Poster No 1464
15th ECCMID, Kopenhagen/Danmark, April 2-5, 2005
1
Increase of resistance to nalidixic acid among four clinically important Enterobacteriaceae
pathogens in three Central European countries
M. Kresken1*, D. Hafner2, on behalf of the Working Group for Antimicrobial Resistance of the
Paul-Ehrlich-Society for Chemotherapy
Abstract
Objectives: Since 1984 when the first fluoroquinolone (FQ) was introduced in Europe the
consumption of the FQ has markedly increased. To evaluate the influence of the
increasing consumption on the prevalence of resistance to nalidixic acid (NAL) and FQ in
clinical isolates of four clinically important members of the family Enterobacteriaceae we
reviewed the susceptibility data from two collaborative studies conducted in 1984 (prior to
the introduction of the first FQ) and in 2001 by the Working Group for Antimicrobial
Resistance of the Paul-Ehrlich-Society for Chemotherapy
Methods: Isolates of Enterobacter cloacae (ECL), Escherichia coli (ECO), Klebsiella
pneumoniae (KPN), and Proteus mirabilis (PMI) collected in 1984 and 2001 from 23 and 26
laboratories, respectively, located in Austria, Germany, and Switzerland, were included.
MICs were determined using the broth microdilution method according to the standard of
the German DIN.
Results: In 1984 and 2001, a total of 1.640 and 1.348 isolates, respectively, were tested.
Resistance to NAL markedly increased in all species between 1984 and 2001, i. e. from
2.0% to 17.5% in ECL, from 1.6% to 19.2% in ECO, from 12.2% to 21.6% in KPN, and from
2.6% to 15.9% in PMI. Of the NAL-resistant ECO isolates collected in the 2001 survey,
26.1% were susceptible and 71.4% resistant to ciprofloxacin (CPFX). Susceptibility rates
of CPFX for ECL, KPN, and PMI were 53.4%, 43.9%, and 30.6%, respectively. Furthermore,
NAL-resistant isolates of all species collected in the 2001 survey exhibited reduced
susceptibility to other therapeutic classes. Notably, susceptibility rates of NAL-resistant
ECO isolates for cefotaxime, ceftazidime, piperacillin/tazobactam, gentamicin, and
tobramycin (89.8%, 93.3%, 85.7%, 68.9%, 71.4%) were significantly lower than those for
NAL-susceptible isolates (99.2%, 99.0%, 94.2%, 91.2%, 95.0%). In contrast, carbapenems
and amikacin retained in vitro activity against NAL-resistant ECO isolates. Similar trends
were observed for the other three species.
Conclusion: Resistance to NAL (and FQ) has markedly increased among
Enterobacteriaceae pathogens recovered from patients in hospitals located in Germany,
Austria, and Switzerland. We strongly recommend a judicious use of FQ in order to
combat the spread of FQ resistance in Enterobacteriaceae. .
Introduction and Purpose
Since 1984 when the first fluoroquinolone (norfloxacin) was introduced in Europe the
consumption of the fluoroquinolones has markedly increased. In Germany, the use of
fluoroquinolones rose from 7 to 13 packs in the retail market and 11 to 19 million counting
units in the hospital market (IMS data). To evaluate the influence of the increasing
consumption on the prevalence of resistance to nalidixic acid and fluoroquinolones in
clinical isolates of four clinically important members of the family Enterobacteriaceae we
reviewed the susceptibility data from two collaborative studies conducted in 1984 (prior to
the introduction of the first fluoroquinolone) and in 2001 by the Working Group for
Antimicrobial Resistance of the Paul-Ehrlich-Society for Chemotherapy.
Methods
Surveillance Network
The Antimicrobial Resistance Surveillance Program of the Paul-Ehrlich-Society for
Chemotherapy was implemented in 1975. It is a program that monitors the prevalence of
antimicrobial susceptibility of frequently encountered bacterial pathogens at regular
intervals via a network of microbiology laboratories located in Austria, all regions of
Germany, and Switzerland. The majority of laboratories is affiliated to university hospitals
or other teaching hospitals.
Bacterial strains
Isolates of Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Proteus
mirabilis collected in 1984 and 2001 from 23 and 26 laboratories, respectively, were
included. Only one isolate per patient was permitted. Isolates were identified by using a
commercial identification system (api-20E, bioMerieux, Nürtingen, Germany).
MICs were determined using the broth microdilution method according to the standard of
the German DIN.
Susceptibility testing
All laboratories used the same method of susceptibility testing. Minimal inhibition
concentrations (MICs) for antibacterial agents were determined by the broth microdilution
method according to the standard of the German DIN (Deutsches Institut für Normung)
58940 guidelines (1). Antibacterial agents tested were nalidixic acid, ciprofloxacin (as
reference fluoroquinolone), and 10 agents of other drug classes: amikacin, cefepime,
cefotaxime, ceftazidime, gentamicin, imipenem, meropenem, piperacillin, piperacillintazobactam, tobramycin. Nalidixic acid breakpoints were ≤ 16 mg/L (susceptible) and ≥ 32
mg/L (resistant). Breakpoints of all other antibacterial agents were those approved by DIN
(2).
Statistical analysis
The results were analysed by using SAS Statistic Software Package. Fisher's exact test
for 2x2 contingency tables was performed. Differences were considered significant when
the P-value was <0.05.
Results
In 1984 and 2001, a total of 1.640 and 1.348 isolates, respectively, were
tested. Resistance to nalidixic acid markedly increased in all species
between 1984 and 2001, i. e. from 2.0% to 17.5% in E. cloacae, from
1.6% to 19.2% in E. coli, from 12.2% to 21.6% in K. pneumoniae, and
from 2.6% to 15.9% in P. mirabilis (Table 1).
Of the 119 nalidixic acid-resistant E. coli isolates collected in the 2001
survey, 31 (26.1%) were susceptible and 85 (71.4%) resistant to
ciprofloxacin (Table 2). Susceptibility rates of ciprofloxacin for E.
cloacae, K. pneumoniae, and P. mirabilis were 53.4%, 43.9%, and
30.6%, respectively (Table 2).
Furthermore, nalidixic acid-resistant isolates of all species collected in
the 2001 survey exhibited reduced susceptibility to other therapeutic
classes. Notably, susceptibility rates of nalidixic acid-resistant E. coli
isolates
for
cefotaxime,
ceftazidime,
piperacillin/tazobactam,
gentamicin, and tobramycin (89.8%, 93.3%, 85.7%, 68.9%, 71.4%) were
significantly lower than those for NAL-susceptible isolates (99.2, 99.0%,
94.2%, 91.2%, 95.0%). In contrast, carbapenems, and amikacin retained
in vitro activity against nalidixic acid-resistant E. coli isolates. Similar
trends were observed for the other three species (Table 3).
Conclusions
1.
Our findings indicate that the prevalence of resistance to nalidixicacid (and fluoroquinolones) in E. coli, E. cloacae, K. pneumoniae,
and P. mirabilis recovered from patients in hospitals located in
Germany, Austria, and Switzerland increased between 1984 and
2001.
2.
Nalidixic acid-resistant isolates were very often co-resistant to
non-quinolone antibacterial agents. Carbapenems retained in vitro
activity to nalidixic-acid resistant isolates of all four species.
3.
The increase of resistance to nalidixic acid (and fluoroquinolones)
seems to be mainly due to the increase in the consumption of
fluoroquinolones, but the hospital epidemiology may also have
contributed markedly to the overall resistance.
4.
We strongly recommend a judicious use of fluoroquinolones in
order to combat the spread of fluoroquinolone resistance in
members of the family Enterobacteriaceae.
Antiinfectives Intelligence GmbH, Immenburgstrasse 20,
53121 Bonn, Germany,
*Fon: + 49-228-444-7060/Fax: +49-228-444-70616;
*E-mail: [email protected]
2
Institute for Pharmacology and Clinical Pharmacology,
University of Düsseldorf, Moorenstrasse 5,
40225 Düsseldorf, Germany
Table 1: Development of nalidixic acid resistance in four members of the family Enterobacteriaceae from 1984 to 2001
MIC (mg/L)
Species
Year
<1
2
4
8
16
32
64
1984
n
3
54
127
9
1
0
0
(n=198) cum-%
1.5
28.8
92.9
97.5
98.0
98.0
98.0
Enterobacter cloacae
2001
n
3
60
91
28
11
1
2
(n=234) cum-%
1.3
26.9
65.8
77.8
82.5
82.9
83.8
1984
n
243
447
124
7
0
3
5
(n=834) cum-%
29.1
82.7
97.6
98.4
98.4
98.8
99.4
Escherichia coli
2001
n
64
295
122
9
10
2
12
(n=619) cum-%
10.3
58.0
77.7
79.2
80.8
81.1
83.0
1984
n
2
30
182
16
1
8
7
(n=263) cum-%
0.8
12.2
81.4
87.5
87.8
90.9
93.5
Klebsiella pneumoniae
2001
n
3
101
79
22
5
6
7
(n=268) cum-%
1.1
38.8
68.3
76.5
78.4
80.6
83.2
1984
n
11
88
227
7
3
3
3
(n=345) cum-%
3.2
28.7
94.5
96.5
97.4
98.3
99.1
Proteus mirabilis
2001
n
4
37
114
30
6
1
2
(n=227) cum-%
1.8
18.1
68.3
81.5
84.1
84.6
85.5
% S, % susceptible; % R, % resistant
128
1
98.0
4
85.5
0
99.4
18
85.9
8
96.6
2
84.0
1
99.4
3
86.8
Table 2: In vitro activity of ciprofloxacin against nalidixic acid-resistant isolates of four members of the Enterobacteriaceae collected in 2001
MIC (mg/L)
n
0.125
0.25
0.5
1
2
4
8
>16
<0.063
n
1
2
8
5
2
6
7
5
5
Enterobacter cloacae
41
cum-%
2.4
7.3
26.8
39.0
43.9
58.5
75.6
87.8
100.0
n
6
7
13
3
2
3
12
17
56
Escherichia coli
119
cum-%
5.0
10.9
21.8
24.4
26.1
28.6
38.7
52.9
100.0
n
2
1
9
12
7
11
7
4
5
Klebsiella pneumoniae
58
cum-%
3.4
5.2
20.7
41.4
53.4
72.4
84.5
91.4
100.0
n
0
1
1
1
8
15
4
4
2
Proteus mirabilis
36
cum-%
0.0
2.8
5.6
8.3
30.6
72.2
83.3
94.4
100.0
% S, % susceptible; % I, % intermediate; % R, % resistant
Species
References
1. Deutsches Institut für Normung, Normenausschuss Medizin (NAMed). (1990). Methoden zur
Empfindlichkeitsprüfung von bakteriellen Krankheitserregern (außer Mykobakterien) gegen
Chemotherapeutika. Mikrodilution. DIN 58940, Teil 8, Juni 1990.
2. Deutsches Institut für Normung, Normenausschuss Medizin (NAMed). (2000). Methoden zur
Empfindlichkeitsprüfung von bakteriellen Krankheitserregern (außer Mykobakterien) gegen
Chemotherapeutika. Bewertungsstufen der minimalen Hemmkonzentration – MHK-Grenzwerte von
antibakteriellen Wirkstoffen. DIN 58940, Teil 4, Januar 2000.
Laboratories participating in the 2001 survey
Austria: Bundesstaatl. Bakteriolog.- Serolog. Untersuchungsanstalt, Innsbruck (F. Allerberger);
Klinische Abt. für Klinische Mikrobiologie, Universität Wien (M. Rotter, S. Prause); Germany:
Zentralinstitut für Laboratoriumsdignostik, Städtische Kliniken Offenbach (K. Fabricius); Labor Dr.
Gärtner, Weingarten (G. Funke, H. Grimm); Institut für Mikrobiologie und Hygiene, Campus Charité Mitte,
Humboldt-Universität, Berlin (E. Halle); Staatl. Medizinal-Untersuchungsamt Niedersachsen, Hannover
(K. Schwegmann); Institut für Laboratoriumsmedizin, Städtisches Klinikum Fulda (H. Krüpe); Institut für
Med. Mikrobiologie der RWTH, Aachen (R. Lütticken); Institut für Medizinische Mikrobiologie und
Krankenhaushygiene, Klinikum der Philipps-Universität, Marburg (R. Mutters); Institut für Medizinische
Mikrobiologie, Westfälische Wilhelms-Universität, Münster (G. Peters, R. Gross); Abteilung für
Mikrobiologie und Krankenhaushygiene, Städtisches Klinikum, Karlsruhe (A. Becker, E. Kniehl); Institut
für Medizinische Mikrobiologie und Infektionsepidemiologie, Universität Leipzig (A. C. Rodloff, B. Pleß);
Institut für Medizinische Mikrobiologie, Klinikum der J.W. Goethe-Universität, Frankfurt am Main (V.
Brade, V. Schäfer, T. Wichelhaus); Institut für Medizinische Mikrobiologie, Universität Rostock (H.
Schmidt, M. Donat); Institut für Medizinische Mikrobiologie, Klinikum der Friedrich-Schiller-Universität,
Jena ( (E. Straube, W. Pfister); Institut für Medizinische Mikrobiologie und Virologie, Klinikum der
Christian-Albrechts-Universität, Kiel (U. Ullmann, S. Schubert); Institut für Infektionsmedizin, WE15 Abt.
für Medizinische Mikrobiologie und Infektionsimmunologie, Universitätsklinikum Benjamin Franklin, FU
Berlin (J. Wagner); Thüringer Landesamt für Lebensmittelsicherheit und Verbraucherschutz,
Medizinaluntersuchung, Erfurt (U. Warweg); Pharmazeutische Mikrobiologie, Rheinische WilhelmsUniversität, Bonn (B. Wiedemann); Institut für Medizinische Mikrobiologie und Hygiene, JohannesGutenberg-Universität, Mainz (M. Maeurer); Institut für Medizinische Mikrobiologie und Virologie,
Heinrich-Heine-Universität,
Düsseldorf
(F.-J.
Schmitz);
Institut
für
Umweltmedizin
und
Krankenhaushygiene, Klinikum der Albert-Ludwigs-Universität, Freiburg (F. Daschner); Institut für
Medizinische Mikrobiologie, Immunologie und Hygiene, Klinikum der Universität zu Köln (H. Seifert);
Max von Pettenkofer Institut für Hygiene und Med. Mikrobiologie; Klinikum Großhadern, München (B.
Grabein); Labor Dr. Limbach & Kollegen, Heidelberg (M. Holfelder, A. Fahr); Switzerland:
Bakteriologielabor, Kantonsspital Basel (R. Frei, M. Jutzi); Institut Neuchatelois de Microbiologie, LaChaux-de-Fonds (H. H. Siegrist); Institut für Med. Mikrobiologie, Universität Zürich (B. Berger-Bächi);
Mikrobiologisches Institut, Kantonsspital Aarau (I. Heinzer)
MIC-50
(mg/L)
>256
3
100.0
34
100.0
5
100.0
87
100.0
9
100.0
43
100.0
2
100.0
30
100.0
MIC-90
(mg/L)
%S
%R
194
98.0
193
82.5
821
98.4
500
80.8
231
87.8
210
78.4
336
97.4
191
84.1
4
2.0
41
17.5
13
1.6
119
19.2
32
12.2
58
21.6
9
2.6
36
15.9
%S
%I
%R
18
43.9
31
26.1
31
53.4
11
30.6
6
14.6
3
2.5
11
19.0
15
41.7
17
41.5
85
71.4
16
27.6
10
27.8
4
4
4
>256
2
4
2
>256
4
32
4
>256
4
4
4
>256
MIC-50
(mg/L)
MIC-90
(mg/L)
2
8
8
>16
1
4
2
8
Table 3: In vitro activity of 10 non-quinolone antibacterial agents against nalidixic acid-susceptible and -resistant isolates of four members of the
Enterobacteriaceae collected in 2001
Escherichia coli
Klebsiella pneumoniae
Proteus mirabilis
Enterobacter cloacae
(Nal-S, n=193; Nal-R, n=41)
(Nal-S, n=500, Nal-R, n=119)
(Nal-S, n=210, Nal-R, n=58)
(Nal-S, n=191, Nal-R, n=36)
Antibacterial
Phenotype
agent
% I+R P-value
%S
% I+R P-value
%S
%S
% I+R P-value
%S
% I+R P-value
Nal-S
97.9
2.1
93.4
6.6
<0.01
Nal-R
87.8
12.2
91.6
8.4
Nal-S
96.9
3.1
99,8
0,2
Cefepime
<0.05
Nal-R
87.8
12.2
96.6
3.4
Nal-S
73.6
26.4
99.2
0.8
Cefotaxime
<0.01
Nal-R
26.8
73.2
89.9
10.1
Nal-S
74.6
25.4
99.0
1.0
Ceftazidime
<0.01
Nal-R
46.3
53.7
93.3
6.7
Nal-S
98.4
1.6
91.2
8.8
Gentamicin
<0.01
Nal-R
78.0
22.0
68.9
31.1
Nal-S
99.0
1.0
99.6
0.4
Imipenem
n. s.
Nal-R
97.6
2.4
100.0
0.0
Nal-S
100.0
0.0
100.0
0.0
Meropenem
n. s.
Nal-R
97.6
2.4
100.0
0.0
Nal-S
67.9
32.1
66.0
34.0
Piperacillin
<0.01
Nal-R
26.8
73.2
19.3
80.7
PiperacillinNal-S
74.1
25.9
94.2
5.8
<0.01
tazobactam
Nal-R
31.7
68.3
85.7
14.3
Nal-S
97.9
2.1
95.0
5.0
Tobramycin
<0.01
Nal-R
78.0
22.0
71.4
28.6
% S, % susceptible; % I+R, % intermediate and resistant; n. s., not significant
Amikacin
n. s.
<0.01
<0.01
<0.01
<0.01
n. s.
n. s.
<0.01
<0.01
<0.01
98.6
77.6
98.6
69.0
98.1
62.1
98.1
60.3
98.1
65.5
100.0
100.0
100.0
100.0
43.3
12.1
92.9
43.1
98.6
56.9
1.4
22.4
1.4
31.0
1.9
37.9
1.9
39.7
1.9
34.5
0.0
0.0
0.0
0.0
56.7
87.9
7.1
56.9
1.4
43.1
<0.01
<0.01
<0.01
<0.01
<0.01
n. s.
n. s.
<0.01
<0.01
<0.01
86.9
77.8
98.4
86.1
99.5
88.9
99.5
88.9
83.8
66.7
95.3
91.7
100.0
100.0
87.4
50.0
99.0
86.1
89.5
66.7
13.1
22.2
1.6
13.9
0.5
11.1
0.5
11.1
16.2
33.3
4.7
8.3
0.0
0.0
12.6
50.0
1.0
13.9
10.5
33.3
n. s.
<0.01
<0.01
<0.01
<0.05
n. s.
n. s.
<0.01
<0.01
<0.01