#
*HPA Colindale, London, UK, # BSAC, Bristol, UK
•
E.coli
is one of the commonest agents of bacteraemia, gastrointestinal and urinary tract infections (UTIs) in the UK.
•While
E. coli lineages causing UTIs and gastrointestinal disease are well known, less is known about those from bacteraemias.
•We compared the phylogeny of
E. coli from bacteraemias in the
UK and Ireland in 2001 vs. 2010
•409 E.coli
isolates from 18 centres across the UK and Ireland from the BSAC Bacteraemia Surveillance
Programme 1
•172 from 2001
•237 from 2010
•Assigned to phylogroups (A, B1, B2 or D) by PCR using a modified method 2 based on the Clermont 3 scheme
•Multi-locus sequence typing was used to analyse 152 isolates from 2001 and 116 isolates from 2010 using the Achtman scheme 4
•Resistance testing performed by agar dilution 5
•ESBL presence confirmed by PCR 5
• A total of 83 STs were detected (see figure 1a) of which:
•47 were only present in 2001
•19 were only present in 2010
•17 were present in both years
• ST73 was the most common ST in both years (20% of isolates in
2001 and 22% in 2010); it is also as a major ST in UTIs 6
• 42% of isolates in 2001, 59% in 2010 belonged to ST73, ST95,
ST131, ST12 and ST127
•Prevalent STs were distributed across multiple centres in both years (figure 1b)
Figure 1. Minimum spanning trees showing ST distribution by; ST117
• The phylogroup distributions of the 2001 and 2010 isolates were similar, and resembled those reported for UTI isolates 7 , with B2 dominant (77% in 2001; 71% in 2010) (figure 2)
• Second most common was phylogroup D (11% 2001 and 14%
2010), followed by group B1 (6% vs 8%) then A (4% vs 6%)
Figure 2. Percentage phylogroups by year
100%
Percentage
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
D
B2
B1
A
2001 2010
Year
• UTIs were the commonest source of bacteraemias (figure 4) including those due to the 5 major STs (except ST127 in 2010, where many bacteraemias had unknown sources)
• There was a significant increase of resistance to gentamicin, ciprofloxacin and cephalosporins in 2010 mainly due to diverse ST types and ST131
• Amoxicillin resistance remained unchanged in both years (56%)
• Numbers of isolates belonging to the international ST131 clone rose from 5/152 in 2001 (4 centres) to 16/116 in 2010 (10 centres)
• None of the ST131 isolates in 2001 was ciprofloxacin-resistant or
ESBL-positive, but 11 were ciprofloxacin-resistant in 2010 and 5
(from multiple centres) had ESBLs. (see table 1)
Figure 4. Sources of bacteraemia by year and ST
100%
Other
80%
Not Known
60%
ST69 Percentage
40%
Rsesipiratory tract
ST393 ST415
ST59
ST131
20%
0%
Gastrointestinal tract
Genitourinary tract
ST73 ST14
ST95
ST404
ST357
2001 2010 2001 2010 2001 2010 2001 2010 2001 2010 2001 2010
ST/Year
ST10
ST88
ST12
ST127
ST80
1a) year
•152 isolates from 2001 (white)
•116 isolates from 2010 (black)
Table 1. Prevalence of resistance
Antimicrobial
Amoxicillin
Gentamicin
Ciprfloxacin
Imipenem
Ceftazdime
% Resistance in 2001
All STs
56%
4%
6%
Major STs Other STs
22%
0%
1%
34%
4%
6%
0%
0%
0%
0%
0%
0%
% Resistance in 2010
All STs
56%
8%
16%
0%
7%
Major STs
30%
4%*
1%*
0%
1% #
Other STs
26%
4%
15%
0%
6%
Percentage of resistant isolates in 2001vs 2010 in all STs, major STs (ST73,
ST95, ST131, ST12 and ST127) and in other non-major STs.
*Resistance in ST131 only #Resistance in ST131 and 1 isolate of ST12
ST95
ST12
ST73
ST127
ST131
1b) centre
•268 isolates coloured by centre
• Phylogroups B2 and D dominated in both years; these harbour virulence factors associated with extra-intestinal E. coli 8
• With the exception of ST131, the major STs in both years remained susceptible to most antimicrobials
• The major STs have been reported to be associated with UTIs 9
• There was a significant increase in cases of bacteraemia caused by the international ST131 clone, with more members of this clone found resistant in 2010 than 2001.
• Resistance to cephalosporins, aminoglycosides and quinolones rose from 2001 to 2010 largely due to diverse STs and ST131
• Carbapenem resistance was not seen
1 www.bsacsurv.org
2 Doumith M., Williams M.J. and Woodford N. unpublished
,
3 Clermont O, Bonacorsi S, Bingen E. Appl Environ Microbiol. 2000 Oct;66(10):4555-8.
4 http://mlst.ucc.ie/mlst/dbs/Ecoli 5 http://www.bsacsurv.org/uploads/protocols/publications/bacteraemia_v3.3_110207.pdf
6 Lau et al . J Clin Microbiol. 2008 March; 46(3): 1076
–1080 7 Jakobsen et al . Foodborne Pathog Dis.
2010 May;7(5):537-47 8 Picard et al . Infect Immun.
1999 Feb;67(2):546-53. 9 Croxall et al . J Antimicrob Chemother.
2011 Nov;66(11):2501-8