331
DIAGN MICROBIOLINFECTDIS 1992;15:331-337
In vitro Activity of Cefquinome, a New Cephalosporin, Compared with Other Cephalosporin Antibiotics Nai-Xun Chin, Jian-Wei Gu, Wei Fang, and Harold C. Neu
The in vitro activity of cefquinome, a new aminothiazolyl cephalosporin with a C-3 bicyclic pyridinium group, was compared with ceftazidime, cefpirome, and cefepime. Cefquinome inhibited members of the Enterobacteriaceae at 16 i~g/ml]. Serratia marcescens were inhibited by < 1 I~g/ml and Pseudomonas aeruginosa by 8 I~g/ml similar to the activity of cefepime. The majority of Haemophilus influenzae and Neisseria gonorrhoeae were inhibited by < 0.25 i~g/ml. Most enterococci had cefquinome MICs of 4-8 i~g/ml. CefquiINTRODUCTION Cefquinome is a new cephem antibiotic that contains an aminothiazolyl group and an iminomethoxy group on the ~-acyl side chain similar to agents such as cefotaxime and ceftriaxone. However, it has a bicyclic pyridinium group attached at C-3, making it similar to cefpirome and cefepime. Cephalosporin agents of this type have been shown to have an extended spectrum of antimicrobial activity with improved inhibition of Gram-positive bacteria (Neu, 1986a). Cefquinome has preliminarily been reported From the Department of Medicine (N.-X.C., J.-W.G., W.F., H.C.N.) and Department of Pharmacology(H.C.N.), Collegeof Physicians and Surgeons, ColumbiaUniversity, New York, New York, USA. Address reprint requests to Dr. N.-X. Chin, Department of Medicine, Collegeof Physiciansand Surgeons, ColumbiaUniversity, 630 West 168 Street, New York, NY 10032, USA. Received 12 June 1991, revised and accepted 27 August 1991. © 1992 ElsevierScience Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0732-8893/92/$5.00
nome was extremely active against group-A streptococci and Streptococcus pneumoniae with MICs < 0.12 i~g/ml. 90% of methicillin-susceptible Staphylococcus aureus 90% were inhibited by 2 i~g/ml. Overall, the in vitro activity of cefquinome was comparable with aminothiazolyl cephalosporins. It inhibited some Enterobacter and Citrobacter freundii resistant to ceftazidime as did cefpirome and cefepime. Cefquinome was not destroyed by the common plasmid [3-lactamases TEM1, TEM-2, SHV-1, or by the chromosomal fl-lactamases of Klebsiella, Branhamella, and Pseudomonas, but it was hydrolyzed by TEM-3, TEM-5, and TEM-9. Its activity was not adversely decreased in different medium or protein, and minimum bactericidal concentrations (MBCs) for most species except for Enterobacter were within a dilution of MICs.
to be active in vitro and in animal protection studies (Isert et al., 1989; Seibert et al., 1989). We investigated the activity of cefquinome in comparison with the activity of ceftazidime, cefpirome, and cefepime.
MATERIALS A N D M E T H O D S Cefquinome and cefpirome were provided by Hoechst (Frankfurt, Germany). Cefpime was provided by Bristol Laboratories (Wallingford, CT) and ceftazidime by Glaxo (Research Triangle Park, NC). Organisms used in this study were isolates obtained from patients seen at the Presbyterian Hospital in New York City in the last 2 years (with the exception of the methicillin-resistant Staphylococcus aureus, which had been collected over several years) and selected ~-lactamase-producing isolates, some of which had been provided by investigators throughout Europe. Only a single isolate from a patient was tested. The characterized ~-lactamase isolates were not used in the general evaluation.
Nai-Xun Chin et al.
332
Minimum inhibitory concentrations (MICs) were determined using Mueller-Hinton agar for staphylococci and aerobic Gram-negative species. Activity against streptococcal species was determined with Mueller-Hinton agar supplemented with 5% sheep blood. Activity against Haemophilus, Neisseria, and Moraxella species was determined with Haemophilus test medium. Activity against Bacteroides spp. and other anaerobic species was determined using Mueller-Hinton agar supplemented with 5% laked sheep blood and vitamin K. An inoculum of 10 4 colonyforming units (CFU) was used for aerobic organisms and 105 CFU for anaerobic organisms according to the NCCLS (1990) guidelines. Incubation was at 35°C for 18-20 hr in ambient air except for Neisseria, which were incubated in the presence of 5% CO2. Anaerobic organisms were incubated for 48 hr in GasPak jars (BBL Microbiology Systems, Cockeysville, MD). The MIC was the lowest concentration that inhibited visible growth on agar. ~-lactamase stability was determined by a spectrophotometric assay as previously published (Neu, 1986b). The concentration of substrate used was 100 ~M. ~-Lactamases were partially purified as previously published (Neu, 1986b). RESULTS
The activity of cefquinome in comparison with the other agents is shown in Table 1. Cefquinome had TABLE 1
excellent activity against the Enterobacteriaceae inhibiting at - 1 ~g/ml most organisms, with the exception of Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Providencia rettgeri. Half of the aforementioned five species were inhibited by < 1 ~g/ml. In general, the most active compounds of the four cephalosporins was cefepime, which inhibited at 0.25 ~g/ml various Proteus species that had cefquinome MICs of > 2 ~g/ml. Cefquinome inhibited ceftazidime-resistant (MIC -> 16 ~g/ml) isolates of Enterobacter cloacae and Citrobacter freundii at 4 ~g/ml. Cefquinome inhibited at 8 ~g/ml a number of Pseudomonas aeruginosa that had ceftazidime MICs of 32 p,g/ml, and 90% of the isolates were inhibited at 8 ~g/ml, including isolates resistant to imipenem (data not shown). Xanthomonas maltophilia were resistant, as were 50% of the Pseudomonas cepacia and most Acinetobacter calcoaceticus. Haemophilus influenzae (~-lactamase-positive isolates) were inhibited at concentrations similar to the other cephalosporins as were the ~-lactamase-producing Moraxella and Neisseria gonorrhoeae. Bacteroides spp. were not inhibited (MIC > 64 p,g/ml). Fusobacterium varium (four isolates not shown) had MICs > 32 ~g/ml. Propionibacterium (three isolates) and peptostreptococci (four isolates) were inhibited by ~ 1 ~g/ml of cefquinome, similar to the concentrations required for cefpirome and cefepime. Cefquinome inhibited 90% of methicillin-susceptible Staphylococcus aureus at 2 p,g/ml, which was sim-
In vitro Activity of Cefquinome Compared with Other Agents MIC (~g/ml)
Organism
No. of Isolates
Agent
Range
50%
90%
Escherichia colia,°
(30)
Cefquinome 0.015-0.5 Ceftazidime 0.06-0.5 Cefpirome 0.015-0.5 Cefepime 0.015-0.25
0.06 0.25 0.03 0.03
0.12 0.5 0.12 0.12
Klebsiella pneumoniae~
(30)
Cefquinome 0.03-0.5 Ceftazidime 0.12-8 Cefpirome 0.015-0.5 Cefepime 0.015-0.5
0.06 0.25 0.06 0.06
0.25 2 0.25 0.12
Klebsiella oxytocaa
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.03-2 0.12->16 0.03-1 0.03-8
0.06 0.25 0.06 0.06
0.25 .5 0.25 0.25
Enterobacter aerogenesa'b
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.06-1 0.12->32 0.03-1 0.03-0.5
0.12 0.5 0.12 0.25
0.25 32 0.5 0.5
Enterobacter cloacae~'b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
0.06-16 0.06->32 0.06-16 0.06-4
0.25 4 0.25 0.25
8 >32 16 2
333
In vitro Activity of C e f q u i n o m e
TABLE 1
Continued MIC (p.g/ml) No. of
Organism
Isolates
Agent
Range
50%
90%
Citrobacter freundii a,b
(30)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03->16 0.03->16 0.03->16 0.03-16
0.06 1 0.12 0.06
Citrobacter diversus a
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-0.12 0.03-0.25 0.015-0.03 0.06
0.06 0.12 0.03 0.06
0.06 0.25 0.03 0.06
Proteus mirabilis
(20)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-2 0.06-0.25 0.015-0.5 0.03-0.5
0.12 0.06 0.015 0.03
0.25 0.12 0.03 0.06
Morganella morganii ~,b
(10)
Cefquinome Ceftazidime Cefplrome Cefepime
0.015-0.5 0.015-1 0.015-0.03 0.015-0.03
0.03 0.06 0.015 0.015
0.12 0.5 0.015 0.015
Proteus vulgaris a,b
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-16 0.03-0.25 0.03-1 0.015-0.12
2 0.06 0.12 0.03
Providencia rettgeri a,b
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-16 0.03->32 0.03-4 0.03-8
2 2 0.25 1
8 4 4 8
Providencia stuartii a,b
(15)
Cefquinome ' Ceftazidime Cefplrome Cefepime
0.03-1 0.03-1 0.03-0.25 0.03-1
0.12 0.12 0.03 0.03
0.25 1 0.06 1
Serratia marcescens a,b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
0.03-4 0.12-16 0.03-4 0.03-4
0.25 0.25 0.12 0.12
1 1 0.5 1
Pseudomonas aeruginosa a,b
(25)
Cefquinome Ceftazidime Cefpirome Cefepime
2-32 1->32 2->32 1-16
4 2 4 2
8 32 32 8
Pseudomonas cepacia a,b
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
0.25->64 2->64 0.12->64 0.12-64
4 16 8 8
32 >64 >64 64
Xanthomonas maltophilia a,b
(12)
Cefquinome Ceftazidime Cefpirome Cefepime
~>~ 2->64 ~>~ 2-64
>~ 16 >64 32
>64 >64 >64
Acinetobacter calcoaeeticus a,b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
16->64 ~>64 ~>64 ~>64
32 16 16 16
>64 >64 >64 >64
4 >16 8 8
16 0.12 0.5 0.06
334
Nai-Xun Chin et al.
TABLE 1
Continued MIC (p,g/ml)
Organism
No. of Isolates
Agent
Range
50%
90%
Salmonella sppY
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-0.5 0.25-1 0.015-0.25 0.015-0.25
0.12 0.5 0.06 0.06
0.25 0.5 0.12 0.12
Shigella sppY
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.015-1 0.06-1 0.015-0.5 0.015-1
0.06 0.12 0.06 0.06
0.25 0.5 0.12 0.12
Aeromonas spp. a,b
(20)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-4 0.124 0.015-2 0.03-8
0.06 0.25 0.06 0.06
0.5 2 0.25 0.5
Yersinia enterocolitica a,b
(10)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-4 0.12-8 0.03-0.12 0.03-0.25
0.12 0.12 0.03 0.03
0.25 1 0.06 0.12
Haemophilus influenzae ~
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-0.25 0.06-0.25 0.06-0.12 0.06-0.25
0.06 0.12 0.06 0.12
0.12 0.25 0.12 0.25
Moraxella catarrhalis
(22)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-2 0.03-0.5 0.06-4 0.12-4
1 0.12 1 0.5
2 0.25 2 2
Bacteroides fragilis a,b
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
32->64 32->64 16-32 32->64
>64 >64 32 32
>64 >64 32 >64
Bacteroides sppY ,b,C
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
>64 32->64 16->32 16->32
>64 >64 32 32
>64 >64 >32 >32
Clostridium perfringens
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
0.5-1 0.5->16 0.25->16 0.5->16
Staphylococcus aureus Methicillin susceptible a
(20)
Cefquinome Ceftazidime Cefpirome Cefepirne
0.5-4 8-14 1-4 2-16
Staphylococcus aureus Methicillin resistant ~>
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
Coagulase-negative Staphylococcus Methicillin susceptible a
(10)
Cefquinome Ceftazidime Cefpirome Cefepime
Coagulase-negative Staphylocccus
(lO)
Cefquinome Ceftazidime
1-16 16->64 1-32 2->64 0.25-8 4-32 0.25-16 0.5-64 1-32 8->64
0.5 4 1 1
1 >16 >16 8
1 16 1 4
2 32 2 8
2 16 2 4
8 64 8 32
0.5 8 0.5 1 2 32
2 32 2 8 16 >64
In vitro Activity of C e f q u i n o m e
TABLE 1
335
Continued MIC (~.g/ml)
Organism
No. of Isolates
Methicillin resistant ~'b
Agent
Range
Cefpirome Cefepime
1-64 1->64
50%
90%
4 16
32 64
Streptococcus pyogenes
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.015-0.06 0.015-0.5 0.015-0.03 0.015-0.12
0.015 0.015 0.015 0.015
0.03 0.25 0.03 0.03
Streptococcus agalactiae
(15)
Cefquinome 0.015-0.06 Ceftazidime 0.12-0.5 Cefpirome 0.015-0.06 Cefepime 0.015-0.12
0.03 0.25 0.015 0.03
0.03 0.5 0.03 0.06
Group-C streptococci
(12)
Cefquinome 0.015-0.12
0.015
0.03
Ceftazidime Cefpirome Cefepime
0.12-4 0.015-0.25 0.015-0.25
0.25 0.015 0.015
0.25 0.03 0.03
0.015 0.25 0.015 0.03
0.12 2 0.12 0.25
Group-F and G streptococci
Streptococcus pneumoniae
(20)
Cefquinome 0.015-0.25 Ceftazidime 0.12-4 Cefpirome 0.015-0.5 Cefepime 0.015-0.5
Enterococcus faecalisb
(22)
Cefquinome Ceftazidime Cefpirome Cefepime
2->64 64->64 2->64 16->64
4 >64 4 32
>64 >64 >64 >64
Enterococcus faecium b
(10)
Cefquinome Ceftazidime Cefpirome Cefepime
8->64 >64 8->64 16->64
32 >64 32 >64
>64 >64 >64 >64
Listeria monocytogenesb
(15)
Cefquinone Ceftazidirne Cefpirome Cefepime
1-32 32->64 1-32 4-64
16 >64 8 32
32 >64 32 64
Corynebacterium jeikeium b
(10)
Cefquinome
>64
>64
>64
aResistant to ampicillin. bResistant to cefazolin. qncludes Bacteroides thetaiotaomicron (5), B. ovatus (2), B. distasonis (2), B. septicum (2), and B. melaninogenicus (4).
ilar to the concentrations of cefpirome and superior to ceftazidime and cefepime. It inhibited 90% of methicillin-resistant Staphylococcus aureus at 8 ~g/ml and methicillin-resistant coagulase-negative staphylococci at ~ 16 ~g/ml. C e f q u i n o m e has excellent activity against hemolytic streptococci of g r o u p s A, B, C, F, and G, inhibiting 90% at -< 0.03 ~g/ml comparable with the other agents. It also inhibited Streptococcus pneumoniae at 0.12 ~g/ml, which included four relatively penicillin-resistant isolates. Half of the Enterococcus faecalis were inhibited by 4 ~g/ml similar to cefpirome, but Enterococcus faecium w e r e resistant as were Corynebacterium jeikeium and most Listeria monocytogenes.
The in vitro activity of c e f q u i n o m e was similar in M u e l l e r - H i n t o n , b r a i n - h e a r t infusion, a n d trypticase soy agar m e d i u m for staphylococci, Enterobacteriaceae, and Pseudomonas aeruginosa. Increasing the inoculum size from 104 to 105 CFU did not increase the MICs for ~-lactamase-producing Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, or Serratia marcescens (five isolates each, data not shown). There was a four- to eightfold increase in MICs of Enterobacter cloacae and Citrobacter freundii at 10 6 CFU c o m p a r e d with 104 CFU. The c e f q u i n o m e MBCs of
Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Proteus mirabilis, and Pseudomonas aeruginosa
Nai-Xun Chin et al.
336
were within one dilution of the cefquinome MICs, but four- to eightfold greater for Enterobacter cloacae, which produced high levels of f3-1actamase constitutively (five isolates each tested). The activity of cefquinome against bacteria with characterized ~-lactamases is shown in Table 2. Cefquinome inhibited Escherichia coli containing TEM1 and TEM-2 at 0.06 and 0.12 ~g/ml, respectively, but the TEM-3, 5, and 7 had MICs of 4 and 8 ~g/ml. The TEM-9-containing strain had an MIC of 64 ~g/ml. The cefquinome MICs were similar to the MICs of ceftazidime against the Pseudomonas aeruginosa isolates containing the Carb 1, 2, 3, and 4 enzymes. Cefquinome had activity comparable with or superior to ceftazidime against all of the organisms with characterized ~3-1actamases. Cefquinome was minimally hydrolyzed, 0.1%, compared with cephaloridine 100% by the plasmid [3-1actamases TEM-1, TEM-2, or SHV-1, OXA-2, and OXA-3, nor was it hydrolyzed by the Klebsiella K-l, Enterobacter P99, Pseudomonas Sabath-Abraham, or Branhamella Bro-1 chromosomal f3-1actamases, Table 3. It was hydrolyzed by TEM-3, TEM-5, TEM-9, Proteus vulgaris (Richmond-Sykes Ic), and by Xanthomonas maltophilia [3-1actamases.
DISCUSSION
Overall, these studies show that cefquinome has activity against Gram-positive species similar to cefpi-
TABLE 2
rome and cefepime and superior to older cephalosporins with analogous C-3 substitutions. It had activity comparable with other cephalosporins against most of the Enterobacteriaceae. Cefquinome is less active than the comparative agents against some Proteus and Providencia, but had activity against Pseudomonas aeruginosa similar to cefepime, inhibiting ceftazidime-resistant isolates. Siebert et al. (1989) reported similar in vitro findings. Previous studies of cefpirome and cefepime have shown that the activity of these agents against bacteria containing the chromosomal ~-lactamases of the Richmond-Sykes type Ia is related to the poor affinity of the compounds for these enzymes (Neu, et al., 1985 and 1986). We did not determine the Ki of cefquinome, but in view of its structure, it is likely that the C-3 bicyclic pyridinium structure accounts for its improved ~-lactamase stability. This moiety also contributes to its excellent activity against Pseudomonas aeruginosa because iminomethoxy aminothiazolyl cephalosporins lack useful anti-Pseudomonas activity unless there is such a moiety at C-3. Isert et al. (1989) have shown that cefquinome has good pharmacokinetic properties in dogs providing sustained blood levels and low protein binding, and that cefquinome was effective in protecting mice against infections caused by Gram-negative and positive bacteria. Thus cefquinome may find future use based on its excellent in vitro activity and pharmacologic properties that may provide a longer halflife than the comparator agents.
Activity of Cefquinome Against Bacteria with Characterized [3Lactamases Compared with Ceftazidime MIC (p,g/ml of)
Organism Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Moraxella catarrhalis Staphylococcus aureus Klebsiella pneumoniae Enterobacter cloacae Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa
Enzyme
Cefquinome
Ceftazidime
TEM-1 TEM-2 TEM-3 TEM-5 TEM-7 TEM-9 SHV-1 OXA-1 Bro-1 PC-1 SHV-1 P-99 PSE-1 PSE-2 PSE-3 PSE-4
0.06 0.12 8 3 4 64 0.25 2 0.06 1 0.25 8 4 4 1 0.5
0.25 0.25 8 8 32 >64 0.5 0.25 0.06 8 0.25 ~64 4 8 4 2
337
In vitro Activity of C e f q u i n o m e
TABLE 3
Stability of C e f q u i n o m e Attack b y ~ - L a c t a m a s e s Relative Rate of Hydrolysisa
(%) Source of Enzyme
Trivial Name
Cefquinome
Ceftazidime
Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa pseudomonas aeruginosa Enterobacter cloacae Klebsiella oxytoca Proteus vulgaris Xanthomonas maltophilia Staphylococcus aureus Moraxella catarrhalis
TEM-1 TEM-2 TEM-3 TEM-5 TEM-9 OXA-2 SHV-1 SHV-1 CARB-1 CARB-2 CARB-3 CARB-4 Sabath-Abraham P99 K-1
DIAGN MICROBIOLINFECTDIS 1992;15:331-337
In vitro Activity of Cefquinome, a New Cephalosporin, Compared with Other Cephalosporin Antibiotics Nai-Xun Chin, Jian-Wei Gu, Wei Fang, and Harold C. Neu
The in vitro activity of cefquinome, a new aminothiazolyl cephalosporin with a C-3 bicyclic pyridinium group, was compared with ceftazidime, cefpirome, and cefepime. Cefquinome inhibited members of the Enterobacteriaceae at 16 i~g/ml]. Serratia marcescens were inhibited by < 1 I~g/ml and Pseudomonas aeruginosa by 8 I~g/ml similar to the activity of cefepime. The majority of Haemophilus influenzae and Neisseria gonorrhoeae were inhibited by < 0.25 i~g/ml. Most enterococci had cefquinome MICs of 4-8 i~g/ml. CefquiINTRODUCTION Cefquinome is a new cephem antibiotic that contains an aminothiazolyl group and an iminomethoxy group on the ~-acyl side chain similar to agents such as cefotaxime and ceftriaxone. However, it has a bicyclic pyridinium group attached at C-3, making it similar to cefpirome and cefepime. Cephalosporin agents of this type have been shown to have an extended spectrum of antimicrobial activity with improved inhibition of Gram-positive bacteria (Neu, 1986a). Cefquinome has preliminarily been reported From the Department of Medicine (N.-X.C., J.-W.G., W.F., H.C.N.) and Department of Pharmacology(H.C.N.), Collegeof Physicians and Surgeons, ColumbiaUniversity, New York, New York, USA. Address reprint requests to Dr. N.-X. Chin, Department of Medicine, Collegeof Physiciansand Surgeons, ColumbiaUniversity, 630 West 168 Street, New York, NY 10032, USA. Received 12 June 1991, revised and accepted 27 August 1991. © 1992 ElsevierScience Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0732-8893/92/$5.00
nome was extremely active against group-A streptococci and Streptococcus pneumoniae with MICs < 0.12 i~g/ml. 90% of methicillin-susceptible Staphylococcus aureus 90% were inhibited by 2 i~g/ml. Overall, the in vitro activity of cefquinome was comparable with aminothiazolyl cephalosporins. It inhibited some Enterobacter and Citrobacter freundii resistant to ceftazidime as did cefpirome and cefepime. Cefquinome was not destroyed by the common plasmid [3-lactamases TEM1, TEM-2, SHV-1, or by the chromosomal fl-lactamases of Klebsiella, Branhamella, and Pseudomonas, but it was hydrolyzed by TEM-3, TEM-5, and TEM-9. Its activity was not adversely decreased in different medium or protein, and minimum bactericidal concentrations (MBCs) for most species except for Enterobacter were within a dilution of MICs.
to be active in vitro and in animal protection studies (Isert et al., 1989; Seibert et al., 1989). We investigated the activity of cefquinome in comparison with the activity of ceftazidime, cefpirome, and cefepime.
MATERIALS A N D M E T H O D S Cefquinome and cefpirome were provided by Hoechst (Frankfurt, Germany). Cefpime was provided by Bristol Laboratories (Wallingford, CT) and ceftazidime by Glaxo (Research Triangle Park, NC). Organisms used in this study were isolates obtained from patients seen at the Presbyterian Hospital in New York City in the last 2 years (with the exception of the methicillin-resistant Staphylococcus aureus, which had been collected over several years) and selected ~-lactamase-producing isolates, some of which had been provided by investigators throughout Europe. Only a single isolate from a patient was tested. The characterized ~-lactamase isolates were not used in the general evaluation.
Nai-Xun Chin et al.
332
Minimum inhibitory concentrations (MICs) were determined using Mueller-Hinton agar for staphylococci and aerobic Gram-negative species. Activity against streptococcal species was determined with Mueller-Hinton agar supplemented with 5% sheep blood. Activity against Haemophilus, Neisseria, and Moraxella species was determined with Haemophilus test medium. Activity against Bacteroides spp. and other anaerobic species was determined using Mueller-Hinton agar supplemented with 5% laked sheep blood and vitamin K. An inoculum of 10 4 colonyforming units (CFU) was used for aerobic organisms and 105 CFU for anaerobic organisms according to the NCCLS (1990) guidelines. Incubation was at 35°C for 18-20 hr in ambient air except for Neisseria, which were incubated in the presence of 5% CO2. Anaerobic organisms were incubated for 48 hr in GasPak jars (BBL Microbiology Systems, Cockeysville, MD). The MIC was the lowest concentration that inhibited visible growth on agar. ~-lactamase stability was determined by a spectrophotometric assay as previously published (Neu, 1986b). The concentration of substrate used was 100 ~M. ~-Lactamases were partially purified as previously published (Neu, 1986b). RESULTS
The activity of cefquinome in comparison with the other agents is shown in Table 1. Cefquinome had TABLE 1
excellent activity against the Enterobacteriaceae inhibiting at - 1 ~g/ml most organisms, with the exception of Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Providencia rettgeri. Half of the aforementioned five species were inhibited by < 1 ~g/ml. In general, the most active compounds of the four cephalosporins was cefepime, which inhibited at 0.25 ~g/ml various Proteus species that had cefquinome MICs of > 2 ~g/ml. Cefquinome inhibited ceftazidime-resistant (MIC -> 16 ~g/ml) isolates of Enterobacter cloacae and Citrobacter freundii at 4 ~g/ml. Cefquinome inhibited at 8 ~g/ml a number of Pseudomonas aeruginosa that had ceftazidime MICs of 32 p,g/ml, and 90% of the isolates were inhibited at 8 ~g/ml, including isolates resistant to imipenem (data not shown). Xanthomonas maltophilia were resistant, as were 50% of the Pseudomonas cepacia and most Acinetobacter calcoaceticus. Haemophilus influenzae (~-lactamase-positive isolates) were inhibited at concentrations similar to the other cephalosporins as were the ~-lactamase-producing Moraxella and Neisseria gonorrhoeae. Bacteroides spp. were not inhibited (MIC > 64 p,g/ml). Fusobacterium varium (four isolates not shown) had MICs > 32 ~g/ml. Propionibacterium (three isolates) and peptostreptococci (four isolates) were inhibited by ~ 1 ~g/ml of cefquinome, similar to the concentrations required for cefpirome and cefepime. Cefquinome inhibited 90% of methicillin-susceptible Staphylococcus aureus at 2 p,g/ml, which was sim-
In vitro Activity of Cefquinome Compared with Other Agents MIC (~g/ml)
Organism
No. of Isolates
Agent
Range
50%
90%
Escherichia colia,°
(30)
Cefquinome 0.015-0.5 Ceftazidime 0.06-0.5 Cefpirome 0.015-0.5 Cefepime 0.015-0.25
0.06 0.25 0.03 0.03
0.12 0.5 0.12 0.12
Klebsiella pneumoniae~
(30)
Cefquinome 0.03-0.5 Ceftazidime 0.12-8 Cefpirome 0.015-0.5 Cefepime 0.015-0.5
0.06 0.25 0.06 0.06
0.25 2 0.25 0.12
Klebsiella oxytocaa
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.03-2 0.12->16 0.03-1 0.03-8
0.06 0.25 0.06 0.06
0.25 .5 0.25 0.25
Enterobacter aerogenesa'b
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.06-1 0.12->32 0.03-1 0.03-0.5
0.12 0.5 0.12 0.25
0.25 32 0.5 0.5
Enterobacter cloacae~'b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
0.06-16 0.06->32 0.06-16 0.06-4
0.25 4 0.25 0.25
8 >32 16 2
333
In vitro Activity of C e f q u i n o m e
TABLE 1
Continued MIC (p.g/ml) No. of
Organism
Isolates
Agent
Range
50%
90%
Citrobacter freundii a,b
(30)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03->16 0.03->16 0.03->16 0.03-16
0.06 1 0.12 0.06
Citrobacter diversus a
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-0.12 0.03-0.25 0.015-0.03 0.06
0.06 0.12 0.03 0.06
0.06 0.25 0.03 0.06
Proteus mirabilis
(20)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-2 0.06-0.25 0.015-0.5 0.03-0.5
0.12 0.06 0.015 0.03
0.25 0.12 0.03 0.06
Morganella morganii ~,b
(10)
Cefquinome Ceftazidime Cefplrome Cefepime
0.015-0.5 0.015-1 0.015-0.03 0.015-0.03
0.03 0.06 0.015 0.015
0.12 0.5 0.015 0.015
Proteus vulgaris a,b
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-16 0.03-0.25 0.03-1 0.015-0.12
2 0.06 0.12 0.03
Providencia rettgeri a,b
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-16 0.03->32 0.03-4 0.03-8
2 2 0.25 1
8 4 4 8
Providencia stuartii a,b
(15)
Cefquinome ' Ceftazidime Cefplrome Cefepime
0.03-1 0.03-1 0.03-0.25 0.03-1
0.12 0.12 0.03 0.03
0.25 1 0.06 1
Serratia marcescens a,b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
0.03-4 0.12-16 0.03-4 0.03-4
0.25 0.25 0.12 0.12
1 1 0.5 1
Pseudomonas aeruginosa a,b
(25)
Cefquinome Ceftazidime Cefpirome Cefepime
2-32 1->32 2->32 1-16
4 2 4 2
8 32 32 8
Pseudomonas cepacia a,b
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
0.25->64 2->64 0.12->64 0.12-64
4 16 8 8
32 >64 >64 64
Xanthomonas maltophilia a,b
(12)
Cefquinome Ceftazidime Cefpirome Cefepime
~>~ 2->64 ~>~ 2-64
>~ 16 >64 32
>64 >64 >64
Acinetobacter calcoaeeticus a,b
(30)
Cefquinome Ceftazidime Cefpirome Cefepime
16->64 ~>64 ~>64 ~>64
32 16 16 16
>64 >64 >64 >64
4 >16 8 8
16 0.12 0.5 0.06
334
Nai-Xun Chin et al.
TABLE 1
Continued MIC (p,g/ml)
Organism
No. of Isolates
Agent
Range
50%
90%
Salmonella sppY
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-0.5 0.25-1 0.015-0.25 0.015-0.25
0.12 0.5 0.06 0.06
0.25 0.5 0.12 0.12
Shigella sppY
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.015-1 0.06-1 0.015-0.5 0.015-1
0.06 0.12 0.06 0.06
0.25 0.5 0.12 0.12
Aeromonas spp. a,b
(20)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-4 0.124 0.015-2 0.03-8
0.06 0.25 0.06 0.06
0.5 2 0.25 0.5
Yersinia enterocolitica a,b
(10)
Cefquinome Ceftazidime Cefplrome Cefepime
0.03-4 0.12-8 0.03-0.12 0.03-0.25
0.12 0.12 0.03 0.03
0.25 1 0.06 0.12
Haemophilus influenzae ~
(15)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-0.25 0.06-0.25 0.06-0.12 0.06-0.25
0.06 0.12 0.06 0.12
0.12 0.25 0.12 0.25
Moraxella catarrhalis
(22)
Cefquinome Ceftazidime Cefplrome Cefepime
0.06-2 0.03-0.5 0.06-4 0.12-4
1 0.12 1 0.5
2 0.25 2 2
Bacteroides fragilis a,b
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
32->64 32->64 16-32 32->64
>64 >64 32 32
>64 >64 32 >64
Bacteroides sppY ,b,C
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
>64 32->64 16->32 16->32
>64 >64 32 32
>64 >64 >32 >32
Clostridium perfringens
(15)
Cefquinome Ceftazidime Cefpirome Cefepime
0.5-1 0.5->16 0.25->16 0.5->16
Staphylococcus aureus Methicillin susceptible a
(20)
Cefquinome Ceftazidime Cefpirome Cefepirne
0.5-4 8-14 1-4 2-16
Staphylococcus aureus Methicillin resistant ~>
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
Coagulase-negative Staphylococcus Methicillin susceptible a
(10)
Cefquinome Ceftazidime Cefpirome Cefepime
Coagulase-negative Staphylocccus
(lO)
Cefquinome Ceftazidime
1-16 16->64 1-32 2->64 0.25-8 4-32 0.25-16 0.5-64 1-32 8->64
0.5 4 1 1
1 >16 >16 8
1 16 1 4
2 32 2 8
2 16 2 4
8 64 8 32
0.5 8 0.5 1 2 32
2 32 2 8 16 >64
In vitro Activity of C e f q u i n o m e
TABLE 1
335
Continued MIC (~.g/ml)
Organism
No. of Isolates
Methicillin resistant ~'b
Agent
Range
Cefpirome Cefepime
1-64 1->64
50%
90%
4 16
32 64
Streptococcus pyogenes
(20)
Cefquinome Ceftazidime Cefpirome Cefepime
0.015-0.06 0.015-0.5 0.015-0.03 0.015-0.12
0.015 0.015 0.015 0.015
0.03 0.25 0.03 0.03
Streptococcus agalactiae
(15)
Cefquinome 0.015-0.06 Ceftazidime 0.12-0.5 Cefpirome 0.015-0.06 Cefepime 0.015-0.12
0.03 0.25 0.015 0.03
0.03 0.5 0.03 0.06
Group-C streptococci
(12)
Cefquinome 0.015-0.12
0.015
0.03
Ceftazidime Cefpirome Cefepime
0.12-4 0.015-0.25 0.015-0.25
0.25 0.015 0.015
0.25 0.03 0.03
0.015 0.25 0.015 0.03
0.12 2 0.12 0.25
Group-F and G streptococci
Streptococcus pneumoniae
(20)
Cefquinome 0.015-0.25 Ceftazidime 0.12-4 Cefpirome 0.015-0.5 Cefepime 0.015-0.5
Enterococcus faecalisb
(22)
Cefquinome Ceftazidime Cefpirome Cefepime
2->64 64->64 2->64 16->64
4 >64 4 32
>64 >64 >64 >64
Enterococcus faecium b
(10)
Cefquinome Ceftazidime Cefpirome Cefepime
8->64 >64 8->64 16->64
32 >64 32 >64
>64 >64 >64 >64
Listeria monocytogenesb
(15)
Cefquinone Ceftazidirne Cefpirome Cefepime
1-32 32->64 1-32 4-64
16 >64 8 32
32 >64 32 64
Corynebacterium jeikeium b
(10)
Cefquinome
>64
>64
>64
aResistant to ampicillin. bResistant to cefazolin. qncludes Bacteroides thetaiotaomicron (5), B. ovatus (2), B. distasonis (2), B. septicum (2), and B. melaninogenicus (4).
ilar to the concentrations of cefpirome and superior to ceftazidime and cefepime. It inhibited 90% of methicillin-resistant Staphylococcus aureus at 8 ~g/ml and methicillin-resistant coagulase-negative staphylococci at ~ 16 ~g/ml. C e f q u i n o m e has excellent activity against hemolytic streptococci of g r o u p s A, B, C, F, and G, inhibiting 90% at -< 0.03 ~g/ml comparable with the other agents. It also inhibited Streptococcus pneumoniae at 0.12 ~g/ml, which included four relatively penicillin-resistant isolates. Half of the Enterococcus faecalis were inhibited by 4 ~g/ml similar to cefpirome, but Enterococcus faecium w e r e resistant as were Corynebacterium jeikeium and most Listeria monocytogenes.
The in vitro activity of c e f q u i n o m e was similar in M u e l l e r - H i n t o n , b r a i n - h e a r t infusion, a n d trypticase soy agar m e d i u m for staphylococci, Enterobacteriaceae, and Pseudomonas aeruginosa. Increasing the inoculum size from 104 to 105 CFU did not increase the MICs for ~-lactamase-producing Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, or Serratia marcescens (five isolates each, data not shown). There was a four- to eightfold increase in MICs of Enterobacter cloacae and Citrobacter freundii at 10 6 CFU c o m p a r e d with 104 CFU. The c e f q u i n o m e MBCs of
Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Proteus mirabilis, and Pseudomonas aeruginosa
Nai-Xun Chin et al.
336
were within one dilution of the cefquinome MICs, but four- to eightfold greater for Enterobacter cloacae, which produced high levels of f3-1actamase constitutively (five isolates each tested). The activity of cefquinome against bacteria with characterized ~-lactamases is shown in Table 2. Cefquinome inhibited Escherichia coli containing TEM1 and TEM-2 at 0.06 and 0.12 ~g/ml, respectively, but the TEM-3, 5, and 7 had MICs of 4 and 8 ~g/ml. The TEM-9-containing strain had an MIC of 64 ~g/ml. The cefquinome MICs were similar to the MICs of ceftazidime against the Pseudomonas aeruginosa isolates containing the Carb 1, 2, 3, and 4 enzymes. Cefquinome had activity comparable with or superior to ceftazidime against all of the organisms with characterized ~3-1actamases. Cefquinome was minimally hydrolyzed, 0.1%, compared with cephaloridine 100% by the plasmid [3-1actamases TEM-1, TEM-2, or SHV-1, OXA-2, and OXA-3, nor was it hydrolyzed by the Klebsiella K-l, Enterobacter P99, Pseudomonas Sabath-Abraham, or Branhamella Bro-1 chromosomal f3-1actamases, Table 3. It was hydrolyzed by TEM-3, TEM-5, TEM-9, Proteus vulgaris (Richmond-Sykes Ic), and by Xanthomonas maltophilia [3-1actamases.
DISCUSSION
Overall, these studies show that cefquinome has activity against Gram-positive species similar to cefpi-
TABLE 2
rome and cefepime and superior to older cephalosporins with analogous C-3 substitutions. It had activity comparable with other cephalosporins against most of the Enterobacteriaceae. Cefquinome is less active than the comparative agents against some Proteus and Providencia, but had activity against Pseudomonas aeruginosa similar to cefepime, inhibiting ceftazidime-resistant isolates. Siebert et al. (1989) reported similar in vitro findings. Previous studies of cefpirome and cefepime have shown that the activity of these agents against bacteria containing the chromosomal ~-lactamases of the Richmond-Sykes type Ia is related to the poor affinity of the compounds for these enzymes (Neu, et al., 1985 and 1986). We did not determine the Ki of cefquinome, but in view of its structure, it is likely that the C-3 bicyclic pyridinium structure accounts for its improved ~-lactamase stability. This moiety also contributes to its excellent activity against Pseudomonas aeruginosa because iminomethoxy aminothiazolyl cephalosporins lack useful anti-Pseudomonas activity unless there is such a moiety at C-3. Isert et al. (1989) have shown that cefquinome has good pharmacokinetic properties in dogs providing sustained blood levels and low protein binding, and that cefquinome was effective in protecting mice against infections caused by Gram-negative and positive bacteria. Thus cefquinome may find future use based on its excellent in vitro activity and pharmacologic properties that may provide a longer halflife than the comparator agents.
Activity of Cefquinome Against Bacteria with Characterized [3Lactamases Compared with Ceftazidime MIC (p,g/ml of)
Organism Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Moraxella catarrhalis Staphylococcus aureus Klebsiella pneumoniae Enterobacter cloacae Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa
Enzyme
Cefquinome
Ceftazidime
TEM-1 TEM-2 TEM-3 TEM-5 TEM-7 TEM-9 SHV-1 OXA-1 Bro-1 PC-1 SHV-1 P-99 PSE-1 PSE-2 PSE-3 PSE-4
0.06 0.12 8 3 4 64 0.25 2 0.06 1 0.25 8 4 4 1 0.5
0.25 0.25 8 8 32 >64 0.5 0.25 0.06 8 0.25 ~64 4 8 4 2
337
In vitro Activity of C e f q u i n o m e
TABLE 3
Stability of C e f q u i n o m e Attack b y ~ - L a c t a m a s e s Relative Rate of Hydrolysisa
(%) Source of Enzyme
Trivial Name
Cefquinome
Ceftazidime
Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa Pseudomonas aeruginosa pseudomonas aeruginosa Enterobacter cloacae Klebsiella oxytoca Proteus vulgaris Xanthomonas maltophilia Staphylococcus aureus Moraxella catarrhalis
TEM-1 TEM-2 TEM-3 TEM-5 TEM-9 OXA-2 SHV-1 SHV-1 CARB-1 CARB-2 CARB-3 CARB-4 Sabath-Abraham P99 K-1
