environmental Screening Methods
• Contact plate
5.
Patient 4
May
June
July
August
September
October
Patient
1
Patient
2
Patient
3
Patient
4
•
•
•
•
Rectal screening swab on the day of admission
No SVH hospital admission for > 2 years
Multiple resistance genes detected
Two repeat CPE screens from faecal specimens
were negative
• Further questioning…
Sampling Method
•
•
•
•
20 ml toilet water
10 drops in 10 ml Tryptone Soya broth
Overnight incubation
Subculture to Brilliance CRE
Results
• Isolated CPEs from four toilets
• Spectrum of CPE:
– K. pneumoniae – KPC
– K. oxytoca - KPC
– C. farmeri – KPC
– C. freundii – KPC
– K. pneumoniae – OXA & NDM
– C. freundii – OXA
– E. cloacae – OXA
Tanks
Cisterns
Flush pipes
Key seal
• Thick biofilm
• Reservoir difficult to
access to enable
adequate cleaning
Decontamination
• Hyperchlorite
• Beer line cleaner
• Potassium hydroxide, Alkaline sodium salts, Borates, tetra
sodium, Surfactants
Questions
• Toilets may initially have become contaminated
with CPE following use by a positive patient
– Is isolation of CPE from toilets simply a marker of
where colonised patients have been?
– Is it possible to acquire CPE following exposure to
toilets?
• Multiple organisms isolated
– Organisms trading plasmids within their own
ecological niche?
* No further cases on this ward since toilets were
replaced
• Toilet aerosols are created by flushing a toilet
• E.coli bioaerosol remained airborne & viable for at
least 4 to 6 hours post-flush
• Concentrations of bacteria aerosols are 12-fold greater
when flushing without the lid down (C. difficile)
• Organisms can be detected for 50 days after initial
seeding due to biofilm formation (Salmonella spp.)
Future Management
• How to manage environmental surveillance &
decontamination in future
– Prevention: Hospital toilet redesign, “biofilm
prophylaxis”
– Development of cleaning methods that will
adequately decontaminate (replacement is
expensive)
– Is routine testing required to ensure
decontamination?
Acknowledgements
•
•
•
•
•
MJ. Waters (Microbiology)
D. Jardine (Microbiology)
L. Brenton (Microbiology)
J. Cocks (Infection Control)
S. Moon (Environmental Services)
Microbiological Diagnostic Unit
Public Health Laboratory
• B. Howden
• J. Kwong
• C. Lane