Susceptibility to antibiotics in isolates of Lactobacillus plantarum RAPD-type Lp299v, harvested from antibiotic treated, critically ill patients after administration of probiotics

Abstract

Recultured Lactobacillus plantarum 299v‐like strains were tested regarding antibiotic susceptibility, and no decrease was detected. Antibiotics are frequently used to treat patients in intensive care units (ICUs) and are associated with a significant risk of selection of resistant bacterial strains. In particular, it is possible that genetic transfer of antibiotic resistance to the resident gastrointestinal flora, as well as to administered probiotics, may be increased in the ICU setting. The aim of the present investigation was to detect possible changes in antimicrobial susceptibility in reisolates of the probiotic strain Lactobacillus plantarum 299v (Lp299v) given to antibiotic treated, critically ill patients. Lp299v‐like strains were identified in cultures of biopsies and fecal samples from 32 patients given the probiotic strain enterally in two previous ICU studies. The patients received a variety of antibiotics. Isolates with the same genomic RAPD profile (RAPD‐type) as Lp299v were obtained to enable monitoring of antibiotic susceptibility by E‐tests. Forty‐two isolates, collected throughout the course of illness, were tested against 22 different antibiotics. No obvious decrease in susceptibility was found for 21 of the tested antibiotics. There was a tendency toward decreased susceptibility to ampicillin. The stable antibiotic susceptibility profiles of the Lp299v‐like isolates studied here suggests this probiotic is less likely to acquire resistance when administered to critically ill patients treated with broad‐spectrum antibiotics.

Full text

MicrobiologyOpen. 2019;8:e642.  
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https://doi.org/10.1002/mbo3.642
www.MicrobiologyOpen.com
1 | INTRODUCTION
Probiotics are widely used in society for health promotion, and they
are often employed in medical settings, primarily to prevent the
side effects of antibiotics. A number of studies and reviews have
suggested that probiotics have beneficial effects on critically ill
patients (Barraud, Bollaert, & Gibot, 2013; Bo et al., 2014; Elaine
et al., 2012; Goldenberg et al., 2013; Manzanares, Margot Lemieux,
Langlois, & Wischmeyer, 2016; Shimizu et al., 2013), whereas other
investigations have shown no advantages of probiotics compared to
Received:27November2017
|
Revised:11Februar y2018
|
Accepted:23March2018
DOI: 10.1002/mbo3.642
ORIGINAL ARTICLE
Susceptibility to antibiotics in isolates of Lactobacillus
plantarum RAPD- type Lp299v, harvested from antibiotic
treated, critically ill patients after administration of probiotics
Bengt Klarin1 | Anders Larsson2 | Göran Molin3 | Bengt Jeppsson4
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
© 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.
This study was pe rformed at Sk åne Universit y Hospital, L und, Sweden and at Probi AB , Lund, Sweden.
1Department of Anaesthesiology and
Intensive Care, Lund University and Skåne
University Hospital, Lund, Sweden
2Department of Surgical Sciences, Section of
Anaesthesiology and Intensive Care, Uppsala
University Hospital, Uppsala, Sweden
3Applie dNutritionandFood
Chemistry, Lund University, Lund, Sweden
4Department of Surgery, Lund University
and Skåne University Hospital, Malmö,
Sweden
Correspondence
Bengt Klarin, Department of
Anaesthesiology and Intensive Care, Skåne
University Hospital, SE-221 85 Lund,
Sweden.
Email: Bengt.Klarin@med.lu.se
Funding information
Region Skåne, Sweden; Scandinavian Society
forAntimicrobialChemotherapyFoundation;
Probi AB, Lund, Sweden.
Abstract
Recultured Lactobacillus plantarum 299v- like strains were tested regarding antibiotic
susceptibility, and no decrease was detected. Antibiotics are frequently used to treat
patients in intensive care units (ICUs) and are associated with a significant risk of se-
lection of resistant bacterial strains. In particular, it is possible that genetic transfer of
antibiotic resistance to the resident gastrointestinal flora, as well as to administered
probiotics, may be increased in the ICU setting. The aim of the present investigation
was to detect possible changes in antimicrobial susceptibility in reisolates of the pro-
biotic strain Lactobacillus plantarum 299v (Lp299v) given to antibiotic treated, criti-
cally ill patients. Lp299v- like strains were identified in cultures of biopsies and fecal
samples from 32 patients given the probiotic strain enterally in two previous ICU
studies. The patients received a variety of antibiotics. Isolates with the same genomic
RAPD profile (RAPD- type) as Lp299v were obtained to enable monitoring of antibi-
oticsusceptibilitybyE-tests.Forty-twoisolates,collectedthroughoutthecourseof
illness, were tested against 22 different antibiotics. No obvious decrease in suscepti-
bility was found for 21 of the tested antibiotics. There was a tendency toward de-
creased susceptibility to ampicillin. The stable antibiotic susceptibility profiles of the
Lp299v- like isolates studied here suggests this probiotic is less likely to acquire re-
sistance when administered to critically ill patients treated with broad- spectrum
antibiotics.
KEY WORDS
antibiotic pressure, antibiotic susceptibility, critically ill patients, E-test, Lactobacillus plantarum
299v, probiotics

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controls (Gu, Wei, & Yin, 2012; Wang et al., 2013). However, little
is known about a number of critical issues in this context, such as
the possible impact of probiotics on the normal microbiological flora
(Imperial & Ibana, 2016), and the effects of administered drugs on
the antibiotic susceptibility of probiotics. Some experimental ani-
mal data support the suggestion that antibiotic resistance genes are
transferred to probiotic strains (Mater, Langella, Gérard Corthier, &
Flores,2008),althoughthisaspecthasnotbeenstudiedinthehos-
pital environment.
The highest antibiotic pressure is in the intensive care units
(ICUs), where patients with few exceptions are given antibiotics,
mainly broad- spectrum agents, as an important part of their treat-
ment. Therefore, in ICUs there is significant ongoing selection of
bacteria with resistance to antibiotics (Karam, Chastre, Wilcox,
& Jean- Louis Vincent, 2016; Zilahi, Artigas, & Martin- Loeches,
2016). The colon can be regarded as a fermenter that has a high
bacterial content, and it is highly likely that there is exchange
of different molecules including genetic material. Probiotics are
used in many ICUs mainly in order to reduce the prevalence of
antibiotic- associated diarrhea. Nonetheless, we hypothesized that
transfer of antibiotic resistance to probiotics could occur in this
context.
Lactobacillus plantarum is considered to be a genomically stabile
species.Furthermore,regulartestsoftheinvitroantimicrobialsus-
ceptibility of Lp299v to a number of agents have failed to reveal any
changes over the years. Guidelines on interpretive breakpoints for
the minimum inhibitory concentration (MIC) values of a number of
antibiotics against strains of the species Lactobacillus plantarum have
beenpublishedby theEuropeanFood SafetyAgency (EFSA) (EFSA
2005) an d were updated f or some of the se agents in 20 08 (EFSA
2008)and2012(EFSA2012).
Lactobacillus plantarum 299v (Lp299v; DSM9843) is the probiotic
component of a number of products that have been commercially
available for more than three decades in Sweden and for several
years in other countries. Moreover, Lp299v in the form of a fruit
drink (ProViva®) has been used as a prophylactic remedy in many
Swedish hospitals, including ICUs. To date, several ICU studies using
the strain Lp299v (Klarin, Johansson, Molin, Larsson, & Jeppsson,
2005; Klarin, Wullt, et al., 2008; McNaught, Woodcock, Anderson,
& MacFie, 20 05), and th e genomical ly closely re lated L. plantarum
299 (= DSM 6595) [Klarin, Molin, Jeppsson, & Larsson, 2008; Rayes,
Seehofer, et al., 2002; Rayes, Hansen, et al., 2002) have not shown
any important side effects of these probiotics.
Two earlier ICU- based studies of critically ill patients receiv-
ing broad- spectrum antibiotics addressed the following issues: (1)
whether administration of Lp299v resulted in adherence of the pro-
biotic to the gut mucosa (Study 1, Klarin et al., 2005) and (2) whether
coadministration of Lp299v with antibiotics reduced colonization of
Clostridium difficile (Study 2, Klarin, Wullt, et al., 200 8). In the present
investigation, 42 isolates of RAPD- type Lp299v cultured from rectal
mucosal biopsies (Study 1) or fecal specimens (Study 2) were inves-
tigated to determine whether antibiotic susceptibility profiles were
altered after gastrointestinal transit in patients on broad- spectrum
antibiotics. The results showed no significant changes in the antibi-
otic susceptibility profiles of Lp299v- like isolates screened against a
panel of 22 broad- spectrum antibiotics. This finding together with
the low incidence of side effects observed in Studies 1 and 2, indi-
cates that the probiotic Lp299v should be a viable candidate for use
in critically ill patients receiving antibiotics.
2 | MATERIALS AND METHODS
2.1 | Samples
In two separate prospective randomized controlled investigations
(Studies 1 and 2) the probiotic strain Lp299v was given enterally
to critically ill adult patients anticipated to require intensive care
for ≥3days. Eigh t patients in Stud y 1 and 22 patient s in Study 2
were given Lp299v. The control groups (seven and 22 patients, re-
spectively) received similar standard treatments but no probiotics
(Figure1). Biopsies were taken in Study 1,and fecalsampleswere
collected in Study 2. Six samples (three from each study) collected
before start of the intervention began were positive for Lp299v. All
other positive samples shown in the figures came from patients ran-
domized to the Lp299v group. In Study 1, a total of 47 biopsies were
taken (27 in the Lp299v group and 20 in the control group), with a
median of three samples per patient. In Study 2, 167 fecal samples
were collected (74 and 93 in Lp299v and control patients, respec-
tively), also with a median of three samples per patient. Lp299v- like
isolates were obtained from biopsies of the rectal mucosa (Study 1),
or from fecal samples (Study 2). In both studies samples were col-
lected at inclusion and thereafter twice a week until discharge from
the ICU. The patients were treated with different types of antibi-
otics, initially empirically and thereafter in accordance with clinical
findings and the results of microbiological cultures. All patients had
received one or more doses of antibiotics before any study product
was given and before the first biopsy or fecal sample.
2.2 | Analyses
Lactobacilli were cultured from rectal mucosal biopsies or fecal
specimens at the time of Studies 1 and 2 using Rogosa agar (Oxoid,
Basingstoke, Hampshire, England) incubated anaerobically at 37°C
for 3 days. Colonies suspected to be Lp299v (large, creamy white-
yellowish, and somewhat irregular in shape) were isolated and fur-
ther identified by randomly amplified polymorphic DNA typing
(RAPD) (Johansson, Quednau, Molin, & Ahrné, 1995). All isolates
werestored at−8 0°C pendinganalysis. Afterreconditioningofthe
frozen strains, Brucella broth suspensions of the respective strain,
were inoculated on Brucella agar plates (Oxoid). E- test strips of 22
antibiotics (detailed below in section 2.3) were applied on the inocu-
lated agar plates, and incubated anaerobically at 35°C for 72 hr. All
analyses were done in duplicate.
To enable comparisons of MIC values of the harvested isolates
and the original strain, the isolates were divided into four groups
according to their exposure to antibiotics and administration of

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KLAR IN et AL.
Lp299v: (1) isolates cultured from samples collected prior to pro-
biotic intervention in each study; (2) isolates obtained from rectal
mucosa biopsies; (3) isolates acquired from fecal samples; (4) isolates
obtained from fecal samples from patients in Study 2 given Lp299v
(as the fruitdrink ProViva®) after conclusion of their participation in
the study. The subjects in group 4 were given the control product
(without probiotics) during the study period, but then as non- ICU
patients at the same Department of Infectious Diseases received the
same treatment as other patients in that ward.
2.3 | Tested antibiotics
A wide panel of antibiotics (E- tests; AB Biodisk, Solna, Sweden)
was tested against the original strains and the Lp299v- like isolates.
The following antibiotics were given to one or more of the study
participants were ampicillin, cefotaxime, ceftazidime, cefuroxime,
clindamycin, erythromycin, gentamicin, imipenem, levofloxacin,
meropenem, metronidazole, netilmicin, piperacillin, tobramicyn,
trimethoprim (to patients given in combination with sulfametoxa-
zole), and vancomycin. To fulfill regulatory requirements for the
company holding the patent on Lp299v (Probi AB), some antibi-
otics seldom used in Sweden were also tested namely; cefepime,
chloramphenicol, kanamycin, linezolid, quinupristin/dalfopristin,
and streptomycin.
3 | RESULTS
3.1 | Studied samples
Forty-t wo cultured Lp299v-like isolates were analyzed together
with the original strain (Lp299v), and with the genomically closely
related strain Lactobacillus plantarum 299.
The strain L. plantarum 299 (DSM6595) has been used in stud-
ies of ICU patients conducted by our group (Klarin, Molin, et al.,
2008) and by other researcher (Oláh, Belágyi, Issekutz, Gamal, &
Bengmark, 2002; Rayes, Seehofer, et al., 2002; Rayes, Hansen, et al.,
2002), and therefore it was also of interest to evaluate the antibiotic
susceptibility of this probiotic. Six isolates were from samples taken
at study inclusion (prior to probiotic intervention), and 24 were from
samplescollectedduring the studyperiods.From threepatientsin
the control group (not given Lp299v) in Study 2, 16 samples (12 of
them positive for Lp 299v) were obtained after conclusion of the ac-
tual study period. These patients required an extended care period
with fur ther antibiotic therapy after their s tay in ICU, and as ordinar y
FIGURE1 FlowdiagramshowingthenumberofpatientsthatparticipatedinStudies1and2

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ward patients they received routine care that included the fruit drink
ProV iva®.
3.2 | MIC determinations
The MIC values determined for Lp299v and L. plantarum 299 were
within a twofold (1 + 1) dilution (Table 1) and thus did not differ
measurably. Both Lp299v and L. plantarum 299 are intrinsically re-
sistant to aminoglycosides, vancomycin, and metronidazole, and in
this study they also had high MIC values for levofloxacin. Ratios of
MICs for the remaining 13 antibiotics to MICs of the Lp299v original
strainareshowninFigures2–5.Wefoundnosignificantchangesin
susceptibility to most of the tested drugs. Differences in MIC lev-
els were within a twofold dilution step (1 + 1) except for ampicillin,
several isolates of which showed an MIC increase in two 1 + 1 steps
(1 + 3). There was no correlation with any increase in MIC for other
antibiotics in the samples that had an increased MIC for ampicillin.
MIC breakpoints for some of the tested antibiotics have been de-
terminedbyEFSA(EFSA2005)(Table1),butnotforantibioticsthat
arefrequentlyusedinICUs.FortheMICbreakpointsthatareavail-
able, none of the observed deviations from the original strain led to
changes from susceptibly to resistance.
The tested isolates were exposed to different antibiotics and
combinations of antibiotics and to the environment in the GI tract
for varying periods of time. In almost all cases the drugs were given
intravenously, and cephalosporins and carbapenems were used most
frequently. In patient s with several subsequent isolates, we found no
gradualchangeinsusceptibility.Fourofthesixpatientswithisolates
from the sample taken at study inclusion had been treated with an-
tibioticsfor 1–20daysbeforestartofthe investigation. Ourresults
demonstrate that the antibiotic susceptibility of the probiotic bac-
terium Lactobacillus plantarum 299v remains stable also after pas-
sage through the GI tract in patients treated with broad- spectrum
antibiotics.
4 | DISCUSSION
The present evaluation was performed on frozen samples that had
beencollec te dint wopreviouss tudiesands toreda t−80 °C(Stu di es
1 and 2) and our aim was to detect changes in antibiotic susceptibil-
ity of a probiotic Lactobacillus strain given to intensive care patients.
These patients were treated with broad- spectrum antibiotics ad-
ministered parenterally, and hence major changes in the microbiota
could be anticipated, in particular selection of antibiotic- resistant
bacterial species or clones. Conceivably, this situation would favor
dissemination of antibiotic resistance that would include the pro-
biotic strain in focus in our study. However, in two cohorts of pa-
tients, we were unable to detect any changes in susceptibility of the
probiotic strain to a number of antibiotics, most of which had been
usedclinicallyatourICU.Furthermore,wefoundnochangesfrom
susceptibility to resistance for any of the tested antibiotics. It was
impossible for us to conclude that transitions cannot occur, because
MIC breakpoints are lacking for many of the antibiotics widely used
to treat critically ill patients. Notwithstanding, the MIC values for
Lp299v for the antibiotics considered, (e.g., cephalosporins and car-
bapenems) were all low, indicating that development of resistance
is less likely.
In six of the 42 samples that we assessed (representing five of
32 individuals) the ampicillin MIC values showed an increase in two
1 + 1 dilution steps (1 + 3), possibly approaching what can be con-
sidered decreased susceptibility. Consecutive samples from some of
those patients showed no trend towards greater reduction in sus-
ceptibility, although the values did shift over time (but were none-
theless higher than values for the original strain). If this was indeed
a true decrease in susceptibility, there probably would have been an
increase over time or a stable increase in the MIC value. None of the
patients of interest were treated with ampicillin. The major part of
TABLE1 MIC values (mg/L) determined by E- tests for L.
plantarum 299 and L. plantarum 299v, and MIC breakpoints for the
species L. plantarumpresentedbyEFSA(EFSA2005)
Antibiotic
L.
plan-
tarum
299
L.
plan-
tarum
299v
EFSA, MIC breakpoints
species L. plantarum
Ampicillin 0.094 0.094 4
Cefepime 0.047 0.047 Not specified/tested
Cefotaxime 0.094 0.094 Not specified/tested
Ceftazidime 0.5 0.75 Not specified/tested
Cefuroxime 0.25 0.5 Not specified/tested
Chloramphenicol 2 2 8
Clindamycin 2 3 4
Erythromycin 0.75 1 4
Gentamicin 32 32 64
Imipenem 0.064 0.064 Not specified/tested
Kanamycin >256 >256 64
Levofloxacin 32 32 Not specified/tested
Linezolid 10.75 4
Meropenem 0.064 0.064 Not specified/tested
Metronidazole >256 >256 Not specified/tested
Neomycin Not
tested
Not
tested
32
Netilmicin 48 32 Not specified/tested
Piperacillin 0.5 0.75 Not specified/tested
Quinupri/
Dalfopri
0.5 0.5 4
Streptomycin >2 56 >256 64
Tetracycline Not
tested
Not
tested
32
Tobramycin >2 56 >2 56 Not specified/tested
Trimethoprim 0.125 0.125 8
Vancomycin >256 >25 6 `Not required`
MIC, minimum inhibitory concentration.

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KLAR IN et AL.
FIGURE2 Reisolates of L. plantarum 299v found in inclusion samples
0
1
2
3
4
Lp299v
S1/6
S1/8
S1/13
S2/III-20
S2/IV-1
S2/IV-4
SZ/X-Y
Study Z (1 or 2)
Study centre X
Pat no Y
Ratios of measured MICs for reisolates of L. plantarum 299v
compared to MICs for the original strain
FIGURE3 Reisolates of L. plantarum 299v collected in Study 1
0
1
2
3
4
Lp299v S1 2 - 4 S1 2 -11 S1 2 -14 S1 8 -22 S1 14 -8 S1 15 -4 S1 15 -7
S1 X - Y
Study 1
Pat no X
Study day Y
Ratios of measured MICs for reisolates of L. plantarum 299v
compared to MICs for the original strain

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KLARIN et AL .
the samples with an increase in the MIC of ampicillin were collected
after several days of treatment in the ICU.
Other species and strains used as probiotics show intrinsic resis-
tance to several antibiotics (Wong, Ngu, Dan, Ooi, & Lim, 2015), al-
though with different patterns compared with L. plantarum 299 and
Lp299v. However, the changes in antibiotic susceptibilit y of bacterial
strains used as probiotics have been studied and have in some cases
been found to be due to increased activity in cellular efflux pump
mechanisms (Thumu & Halami, 2012). This may explain the observed
change in the MIC of ampicillin.
Lp299v and L. plantarum 299 have been used in several clinical
studies without any reports of infections with pathogens showing
extended antimicrobial resistance that might have originated from
these two strains. Therefore, we focused the present postexposure
survey focused on these probiotics.
The GI tract is estimated to harbor 600 or more bacterial spe-
cies, some of which exhibit intrinsic or acquired resistance to various
antibiotics. Inevitably, such species or strains may be positively se-
lected to varying degrees during antibiotic treatment, as exemplified
by the occurrence of antibiotic- associated diarrhea, which is often
caused by the opportunistic pathogen Clostridium difficile (Kevin,
Brown, K hanafer, Nick Daneman , & Fismana, 2013; Nap olitano &
Edmiston,2017;Vardakas, Trigkidis, Boukouvala,&Falagas, 2016).
An investigation of pharyngeal streptococci in healthy volunteers
demonstrated that even short periods of treatment with macrolides
(3 days for azitromycin) were sufficient to increase the proportion
of macrolide- resistant strains from 26% to 86%, and such ecological
changes persisted for at least 6 months (Malhotra- Kumar, Lammens,
Coenen, Van Herck, & Goossens, 2007). Also a study of patients
admitted for thoracic surgical procedures and given cefazolin for
various lengths of time showed a significant increase in the prev-
alence of resistant Escherichia coli at discharge compared to admis-
sion (Jonkers, Swennen, London, Driessen, & Stobberingh, 2002).
The figures reported in the cited study may not be representative
for all species and locations, but they do reveal dramatic changes
in selection of resistant strains within a few days of antibiotic treat-
ment. Many of the retrieved isolates in the present investigation
came from patients with prolonged antibiotic load, and the probabil-
ity of either an induced resistance or selection of resistant bacteria
would be considered high in such subjects. Gram- negative bacteria
may play the most important role in infections originating from the
GI tract, although gram- positive pathogens are also a clinical issue.
Increasing occurrence of multidrug- resistant cocci is becoming a se-
rious problem in many clinics and above all in critically ill patients
(Lee, Lee, Park, Jeong, & Lee, 2015; Munita, Bayer, & Arias, 2015).
Selective decontamination has been applied for many years and has
been considered not to carry any risk of development of resistant
bacteria, although modern techniques have disproved that assump-
tion (Buelow, Bello González, & Verslius, 2014; Buelow et al., 2017).
In contrast the use of probiotics has appeared as a complement in
the prevention of emergence of antibiotic resistance (Ouwehand,
Forssten,Hibberd,Lyra,&Stahl,2016).
Treatment with antibiotics changes the intestinal microbiota in
an unfavorable way, but ongoing research concerning this topic and
FIGURE4 Reisolates of L. plantarum 299v collected in Study 2
0
1
2
3
4
Lp299v II 2-13 II 2-15 III 1-4 III 4-2 III 4-4
III 7-3 III 14-11 III 15-8 III 16-4 III 19-4 IV 1-13
IV 3-7 IV 5-9 IV 5-13 IV 8-15 V 1-3 V 1-4
N X - Y
Study centre N
Pat no X
Study day Y
Ratios of measured MICs for reisolates of L. plantarum 299v
compared to MICs for the original strain

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KLAR IN et AL.
use of probiotics as a complement in restoring a microbial balance
has provided promising results. It is necessary to find suitable com-
mensals of human origin for use in approaches developed to rees-
tablish balance and colonization resistance (Blaser, 2016; Pamer,
2016) is of vital importance. The results of our investigation identify
Lp299v, alone or more likely in combination with other strains as
a possible candidate for use in this context. Lp299v was originally
detected in human feces.
Clearly, it is necessary to consider the question of whether
the analyzed strains actually constituted bacteria that had been
exposed long enough to the conditions that prevail in the endoge-
nous fermenter—the colon. We have previously demonstrated that
Lp299v becomes established on the rectal mucosa to the same ex-
tent in antibiotic treated, critically ill patients as in healthy volun-
teers (Klarin et al., 2005). Introduced exogenous bacteria and fungi
(probiotics or other microorganisms) are chiefly visitors to the GI
tract, whereas the commensal microbiome is by definition prone to
remain. Administered Lp299v bacteria adhere to the mucosa and
stay there for shorter or longer periods of time. The mechanism for
this adhesion occurs via a mannose entity on the epithelium cell site
(Adlerberth et al., 1996) and hence it is plausible that Lp299v first
adheres to the mucosa, after which the bonding at that location is
disrupted and the bacteria are transported with the luminal content
and then adhere at another binding site a bit further down the gut.
This process is repeated and might be considered analogous to a
chromatography column. In addition, since the Lp299v thrive in the
gut, new generations of this strain—with the same genetic profile—
should be released. Inasmuch as Lp299v has been found to remain
adhered to the rectal mucosa long after cessation of oral adminis-
tration (Johansson et al., 1993), it is reasonable to assume that the
mannose- to- bacterium adherence bond is fairly strong. This implies
that the exposure time necessary for exchange of genetic material
in the GI tract should be sufficient, and also that the feces samples
taken can actually can represent exposed bacteria and not merely
bacteria that have rapidly passed through the gut.
In our study, the MIC values were not identical for the exposed
bacteria and the native strain, which strengthens our argument that
the cultured strains represent bacteria that had been properly ex-
posed to the fermentative environment of the GI tract. It is distinctly
possible that the retrieved Lp299v bacteria had adhered to the mu-
cosal epithelium several times in different locations during their
journey to the rectum or that they were indeed new generations of
this strain.
We found no changes in antibiotic susceptibility, and thus we
conclude that the Lp299v genome is stable. Therefore it can also
be assumed that there is little risk that Lp299v genetic material will
spread to other species.
Conditions in the human (and animal) GI tract, and especially
in the colon, are suitable for genetic exchange between species
(Salyers, Gupta, & Wang, 2004), with some species being more
pr one th a no the rstoa c ta sd ono r sa nd/o rr e ci pie nts .Furth erm o re ,
animal studies have provided overwhelming evidence for in vivo
FIGURE5 Reisolates of L. plantarum 299v collected from control patients after concluding participation in Study 2
0
1
2
3
4
Lp299v II 1-11 II 1-13
II 1-16 II 1-19 II 18-24
II 18-28 II 18-32 II 18-35
II 18-38 II 18-42 II 18-45
II 20-24
N X - Y
Study site N
Pat no X
Day after
study start Y
Ratios of measured MICs for reisolates of L. plantarum 299v
compared to MICs for the original strain

8 of 9
|
KLARIN et AL .
bacterial transfer of resistance genes (Moubareck, Bourgeois,
Courvalin, & Doucet- Populaire, 2003; Tannock, Bateup, &
Jenkinson, 1993). It also seems likely that bacteria transiently col-
onizing the intestine (e.g., probiotics) can take part in the exchange
of resistance genes. Accordingly, as part of the safety profile of
probiotics in preparations marketed as health products and for
prophylactic use in hospitals, it should be confirmed that the bac-
teria strains in these products are not prone to development of
antibiotic resistance, and this should be demonstrated by available
in vitro and in vivo methodology.
In conclusion, we found no evidence that Lactobacillus planta-
rum 299v is prone to acquiring genetic material coding for antimi-
crobial resistance in antibiotic treated, critically ill patients. In the
context of susceptibility, L. plantarum 299v is also stable against
antimicrobial agents in clinical settings with high antimicrobial
pressure.
ACKNOWLEDGMENTS
This study was supported by grants from Region Skåne, Sweden, the
Scandinavian Society for AntimicrobialChemotherapy Foundation,
and an unconditional grant from Probi AB, Lund, Sweden.
CONFLICT OF INTEREST
GM and BJ are stock holders in Probi AB.
ORCID
Bengt Klarin http://orcid.org/0000-0002-3531-8188
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SUPPORTING INFORMATION
Additional Supporting Information may be found online in the
supporting information section at the end of the article.
How to cite this article: Klarin B, Larsson A, Molin G, Jeppsson
B. Susceptibility to antibiotics in isolates of Lactobacillus
plantarum RAPD- type Lp299v, harvested from antibiotic
treated, critically ill patients after administration of probiotics.
MicrobiologyOpen. 2019;8:e642. https://doi.org/10.1002/
mbo3.642