In vitro susceptibility of arcobacter butzleri to six antimicrobial drugs
Arch. Med. Vet. XXXVI, Nº 2, 2004
In vitro susceptibility of Arcobacter butzleri to six antimicrobial drugs*
Susceptibilidad in vitro
de Arcobacter butzleri
a seis drogas antimicrobianas
L. OTTH, T.M., M. WILSON, T.M., R. CANCINO, T.M., H. FERNANDEZ1, T.M., D. SC.
Instituto de Microbiología Clínica, Universidad Austral de Chile, PO BOX 567. Valdivia. Chile.
Se determinaron los patrones de susceptibilidad de 50 cepas de A. butzleri
mediante el método del E-test.
Ninguna cepa fue resistente a gentamicina y tetraciclina, pero, hubo cepas resistentes a eritromicina (2%) y ciprofloxacina (2%). Además, el 90 y el 98% de las cepas fueron resistentes a ampicilina y cloramfenicol respectivamente. Solamente dos de las 45 cepas ampicilina-resistentes fueron productoras de ß-lactamasa.
: Arcobacter butzleri,
susceptibilidad antimicrobiana, bacterias emergentes, E-test, ß-lactamasa
: Arcobacter butzleri
, antibiotic susceptibility, emerging bacteria, E-test, ß-lactamase.
contaminated water (Jacob et al
., 1998, Mansfield and Forsythe, 2000).
The genus Arcobacter
belongs to the family
Some studies have been carried out in indus
, class Proteobacteria, sub
trialized countries in order to establish the sus
class Gracillicutes and comprises four species
ceptibility of Arcobacter to several antimicrobial
, A. cryaerophilus
drugs. As the antibiotic resistance of Arcobacter
and A. skirrowii
, formerly known as
strains from developing countries is not known,
the aim of this study was to assess the suscepti
bility and resistance patterns of A. butzleri
The first isolates were obtained by Ellis et al
(1977) from aborted bovine fetuses. Further studies related these microorganisms with mastitis and
abortion in the bovine, ovine, equine and porcine species (Logan et al
., 1982; Vandamme 2000).
A total of 50 strains of A. butzleri
Of the four described species, only A.
from cattle (5), pelicans (8) duck feces (2) mus
and A. butzleri
have been isolated
sels (17), chicken livers for human consumption
from human beings, and are associated with bac
(8) and river water (10) were examined. All the
teremia and diarrhea. A. butzleri
has been iso
strains were isolated using the enrichment me
lated from patients with endocarditis, peritonitis
dium of de Boer et al
. (1996), incubated aerobi
and appendicitis. Both are considered as emerg
cally at 26ºC for 48 h. They were then plated on
ing foodborne pathogens that could be acquired
the medium of Atabay and Corry (1998) and in
by consuming mussels, poultry meat, offal and
cubated as described above. All the strains were identified phenotypically using the standard tests
Financial Support: Grant FONDECYT 1030245.
L. OTTH, M. WILSON, R. CANCINO, H. FERNANDEZ
Susceptibility to ampicillin, ciprofloxacin,
complemented with a disc diffusion test for de
chloramphenicol, erythromycin, gentamicin and
tecting ampicillin-sulbactam susceptibility.
tetracycline was assessed using the E-test method
The results of the E-test are shown in table 1
(AB Biodisk, Solna, Sweden). This method has
and are expressed as the Minimal Inhibitory Con
been used previously in our laboratory for test
centrations 50 and 90 (MIC and MIC ), corre
ing Campylobacter jejuni
(Fernández et al
sponding to the antibiotic concentration that in
2000). In brief, several colonies of each strain,
hibits at least the 50 or 90% of the strains respec
obtained from a fresh culture on a blood agar
plate, were suspended in 5 ml of Mueller-Hinton
All the strains were susceptible to gentami
broth to a turbidity equal to 0.5 MacFarland stan
cin and tetracycline. The lowest MIC and MIC
dard. The suspensions were inoculated with ster
values were obtained with gentamicin and
ile swabs onto 150 mm diameter Mueller-Hinton
ciprofloxacin. The latter, together with erythro
agar plates supplemented with 5% sheep blood.
mycin, showed the lowest percentages of resis
The agar surfaces were allowed to dry, and six
E-test strips were applied to each plate. Plates
were incubated aerobically at 26ºC for 48 h and
obtained with ampicillin and chloramphenicol
inhibitory concentrations were read at the point
which also showed high percentages of resistance
where the elliptical zone of inhibition intersected
the E-test strip. Staphylococcus aureus
All the strains were susceptible to gentami
25923, Escherichia coli
ATCC 25922 and a C.
cin and tetracycline. With regard to erythromy
isolate of known susceptibility/resistance
cin and ciprofloxacin we found that 98% of the
were used as control strains. The susceptibility
strains were susceptible to both antibiotics with
criteria were those defined for C. jejuni
one strain resistant to erythromycin and another
National Committee for Clinical Laboratory Stan
to ciprofloxacin. These results are similar to those
dards (National Committee for Clinical Labora
reported by Atabay and Aydin (2001). They
found that all 39 strains of A. butzleri
studied by the disk diffusion method were susceptible to tet
racycline, to the aminoglycoside tobramicin and to the quinolones danofloxacin and enrofloxacin.
All the ampicillin-resistant strains (45) were
Harrass et al
. (1998) reported that two out of 89
tested for ß-lactamase using the chromogenic
strains were resistant to tetracycline
cephalosporin method (DIFCO Laboratories)
and another two showed intermediate resistance
TABLE 1. MIC , MIC
and percentages of resistance obtained
for 50 strains of A. butzleri.
y porcentajes de resistencia obtenidos en 50 cepas de A.
ARCOBACTER BUTZLERI, SUSCEPTIBILIDAD ANTIMICROBIANA, BACTERIAS EMERGENTES, E-TEST, ß-LACTAMASA
to erythromycin, also using the disc diffusion
of this test to determine beta lactamase produc-
method. Kiehlbauch et al. (1992), using the broth
tion in species of the genus Arcobacter has not
microdilution method, found that aminoglyco-
been described before, we repeated these tests
sides, quinolones and tetracyclines were most
with a disc diffusion test, using ampicillin and
active in vitro against 64 strains of C. butzleri
ampicillin-sulbactam discs. Both strains were
resistant to ampicillin but susceptible to the com-
The other two antibiotics included in our study
bination ampicillin-sulbactam. As sulbactam is
were ampicillin and chloramphenicol with five
a beta lactamase inhibitor we conclude that in
strains susceptible to the former and only one to
these two strains the ampicillin resistance mecha-
the latter. These results are in agreement with
nism could be mediated by beta lactamase pro-
those reported by other authors for ampicillin
(Kiehchelbauch et al., 1992; Harrass et al., 1998;
Finally, we conclude that, in general, our
Atabay and Aydin, 2001). However, some dif-
strains are susceptible to gentamicin, tetracycline,
ferences have been observed with relation to
erythromycin and ciprofloxacin. They have high
chloramphenicol. While Kiehlbauch et al. (1992)
resistance to ampicillin and chloramphenicol.
reported 100% resistance, Harrass et al. (1998)
Further studies should be conducted in order to
found 11.2% of strains to be resistant, but all the
establish the resistance mechanisms in A. butzleri
strains studied by Atabay and Aydin (2001) were
as well as to explain the geographical differences
susceptible to this antibiotic. Such differences
observed in their susceptibility to these antimi-
could be due to local differences, probably re-
lated to the use of this antibiotic. In Chile,chloramphenicol is the drug of choice in the treat-
ment of typhoid fever which, declining in inci-dence, remains endemic here (Fica et al., 2001).
The susceptibility patterns of 50 A. butzleri strains
All the ampicillin resistant strains of A.
to six antimicrobial agents were determined using the
butzleri (45) were tested for beta lactamase pro-
E-test method. No strain was found to be resistant to
duction. Table 2 shows the results obtained with
gentamicin and tetracycline, but two different strains(2%) were resistant to erythromycin and ciproflo-
the chromogenic cepahlosporin test and the disc
xacin. Ninety and 98% of the strains were resistant to
diffusion susceptibility test for ampicillin-
ampicillin and chloramphenicol, respectively. Only
sulbactam. Only two strains were able to produce
two of the 45 ampicillin resistant strains were able to
ß-lactamase, giving a positive chromogenic
cepaholosporin test. However, because the use
TABLE 2. ß-Lactamase production and suscep-
ATABAY, I., J. CORRY. 1998. Evaluation of a new
tibility to ampicillin-sulbactam in 45 A. butzleri
Arcobacter enrichment medium and comparison
ampicillin resistant strains.
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Glossary: A Quick Guide to the MathematicalI just found this here : www.math.ucdavis.edu/, couldn’t resist sharing. • absolute maximum. The all-time, one-and-only, single, absolute andtotal maximum value of a function over a specified domain of the function. (Although it is the unique maximum value, it could occur at more thanone point, as when you have two mountain peaks of exactly the sam