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©INTERNATIONAL CENTRE FOR DIARRHOEAL
DISEASE RESEARCH, BANGLADESH
J HEALTH POPUL NUTR 2011 Dec;29(6):547-551
ISSN 1606-0997 | $ 5.00+0.20
Correspondence and reprint requests should be
addressed to:
Prof. William B. Greenough III
5505 Hopkins Bayview Circle
Baltimore, MD 21224
USA
Email: wgreeno2@jhmi.edu
Fax: 410-550-2513
Alternate corresponding author:
Dr. Alison M. Laffan
Email: alaffan14@gmail.com
Lactoferrin for the Prevention
of Post-antibiotic Diarrhoea
Alison M. Laffan1, Robin McKenzie2, Jennifer Forti3, Dawn Conklin3, Richard Marcinko3,
Ruchee Shrestha3, Michele Bellantoni3, and William B. Greenough III3
1Department of Epidemiology, 2Division of Infectious Diseases, and 3Division of Geriatric Medicine,
Johns Hopkins University, Baltimore, MD 21224, USA
ABSTRACT
Antibiotic-associated diarrhoea (AAD) is a common cause of morbidity and mortality. Older individuals in
long-term care facilities are particularly vulnerable due to multisystem illnesses and the prevailing condi-
tions for nosocomial infections. Lactoferrin, an antimicrobial protein in human breastmilk, was tested to
determine whether it would prevent or reduce AAD, including Clostridium difficile in tube-fed long-term care
patients. Thirty patients were enrolled in a randomized double-blind study, testing eight weeks of human re-
combinant lactoferrin compared to placebo for the prevention of antibiotic-associated diarrhoea in long-term
care patients. Fewer patients in the lactoferrin group experienced diarrhoea compared to controls (p=0.023).
Based on the findings, it is concluded that human lactoferrin may reduce post-antibiotic diarrhoea.
Key words: Antibiotics; Clostridium difficile; Colitis; Diarrhoea; Diarrhoea, Drug-induced; Elderly; Lactofer-
rin
INTRODUCTION
Up to 25% of patients treated with broad-spectrum
antibiotics experience diarrhoea (1), and this anti-
biotic-associated diarrhoea (AAD) can vary from
mild nuisance loose or watery stools to severe diar-
rhoea, including colitis. Patients in long-term care
are particularly vulnerable, and AAD is an impor-
tant cause of disability and death in this popula-
tion (2). However, Clostridium difficile, a known
aetiologic agent, explains less than half of these
cases. The consequences of AAD can be severe,
leading to debility due to volume depletion, enteral
protein loss, and a chronic inflammatory state (3).
Ironically, AAD is also being treated with antibio-
tics and may contribute to the growing problem of
antibiotic-resistant pathogens (4). To prevent post-
antibiotic diarrhoea, we employed a normal hu-
man breastmilk protein—lactoferrin—which has
both anti-inflammatory and antimicrobial prop-
erties (5) and has recently been shown to reduce
the duration of diarrhoea in children (6). We tested
whether recombinant human lactoferrin grown
in rice could prevent post-antibiotic diarrhoea in
long-term care residents.
MATERIALS AND METHODS
Nursing-home residents were randomized to re-
ceive, by gastrostomy tube, lactoferrin (5 mg/mL)
or placebo via a flush solution. Both product and
placebo were dissolved in 600 mL of 0.3% saline
solution and were similar in appearance, ensuring
that patients and staff be blind to treatment condi-
tion. The solution was administered each day for 56
days. Nurses and nursing assistants recorded stool
quality on each shift, and stool samples were tested
for C. difficile at enrollment, day 14, 42, and 56.
We conducted an interim analysis when 50% of
the enrollment goal was completed (16 partici-
pants), leading to a change in the inclusion criteria
and the randomization scheme. Thus, the study
was divided into two phases—phase 1 and phase
2. During phase 1, patients initially colonized with
C. difficile (C. difficile antigen present in stool sam-
ples) were excluded from participation, leading to
38% (6/16) of the participants being disenrolled
immediately. Phase 2 amended the protocol such
that the participants be only excluded if they had
clinically-confirmed disease due to C. difficile
Laffan AM et al.
Prevention of post-antibiotic diarrhoea
JHPN
548
(stool samples testing positive for C. difficile anti-
gen and toxin A and B). Since all participants
who were excluded from the study due to C. difficile
colonization were from the lactoferrin group (6/6),
we altered the randomization scheme in phase 2.
Phase 2 randomization was changed to two lacto-
ferrin enrollees for each placebo enrollee to ensure
a large sample-size enough for comparison between
lactoferrin and control groups.
Study subjects
Patients at the 41-bed ventilator rehabilitation unit
of the Johns Hopkins Geriatric Center beginning
a new course of broad-spectrum antibiotics (not
including metronidazole, vancomycin, and lin-
ezolid) were approached for participation in this
study, if they had met the following inclusion cri-
teria: (a) nutrition via an enteral feeding-tube; (b)
free from antibiotics for 10 days before entry into
the study; (c) not allergic to rice or rice products;
and (d) not colonized with C. difficile (phase 1) or
no signs or symptoms of clinically-confirmed C.
difficile-assoc-iated disease (phase 2).
C. difficle testing
All stool samples were tested for C. difficile anti-
gens using a rapid enzyme immunoassay Techlab
(CDIFF-CHEK). Samples testing positive for C. dif-
ficile antigens were further tested for cytotoxins
using a cell culture cytotoxicity assay (7). Samples
testing positive for C. difficile antigen and toxin A
and B were classified as infected with C. difficile.
Samples that tested positive for C. difficile antigen
only were classified as colonization.
Statistical analysis
Diarrhoea was defined as two or more loose stools
(conforming to the shape of a container) within a
24-hour period. Each 24-hour period meeting this
criterion was classified as a diarrhoea-day. Compari-
sons between lactoferrin and control groups were
made on the mean and the total number of diar-
rhoea-days. Further, an episode of diarrhoea was
defined as consecutive days of diarrhoea, ending
after two successive 24-hour periods without di-
arrhoea. The participants were also compared on
time-to-first episode of diarrhoea, or time from en-
rollment into the study to the first diarrhoea-day.
The participants never experiencing diarrhoea were
censored at the last day of participation in the study
as diarrhoea-free.
Non-parametric tests were used for comparisons
between lactoferrin and control groups because of
the small sample-sizes and failure to meet normali-
ty assumptions for continuous data. Categorical
variables were compared using Fisher’s exact test,
and statistical significance was assessed using the
Wilcoxon signed-rank test for continuous parame-
ters. The group differences in time-to-diarrhoea
were assessed using the log-rank test.
Ethical aspects
Informed consent was obtained from the patient
or healthcare agent before enrollment. The Institu-
tional Review Board of the Johns Hopkins Medi-
cine approved the study.
RESULTS
Data relating to stool for 22 participants (13 con-
trol and 9 lactoferrin participants) were analyzed.
The remaining eight participants were excluded
from analysis because they did not complete the
study. Each of these participants was exited from
the study during the first week of participation, and
the large majority (6/8) was exited from the study
immediately because of a positive C. difficile anti-
gen test results, during phase 1 of the study. Two
other participants were disenrolled when they were
found to have clinical infections due to C. difficile.
These infections, noted at day 3 and 8, were classi-
fied as existing before enrollment into the study by
the principal investigator (WBG).
The table compares the lactoferrin group with the
control group at enrollment. No significant dif-
ferences were found in comparisons between the
two groups. However, shorter times since the last
antibiotic therapy were observed in the lactofer-
rin group (p=0.07), and these participants were
more likely to be enrolled in the second phase of
the study (p=0.07).
Fewer patients (4/9; 44.4%) in the lactoferrin group
experienced diarrhoea compared to the control
group (12/13; 92.3%; p=0.023). Those treated with
lactoferrin were at a significantly reduced risk of ex-
periencing diarrhoea compared to the participants
in the control group [odds ratio (OR)=0.07, 95%
confidence interval (CI) 0.001-0.97]. Comparisons
of the mean number of diarrhoea-days (control: 9.3
vs lactoferrin: 4.0 days, p=0.072) and the percentage
of the study days with diarrhoea (control: 17.1%
vs lactoferrin: 8.0%, p=0.068) showed a trend to-
wards more diarrhoea in the control group. In addi-
tion, time-to-diarrhoea was shorter for the control
group compared to the lactoferrin group (median
time control: 7 vs lactoferrin: 60+ days, p=0.067).
This trend can be seen in the figure, which shows
the proportion of the participants free from diar-
rhoea as a function of time since enrollment into
the study for lactoferrin (dashed line) and control
(solid line) groups.
During the study period, five participants (2 con-
trol and 3 lactoferrin) became infected with C. diffi-
Prevention of post-antibiotic diarrhoea Laffan AM et al.
Volume 29 | Number 6 | December 2011 549
Table. Characteristics of participants at enrollment
Characteristics
Lactoferrin (n=9) Control (n=13)
p value
Mean
or no.
Range
or %
Mean or
no.
Range
or %
Age (years) 62.1 23.2-83.9 62.4 34.8-91.1 0.92
Male (no., %) 5 55.6 3 23.1 0.38
Black (no., %) 2 22.2 5 38.5 0.65
Anaemia (no.,%)*5 55.6 4 30.8 0.24
Time (years) on unit 0.5 0.01-1.9 1.6 0.01-6.9 0.35
Time (years) on tube-feeding 0.85 0.14-5.17 0.64 0.04-2.54 0.57
Time (days) since last antibiotic 29 18-48 48 20-99 0.07
Phase 1 of study (no., %) 1 11.1 7 53.9 0.07
Time (days) in study 50.4 19-61 45.6 25-60 0.25
C. difficile antigen+ (no., %) 2 22.2 2 15.4 1.00
The differences between lactoferrin and control groups were tested using Fisher’s exact test for
proportions and Wilcoxon signed-rank test for continuous parameters. *Anaemia was defined as
use of ferrous sulphate
Control Lactoferrin
Study time (days)
8060403020100
0.00
0.10
0.20
0.30
0.40
Proportion of participants free from diarrhoea
0.50
0.60
0.70
0.80
0.90
1.00
Fig. Kaplan-Meier plot of time-to-diarrhoea
The vertical axis represents the proportion of the participants free of diarrhoea at a given time
(horizontal axis) measured in days since enrollment into the study. Participants never experienc-
ing diarrhoea were censored at the last observed study date. The group receiving lactoferrin
(dashed line) was compared with those given placebo (solid line)
cile (positive for C. difficile antigen and toxins), and
of these participants, 2/2 in the control group and
1/3 in the lactoferrin group experienced diarrhoea.
The differences between control and lactoferrin
groups were not significant (p>0.15 for both).
DISCUSSION
Antibiotics destroy normal intestinal microbial flo-
ra often leading to diarrhoea (8). Older individuals
in long-term care settings are particularly vulner-
able (9). The risk of morbidity or mortality due to
diarrhoeal disease is higher in those aged over 65
years (2). Although C. difficile is recognized as an
important cause of AAD, evidence of infection due
to C. difficile is found in less than half of all cases
(3), and current treatment requires administration
Laffan AM et al.
Prevention of post-antibiotic diarrhoea
JHPN
550
of antibiotics. Alternative strategies are needed to
prevent or treat C. difficile and other AADs. The pi-
lot study reported here tested human recombinant
lactoferrin as a preventive tool against post-antibio-
tic diarrhoea.
Lactoferrin, a normal human protein found in
breastmilk and leukocytes, has both antibacterial
and anti-inflammatory properties (5). This protein
does not damage protective microbial flora of the
intestine. Human lactoferrin was prepared by in-
serting the human gene into rice to prepare large
amounts at low cost (10) and is nearly identical to
native human lactoferrin (11). Administering high
concentrations (5 mg/mL) of this product produced
no adverse effects in our population of frail older
adults, indicating that lactoferrin is safe.
It was recently reported that recombinant lactofe-
rrin with lysozyme reduced the duration of diar-
rhoea compared to placebo controls in children
when delivered via an oral rehydration solution
(6). These results suggest that at least some of the
effect of breastfeeding to prevent diarrhoea may be
due to lactoferrin (12). Here, we have administered
this breastmilk component to older individuals;
with a result similar to the benefits to infants. Our
results offer an interesting alternative approach to
preventing and, perhaps, treating post-antibiotic
diarrhoea.
Although not the primary outcome, we did moni-
tor for C. difficile-associated infection. There were
too few infections due to C. difficile to assess the ef-
fects of lactoferrin on this important cause of post-
antibiotic diarrhoea.
In this small study, we had observed a significant
reduction in diarrhoea between treatment and pla-
cebo groups, suggesting that lactoferrin may be ef-
fective in preventing AAD. Caution should be taken
in interpreting these results because this study was
designed as a pilot project and enrolled a small
number of patients. Further, we were forced to alter
the study protocol mid-way through the project to
achieve balance in treatment groups. However, giv-
en our significant findings, this novel preventive
approach warrants further investigation in larger
trials.
In addition to efficacy trials, more research on the
mechanisms through which lactoferrin may work
to prevent AAD is needed. Results of research in-
dicate that human lactoferrin provides a readily-
absorbable source of iron to any patients with
iron-deficiency anaemia (13), and this provides a
possible additional benefit of lactoferrin adminis-
tration. We attempted to investigate this hypothe-
sis post-hoc using information on treatment for
anaemia (use of ferrous sulphate) and red blood cell
counts; however, due to the small sample-sizes and
the post-hoc nature of the analysis, we were unable
to show an effect of red blood cell counts in these
patients. Future studies should consider the inclu-
sion of a full measure of iron status and parameters
of anaemia to explicitly test the potential added
benefit of administration of recombinant lactofer-
rin beyond its antibacterial and anti-inflammatory
properties.
Lactoferrin when administered at the start of an-
tibiotic treatment reduced the attack rate of diar-
rhoea over an eight-week period. There were too
few instances of C. difficile to assess the effects on
this cause of post-antibiotic diarrhoea. Our results
offer an interesting alternative approach to prevent-
ing and, perhaps, treating post-antibiotic diarrhoea.
Further research should incorporate larger sample-
sizes powered to determine any effect on C. difficile
as a serious complication of antibiotic therapy.
ACKNOWLEDGEMENTS
Ventria Bioscience, the manufacturer of the lacto-
ferrin flush solution, funded this research project.
This funding included a small amount of salary
support given to Johns Hopkins University for Wil-
liam B. Greenough III, Robin McKenzie, Richard
Marcinko, and Alison M. Laffan. Dr. Delia Bethel,
a Ventria scientist
advised on protocol design, pro-
vided the randomiza
tion, and assisted with data
entry. All analyses were conducted independent of
Ventria Bioscience.
The results of this study were presented at the 2009
meeting of the American Geriatric Society, Chica-
go, IL, USA.
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