VOL.

XXX NO. 12

THE

JOURNAL

OF

ANTIBIOTICS

1107

PIPERACILLIN (T-1220), A NEW SEMISYNTHETIC PENICILLIN: IN VITRO ANTIMICROBIAL ACTIVITY COMPARISON WITH CARBENICILLIN, TICARCILLIN, AMPICILLIN, CEPHALOTHIN, CEFAMANDOLE AND CEFOXITIN R. N. JONES Clinical

Microbiology

Laboratory, Kaiser Foundation Hospital Clackamas, Oregon 97015, U.S.A.

Laboratories

C. THORNSBERRY Antimicrobic

Investigation

Section,

Center

for Disease

Control,

Atlanta,

Georgia

30333 , U.S.A.

A. L. BARRY

Clinical Microbiology Laboratories, University of California (Davis) Sacramento Medical Center, Sacramento, California 95817, U.S.A. P. C. FUCHS Department

of Pathology,

St. Vincent Hospital

and Medical

Center , Portland,

Oregon

97225, U.S.A.

T. L. GAVAN Department

of Microbiology,

The Cleveland

Clinic,

Cleveland,

Ohio

44106, U.S.A.

and E. H. GERLACH Microbiology

Laboratory, (Received

St. Francis

Hospital,

for Publication

Wichita,

October

Kansas

67214, U.S.A.

3, 1977)

Piperacillin (T-1220) is a new semisynthetic penicillin with an unusually broad spectrum of antimicrobial activity. In vitro comparisons of this drug with 6 other beta-lactam antimicrobics (ticarcillin, carbenicillin, ampicillin, cephalothin, cefamandole and cefoxitin) were conducted. These included minimal inhibitory concentrations (MIC) against 394 bacterial isolates, the minimal lethal concentrations (MLC) against 79 of those, as well as the effect of inoculum size on the MIC and MLC of the drugs. Piperacillin had significantly greater activity than did the other penicillins against Pseudomonas species and Klebsiella pneumoniae. Against P. aeruginosa piperacillin was 8- and 16-fold more active than ticarcillin and carbenicillin, respectively. The MLC of piperacillin rarely differed from the MIC by more than one loge dilutions except against P. aeruginosa in which the MLC was 4-fold greater or more than the MIC of 45% of isolates tested. Ticarcillin, carbenicillin and cefoxitin showed minimal inoculum size effects. Cefamandole results showed the greatest inoculum size variation with 55 % and 37 % of isolates showing an 8-fold increase in MIC and MLC respectively by increasing inoculum from 105 to 107 CFU/ml. Piperacillin was intermediately effected having 25% of strains > 8-fold increase in MIC.

Piperacillin,

sodium 6-[D(-)-a(4-ethyl-2,3-dioxo-l-piperazinylcarbonylamino)-a-

phenylacetamido]

penicillinate, is a new semisynthetic penicillin derived from aminobenzyl-penicillin (Fig. 1). This compound

formerly

tent antibacterial previously as carbenicillin been reported

and ticarcillin. in humans

In addition,

and in experimental

favorable animals

refractory

pharmacokinetics (abstracts

known

as T-1220,

activity against

has po-

bacterial species

to such related

compounds

and infection

studies have

349 and 350, Sixteenth

Interscience

THE

1108

Conference

on Antimicrobial

directly compares

ticarcillin,

cefamandole

and cefoxitin.

OF

ANTIBIOTICS

Agents and Chemotherapy,

the antimicrobial

carbenicillin,

JOURNAL

activity

and ampicillin,

of piperacillin

Chicago,

DEC.

1976).

This in vitro investigation

with that of related semisynthetic

plus three reference cephalosporins-cephamycins,

Materials

1977

penicillins cephalothin,

and Methods

Antibiotics: The ceutical

beta-lactam

cephalothin Rahway, and

antimicrobic

companies: from New

ampicillin

Piperacillin Eli Lilly

Jersey; from

standard

Lederle

& Company,

carbenicillin

Bristol

laboratory from

Indianapolis, and

Laboratories,

powders

Laboratories,

were supplied Pearl

Indiana;

ticarcillin

from

Syracuse,

New

River,

cefoxitin

Beecham

by the following

New from

pharma-

York;

cefamandole

Merck

Sharp

Laboratories,

Bristol,

and

& Dohme, Tennessee;

York.

Organisms: A total of 394 bacterial isolates were contributed by the collaborating laboratories for this study. These include 149 strains of the Enterobacteriaceae, 160 strains of non-enterobacteriaceae grain-negative bacilli, and 85 strains of gram-positive cocci. They were further subdivided into the following genus and species categories: 29 Escherichia coli, 25 Klebsiella pueumoniae, 24 Enterobacter species, 27 indolepositive Proteus species, 24 Proteus mirabilis, 20 Serratia species, 108 Pseudomonas aeruginosa, 10 Pseudomonas cepacia, 6 Pseudomonas fluorescens-putida, 10 Pseudomonas maltop/tilia, 4 Pseudomonas stut_eri, 11 Acinetobacter anitratus, 11 Aeromonas hydrophila, 30 Staphylococcus aureus (10 methicillinresistant), 15 Streptococcus faecalis, 20 Streptococcus pueumoniae and 20 Streptococcus pyogenes. Most of the isolates were tested in duplicate by two of the collaborating laboratories (Center for Disease Control and the Sacramento Medical Center) in a manner previously reported.1,2 A third laboratory, Kaiser Foundation, also tested a more limited number (MLCs and inoculum size studies). No significant variation in MIC results were encountered between these participating laboratories. Antimicrobic Susceptibility Testing: Minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. MUELLER-HINTON broth was commercially dispensed in a single lot of plastic trays (Micro Media Systems, San Jose, California) and distributed to the testing laboratories. The trays were stored at -60 C until inoculated . Prior to use the trays were thawed at room temperature (approximately 2030 minutes) and inoculated with disposable inoculators delivering 5 ul to each well. At all three laboratories, a logarithmic phase broth culture was diluted to match the turbidity of a 0.5 MAcFARLAND standard. The suspension was then diluted 1 : 50 in sterile water containing 0.02 Tween 80 and dispensed as described earlier. Final inoculum achieved was 1 x 105 colony forming units (CFU) per ml. For the testing of the fastidious streptococci including S. pyogeues and S. pneumoniae, the inoculum was standardized in MUELLER-HINTON broth containing 5 % lysed rabbit blood and 0.1 ml of this adjusted cell suspension was added to each microdilution well, giving a final concentration of 1 x 105 CFU/ml.

The MIC was recorded as the lowest concentration totally inhibiting bacterial growth (clear well), after approximately 18 hours of incubation at 35°C in a forced air incubator. Occasionally, visible growth occurred in concentrations I -2 wells above the MIC (the skipped-tube phenomenon). Minimum lethal concentrations were determined for 79 organisms from seven genera by subculturing 5 /rl from each microdilution well. The 5 /tl subcultures were transferred to trypticase soy agar with 5%) sheep blood. The subcultures were made with multiple inocul un replicator onto a 150 x 100 nom plate. After 48 hours of incubation, the endpoints were read as the lowest concentration yielding no more than 0.1 % survivors (99.9 % kill). The effect of varying the inoculum concentrations on MIC-MLC endpoints was studied on 79 rapid growing facultative anaerobes. Trays were inoculated to achieve final concentrations of 103, 105, and 107CFU/rnl. MICs and MLCs were interpreted as described above.

VOL.

XXX

NO.

12

THE

JOURNAL

OF

ANTIBIOTICS

1109

Results MIC Table

I

increasing

for

tabulation

Piperacillin

is

the

clinically

pared

to

for

activity at

128

comparable

piperacillin

and

to

pounds

versus

of

within

in

in

Ampicillin Pr.

and and

vulgaris.

and

characteristics

as also

was

cephalothin

compared

are

Proteus

activity

would

rank

%

at

to

currently

among

at

64

is

/,cg/ml

in

This

and

contrast is

generation

latter

available

the

activity

second The

features

the

cefoxitin

Pr.

noteworthy

4 /cg/ml).

two

com-

cephalosporin

with

broader

coverage

indole-positive

Proteus

effects

this

inhibitory

and

%

com-

species.

comparable

ineffective

92

tested.

tested

ampicillin.

8 ,ug/ml)

these

encountered

had

at

(96

incorporates

indole-positive

ticarcillin

Cefamandole

cefoxitin

populations.

species

Most

of

were

species

the

to

species

bacterial

of

8 ,ug/ml (88%

species

Enterobacteriaceae

inhibits

at

bacterial These

ampicillin.

piperacillin

cephalothin

8 ,ug/ml)

susceptibility

for

0%

five

susceptible

four 7492%

0-72%

and

and

of

inhibit

where

piperacillin

carbenicillin

group.

vitro

species

variation

and

for

antibiotics.

the

would

ticarcillin

at

beta-lactam

against

piperacillin

%

results

distribution

pneumoniae

(92

Enterobacter

Species

other

bimodal

cephalosporin

However,

Piperacillin,

six

penicillin

or

reference

favorable

both

susceptibility

carbenicillin/ticarcillin

cefamandole

derivatives1,2,3).

the

levels

Klebsiella

for

that

possess

of semisynthetic

carbenicillin

,ug/ml

cephalosporins,

and

of

serum

36-79%

36%

C

percentage

active

achievable

piperacillin to

cumulative

because

most

Comparisons

the

concentrations

grouped

At

summarizes

is

rettgeri

the

> Pr.

most

morganii

against active >

species. genus

against

Pr.

sub-

Pr.

vulgaris

as

rettgeri

previously

reported.1,2,3) Like coccal

second

and piperacillin

was

most

active

The

median

among

with

Piperacillin

more

achievable

was

8 -

against

active

(median

susceptibility in 16 Ps.

inhibitory

clear

were

inhibited

piperacillin.

five

and

bacterial

were

and

have

unimodal against

than

MIC=

was

the

three

carbenicillin I ltg/ml)

the

two

staphylo-

leg/ml

the

of

carbeni-

overlap in

of

contrast

groups.

the

against narrow

MICs to

car-

Cephalothin

most

ticarcillin

S.

ranges

Serratia MICs

faecalis.

medians

isolates to

Streptococcus

against median

against

cephalosporins

other

mirabilis,

active had

five

susceptibility

Proteus

cephalosporins and

with

128 is

strains

the

beta-lactams

effective

Piperacillin

Ampicillin

of

against

reports4,5).

other

species

antibiotics

active

six

by note

deficient

distribution prior

activity

Of and

bimodal confirming

seven

expressed

Table

times

3.

versus

Only

more

cepacia,

aeruginosa

Ps.

times

median

than

prior

anitratus

Ps. Ticarcillin

of

well

non-enterobacteriaceae

active

against

and

carbenicillin

ticarcillin

species _

16

Only above

leg/ml. ampi-

clinically

fluorescence was

all

putida, one

log2

gram-negative

Pseudomonas

4 dilution

species

against

Ps.

8 times

against

more

tested.

aeruginosa,

active

Ps. than

bacilli Piperacillin

128 stutzeri

and

carbenicillin

256

times equally against

reports6,7). isolates

and

MICs

was

against

maltophilia.

confirming

carbenicillin

as piperacillin

active

32

Acinetobacter piperacillin,

a

pyogenes.

more

isolates of

decreased

concentrations.

The shown

8-fold

aureus ,ug/ml

piperacillin

These

1 leg/ml.

S. 64

had

penicillinase-producing

for

Streptococcus

was

was

are

2.

of

at

cephalosporins

All

MIC

%

show

values

Table

and

a median

cillin

the

MIC

85

against which

antibiotics.

pneumoniae

to

ampicillin

in

piperacillin

methicillin-sensitive

ticarcillin

presented

beta-lactam

cephalosporins,

compared

and and

are

All

ticarcillin

benicillin

Ps.

generation

species1•`5).

cillin of

the

ticarcillin.

were

only There

inhibited was

a

by marked

clinically susceptibility

achievable variation

concentrations for

Aeromonas

of

THE

1110

JOURNAL

OF

ANTIBIOTICS

DEC.

1977

Table 1. Cumulative percentage susceptibility of five bacterial species (135 organisms) to increasing concentrations of piperacillin and six other beta-lactam antibiotics. Antibiotic

Organism (#) E. coli (29)

Staphylococcus aureus (20) Methicillin-sensitive

Staphylococcus aureus (10) methicillin-resistant

Includes Includes

72 7 17 17

3 72

28 48 55 10 59

21

4

63 4 33

4 46

17

4

8

16

79 52 69 69 41 93 79

86 69 76 72 72 97 90

90 79

75 46 54 4

88 58

84

8 67 8

71 17

83 54 58 8 21 83 25

12

56

80

40

52 15 19

PIPER CARB TICAR AMPI CEPHA CEFAM CEFOX

20 20 25 25 95 55

19 4

tobramycin.

24 92 96

63 44 37 4 4 22 15

67 48 41 7

56 52

67 56 II

70 67

37 37

44 52

48 85

58 93

25 25

35

45 100 100 20

50 75 80 60

60 95 95

35

45 50 50 55

with cefamandole isolates

tested,

95

90

88

96 75 71 58 38 92 33

54

96 36 36 84

92 4 20 80 100

40 96 100

79 83 71 46

64 64

74 78 78 22 15 78

74 11 74 96

85 81 63 30 85

48 19 100

100 100 70

85

95

100

90

100

10 20 20 30

90 90 100

10

50 100 100

100 100 100

(8) and Enterobacter vuharis (6).

and piperacillin

was accompanied

concentrations

86 93

92 71 67 33 29

63 63 17 25 88

and ticarcillin.

a,;glomerans

(6).

being most active.

several strains were resistant

carbenicillin

97

100

and the sensitive strains

to the aminoglycosides

e.g. piperacillin,

93

256

100

70

90 80

128

100

70

(>8ltg!ml)

of Ps. aeruginosa by increased

resistance

Only the piperacillin

for these gentamicin

resistant

to genta-

are shown

in

to the

MICs re-

and gentamicin-

strains. MIC-MLC

The MLC/MIC

13

88 92

i

mained at or below clinically achievable resistant

100 97

80 88 96

30

These 14 isolates

resistance

penicillins

86

48 80 72

90

64

79

4 72 8

PIPER CARB TICAR AMPI CEPHA CEFAM CEFOX

the 108 Ps. aeruginosa

32

I

Enterobacter cloacae (10), Enterobacter aerogenes Proteus morganii (12), Proteus retteeri (9), Proteus

Table 4. Increased

tobramycin

2

76 14

PIPER CARB TICAR AMPI CEPHA CEFAM CEFOX

1rvdroplrila to the seven antimicrobics

semisynthetic

34

PIPER CARB TICAR AMPI CEPHA CEFA M CEFOX

Proteus species° (27) Indole-positive

Among

1

PIPER CARB TICAR AMPI CEPHA CEFAM CEFOX

Klebsiella pneunroniae (25)

micin and/or