Transcript No Slide Title

Extended Spectrum -Lactamase (ESBL) Phenotypes In Enteric Bacilli from the
Asia-Pacific Region: Report from the SENTRY Antimicrobial Surveillance Program
Poster #293
Ronald N. Jones, M.D.
The JONES Group / JMI Laboratories
345 Beaver Kreek Centre, Suite A, North Liberty, Iowa 52317
Phone: 319-665-3370 Fax: 319-665-3371
[email protected]
J Turnidge, J Bell, ML Beach, RN Jones*,
SENTRY Participants Group (Asia-Pacific). Women’s and Children’s Med Ctr, Adelaide, Australia; Univ of Iowa, Iowa City, IA; The JONES Group/JMI Laboratories, N. Liberty, IA
ABSTRACT
Background: ESBL-production among various Enterobacteriaceae presents a serious
threat to continued clinical efficacy of newer -lactams. Regional and national differences
in rates of occurrence have been cited, but limited results have been reported from the
Asia- Pacific area and S. Africa.
Methods: The SENTRY Program monitored 17 laboratories (seven nations) in 1998-99
via the referral of strains to a regional monitor. E. coli (EC; 1103), Klebsiella spp. (KSP;
643), P. mirabilis (PM; 111) and Enterobacter spp. (EBS; 283) were screened for ESBL
phenotypes using NCCLS methods and criteria. All isolates were clinical infections
including bacteremias, pneumonia and UTI. At least one ESBL strain was detected at
each participating site.
Results: The ESBL-phenotype rates overall among species were: EC (7.9%), KSP
(22.7%), PM (1.8%) and EBS (5.3%). Several phenotypic strains were not CA inhibitable
(cefoxitin MIC, 32 g/ml), consistent with an amp C patterns thus corrected ESBL rates
were 3.6, 12.8 and 0.9 for EC, KSP and PM. Highest EC ESBL rates were in Hong Kong
(8.5%) and mainland China (8.3%), while EC amp C patterns were highest in mainland
China (17.7%) and The Philippines (9.5%). In KSP, ESBLs were highest in Singapore
(34.4%) a mainland China (22.7%) and amp C’s in the Philippines (29.9%) and China
(12.1%). S. Africa ESBL rates were 2.9 and 38.2% for EC and KSP. ESBL transfer into
EBS was observed in Singapore (11.1%), China (20.6%), The Philippines (4.1%), Taiwan
(18.2%) and S. Africa (16.7%); into PM in Japan and The Philippines.
Conclusions: Widely different patterns of ESBL-phenotypes have emerged in the AsiaPacific Region. Rates vary from rare isolations in Australia (0.2-5.2%) to alarmingly
elevated occurrences in Singapore, The Philippines, mainland China and S. Africa.
Phenotypic patterns and preferred substrates for detection also vary indicating variable
enzyme types (TEM, SHV, OXA, CTX-M, etc.). Continued monitoring and local
interventions appear prudent.
MATERIALS AND METHODS – CON’T
ESBL phenotype criteria
Isolates of Klebsiella spp., P. mirabilis, and E. coli with elevated MIC results ( 2 g/ml) for
ceftazidime and/or ceftriaxone and/or aztreonam were considered as possible ESBL-producing
phenotypes according to NCCLS criteria.
Characterization of the ESBL phenotype
The production of an ESBL was confirmed by using the agar dilution technique. Agar plates
containing - lactam substrates (ceftriaxone, cefotaxime, ceftazidime, and cefepime) with and without
clavulanate (2 g/ml) were used. The variations of the MIC for the -lactam alone and for lactam/clavulanate combination were compared. A reduction of the -lactam MIC of more than two
log2 dilutions (> four-fold) in the presence of clavulanate indicated ESBL production (see NCCLS
criteria).
Among Gram-negative bacteria, the production of -lactamases is the most important mechanism of
resistance to -lactam agents. Members of the family Enterobacteriaceae, commonly express plasmidencoded -lactamases which confer resistance to penicillins but not to extended-spectrum
cephalosporins. In 1983, a novel group of enzymes, subsequently named extended-spectrum lactamases (ESBL), was detected among Serratia marcescens and Klebsiella pneumoniae in Europe.
This group of enzymes has mainly arisen from genes coding common plasmid- mediated enzymes,
such as TEM-1 or -2 and SHV-1, which possess minor gene point mutations. The ESBLs are capable of
hydrolyzing many -lactams (except the carbapenems) and most of them are inhibited by the clinically
available -lactamase-inhibitors.
ESBL-producing clinical strains have been isolated from many parts of the world. However, their
frequency of occurrence varies widely. The identification of ESBL-producing isolates is important since
the activity of the extended-spectrum cephalosporins may not be accurately predicted from
standardized susceptibility tests. In 1999, the NCCLS published methods for screening and confirming
the presence of ESBLs in K. pneumoniae, K. oxytoca, and Escherichia coli. Considering that ESBL’s
can have different preferred -lactam substrates, and confirmatory tests demand time and additional
cost, it is important to establish locally which substrate must be tested for optimal detection of such
isolates.
The objective of this evaluation was to describe in detail the frequency of occurrence, the preferred
substrate, and the co-resistance patterns of the ESBL-producing isolates collected from medical
centers in the Asia-Pacific (also South Africa) region through the SENTRY Antimicrobial Surveillance
Program (1998-99).
RESULTS
 E. coli, K. pneumoniae and P. mirabilis accounted for more than 25% of all bacterial samples
isolated from the Asian-Pacific region. The ESBL phenotype was more commonly observed among
K. pneumoniae (24.5%) than E. coli (7.9%) or P. mirabilis isolates (1.8%).
 Isolates of E. coli exhibiting an ESBL phenotype were more frequently isolated from blood (47.1%),
followed by urine (28.7%) and respiratory (17.2%) sites (Table 1). This pattern was not the same
among the K. pneumoniae isolates, where isolates exhibiting an ESBL phenotype were isolated
almost equally from blood (40.6%) and respiratory (38.4%) sites.
 Among the 87 possible ESBL-producing E. coli, 57.5% of them were isolated by the centers in
 Among the 564 K. pneumoniae, 138 isolates were classified as possible ESBL-producers. Over
one-third (38.0%) of them were collected from The Philippine center followed by China (24.0%) and
the Singapore (18.1%) centers. The local frequency of occurrence of the ESBL phenotype varied
widely among the Asian-Pacific centers; highest in the Chinese (15.5%-40%), Philippine (38.8%),
Singaporean (39.1%) and South African (35.3%) centers.
 Among the 111 P. mirabilis isolates, only two demonstrated an ESBL-phenotype; the Japanese
isolate was confirmed as an ESBL producer, but this strain occurred in a center with the lowest
prevalence rates of ESBL phenotypes among E. coli and K. pneumoniae.
 The spread of plasmids encoding ESBL to species that usually produce chromosomal Amp C
enzymes, such as Enterobacter spp. and Serratia marcescens, has been observed in some
institutions. Seven of 17 medical centers evaluated in this study had Enterobacter isolates
exhibiting the ESBL phenotype (Table 3). These isolates showed high MICs for cefepime (16
g/ml) that decreased at least eight-fold in the presence of clavulanate. The local frequency of
occurrence of the ESBL phenotype among Enterobacter spp. varied from 4.1% (The Philippines) to
35.7% (one of the Chinese medical centers). The spread of ESBL to Enterobacter species could
not be directly related to the high prevalence of ESBL-producing K. pneumoniae and/or E. coli.
 Different ESBLs hydrolyze -lactams to varying degrees, substrate specificity (Table 4). Aztreonam
was the preferred substrate for the detection of the ESBL phenotype among the E. coli, followed by
ceftazidime; whereas among the K. pneumoniae ESBL phenotypes, ceftazidime was the best
substrate, followed by aztreonam and ceftriaxone. ESBLs derivatives from the CTX-M genes
generally hydrolyze aztreonam and ceftriaxone at higher rates than ceftazidime indicating that such
enzymes may be prominent among the Chinese isolates.
 The ciprofloxacin resistance rates were very high among isolates collected from China, Singapore,
MATERIALS AND METHODS
Bacterial Strains
A total of 1,103 Escherichia coli, 643 Klebsiella spp., and 111 Proteus mirabilis isolates were collected
from diverse body sites by the SENTRY Program between January 1998 and December 1999 in the
Asian-Pacific region (17 medical centers). The medical centers were distributed throughout 14 cities in
seven countries: Australia (four centers), China (four centers, including a site located in Hong Kong),
Japan (three centers), Taiwan (three centers), The Philippines (one center), Singapore (one center),
and South Africa (one center). Because there is only one African site included in the SENTRY Program,
its data was analyzed with the Asia-Pacific Region. Only one isolate per patient was evaluated in this
study.
Susceptibility Testing
The isolates were identified to the species level by the participating center and sent to the monitoring
laboratory (Women and Children’s Hospital, Adelaide, Australia) for identification confirmation and
reference susceptibility testing. Antimicrobial susceptibility testing of the possible ESBL-producers was
performed by reference broth microdilution method as described by the National Committee for Clinical
Laboratory Standards (NCCLS). Quality control (QC) was performed using E. coli ATCC 25922, S.
aureus ATCC 29213, and P. aeruginosa ATCC 27853. All QC results were within published ranges.
Occurrence by site of infection
Species (No. of isolates)
and The Philippines (Table 5). Co-resistances to tobramycin, gentamicin, tetracyclines, and
trimethoprim/sulfamethoxazole were common throughout isolates collected from several centers.
Resistance to cefoxitin was observed in 47(54.0%) E. coli and 64 (45.7%) K. pneumoniae isolates
exhibiting ESBL phenotype. This pattern was mainly observed among E. coli and K. pneumoniae
isolated from the Chinese and The Philippines centers, respectively. Interestingly, 23 (48.9%) of 47
E. coli and 47 (70.1%) of 67 K. pneumoniae were inhibited by clavulanic acid, confirming the
production of ESBL. All the E. coli strains resistant to cefoxitin (MICs 32 g/ml) isolated from
Australia, Taiwan, Japan, and China (medical center 209) showed confirmatory tests negative for
ESBL production, probably indicating the production of Amp C enzymes. On the other hand, all
cefoxitin-resistant E. coli strains isolated from China (medical center 208), Singapore, and South
Africa showed positive confirmatory tests for ESBL production. ESBL-producing isolates could be
resistant to cefoxitin due to other mechanisms of resistance, such as loss or decrease of outer
membrane proteins.
 The best spectrum against ESBL-producing isolates was obtained with the carbapenems (Table 6).
Against ESBL-producing E. coli, amikacin (susceptibility of 86.5%) was the second best choice
followed by piperacillin/tazobactam (susceptibility of 70.1%), while against ESBL-producing K.
pneumoniae, the opposite was observed with more than 87% of the isolates susceptible to
piperacillin/tazobactam.
Year
Escherichia coli (87)
1998
1999
Blood
29
12
Respiratory
7
8
SSTIb
Urine
4
2
20
5
Klebsiella pneumoniae (138)
1998
1999
32
24
30
23
6
2
18
3
Proteus mirabilis (2)
1998
1999
1
-
-
1
-
-
aThe
China, followed by The Philippines (23.0%) and Taiwan (8.0%) centers. Approximately one-half of
the Chinese isolates were collected from a single center located in Hong-Kong.
INTRODUCTION
TABLE 1. Occurrence and trends in the Asia Pacific Region
for isolates having an ESBL phenotypea
(SENTRY Program, 1998-99)
ESBL phenotype was defined according to the NCCLS (2001) criteria.
skin and soft tissue.
bSSTI,
TABLE 2. Comparison of ESBL phenotype occurrence rates
among the Asia Pacific medical centers (SENTRY Program,
1998-99).
E. coli
Country/medical
center no.
Australia
200
201
202
203
China
204
208
209
210
Japan
205
206
207
Taiwan
214
215
216
The Philippines
211
Singapore
212
South Africa
213
Total no.
of isolates
K. pneumoniae
No. of ESBL
(%)
Total no.
of isolates
No. of ESBL
(%)
P. mirabilis
Total no.
of isolates
No. of ESBL
(%)
109
139
90
109
0
1 (0.7)
1 (1.1)
0
39
31
35
48
0
0
0
7(14.6)
12
15
8
13
0
0
0
0
153
34
18
44
25 (16.3)
10 (29.4)
4 (22.2)
11 (25.0)
69
5
19
42
10 (15.5)
2 (40.0)
7 (36.8)
14 (33.3)
12
0
0
6
0
0
0
0
0
0
2 (4.2)
23
18
41
3 (13.0)
1 (5.5)
1 (2.4)
3
3
2
1(33.3)
0
0
30
17
48
55
8
12
5 (10.0)
2 (25.0)
0
30
4
7
3 (10.0)
0
1(14.3)
4
0
1
0
0
0
126
20 (15.9)
134
52 (38.8)
14
1(7.1)
77
4 (5.2)
64
25 (39.1)
10
0
34
2 (5.9)
34
12 (35.3)
8
0
TABLE 3. Comparison of ESBL occurrence rates among
E. coli and K. pneumoniae isolates in those institutions
having ESBL production in Enterobacter spp.
E. coli
Country/medical
center no.
China
209
210
Taiwan
214
215
The Philippines
211
Singapore
212
South Africa
213
Total no.
of isolates
K. pneumoniae
No. of ESBL Total no.
(%)
of isolates
P. mirabilis
No. of ESBL Total no.
(%)
of isolates
No. of ESBL
(%)
18
44
4 (22.2)
11 (25.0)
19
42
7 (36.8)
14 (33.3)
18
14
2 (11.1)
5 (35.7)
55
8
5 (9.1)
2 (25.0)
30
4
3 (10.0)
0
6
4
1(16.7)
1 (25.0)
126
20 (15.9)
134
52 (38.8)
49
2 (4.1)
4 (5.2)
64
25 (39.1)
18
2 (11.1)
77
34
2 (5.9)
34
12 (35.3)
12
2 (16.7)
TABLE 4: Distribution of the preferred -lactam substrate
for detection of ESBL isolates
in the Asia Pacific region
Country/substrate
No. ESBL
Australia
Aztreonam
Ceftriaxone
Ceftazidime
China
Aztreonam
Ceftriaxone
Ceftazidime
Japan
Aztreonam
Ceftriaxone
Ceftazidime
Taiwan
Aztreonam
Ceftriaxone
Ceftazidime
The Philippine
Aztreonam
Ceftriaxone
Ceftazidime
Singapore
Aztreonam
Ceftriaxone
Ceftazidime
South Africa
Aztreonam
Ceftriaxone
Ceftazidime
All nations
Aztreonam
Ceftriaxone
Ceftazidime
aESBL-producing
E. coli
% detected
K. pneumoniae
No. ESBL
% detected
P. mirabilis
No. ESBL
% detected
6
2
1
1
100.0
50.0
50.0
7
7
85.7
100.0
100.0
-a
-a
-a
-a
-a
-a
94.0
72.0
78.0
32
30
30
97.0
91.0
91.0
-a
-a
-a
-a
-a
-a
1
2
100.0
50.0
100.0
3
3
5
60.0
60.0
100.0
1
1
0
100.0
100.0
6
5
7
85.7
71.4
100.0
3
4
4
75.0
100.0
100.0
-a
-a
-a
-a
-a
-a
17
13
18
85.0
65.0
90.0
50
49
52
96.2
94.2
100.0
0
0
1/1
0.0
0.0
100.0
4
4
4
100.0
100.0
100.0
23
24
24
92.0
96.0
96.0
-a
-a
-a
-a
-a
-a
2
2
2
100.0
100.0
100.0
12
12
12
100.0
100.0
100.0
-a
-a
-a
-a
-a
-a
80
62
73
92.0
71.3
84.0
129
129
134
93.5
93.5
97.1
1
1
1
50.0
50.0
50.0
Escherichia coli (87)
Klebsiella pneumoniae (134)
g/ml
g/ml
4
7
36
39
2
Antimicrobial agents
MIC50/90
% susc.a
MIC50/90
% susc.a
Piperacillin/Tazobactam
Cefoxitin
Imipenem
Ciprofloxacin
Amikacin
Gentamicin
Tobramycin
Tetracycline
8/>64
32/>32
0.25/0.5
>2/>2
2/32
8/>16
8/>16
>8/>8
70.1
25.3
100.0
34.5
86.5
24.1
31.0
23.0
2/>16
16/>32
0.25/1
1/>2
8/32
16/>16
16/>16
16/>16
87.3
43.5
100.0
55.8
84.1
41.3
27.5
46.3
aBreakpoints
Species/nation/
medical center
(no. isolates)
Escherichia coli
Australia
201 (1)
202 (1)
China
204 (25)
208 (10)
209 (4)
210 (11)
Japan
207 (2)
Taiwan
214 (5)
215 (2)
The Philippine
211 (20)
Singapore
212 (4)
South Africa
213 (2)
Klebsiella pneumoniae
Australia
203 (7)
China
204 (10)
208 (2)
207 (7)
210 (4)
Japan
205 (3)
206 (1)
207 (1)
Taiwan
214 (3)
216 (1)
The Philippines
211 (52)
Singapore
212 (25)
South Africa
213 (12)
of susceptibility defined by NCCLS (2001).
CONCLUSIONS

The number of ESBL phenotype isolates detected in E. coli and Klebsiella
pneumoniae by the SENTRY Program varied widely among the Asia-Pacific medical
centers. Most of them had a high frequency of occurrence of the ESBL phenotype
comparable only to those reported by us in Latin American medical centers.

The antimicrobial resistance patterns observed among these isolates confirm that
the therapeutic options for treatment of infections caused by ESBL pathogens is
very limited, and only a few drugs such as carbapenems constitute a safe option.

The results presented by this report emphasise the importance of regional
antimicrobial surveillance studies such as the SENTRY Antimicrobial Surveillance
Program in combating and controlling antimicrobial resistance.
Proteus mirabilis isolates were not detected.
TABLE 5: Co-resistance phenotypes observed among the
ESBL-producing isolates by nation and medical center.
aCipro
TABLE 6: Antimicrobial activity of selected antimicrobial
agents against ESBL-producing isolates collected by
SENTRY Antimicrobial Surveillance Program in the AsiaPacific region, 1998-99
No. of isolates (%) resistant to:
Cefoxitin
Ciproa
Amika
Genta
Tobraa
Tetraa
TMP/SMX
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0
0
0
0
0
0
0
0
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