- Email: [email protected]
In vitro activity of ampicillin, cefoperazone, their combinations with sulbactam and other antimicrobials: survey of Russian isolates
Antimicrobial Agents ELSEVIER
International Journal of Antimicrobial Agents 7 (1996) 109-I 17
In vitro activity of ampicillin, cefoperazone, their combinations with sulbactam and other antimicrobials: survey of Russian isolates Sergei V. Sidorenko *, Svetlana P. Rezvan, Alexandra S. Tikchonova, Larysa A. Krotova, Larysa E. Ansolis, Elena A. Tzvigun National Research Center for Antibiotics,
Nagatiskaya
3a, St. 113105, Moscow, Russian Fe&ration
Accepted 23 February 1996
Methodological differences makes it difficult to compare results of antimicrobial susceptibility testing obtained in Russia and in other regions. During the period from October 1993 to May 1994 susceptibility of 1296 isolates of bacteria was investigated according to NCCLS standards by the broth microdilution method. The order of activity of antibiotics against Gram-negative bacteria based on percent of susceptible strains from common hospitals were: amikacin (98%) > ciprofloxacin (93%) = imipenem (93%) > cefoperazone/sulbactam (92%) > ceftazidime (89%) > ceftriaxone (81%) > cefotaxime (80%) > cefoperazone (77%) > gentamicin (71%) > ampicillin/sulbactam (51%) > cefazoline (45%) > ampicillin (25%). The order of activity against strains from teaching hospitals was similar but the percent of susceptible strains was lo-20% less for the majority of antibiotics. The susceptibility level of Gram-negative isolates from Moscow teaching hospitals is lower than from Northern America and Europe. Ampicilllnlsulbactam and cefoperazone/sulbactam, as well as other cephalosporins, demonstrated high activity against methicillinsusceptible staphylococci and penicillin-susceptible pneumococci. B-lactams/&lactamase inhibitor combinations were active against 100% strains of anaerobic bacteria. Keywords: Ampicillin/sulba,ctam;
Cefoperazone/sulbactam;
Susceptibility; Antibiotics
1. Introduction The p-lactamases form a large family of enzymes that can hydrolyze the &lactam ring of antimicrobial agents [2,3,4]. An enzymatic resistance mechanism is the most important clinically among different species of bacteria (staphylococci, enterobacteria, bacteroides, etc.). Development of specific /3-lactamase inhibitors is one of the strategies used to cope with the problem of /3-lactamase-producing bacteria [7]. Suicide inhibitors such as clavulanic acid, sulbac:tam and tazobactam represent the current state of the art in /3-lactamase inhibition [8]. A number of formulations of the inhibitors mentioned above with penicillins have been licensed (ampicillin/ sulbactam, amoxicillin/clavulanic acid, ticarcillin/clavulanic acid piperacillin/tazobactam). Cefoperazonefsul* Corresponding author. Tel.: +7 095 1114166;fax: +7 095 1189366; e-mail: [email protected]. 0924-8579/96/$32.00 0 1996 :Elsevier Science B.V. All rights reserved PII: 0924-8579(96)00308-l
is the only available combination of cephalosporin antibiotic with fi-lactamase inhibitor [ 111. The aim of the study was to evaluate the susceptibility of fresh isolates from different centers in Russia to ampicillin, cefoperazone and their combinations with sulbactam, as well as to other antimicrobials. bactam
2. Materials and methods During the period from October 1993 to May 1994, 1116 strains of Gram-negative and Gram-positive aerobic and 180 strains of anaerobic bacteria were isolated in different institutions of Moscow and Smolensk from patients with urinary tract infections, upper and lower respiratory tract infections, and systemic and wound infections. Isolates were identified in local laboratories using routine tests and were stored in permanent culture. Identification of isolates was conformed in our laboratory using ‘Minitek’ (Bccton Dickinson,
110
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (1996) 109-117
Schaedler broth was used for Bacteroides fragilis and fragilis group, Actinomyces spp. and Propionibacterium spp. Serial agar dilution technique in Wilkins-Chalgren agar with 5% of defibrinated sheep blood was used for Gram-positive anaerobic cocci and Prevotelia spp. susceptibility testing. Bacteroides fragilis ATCC 25285 was used as a reference strain. NCCLS-recommended break-points were used for interpretation of susceptibility testing results [ 14,15,16].
Cockeysville, USA) miniaturised microorganism differentiation systems (Minitek Enterobacteriaceae II set; Minitek Nonfermenter set; Minitek Gram-positive set; Minitek Anaerobe II set). Antibiotic susceptibility was determined by broth the microdilution technique [ 141in microtiter plates with deep-frozen dilutions of antibiotics, or by agar dilution techniques for some anaerobes
[l% The 21 antibiotics and the range of dilutions at which they were tested were as follows: penicillin G, 0.06-8.0 mg/l; ampicillin, ampicillin/sulbactam (2: l), cefoperazone, cefoperazone/sulbactam (1: l), cefotaxime, ceftriaxone, ceftazidime, cefazoline, cefoxitin, oxacillin, imipenem, 0.25-64.0 mg/l; ciprofloxacin, 0.06-16.0 mg/l; gentamicin, O-25-32.0 mg/l; amikacin, 0.5-64.0; vancomycin, 0.25-32.0 mgil; doxycycline, 0.5-64.0 mg’l; rifampin; erythromycin,; metronidazole, 0.12- 16.0 mg/l; chloramphenicol, 0.5-64.0. Different sets of antibiotics were used for susceptibility testing of Gramnegative and Gram-positive aerobes as well as of anaerobes. Most of the susceptibility tests of aerobic bacteria were performed using Mueller-Hinton broth (reference strains were: Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Pneumococci were tested using Haemophilus Test Medium (reference strain: Streptococcus pneumoniae ATCC 496 19) [lo].
3. Results The activities of the antimicrobials against Gramnegative aerobic species are shown in Table 1. Isolates from common and large teaching hospitals were analyzed separately. As interpretative criteria for cefoperazone/sulbactam were not available from the NCCLS, the recommendations of the manufacturer were used (susceptible, MIC < 16.0/16.0 &ml; resistant, MIC > 64.0/64.0 &nl). Differences in susceptibilities were found between isolates from common and teaching hospitals. More than 80% of the Escherichia coli, Klebsiella spp., Enterobacter aerogenes, Morganella morganii, Proteus mirabilis, Proteus vulgaris, and Serratia spp. isolates
from common hospitals were susceptible to cefoperazone/sulbactam, third generation cephalospotins, imipenem, ciprotloxacin, amikacin and ciproflox-
Table I Susceptibility (&ml) of Gram-negative aerobes Species (number teaching/ common)
Antibiotics
E. coli (81/l 17)
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
4 4
Ampicillin Ampicillin/sulbactam Ce.foperaxone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64
Klebsiella spp. wJ93)
MICSO Teaching
0.5
0.5 0.5 0.5 2 0.25
Common I6 8 I I I I I I 0.25
I 4 0.06
32 8 4 4 4 4 64 0.5 4 2 0.125
% Susceptible NCCLS
MIGW
I 0.06 64 8 I I I 1 0.5 2 0.25
1 1 0.06
Teaching >64 64 64 32 64 64 32 >64 4 >32 >64 0.12 >64 >64 >64 64 >64 >64 >64 >64 4 32
>64 4
Common
Teaching
Common
I6 8 I I 2 32 I 4 4 0.12
55.6 63.0 82.7 88.9 80.2 82.7 81.5 67.9 100.0 77.8 81.5 96.3
48.7 59.8 90.6 98.3 93.2 94.0 98.3 84.6 99.1 90.6 98.3 100.
>64 32 32 I6 8 8 8 64 2 32 2 0.25
7.6 38.5 71.2 75.0 65.4 61.5 69.2 36.5 92.3 48.1 67.3 82.7
10.7 52.6 88.2 95.7 91.4 92.5 90.3 63.4 98.9 68.8 97.8 97.8
64 64
6: V. Siakwenko et al. /International Journal of Antimicrobial Agents 7 (19%)
109-117
111
Table 1 (Continued) Species (number teaching/ common)
Antibiotics
Enterobacter
Ampicillin Annpicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline imipenem Gentamicin Amikacin Ciprofloxacin
aerogenes (20/l 5)
Enterobacter cloacae (18132)
M. morganii (21113)
P. mirabilis (28131)
P. vulgaris (23/26)
M&, Teaching
>64 32 8 2
MICs,, Common
32 8 2
1
Teaching
Common
Teaching
Common
>64 >64 >64
>64 64 64
32 >64 >64 >64 >&I 1 >32 64 1
8 32 32 32 >64
10.0 25.0 65.0 80.0 70.0 60.0 70.0 25.0 100.0 45.0 65.0 100.0
20.0 60.0 86.7 93.3 86.7 86.7 86.7 13.3 100.0 86.7 100. 100.0
>64 >64 64 16 64 64 16 >64 2 32 4 0.125
16.7 38.9 44.4 55.6 44.4 38.9 55.6 0 100.0 33.3 77.9 100.0
21.9 43.8 78.2 90.6 78.1 72.2 81.2 9.3 96.9 84.4 96.9 96.0
64 32 16 2 4 4 4 64 4 8 4 0.06
9.5 38. I 71.4 100.0 90.5 100.0 100.0 9.5 47.6 28.6 19.0 90.5
0 38.5 100.0 100.0 100.0 100.0 100.0 0 100.0 61.5 100.0 100.0
39.3 67.9 89.3 100.0 100.0 100.0 96.4 67.9 92.9 57.1 78.6 100.0 17.4 60.9 69.6 82.6 78.3 73.9 73.9 8.7 100.0
51.6 77.4 83.9 93.5 100.0 100.0 100.0 61.3 93.5 67.7 100.0 87.1 19.2 73.1 73.1 80.8 80.8 80.8 80.8 7.7 92.3
0.5 4 2 >64 0.125 8 2 0.125
2 2 0.5 >64 0.125 0.5
Ampicillin Annpicillin/sulbactam Cefoperazone CefoperazoneJsulbactam Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 64 32 8 16 16 I >64 0.5 32 2 0.5
32 16 0.5 0.5 0.5 0.5 0.5 >64 0.5 1 1 0.125
>64 >64 >64 64 >64 >64 >64 >64
Ampicillin Annpicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 16 16
>64 16 2
1 1
1
>64 16 32 4 8 4 8 >64 8 >32 >64 0.06
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Irmpenem Gentamicin Amikacin Ciprofloxacin Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imi penem
>64 4
4 2
1 1
1 I 1 I
0.5
1 >64 8 16 >64 0.06
0.125 0.125 0.125 4
I 4 2 0.06 >64 4 4 2
I I 0.5 >64
I
1 0.06
1
1 1 >64 2 2 2 0.06
0.5 4 2 2 2 0.06 >64 4 2
I I 1 0.5 >64 I
% Susceptible NCCLS
I >32 64 1
>64 32 32 4 0.5 0.5 0.5 64 4 32 >64 0.5 >64 32 64 64 >64 >64 >64 >64 4
I 16 8 I
>64 64 64 16
I I 1 64 4 32 8 4 >64 64 64 32 32 64 64 64 4
112
S. V. Sidorenko ei al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
Table 1 (Continued) Species (number teaching/ common)
Antibiotics
Teaching
Gentamicin Amikacin Ciprofloxacin C. fret&i (26l23)
Serratia spp. (28116)
spp. (27/27)
P. aeruginosa
Other Cram-negative (21/2)
Common
8 32 0.06
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 64 I6 8 8 8 8 >64 0.5 8 4 0.125
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
64 64 16 8 4 4 1 >64 0.25 32 8
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 >64
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 >64 32 16 32 32 4 >64 4 8 8 0.5
Ampicillin AmpicilWsulbactam Cefoperazone CefoperaxoneAulbactam
64 32 I
I
32 16 32 32 4 >64
I >32 16 0.5
1
% Susceptible NCCLS
MI&t,
MICso
2 1 0.06 32 4
1 I 1
I 0.5 2 0.25
I 2 0.06 >64 32 2
1 0.5 0.5 0.5 >64 0.5 4 2 0.06 >64 I6 64 8 8 8 4 >64 0.25 8
I 0.25 >64 >64 32 16 32 I6 4 >64 8 I6 2 0.5 -
Teaching
Common
43.5 47.8 91.3
53.8 92.3 92.3
32 8 0.25
30.7 30.7 50.0 80.7 50.0 50.0 57.7 26.9 92.3 34.6 69.2 76.9
30.4 69.6 73.9 100. 73.9 73.9 69.6 56.5 100.0 82.6 100.0 91.3
>64 64 >64 16 >64 >64 64 >64 8 32 >64 8
>64 64 64 16 8 8 4 >64 4 3 4 0.25
3.6 21.4 64.3 92.9 78.6 64.3 85.7 3.6 85.7 39.3 64.3 53.6
12.5 43.8 56.3 100. 100. 100. 100. 6.3 100. 68.8 93.8 93.8
>64 >64 >64 >64 >64 >64 64 >64 >64 >32 >64 8
>64 >64 >64 8 32 32 16 >64 2 32 >64
7.4 25.9 14.8 59.3 41.1 41.1 59.3 7.4 66.1 37.0 51.9 77.8
7.4 41.1 29.6 81.5 59.3 51.9 88.9 0 100.0 41.1 88.9 96.3
>64 >64 >64 >64 >64 >64 64 >64 I6 >32 >64 4
>64 >64 >64 64 >64 >64 32 >64 32 >32 8 2
0 0 48.4 64.1 4.7 12.5 61.0 0 64.1 43.8 78.1 71.9
0 0 46.1 68.8 II.1 20.0 13.3 0 46.7 33.3 100.0 13.3
>64 64 8 4
-
57.1 76. I iOO.0 100.0
100.0 100.0 100.0 100.0
Teaching
Common
64 >64 I
32 4
>64 >64 >64 64
>64 >64 64
32 64 32 >64 I 32 >64 4
1
4 32 64 >64 64
I
I
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%)
109-117
113
Table 1 (Continued) Species (number teachingl common)
Antibiotics
MU&, Teaching
Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
acin. Eighty percent activity against Enterobacter cloacae was exceeded by cefoperazonelsulbactam, ceftazidime, imipenem, ciprofloxacin and aminoglycosides; against Cirtobacter freundii by cefoperazonelsulbactam, imipenem, ciprofloxacin and aminoglycosides; against Acinetobacter spp. by cefoperazonelsulbactam, imipenem, ciprofloxacin, ceftazidime and amikacin; and against P. aeruginosa by amikacin only. The susceptibility levels of isolates from teaching hospitals were 10-W! lower. The most pronounced differences were seen in the activities of third generation cephalosporins and gentamicin against Klebsiella spp., Enterobacter spp., Citrobacter spp., Serratia spp., and Acinetobacter spp. The results of suscept.ibility testing of staphylococci are presented in Table 2. The susceptibilities of methicillin-sensitive (MS) and methicillin-resistant (MR) staphylococci were analyzed separately. The majority of antibiotics under study were highly active against methicillin-sensitive staphylococci (both aureus and coagulase-negative). The only drug practically inactive was ampicillin. Among S. aureus 66.2% of strains were susceptible to ampicillin/sulbactam and 33.8% were intermediate (MIC = 16.0 pg/ml). Coagulasenegative staphylococci were highly susceptible (94.2% of susceptible strains). Erythromycin was poorly active against both S. aureus and coagulase-negative staphylococci. Doxycyline demonstrated a significant and practically equal level of activity against both groups of staphylococci (71.0-78.3% of susceptible strains). Vancomycin was the most active agent against methicillin-resistant staphylococci (only one strain of intermediately susceptible coagulase-negative staphylococci was isolated), followed by rifampin. A high level of activity was detected with ciprofloxacin (69.2% of S. aureus susceptible strains and 100% of coagulasenegative staphylococci). MICs of some /3-lactams against methicillin-resistant staphylococci below breakpoints are not of clinical value. Results of susceptibility testing of pneumococci are
1 1 1 1 0.5 1 1 0.25
% Susceptible NCCLS
MIC90 Common -
-
Teaching 8 8 4 4 1 4 4 0.5
Common -
Teaching
Common
100.0 100.0 100.0 61.0 100.0 90.5 100.0 100.0
100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
presented in Table 3. Four relatively penicillin-resistant strains of pneumococci were isolated and two of them were fully susceptible to other fl-lactams, while two were inhibited by 0.5 mgil of ampicillin and by more than 1.0 mg/l of cephalosporins. One of relatively penicillinresistant strains was resistant to doxycycline, one to chloramphenicol and one to both drugs. One strain showed doxycycline-chloramphenicol resistance. Results of susceptibility testing of anaerobes are presented in Table 4. Ampicillin and cefoperazone in combination with sulbactam were active against 100% of the strains of anaerobic microorganisms in the study. One imipenem-resistant strain of Bacteroides fragilis was detected (MIC = 16.0 mg/l). Cefoxitin demonstrated activity against 73.4% of strains of this species, cefoperazone against 57.8% and metronidazole against 100% All antibiotics in the study, except ampicillin, were active against 100% of strains of Bacteroides fragilis group and Prevotella spp. Gram-positive anaerobic cocci were fully susceptible to all antibiotics. All antibiotics, except metronidazole, were highly active against Grampositive, none spore-forming bacilli. A relatively low level of susceptibility to cefoxitin was detected in Actinomyces spp. (46.7% of susceptible strains). 4. Discussion The wide spread of plasmid-mediated fl-lactamases and particularly of their ‘extended-spectrum’ mutants, as well as the selection of stably derepressed hyperproducers of Class I /3-lactamases are the main causes of therapeutic failures with penicillin and cephalosporin antibiotics [9]. The problem of resistance could be, at least partly, overcome by /3-lactams/&lactamase inhibitor combinations. The addition of sulbactam to cefoperazone increased the susceptibility level of Acinetobacter spp. isolates from teaching hospitals by 45.5% (this may be due to some activity of sulbactam itself against this species [ 191); of A4. morganii, C. freundii and Serratia spp.
114 Table 2 Susceptibility (&nl)
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
of staphylococci
Species
Antibiotics
S. aureus
MS only (83)
S. aureus
MR only (26)
Staphylococcus
(coagulase-negative) MS only (69)
Staphylococcus
(coagulase-negative) MR only (47)
MICSO
MICw
Ampicillin Ampicillinkulbactam Cefoperazone Cefopemzonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin lmipenem Doxycycline Rifampin Erythromycin
8 8 4 8 1 0.5 2
8 16 16 16 8
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin
8 8 64 32 64 0.5 2 64
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin
by 28-30%; of Enterobacter spp., Proteus spp., and by IO%-15%. This observation may reflect, to a certain extent, the prevalence of extended spectrum fl-lactamases in the Moscow region. The addition of sulbactam to ampicillin also increased the susceptibility of Gram-negative bacteria but it didn’t Pseudomonas
0.5
0.12
16 0.12 16
2 2 0.5 8 0.5 16
4.8 66.2 95.2 100.0 97.6 97.6 100.0 100.0 100.0 78.3 97.6 47.0
8 32 64 64 28 4 2 64 8 32 16 16
0 53.8 30.8 38.5 30.8 69.2 100.0 0 57.7 23.1 84.6 0
8 8 16 16 8
24.6 94.2 100.0 100.0 95.7 100.0 100.0 100.0 100.0 71.0 98.6 27.5
0.5
1.0 1 0
2 2 8
0.12 16 4 16 128 128 32 co.12 2 32 8 16 0.12 16
% Susceptible NCCLS
4 32 128 128 32 0.25 2 32 16 32 2 16
0 17.0 12.8 12.8 10.6 100.0 97.9 0 8.5 14.9 89.4 4.3
reach a significant level (more than 60% of susceptible strains for E. colz’ and Proteus spp. only). The order of activity of antibiotics against Gramnegative bacteria based on percent of susceptible strains from common hospitals were: amikacin (98%) > ciprofloxacin (93%) = imipenem (93%) > cefoperazone/
6: V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
115
Table 3 Susceptibility (&ml) of pneurnococci % Susceptible NCCLS
Species
Antibiotics
MICso
MICw
S. vneumoniae (42-l
Penicillin G Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone./sulbactam Cefotaxime Erythromycin Rifampin Doxycycline Ciprofloxacin Chlorampbenicol
<0.06 <0.06
0.06
co.25 co.12 co.06 16 2 4
90.4 95.2 95.2 95.2 95.2 95.2 100.0 100.0 71.5 69.0 95.2
MICSO
MICw
% Susceptible NCCLS
28 4 128 16 128 2 2
20.0 100.0 57.8 100.0 73.4 98.9 100.0 13.3 100.0 100.0 100.0 100.0 100.0 100.0
0.06
co.5
Table 4 Susceptibility (&ml) of anaerobes Species
Antibiotics
B. fragilis (90)
Ampicillin Ampicillinkrlbactam Cefoperazone Cefoperazonekulbactam Cefoxitin Imipenem Metronidazole
Bacteroides spp. fragilis group
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefoxitin lmipenem Metronidaxole
8 0.5 4 2 8 0.12 0.5
16
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefoxitin Imipenem Metronidazole
4 4 4 2 4 5 0.5
16 16 16 8 16
Ampicillin Ampicilliukulbactam Cefoperazone Cefoperazonekulbactam Cefoxitin Imipenem Metronidazole
0.12 0.12
(15)
Prevotella spp. (16)
Gram-positive cocci (25)
Propionibacterium acnes (18)
Actinomyces spp (16)
Ampicillin Ampicillinkulbactam Cefoperazone Cefoxitin Imipenem Metronidazole Ampicillin Ampicillinkulbactam Cefoperazone Cefoperaxone/sulbactam Cefoxitin Imipenem Metronidazole
32 2 32 8 16 0.5 2
1 0.5 0.25 0.03 0.5 co.12 co.12 c 0.25 co.25 co.03 >I28 0.25 0.25 1
I 128 c 0.06 >I28
I 16 8 16 0.5
1
2
55.6 100.0 100.0 100.0 100.0 100.0 100.0
0.25 0.25 4 2 I 0.06 2
100.0 100.0 100.0 100.0 100.0 100.0 100.0
1
co.12 co.12 co.25
I co.03 >I28 I
2 16 16 128 2 >I28
100.0 100.0 100.0 100.0 100.0 0 100.0 100.0 100.0 100.0 46.7 100.0 0
116
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) IO9- I1 7
sulbactam (92%) > ceftazidime (89%)> ceftriaxone (81%) > cefotaxime (80%) > cefoperazone (77%) > gentamicin (71%) > ampicillin/sulbactam (51%) > cefazoline (45%) > ampicillin (25%). The order of activity against the strains from teaching hospitals was similar (the only significant difference was the level of amikacin activity): imipenem (86%) > ciprofloxacin (84%) > cefoperazone/sulbactam (80%) > ceftazidime (74%) > amikacin (68%) > cefoperazone (64%) > cefotaxime (61%) > ceftriaxone (600/) > gentamicin (50%) > ampicillin/sulbactam (37%) > cefazoline (29%) > ampicillin (21%). The activity of cefoperazone and other third-generation cephalosporins against Gramnegative bacteria was nearly identical. The risk of infection due to resistant strains is significantly higher in teaching hospitals than in common hospitals. The differences in susceptibilities of Gram-negative isolates from these settings to third generation cephalosporins were from 15% to more than 30%. For the majority of antimicrobials (third generation cephalosporins and aminoglycosides) susceptibility rates of Russian Gram-negative isolates from teaching hospitals were a little lower than European isolates and significantly lower than North American isolates. Isolates from Russian common hospitals were more susceptible than strains from other geographical regions [13,181 Of particular interest and trouble was the observation of very low susceptibility levels of Gram-negative bacteria from teaching hospitals to gentamicin and amikacin, high prevalence of APH (3’)-VI and AAC (6/)-I aminoglycoside-modifying enzymes in the Moscow region, was shown earlier [ 171. Imipenem has been available in Russia since 1991 and it is widely used in intensive care units of large teaching hospitals in Moscow. We have detected some strains of Enterobacteriaceae (h4. morganii, Serratia spp. and others) with evaluated MICs levels (4.0-8.0 &ml), but only a limited number of Acinetobacter and Pseudomonas strains have shown high a level of resistance (MICs > 16.0 &ml). Their is no significant difference in imipenem resistance among Gram-negative bacteria between Russia and Western Europe [ 181. The susceptibility level of Gram-negative bacteria to ciprofloxacin, even in teaching hospitals, is not lower than in Western Europe, and in common hospitals even higher than in North America [ 181. This may be due to the reason that quinolons are not very popular in the treatment of hospital-acquired infections. Unfortunately data on antibiotic consumption in different types of hospitals in Russia are unavailable. But in general it can be assumed that third generation caphalosporins and amikacin are much less available in common than in teaching hospitals. Gentamicin and first generation cephalosporins are the most popular
antibiotics in common hospitals. Improper clinical practice of antibiotic administration, as well as a high prevalence of hospital-acquired infections, followed by selection of resistant strains can be suspected in teaching hospitals. A relatively high portion of S. aureus strains were moderately susceptible to ampicillin/sulbactam (33.8%) but resistant strains were not detected. A number of strains of methicillin-resistant staphylococci demonstrated MICs to /3-lactams below break-points. Such findings are not uncommon for heterogeneously resistant strains of staphylococci [ 121,but all of them should be reported as resistant to &lactams. Cefoperazone/sulbactam demonstrated high activity against pneumococci, methicillin-susceptible staphylococci and anaerobic microorganisms. There were no significant differences in susceptibility levels of Russian isolates of anaerobes and of isolates from other regions [1,5,61. In summary, cefoperazone/sulbactam has been shown to exceed the activity of third-generation cephalosporins against a wide variety of Gram-positive and Gramnegative organisms, including non-fermenters. Taking into account its excellent activity against anaerobic bacteria, cefoperazone/sulbactam may be useful for the empirical monotherapy of serious, and especially, mixed infections. Acknowledgments Participating investigators: L.S. Stratchounsky (Smolensk Regional Hospital); T.S. Gardun (Moscow City Hospital No. 79); N. Speranskaya (Glavmosstroi Hospital); L.E. Ansolis (Moscow City Clinical Hospitals No. 8); S.V. Polykarpova (Moscow City Clinical Hospital No. 15); A.M. Polovoi (N.N. Burdenko Central Military Clinical Hospital); N.V. Beloborodova (N.F. Filatov Clinical Hospital). This study was supported by a grant from Pfizer International. References
111Baquero F, Reig M. Resistance of anaerobic bacteria to antimicrobial agents in Spain. Eur J Clin Microbial Infect Dis 1991;11:1016-1020. 121Bush K. Characterization of S-lactamases. Antimicrob Agents Chemother 1989;33:.259-263. [31 Bush K. Classification of S-lactamases: groups I, 2a, 2b and 2b’. Antimicrob Agents Chemother 1989;33:264-270. [41 Bush K. Classification of &lactamases: groups 2c, 2d, 2e, 3 and 4. Antimicrob Agents Chemother 1989;33:271-276. Dl Clark RB, Bartelt MA, Chan EL, Dalton HP. Multicenter study on antibiotic susceptibilities of anaerobic bacteria to cefoperazone-sulbactam and other antimicrobial agents. J Antimicrob Chemother 1992;29:56-67. [61 Cuchural GJ, Tally FP, Jacobus NV. Comparative activities of newer B-lactam agents against members of the Bacteroides fragilis group.Antimicrob Agents Chemother 1990;34:479-480. [71 English AR, Retsema JA, Girard AE, Lynch JE, Barth WE.
S. Y. Sidorenko et al. /internaiionai Journal of Antimicrobial
a fl-lactamase inhibitor that extends antibacterial spectrum of &lactams: initial bacteriological characterizations. Antimicrob Agents Chemother 1978;14:414-419. Jacobs MR, Aronoff SC, Johenning S, Shlaes DM, Yamabe S. Comparative activities of &lactamase inhibitors YTR830, clavulanate, and sulbactam combined with ampicillin and broad spectrum penicillins against defined &lactamase-producing aerobic Gram-negative bacilli. Antimicrob Agents Chemother 1986;29:980-985. Jacoby GA, Archer GL. New mechanisms of bacterial resistance to antimicrobial agents. ‘N Engl J Med 1991;324:601-612. Jorgensen JH, Redding JS, Maher LA, Howell AW. Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. J Clin Microbial 1987;25:2105-2113. Kawasaki K, Niini H, Oki T et al. Antibacterial activity of sulbactam and sulbactam/cefoperazone. Chemotherapy (Tokyo) 1984;32 Suppl 478-96. de Lencastre H, Figueiredo AM, Urban C, Rahal J, Tomasz A. Multiple mechanisms of methicillin resistance. and improved methods for detection in clinical isolates of Staphylococcus aureus. Antimicrob Agents Chemother 1991;35:632-639. Murray RP, Jones RN, Allen SD, Erwin ME, Fusch PC, Gerlach EH. Multilaboratory evaluation of the in vitro activity of 13 beta-lactam antibiotics against 1474 clinical isolates of aerobic and anaerobic bacteria. Diagn Microbial Infect Dis 1993;16:191-203.
Q-45899,
[8)
[9] [lo]
[I l]
[I21
[13]
Agents 7 (19%)
IO9-I17
117
[14] National Committee for Clinical Laboratory Standards. Method for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. Approved standard M7-A2, 2nd edn. Villanova, PA: NCCLS, 1990. [IS] National Committee for Clinical Laboratory Standards. Methods for antimicrobial susceptibility testing of anaerobic bacteria. Approved standard Ml l-A2. Villanova, PA: NCCLS, 1990. [I61 National Committee for Clinical Laboratory Standards. Performance standards for antimicrobial susceptibility testing. Third informational supplement, MlOO-S3. Villanova, PA: NCCLS, 1991. [I71 Reshedko G, Vakulenko S, Sidorenko S, Krotova L, Stratchounsky L. Profile of aminoglycoside modifying enzymes in two regions of Russia [abstract 1621.In: Abstracts of the 6th International Congress Infectious Diseases, 1994. [18] Thomsberry C, Brown SD, Yee YC, Bouchillon SK, Marler JK, Rich T. In vitro activity of cefepime and other antimicrobials: survey of European isolates. J Antimicrob Chemother 1993;32 Suppl B:31-54. [19] Urban C, Go E, Mariano N, Rahal JJ. Interaction of sulbactam, clavulanic acid and tazobactam with penicillin-binding proteins of imipenem-resistant and -susceptible Acinetobacter baumanii. FEMS Microbial L&t 1995;125:193-197.
International Journal of Antimicrobial Agents 7 (1996) 109-I 17
In vitro activity of ampicillin, cefoperazone, their combinations with sulbactam and other antimicrobials: survey of Russian isolates Sergei V. Sidorenko *, Svetlana P. Rezvan, Alexandra S. Tikchonova, Larysa A. Krotova, Larysa E. Ansolis, Elena A. Tzvigun National Research Center for Antibiotics,
Nagatiskaya
3a, St. 113105, Moscow, Russian Fe&ration
Accepted 23 February 1996
Methodological differences makes it difficult to compare results of antimicrobial susceptibility testing obtained in Russia and in other regions. During the period from October 1993 to May 1994 susceptibility of 1296 isolates of bacteria was investigated according to NCCLS standards by the broth microdilution method. The order of activity of antibiotics against Gram-negative bacteria based on percent of susceptible strains from common hospitals were: amikacin (98%) > ciprofloxacin (93%) = imipenem (93%) > cefoperazone/sulbactam (92%) > ceftazidime (89%) > ceftriaxone (81%) > cefotaxime (80%) > cefoperazone (77%) > gentamicin (71%) > ampicillin/sulbactam (51%) > cefazoline (45%) > ampicillin (25%). The order of activity against strains from teaching hospitals was similar but the percent of susceptible strains was lo-20% less for the majority of antibiotics. The susceptibility level of Gram-negative isolates from Moscow teaching hospitals is lower than from Northern America and Europe. Ampicilllnlsulbactam and cefoperazone/sulbactam, as well as other cephalosporins, demonstrated high activity against methicillinsusceptible staphylococci and penicillin-susceptible pneumococci. B-lactams/&lactamase inhibitor combinations were active against 100% strains of anaerobic bacteria. Keywords: Ampicillin/sulba,ctam;
Cefoperazone/sulbactam;
Susceptibility; Antibiotics
1. Introduction The p-lactamases form a large family of enzymes that can hydrolyze the &lactam ring of antimicrobial agents [2,3,4]. An enzymatic resistance mechanism is the most important clinically among different species of bacteria (staphylococci, enterobacteria, bacteroides, etc.). Development of specific /3-lactamase inhibitors is one of the strategies used to cope with the problem of /3-lactamase-producing bacteria [7]. Suicide inhibitors such as clavulanic acid, sulbac:tam and tazobactam represent the current state of the art in /3-lactamase inhibition [8]. A number of formulations of the inhibitors mentioned above with penicillins have been licensed (ampicillin/ sulbactam, amoxicillin/clavulanic acid, ticarcillin/clavulanic acid piperacillin/tazobactam). Cefoperazonefsul* Corresponding author. Tel.: +7 095 1114166;fax: +7 095 1189366; e-mail: [email protected]. 0924-8579/96/$32.00 0 1996 :Elsevier Science B.V. All rights reserved PII: 0924-8579(96)00308-l
is the only available combination of cephalosporin antibiotic with fi-lactamase inhibitor [ 111. The aim of the study was to evaluate the susceptibility of fresh isolates from different centers in Russia to ampicillin, cefoperazone and their combinations with sulbactam, as well as to other antimicrobials. bactam
2. Materials and methods During the period from October 1993 to May 1994, 1116 strains of Gram-negative and Gram-positive aerobic and 180 strains of anaerobic bacteria were isolated in different institutions of Moscow and Smolensk from patients with urinary tract infections, upper and lower respiratory tract infections, and systemic and wound infections. Isolates were identified in local laboratories using routine tests and were stored in permanent culture. Identification of isolates was conformed in our laboratory using ‘Minitek’ (Bccton Dickinson,
110
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (1996) 109-117
Schaedler broth was used for Bacteroides fragilis and fragilis group, Actinomyces spp. and Propionibacterium spp. Serial agar dilution technique in Wilkins-Chalgren agar with 5% of defibrinated sheep blood was used for Gram-positive anaerobic cocci and Prevotelia spp. susceptibility testing. Bacteroides fragilis ATCC 25285 was used as a reference strain. NCCLS-recommended break-points were used for interpretation of susceptibility testing results [ 14,15,16].
Cockeysville, USA) miniaturised microorganism differentiation systems (Minitek Enterobacteriaceae II set; Minitek Nonfermenter set; Minitek Gram-positive set; Minitek Anaerobe II set). Antibiotic susceptibility was determined by broth the microdilution technique [ 141in microtiter plates with deep-frozen dilutions of antibiotics, or by agar dilution techniques for some anaerobes
[l% The 21 antibiotics and the range of dilutions at which they were tested were as follows: penicillin G, 0.06-8.0 mg/l; ampicillin, ampicillin/sulbactam (2: l), cefoperazone, cefoperazone/sulbactam (1: l), cefotaxime, ceftriaxone, ceftazidime, cefazoline, cefoxitin, oxacillin, imipenem, 0.25-64.0 mg/l; ciprofloxacin, 0.06-16.0 mg/l; gentamicin, O-25-32.0 mg/l; amikacin, 0.5-64.0; vancomycin, 0.25-32.0 mgil; doxycycline, 0.5-64.0 mg’l; rifampin; erythromycin,; metronidazole, 0.12- 16.0 mg/l; chloramphenicol, 0.5-64.0. Different sets of antibiotics were used for susceptibility testing of Gramnegative and Gram-positive aerobes as well as of anaerobes. Most of the susceptibility tests of aerobic bacteria were performed using Mueller-Hinton broth (reference strains were: Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Pneumococci were tested using Haemophilus Test Medium (reference strain: Streptococcus pneumoniae ATCC 496 19) [lo].
3. Results The activities of the antimicrobials against Gramnegative aerobic species are shown in Table 1. Isolates from common and large teaching hospitals were analyzed separately. As interpretative criteria for cefoperazone/sulbactam were not available from the NCCLS, the recommendations of the manufacturer were used (susceptible, MIC < 16.0/16.0 &ml; resistant, MIC > 64.0/64.0 &nl). Differences in susceptibilities were found between isolates from common and teaching hospitals. More than 80% of the Escherichia coli, Klebsiella spp., Enterobacter aerogenes, Morganella morganii, Proteus mirabilis, Proteus vulgaris, and Serratia spp. isolates
from common hospitals were susceptible to cefoperazone/sulbactam, third generation cephalospotins, imipenem, ciprotloxacin, amikacin and ciproflox-
Table I Susceptibility (&ml) of Gram-negative aerobes Species (number teaching/ common)
Antibiotics
E. coli (81/l 17)
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
4 4
Ampicillin Ampicillin/sulbactam Ce.foperaxone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64
Klebsiella spp. wJ93)
MICSO Teaching
0.5
0.5 0.5 0.5 2 0.25
Common I6 8 I I I I I I 0.25
I 4 0.06
32 8 4 4 4 4 64 0.5 4 2 0.125
% Susceptible NCCLS
MIGW
I 0.06 64 8 I I I 1 0.5 2 0.25
1 1 0.06
Teaching >64 64 64 32 64 64 32 >64 4 >32 >64 0.12 >64 >64 >64 64 >64 >64 >64 >64 4 32
>64 4
Common
Teaching
Common
I6 8 I I 2 32 I 4 4 0.12
55.6 63.0 82.7 88.9 80.2 82.7 81.5 67.9 100.0 77.8 81.5 96.3
48.7 59.8 90.6 98.3 93.2 94.0 98.3 84.6 99.1 90.6 98.3 100.
>64 32 32 I6 8 8 8 64 2 32 2 0.25
7.6 38.5 71.2 75.0 65.4 61.5 69.2 36.5 92.3 48.1 67.3 82.7
10.7 52.6 88.2 95.7 91.4 92.5 90.3 63.4 98.9 68.8 97.8 97.8
64 64
6: V. Siakwenko et al. /International Journal of Antimicrobial Agents 7 (19%)
109-117
111
Table 1 (Continued) Species (number teaching/ common)
Antibiotics
Enterobacter
Ampicillin Annpicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline imipenem Gentamicin Amikacin Ciprofloxacin
aerogenes (20/l 5)
Enterobacter cloacae (18132)
M. morganii (21113)
P. mirabilis (28131)
P. vulgaris (23/26)
M&, Teaching
>64 32 8 2
MICs,, Common
32 8 2
1
Teaching
Common
Teaching
Common
>64 >64 >64
>64 64 64
32 >64 >64 >64 >&I 1 >32 64 1
8 32 32 32 >64
10.0 25.0 65.0 80.0 70.0 60.0 70.0 25.0 100.0 45.0 65.0 100.0
20.0 60.0 86.7 93.3 86.7 86.7 86.7 13.3 100.0 86.7 100. 100.0
>64 >64 64 16 64 64 16 >64 2 32 4 0.125
16.7 38.9 44.4 55.6 44.4 38.9 55.6 0 100.0 33.3 77.9 100.0
21.9 43.8 78.2 90.6 78.1 72.2 81.2 9.3 96.9 84.4 96.9 96.0
64 32 16 2 4 4 4 64 4 8 4 0.06
9.5 38. I 71.4 100.0 90.5 100.0 100.0 9.5 47.6 28.6 19.0 90.5
0 38.5 100.0 100.0 100.0 100.0 100.0 0 100.0 61.5 100.0 100.0
39.3 67.9 89.3 100.0 100.0 100.0 96.4 67.9 92.9 57.1 78.6 100.0 17.4 60.9 69.6 82.6 78.3 73.9 73.9 8.7 100.0
51.6 77.4 83.9 93.5 100.0 100.0 100.0 61.3 93.5 67.7 100.0 87.1 19.2 73.1 73.1 80.8 80.8 80.8 80.8 7.7 92.3
0.5 4 2 >64 0.125 8 2 0.125
2 2 0.5 >64 0.125 0.5
Ampicillin Annpicillin/sulbactam Cefoperazone CefoperazoneJsulbactam Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 64 32 8 16 16 I >64 0.5 32 2 0.5
32 16 0.5 0.5 0.5 0.5 0.5 >64 0.5 1 1 0.125
>64 >64 >64 64 >64 >64 >64 >64
Ampicillin Annpicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 16 16
>64 16 2
1 1
1
>64 16 32 4 8 4 8 >64 8 >32 >64 0.06
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefaxoline Irmpenem Gentamicin Amikacin Ciprofloxacin Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imi penem
>64 4
4 2
1 1
1 I 1 I
0.5
1 >64 8 16 >64 0.06
0.125 0.125 0.125 4
I 4 2 0.06 >64 4 4 2
I I 0.5 >64
I
1 0.06
1
1 1 >64 2 2 2 0.06
0.5 4 2 2 2 0.06 >64 4 2
I I 1 0.5 >64 I
% Susceptible NCCLS
I >32 64 1
>64 32 32 4 0.5 0.5 0.5 64 4 32 >64 0.5 >64 32 64 64 >64 >64 >64 >64 4
I 16 8 I
>64 64 64 16
I I 1 64 4 32 8 4 >64 64 64 32 32 64 64 64 4
112
S. V. Sidorenko ei al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
Table 1 (Continued) Species (number teaching/ common)
Antibiotics
Teaching
Gentamicin Amikacin Ciprofloxacin C. fret&i (26l23)
Serratia spp. (28116)
spp. (27/27)
P. aeruginosa
Other Cram-negative (21/2)
Common
8 32 0.06
Ampicillin Ampicillin/sulbactam Cefoperaxone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefaxoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 64 I6 8 8 8 8 >64 0.5 8 4 0.125
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
64 64 16 8 4 4 1 >64 0.25 32 8
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftaxidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 >64
Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperaxone/sulbactam Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
>64 >64 32 16 32 32 4 >64 4 8 8 0.5
Ampicillin AmpicilWsulbactam Cefoperazone CefoperaxoneAulbactam
64 32 I
I
32 16 32 32 4 >64
I >32 16 0.5
1
% Susceptible NCCLS
MI&t,
MICso
2 1 0.06 32 4
1 I 1
I 0.5 2 0.25
I 2 0.06 >64 32 2
1 0.5 0.5 0.5 >64 0.5 4 2 0.06 >64 I6 64 8 8 8 4 >64 0.25 8
I 0.25 >64 >64 32 16 32 I6 4 >64 8 I6 2 0.5 -
Teaching
Common
43.5 47.8 91.3
53.8 92.3 92.3
32 8 0.25
30.7 30.7 50.0 80.7 50.0 50.0 57.7 26.9 92.3 34.6 69.2 76.9
30.4 69.6 73.9 100. 73.9 73.9 69.6 56.5 100.0 82.6 100.0 91.3
>64 64 >64 16 >64 >64 64 >64 8 32 >64 8
>64 64 64 16 8 8 4 >64 4 3 4 0.25
3.6 21.4 64.3 92.9 78.6 64.3 85.7 3.6 85.7 39.3 64.3 53.6
12.5 43.8 56.3 100. 100. 100. 100. 6.3 100. 68.8 93.8 93.8
>64 >64 >64 >64 >64 >64 64 >64 >64 >32 >64 8
>64 >64 >64 8 32 32 16 >64 2 32 >64
7.4 25.9 14.8 59.3 41.1 41.1 59.3 7.4 66.1 37.0 51.9 77.8
7.4 41.1 29.6 81.5 59.3 51.9 88.9 0 100.0 41.1 88.9 96.3
>64 >64 >64 >64 >64 >64 64 >64 I6 >32 >64 4
>64 >64 >64 64 >64 >64 32 >64 32 >32 8 2
0 0 48.4 64.1 4.7 12.5 61.0 0 64.1 43.8 78.1 71.9
0 0 46.1 68.8 II.1 20.0 13.3 0 46.7 33.3 100.0 13.3
>64 64 8 4
-
57.1 76. I iOO.0 100.0
100.0 100.0 100.0 100.0
Teaching
Common
64 >64 I
32 4
>64 >64 >64 64
>64 >64 64
32 64 32 >64 I 32 >64 4
1
4 32 64 >64 64
I
I
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%)
109-117
113
Table 1 (Continued) Species (number teachingl common)
Antibiotics
MU&, Teaching
Cefotaxime Ceftriaxone Ceftazidime Cefazoline Imipenem Gentamicin Amikacin Ciprofloxacin
acin. Eighty percent activity against Enterobacter cloacae was exceeded by cefoperazonelsulbactam, ceftazidime, imipenem, ciprofloxacin and aminoglycosides; against Cirtobacter freundii by cefoperazonelsulbactam, imipenem, ciprofloxacin and aminoglycosides; against Acinetobacter spp. by cefoperazonelsulbactam, imipenem, ciprofloxacin, ceftazidime and amikacin; and against P. aeruginosa by amikacin only. The susceptibility levels of isolates from teaching hospitals were 10-W! lower. The most pronounced differences were seen in the activities of third generation cephalosporins and gentamicin against Klebsiella spp., Enterobacter spp., Citrobacter spp., Serratia spp., and Acinetobacter spp. The results of suscept.ibility testing of staphylococci are presented in Table 2. The susceptibilities of methicillin-sensitive (MS) and methicillin-resistant (MR) staphylococci were analyzed separately. The majority of antibiotics under study were highly active against methicillin-sensitive staphylococci (both aureus and coagulase-negative). The only drug practically inactive was ampicillin. Among S. aureus 66.2% of strains were susceptible to ampicillin/sulbactam and 33.8% were intermediate (MIC = 16.0 pg/ml). Coagulasenegative staphylococci were highly susceptible (94.2% of susceptible strains). Erythromycin was poorly active against both S. aureus and coagulase-negative staphylococci. Doxycyline demonstrated a significant and practically equal level of activity against both groups of staphylococci (71.0-78.3% of susceptible strains). Vancomycin was the most active agent against methicillin-resistant staphylococci (only one strain of intermediately susceptible coagulase-negative staphylococci was isolated), followed by rifampin. A high level of activity was detected with ciprofloxacin (69.2% of S. aureus susceptible strains and 100% of coagulasenegative staphylococci). MICs of some /3-lactams against methicillin-resistant staphylococci below breakpoints are not of clinical value. Results of susceptibility testing of pneumococci are
1 1 1 1 0.5 1 1 0.25
% Susceptible NCCLS
MIC90 Common -
-
Teaching 8 8 4 4 1 4 4 0.5
Common -
Teaching
Common
100.0 100.0 100.0 61.0 100.0 90.5 100.0 100.0
100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
presented in Table 3. Four relatively penicillin-resistant strains of pneumococci were isolated and two of them were fully susceptible to other fl-lactams, while two were inhibited by 0.5 mgil of ampicillin and by more than 1.0 mg/l of cephalosporins. One of relatively penicillinresistant strains was resistant to doxycycline, one to chloramphenicol and one to both drugs. One strain showed doxycycline-chloramphenicol resistance. Results of susceptibility testing of anaerobes are presented in Table 4. Ampicillin and cefoperazone in combination with sulbactam were active against 100% of the strains of anaerobic microorganisms in the study. One imipenem-resistant strain of Bacteroides fragilis was detected (MIC = 16.0 mg/l). Cefoxitin demonstrated activity against 73.4% of strains of this species, cefoperazone against 57.8% and metronidazole against 100% All antibiotics in the study, except ampicillin, were active against 100% of strains of Bacteroides fragilis group and Prevotella spp. Gram-positive anaerobic cocci were fully susceptible to all antibiotics. All antibiotics, except metronidazole, were highly active against Grampositive, none spore-forming bacilli. A relatively low level of susceptibility to cefoxitin was detected in Actinomyces spp. (46.7% of susceptible strains). 4. Discussion The wide spread of plasmid-mediated fl-lactamases and particularly of their ‘extended-spectrum’ mutants, as well as the selection of stably derepressed hyperproducers of Class I /3-lactamases are the main causes of therapeutic failures with penicillin and cephalosporin antibiotics [9]. The problem of resistance could be, at least partly, overcome by /3-lactams/&lactamase inhibitor combinations. The addition of sulbactam to cefoperazone increased the susceptibility level of Acinetobacter spp. isolates from teaching hospitals by 45.5% (this may be due to some activity of sulbactam itself against this species [ 191); of A4. morganii, C. freundii and Serratia spp.
114 Table 2 Susceptibility (&nl)
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
of staphylococci
Species
Antibiotics
S. aureus
MS only (83)
S. aureus
MR only (26)
Staphylococcus
(coagulase-negative) MS only (69)
Staphylococcus
(coagulase-negative) MR only (47)
MICSO
MICw
Ampicillin Ampicillinkulbactam Cefoperazone Cefopemzonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin lmipenem Doxycycline Rifampin Erythromycin
8 8 4 8 1 0.5 2
8 16 16 16 8
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin
8 8 64 32 64 0.5 2 64
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazonekulbactam Cefazoline Ciprofloxacin Vancomycin Oxacillin Imipenem Doxycycline Rifampin Erythromycin
by 28-30%; of Enterobacter spp., Proteus spp., and by IO%-15%. This observation may reflect, to a certain extent, the prevalence of extended spectrum fl-lactamases in the Moscow region. The addition of sulbactam to ampicillin also increased the susceptibility of Gram-negative bacteria but it didn’t Pseudomonas
0.5
0.12
16 0.12 16
2 2 0.5 8 0.5 16
4.8 66.2 95.2 100.0 97.6 97.6 100.0 100.0 100.0 78.3 97.6 47.0
8 32 64 64 28 4 2 64 8 32 16 16
0 53.8 30.8 38.5 30.8 69.2 100.0 0 57.7 23.1 84.6 0
8 8 16 16 8
24.6 94.2 100.0 100.0 95.7 100.0 100.0 100.0 100.0 71.0 98.6 27.5
0.5
1.0 1 0
2 2 8
0.12 16 4 16 128 128 32 co.12 2 32 8 16 0.12 16
% Susceptible NCCLS
4 32 128 128 32 0.25 2 32 16 32 2 16
0 17.0 12.8 12.8 10.6 100.0 97.9 0 8.5 14.9 89.4 4.3
reach a significant level (more than 60% of susceptible strains for E. colz’ and Proteus spp. only). The order of activity of antibiotics against Gramnegative bacteria based on percent of susceptible strains from common hospitals were: amikacin (98%) > ciprofloxacin (93%) = imipenem (93%) > cefoperazone/
6: V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) 109-117
115
Table 3 Susceptibility (&ml) of pneurnococci % Susceptible NCCLS
Species
Antibiotics
MICso
MICw
S. vneumoniae (42-l
Penicillin G Ampicillin Ampicillin/sulbactam Cefoperazone Cefoperazone./sulbactam Cefotaxime Erythromycin Rifampin Doxycycline Ciprofloxacin Chlorampbenicol
<0.06 <0.06
0.06
co.25 co.12 co.06 16 2 4
90.4 95.2 95.2 95.2 95.2 95.2 100.0 100.0 71.5 69.0 95.2
MICSO
MICw
% Susceptible NCCLS
28 4 128 16 128 2 2
20.0 100.0 57.8 100.0 73.4 98.9 100.0 13.3 100.0 100.0 100.0 100.0 100.0 100.0
0.06
co.5
Table 4 Susceptibility (&ml) of anaerobes Species
Antibiotics
B. fragilis (90)
Ampicillin Ampicillinkrlbactam Cefoperazone Cefoperazonekulbactam Cefoxitin Imipenem Metronidazole
Bacteroides spp. fragilis group
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefoxitin lmipenem Metronidaxole
8 0.5 4 2 8 0.12 0.5
16
Ampicillin Ampicillinkulbactam Cefoperazone Cefoperazone/sulbactam Cefoxitin Imipenem Metronidazole
4 4 4 2 4 5 0.5
16 16 16 8 16
Ampicillin Ampicilliukulbactam Cefoperazone Cefoperazonekulbactam Cefoxitin Imipenem Metronidazole
0.12 0.12
(15)
Prevotella spp. (16)
Gram-positive cocci (25)
Propionibacterium acnes (18)
Actinomyces spp (16)
Ampicillin Ampicillinkulbactam Cefoperazone Cefoxitin Imipenem Metronidazole Ampicillin Ampicillinkulbactam Cefoperazone Cefoperaxone/sulbactam Cefoxitin Imipenem Metronidazole
32 2 32 8 16 0.5 2
1 0.5 0.25 0.03 0.5 co.12 co.12 c 0.25 co.25 co.03 >I28 0.25 0.25 1
I 128 c 0.06 >I28
I 16 8 16 0.5
1
2
55.6 100.0 100.0 100.0 100.0 100.0 100.0
0.25 0.25 4 2 I 0.06 2
100.0 100.0 100.0 100.0 100.0 100.0 100.0
1
co.12 co.12 co.25
I co.03 >I28 I
2 16 16 128 2 >I28
100.0 100.0 100.0 100.0 100.0 0 100.0 100.0 100.0 100.0 46.7 100.0 0
116
S. V. Sidorenko et al. /International Journal of Antimicrobial Agents 7 (19%) IO9- I1 7
sulbactam (92%) > ceftazidime (89%)> ceftriaxone (81%) > cefotaxime (80%) > cefoperazone (77%) > gentamicin (71%) > ampicillin/sulbactam (51%) > cefazoline (45%) > ampicillin (25%). The order of activity against the strains from teaching hospitals was similar (the only significant difference was the level of amikacin activity): imipenem (86%) > ciprofloxacin (84%) > cefoperazone/sulbactam (80%) > ceftazidime (74%) > amikacin (68%) > cefoperazone (64%) > cefotaxime (61%) > ceftriaxone (600/) > gentamicin (50%) > ampicillin/sulbactam (37%) > cefazoline (29%) > ampicillin (21%). The activity of cefoperazone and other third-generation cephalosporins against Gramnegative bacteria was nearly identical. The risk of infection due to resistant strains is significantly higher in teaching hospitals than in common hospitals. The differences in susceptibilities of Gram-negative isolates from these settings to third generation cephalosporins were from 15% to more than 30%. For the majority of antimicrobials (third generation cephalosporins and aminoglycosides) susceptibility rates of Russian Gram-negative isolates from teaching hospitals were a little lower than European isolates and significantly lower than North American isolates. Isolates from Russian common hospitals were more susceptible than strains from other geographical regions [13,181 Of particular interest and trouble was the observation of very low susceptibility levels of Gram-negative bacteria from teaching hospitals to gentamicin and amikacin, high prevalence of APH (3’)-VI and AAC (6/)-I aminoglycoside-modifying enzymes in the Moscow region, was shown earlier [ 171. Imipenem has been available in Russia since 1991 and it is widely used in intensive care units of large teaching hospitals in Moscow. We have detected some strains of Enterobacteriaceae (h4. morganii, Serratia spp. and others) with evaluated MICs levels (4.0-8.0 &ml), but only a limited number of Acinetobacter and Pseudomonas strains have shown high a level of resistance (MICs > 16.0 &ml). Their is no significant difference in imipenem resistance among Gram-negative bacteria between Russia and Western Europe [ 181. The susceptibility level of Gram-negative bacteria to ciprofloxacin, even in teaching hospitals, is not lower than in Western Europe, and in common hospitals even higher than in North America [ 181. This may be due to the reason that quinolons are not very popular in the treatment of hospital-acquired infections. Unfortunately data on antibiotic consumption in different types of hospitals in Russia are unavailable. But in general it can be assumed that third generation caphalosporins and amikacin are much less available in common than in teaching hospitals. Gentamicin and first generation cephalosporins are the most popular
antibiotics in common hospitals. Improper clinical practice of antibiotic administration, as well as a high prevalence of hospital-acquired infections, followed by selection of resistant strains can be suspected in teaching hospitals. A relatively high portion of S. aureus strains were moderately susceptible to ampicillin/sulbactam (33.8%) but resistant strains were not detected. A number of strains of methicillin-resistant staphylococci demonstrated MICs to /3-lactams below break-points. Such findings are not uncommon for heterogeneously resistant strains of staphylococci [ 121,but all of them should be reported as resistant to &lactams. Cefoperazone/sulbactam demonstrated high activity against pneumococci, methicillin-susceptible staphylococci and anaerobic microorganisms. There were no significant differences in susceptibility levels of Russian isolates of anaerobes and of isolates from other regions [1,5,61. In summary, cefoperazone/sulbactam has been shown to exceed the activity of third-generation cephalosporins against a wide variety of Gram-positive and Gramnegative organisms, including non-fermenters. Taking into account its excellent activity against anaerobic bacteria, cefoperazone/sulbactam may be useful for the empirical monotherapy of serious, and especially, mixed infections. Acknowledgments Participating investigators: L.S. Stratchounsky (Smolensk Regional Hospital); T.S. Gardun (Moscow City Hospital No. 79); N. Speranskaya (Glavmosstroi Hospital); L.E. Ansolis (Moscow City Clinical Hospitals No. 8); S.V. Polykarpova (Moscow City Clinical Hospital No. 15); A.M. Polovoi (N.N. Burdenko Central Military Clinical Hospital); N.V. Beloborodova (N.F. Filatov Clinical Hospital). This study was supported by a grant from Pfizer International. References
111Baquero F, Reig M. Resistance of anaerobic bacteria to antimicrobial agents in Spain. Eur J Clin Microbial Infect Dis 1991;11:1016-1020. 121Bush K. Characterization of S-lactamases. Antimicrob Agents Chemother 1989;33:.259-263. [31 Bush K. Classification of S-lactamases: groups I, 2a, 2b and 2b’. Antimicrob Agents Chemother 1989;33:264-270. [41 Bush K. Classification of &lactamases: groups 2c, 2d, 2e, 3 and 4. Antimicrob Agents Chemother 1989;33:271-276. Dl Clark RB, Bartelt MA, Chan EL, Dalton HP. Multicenter study on antibiotic susceptibilities of anaerobic bacteria to cefoperazone-sulbactam and other antimicrobial agents. J Antimicrob Chemother 1992;29:56-67. [61 Cuchural GJ, Tally FP, Jacobus NV. Comparative activities of newer B-lactam agents against members of the Bacteroides fragilis group.Antimicrob Agents Chemother 1990;34:479-480. [71 English AR, Retsema JA, Girard AE, Lynch JE, Barth WE.
S. Y. Sidorenko et al. /internaiionai Journal of Antimicrobial
a fl-lactamase inhibitor that extends antibacterial spectrum of &lactams: initial bacteriological characterizations. Antimicrob Agents Chemother 1978;14:414-419. Jacobs MR, Aronoff SC, Johenning S, Shlaes DM, Yamabe S. Comparative activities of &lactamase inhibitors YTR830, clavulanate, and sulbactam combined with ampicillin and broad spectrum penicillins against defined &lactamase-producing aerobic Gram-negative bacilli. Antimicrob Agents Chemother 1986;29:980-985. Jacoby GA, Archer GL. New mechanisms of bacterial resistance to antimicrobial agents. ‘N Engl J Med 1991;324:601-612. Jorgensen JH, Redding JS, Maher LA, Howell AW. Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. J Clin Microbial 1987;25:2105-2113. Kawasaki K, Niini H, Oki T et al. Antibacterial activity of sulbactam and sulbactam/cefoperazone. Chemotherapy (Tokyo) 1984;32 Suppl 478-96. de Lencastre H, Figueiredo AM, Urban C, Rahal J, Tomasz A. Multiple mechanisms of methicillin resistance. and improved methods for detection in clinical isolates of Staphylococcus aureus. Antimicrob Agents Chemother 1991;35:632-639. Murray RP, Jones RN, Allen SD, Erwin ME, Fusch PC, Gerlach EH. Multilaboratory evaluation of the in vitro activity of 13 beta-lactam antibiotics against 1474 clinical isolates of aerobic and anaerobic bacteria. Diagn Microbial Infect Dis 1993;16:191-203.
Q-45899,
[8)
[9] [lo]
[I l]
[I21
[13]
Agents 7 (19%)
IO9-I17
117
[14] National Committee for Clinical Laboratory Standards. Method for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. Approved standard M7-A2, 2nd edn. Villanova, PA: NCCLS, 1990. [IS] National Committee for Clinical Laboratory Standards. Methods for antimicrobial susceptibility testing of anaerobic bacteria. Approved standard Ml l-A2. Villanova, PA: NCCLS, 1990. [I61 National Committee for Clinical Laboratory Standards. Performance standards for antimicrobial susceptibility testing. Third informational supplement, MlOO-S3. Villanova, PA: NCCLS, 1991. [I71 Reshedko G, Vakulenko S, Sidorenko S, Krotova L, Stratchounsky L. Profile of aminoglycoside modifying enzymes in two regions of Russia [abstract 1621.In: Abstracts of the 6th International Congress Infectious Diseases, 1994. [18] Thomsberry C, Brown SD, Yee YC, Bouchillon SK, Marler JK, Rich T. In vitro activity of cefepime and other antimicrobials: survey of European isolates. J Antimicrob Chemother 1993;32 Suppl B:31-54. [19] Urban C, Go E, Mariano N, Rahal JJ. Interaction of sulbactam, clavulanic acid and tazobactam with penicillin-binding proteins of imipenem-resistant and -susceptible Acinetobacter baumanii. FEMS Microbial L&t 1995;125:193-197.