Rev Biomed 1998; 9:92-96.
Helicobacter pylori: susceptibility
to amoxycillin, erythromycin,
nitrofurantoin and metronidazole
in Costa Rica.
Eugenia M. Quintana-Guzmán1, María L. Arias-Echandi1, Pilar Salas-Chaves1, Henry Davidovich-Rose2,Karl Schosinsky-Neverman1.
1Facultad de Microbiología, Universidad de Costa Rica, 2Servicio de Gastrocopía, Hospital de SanVicente de Paul, Heredia, Costa Rica.
These results support the idea of
To determine the sensibility pattern of
evaluating new treatment therapies in Costa Rican
strains of H. pylori
isolated from Costa Rican
inhabitants in order to eradicate this bacteria.
(Rev Biomed 1998; 9:92-96)
Material and methods.
The susceptibility to
antibiotics of 41 strains of Helicobacter pylori
Key words: Helicobacter pylori
isolated from 34 Costa Rican patients, 20 male and
14 female, was evaluated using the disk diffussiónmethodology. Six different antibiotic discs weretested (amoxycillin (10 µg), erythromycin (5 µg)
tetracycline (10 µg), ciprofloxacin (1 µg),
Helicobacter pylory: Susceptibilidad de la
nitrofurantoin (50 µg) and metronidazole (5 µg)).
amoxilina, eritromicina, tetraciclina,
Metronidazole showed the greatest rate
ciprofloxacina, nitrofurantoína y metronidazol
of resistance (95.1%), followed by erythromycin
en Costa Rica.
(92.6%). Nitrofurantoin and ciprofloxacin
Determinar los patrones de sensibilidad
presented the highest rates of sensibility (90.2 and
de cepas de Helicobacter pylori
aisladas de habi-
92.7% respectively). There is no statistical
difference in the percentages of resistance between
Material y métodos.
Se ev aluó la suceptibilidad
a antibióticos a 41 cepas de Helicobacter pylori
Corresponding addres: Dra. María L. Arias-Echandi. Facultad de Microbiología, Universidad de Costa Rica, Ciudad Universitaria "Rodrigo Facio".
Costa Rica, América Central.
Received October 16, 1997; Accepted January 21, 1998.
This paper is also available at http://www.uady.mx/~biomedic/rb98923.html
Vol. 9/No. 2/Abril-Junio, 1998
EM Quintana-Guzmán, ML Arias-Echandi, P Salas-Chaves y col.
aisladas a partir de 34 pacientes costarricenses, 20
ces gastric HCl and makes the mucus present more
hombre y 14 mujeres, usasando la metodología de
fluid, allowing an increased exposure to the mu-
difusión en disco. Se analizaron seis diferentes dis-
cosa (4). The effect on the mucosa is increased by
cos de antibióticos (amoxilina (10 µg), eritromicina
the action of a cytotoxic toxin, which produces a
(5 µg), tetraciclina (10 µg), ciprofloxacina (1 µg),
vacuolization of the gastric epithelial cells. These
nitrofurantoína (50 µg) y metronidazol (5 µg).
characteristics, joined with other environmental
El metronidazol presentó el mayor
predisposing factors such as stress, smoking, use
porcentaje de resistencia (95.1%), seguido por
of certain drugs, etc., play a very important role in
la eritromicina (92.6%). Los antibióticos que
the development of peptic ulcer (4).
presentaron los mayores porcentajes de suscep-
tibilidad fueron la nitrofurantoína (90.2%) y la
with different antimicrobial agents, in order to
ciprofloxacina (92.7%). No hubo diferencia es-
determine which one is the most efficient in the
tadística en los porcentajes de resistencia a los
erradication of this microorganism from the gas-
antibióticos entre hombres y mujeres.
tric mucosa (5-7). Although the organism is sen-
Los resultados apoyan la idea de
sitive to many antibiotics in vitro
, the in vivo
evaluar nuevas terapias de tratamiento en los
dication rate is often disappointing based on a
pacientes costarricenses para lograr erradicar esta
quick appearance of resistant strains and due to
bacteria. (Rev Biomed 1998; 9:92-96)
the very acid gastric pH, antibiotics present lo-wer inhibitory concentrations.
Palabras clave: Helicobacter pylori
therapeutic regimes are applied, two combine theaction of bismuth and metronidazole withtetracycline or amoxycillin the third one uses
omeprazole and amoxicillin. None of these three
) is a genus of
regimes is completely satisfactory, what's more,
microaerophilic, motile, Gram negative curved
they imply important side effects and a reduced
bacilli, that is widespread in the community and
therapeutic effectivity in populations that present
usually persists throughout a patients’ life. It is
a high resistance to nitromidazoles (8). As a result,
considered to be the most important factor in the
5-20% of patients with a potentially curable
aetiology of duodenal ulcer and the majority of the
disease stay at risk of developing recurrent or
benign, non-drug induced gastric ulcers. It has also
complicated ulcer disease or progession of gatritis
been associated as a risk factor in the development
In Costa Rica, the first description of this
Due to its wide distribution, association
agent was made in 1988 (11,12). Its prevalence
with different pathological effects and especially
in patients with gastritis is of 70% and in peptic
with cancer, in 1994 the National Institute of
ulcer near to 90%. The actual treatment offered
Health Consensus Development Conference on
to Costa Rican patients includes the use of
in peptic ulcer disease recommended
metronidazole and tetracycline or amoxycillin,
its eradication in all patients with documented
agents associated with side effects and resistance
presents urease activity, a condi-
tion that represents an adaptation for the gastric
sensibility pattern of strains of H. pylori
enviroment (1). This enzyme has been describred
from Costa Rican inhabitants, evaluating the most
as an important virulence factor since it neutrali-
commonly used antibiotics in order to determine
H. pylori a antibióticos.
the effect of these on the potential eradication of
zone were considered as resistant mutants. An
inhibition zone of < 21 mm for amoxycillin and14 mm for metronidazole was considered asresistant (13).
MATERIAL AND METHODS.
For 41 H. pylori
strains, the susceptibility to
Forty one clinical isolates coming from 34
patients (20 male and 14 female) that assisted to
ciprofloxacin, nitrofurantoin and metronidazole
the Gastroscopy Service, Hospital San Vicente de
was determined by disc diffusion test. The overall
Paul, Heredia, Costa Rica were studied for their
resistance to these antibiotics is presented in table
sensibility pattern at the Microbiology Faculty,
1. The antibiotic that exhibited the greatest rate of
University of Costa Rica. The isolates were
resistance was metronidazole (95.1%) followed by
identified using Gram stain, motility, oxidase,
nitrofurantoin presented the highest rates of
The strains were stored at -70oC in tryptic
sensibility (7.4 and 9.8%, respectively).
soy broth (TSB) containing 15% (v/v) glycerol for
For the different antibiotics tested, there is
less than a month before the antibiotic analysis.
no statistical difference in the percentage of
resistance to all the six antibiotics tested.
The susceptibility to antibiotics was tes-
ted using the disk diffusion assay, according
to the methodology described by López Brea
Resistance of H. pylori to amoxycillin,
& Alarcón (13). Freezed vials containing the
ciprofloxacin, erythromycin, metronidazole,
different strains were inoculated on blood agar
nitrofurantoin and tetracycline in 41 different
and incubated microaerophylically (Anaerobic
isolates from Costarrican patients.
System BBL®) for five days. Colonies weresuspended in 1 mL tryptic soy broth pH 7.2
to a density of 0.5 McFarland (approximately106 CFU/mL). 0.5 mL of this inoculum was
flooded to a non selective blood agar plate and
allowed to dry for 5-10 min. Six different dis-
c s w e r e t e s t e d ( a m o x y c i l l i n ( 1 0 µ g ) ,
erythromycin (5 µg), tetracycline (10 µg), ci-
profloxacin (1 µg), nitrofurantoin (50 µg) and
metronidazole (5 µg) (Piqaux®). They wereincubated under microaerophilic conditions at
35oC for 72 h.Lecture.
based on the size fo the inhibition zone defined
Numerous eradication regimes to cure H.
for tetracycline, erythromycin, ciprofloxacin
infections have been published. New the-
and nitrofurantoin, large zones of inhibition
rapies keep being lauched, some with adequate
around the disc were defined as sensible and
effects and others with variable eradication re-
growth to the edge of the disc meant resistance,
any small colonies growing within the inhibition
Because the eradication of H. pylori
Vol. 9/No. 2/Abril-Junio, 1998
EM Quintana-Guzmán, ML Arias-Echandi, P Salas-Chaves y col.
always been successful, reasons for such failures
19.6% in the present study. Literature indicates that
have been suggested to be due either to side effects
this antibiotic also exhibits very low eradication
presented by the patient with the eventual
abandonment of the treatment, or to the resistance
The resistance to amoxycillin by H. pylori
of the bacteria to the antibiotics used.
not been evaluated by big models, but there is an
is relatively sensible to a wide variety
important number of people that present allergy to
of antibiotics in vitro
, but in vivo
is quite difficult to
eradicate (15) from the gastric mucosa, due to
Nitrofurantoin is a drug of small use around
desnaturalization of the molecules by acid pH (13),
the world except for Latin America, it is expected
impermeability to these or even their evacuation of
to present an eradication rate for Helicobacter pylori
around 70%. In this work, nitrofurantoin presented
The resistance to different antibiotics vary
a very high sensibility, being of 90.2%.
considerably around the world. Some of this
The H. pylori
strains analyzed presented an
variations may be due to different techniques defining
important susceptibility to ciprofloxacin (92.7%), an
resistance (16). Nevertheless, the increased
universal behavior (20), since this antibiotic presents
use of certain antibiotics for different purposes
a resistance rate ranging from 5 to 15%, which could
created a selective pressure for the development of
be explained based in a lower comsumption of this
drug resistance. Often, many of these users would
be asymptomatically infected with H. pylori
The monotherapy for the eradication of H.
is not used anymore. New therapies include
The use of antibiotics in our country has been
the use of antiacids or bismuth with metronidazole
indiscriminated, this explains the very high resistant
and amoxycillin or tetracycline, even though the
rates found in this work to common antibiotics such
patient may present resistance to them. What's more,
as metronidazole (95.1%) and erythromycin
numerous studies show that when triple therapy is
(92.6%). Clinical studies have shown that metroni-
given to patients harboring resistant strains,
dazole resistance has developed after ineffective
eradication can still be obtained in a considerable
treatments, either in gynecological infections or for
number (22) especially if theraphy of longer duration
diarrheal illnesses (17). The world-wide prevalence
of metronidazole resistance, which develops rather
There was no statistical difference between
quickly (18) ranges from 10 to 90%, being Europe
males and females in the resistance to the different
and Australia the populations that present the lo-
antibiotics evaluated as has been found in other
west resistance rates and Central Africa the one with
studies (17), this can be explained by the
highest resistance rate (70-90%) (17). Our country
indiscriminate and abusive use of antibiotics that has
has to be included in this last group. Nevertheless,
been going on in the country for years.
there is no scientific basis to believe that strains of
This study shows an important resistance to
resistant to metronidazole are more likely
metronidazole, erythomycine and tetracycline from
than sensitive strains to cause ulcer disease, dyspep-
the population, so considerable effort has to be
directed towards the introduction of new therapies
Treatment of H. pylori
with erythromycin has
that include the use of antibiotics such as
shown very poor results, the susceptibility rate
nitrofurantoin and ciprofloxacin in order to eradicate
described is lower than 10%, similar to the results
this bacteria. The ideal treatment should be simple,
obtained (7.4%). This may be due to a reduction in
effective, economic, free of side effects and with high
the efficiency of the molecule at an acidic pH (19).
rates of eradication. Also, further in vivo
Tetracyclines presented an eradication rate of
be done with Costa Rican inhabitants in order to
H. pylori a antibióticos.
find the most simple and effective forms of therapy
11.- Rivera P, Hernández F, Sigarán M, Aguilar-Ortíz M.
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12.- Hernández F, Rivera P, Sigarán M. The first cases of
We wish to thank Laura Villalobos for her
reported from Costa Rica. Rev Biol Trop
13.- López Brea M, Alarcón T. Sensibilidad antimicrobiana
en la infección por Helicobacter pylori
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Vol. 9/No. 2/Abril-Junio, 1998
N O R T H A M E R I C A N E L E C T R I C R E L I A B I L I T Y C O U N C I L P r i n c e t o n F o r r e s t a l V i l l a g e , 1 1 6 - 3 9 0 V i l l a g e B o u l e v a r d , P r i n c e t o n , N e w J e r s e y 0 8 5 4 0 - 5 7 3 1 Electricity Sector Influenza Pandemic Planning, Preparation, and Response Reference Guide Introduction Business continuity planning
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