Management of a cluster of Clostridium difficile infections among patients with osteoarticular infections
Färber et al. Antimicrobial Resistance and Infection Control
Management of a cluster of Clostridium difficile infections among patients with osteoarticular infections
Jacqueline Färber 0
Sebastian Illiger 2
Fabian Berger 1
Barbara Gärtner 1
Lutz von Müller 5
Christoph H. Lohmann 2
Katja Bauer 0
Christina Grabau 4
Stefanie Zibolka 4
Dirk Schlüter 0 3
Gernot Geginat 0
0 Institute of Medical Microbiology, Infection Control and Prevention, Otto-von-Guericke University of Magdeburg , Leipziger Straße 44, 39120 Magdeburg , Germany
1 Institute of Medical Microbiology and Hygiene, Consultant Laboratory for Clostridium difficile, University of Saarland , Saarland , Germany
2 Department of Orthopedic Surgery, Otto-von-Guericke University of Magdeburg , Magdeburg , Germany
3 Organ-specific Immune Regulation, Helmholtz Centre for Infection Research , Braunschweig , Germany
4 Central pharmacy, Otto-von-Guericke University of Magdeburg , Magdeburg , Germany
5 Institute for Laboratory Medicine , Microbiology and Hygiene, Christophorus Kliniken, Coesfeld , Germany
Background: Here we describe a cluster of hospital-acquired Clostridium difficile infections (CDI) among 26 patients with osteoarticular infections. The aim of the study was to define the source of C. difficile and to evaluate the impact of general infection control measures and antibiotic stewardship on the incidence of CDI. Methods: Epidemiological analysis included typing of C. difficile strains and analysis of possible patient to patient transmission. Infection control measures comprised strict isolation of CDI patients, additional hand washings, and intensified environmental cleaning with sporicidal disinfection. In addition an antibiotic stewardship program was implemented in order to prevent the use of CDI high risk antimicrobials such as fluoroquinolones, clindamycin, and cephalosporins. Results: The majority of CDI (n = 15) were caused by C. difficile ribotype 027 (RT027). Most RT027 isolates (n = 9) showed high minimal inhibitory concentrations (MIC) for levofloxacin, clindamycin, and remarkably to rifampicin, which were all used for the treatment of osteoarticular infections. Epidemiological analysis, however, revealed no closer genetic relationship among the majority of RT027 isolates. The incidence of CDI was reduced only when a significant reduction in the use of fluoroquinolones (p = 0.006), third generation cephalosporins (p = 0.015), and clindamycin (p = 0.001) was achieved after implementation of an intensified antibiotic stewardship program which included a systematic review of all antibiotic prescriptions. Conclusion: The successful reduction of the CDI incidence demonstrates the importance of antibiotic stewardship programs focused on patients treated for osteoarticular infections.
C; difficile; Ribotype 027; Rifampicin; Osteoarticular infections; Antibiotic stewardship
Clostridium difficile is a gram-positive, anaerobic
bacterium which is ubiquitously present in the gastrointestinal
tract of humans and animals [1, 2]. As a spore-forming
bacterium, C. difficile has the ability to persist and to
remain infectious in the environment for extended periods
of time. Spores are highly resistant to desiccation and
alcohol disinfectants . The main risk factors for
development of C. difficile infection (CDI) are (i) previous
antibiotic treatment, in particular with high risk
antibiotics such as 3rd generation cephalosporins, clindamycin,
and fluoroquinolones, (ii) long hospitalization, (iii)
underlying comorbidities, and (iv) high age of patients
[1, 3]. Also specific risk factors for ribotype 027 (RT027)
such as selective decontamination of the digestive tract
and a longer length of stay in the ICU have been
reported . Despite it is well established that
antimicrobial therapy with clindamycin and levofloxacin results in
dysbiosis and enhanced risk to develop CDI, it is
suspected that simultaneous therapy with rifampicin to
some degree protects patients from CDI [5–7]. The
increasing incidence of severe CDI among hospitalized
patients is an enormous clinical problem [8, 9]. However,
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data on the CDI incidence among patients with
prosthetic joint infections are scarce . In addition, the
CDI incidence among orthopedic patients after clean
surgery such as primary arthroplasty of the hip or knee
is very low (0.17%) . A much higher CDI incidence
of 7.1%, however, has been reported after open reduction
and internal fixation of intertrochanteric femoral
fractures, which in all cases occurred after previous
antibiotic therapy .
Between June 2014 and December 2015 we observed
an increased incidence of CDI among patients suffering
from mostly implant-associated osteoarticular infections,
where the majority of CDIs (57%) was caused by C.
difficile RT027. The aims of this study were to define risk
factors, possible sources of infection, and to evaluate the
impact of general infection control measures and
antibiotic stewardship on the incidence of CDI in this
difficult to treat group of patients.
Patient population, CDI case definition, and analysis of
The current study was initiated after recognition of a
possible CDI outbreak in the first quarter 2015 on the
septic ward of the department of orthopedic surgery.
This department with three independent wards is part of
an 1,100 bed tertiary care university hospital and acts as
a regional referral center for the treatment of
osteoarticular infections. Patients with osteoarticular infections
stay on a specialized ward to which we refer as “septic
For the study hospital-acquired CDI was defined as
new onset of diarrhea 48 h after hospital admission and
laboratory-confirmed detection of C. difficile toxin genes
by PCR. Severe CDI was defined by the presence of at
least one of the following symptoms: fever >38.5 °C,
decreased kidney function (creatinine >1.5x103g/L) and/or
high leukocyte count (>15 × 109 cells/L). A recurrent
CDI case was defined as new onset of CDI within
8 weeks after resolution of a previous CDI episode. No
children were included in the study. An outbreak
situation was defined as two or more CDI cases on a
single ward within 28 days. Risk factors for infection with
C. difficile RT027 were evaluated by comparing patients
with CDI caused by RT027 with patients infected with
Infection control and antibiotic stewardship
Infection control measures were implemented after
recognition of an enhanced CDI incedence. The infection
control bundle included (i) handwashing with soap after
disinfection, to reduce first vegetative forms of C.
difficile or other bacteria and secondly spores of C. difficile,
(ii) use of hygienic bags for bedpans, (iii) strict isolation
or cohorting of infected patients, (iv) personalized use of
all materials with direct contact to the patient e.g.
stethoscope, and (v) disinfection of surfaces and
equipment in all wards, operating rooms and physiotherapy
with peracetic acid and peroxide hydrogen vaporization
after discharge of patients. Intensified environmental
cleaning procedures were controlled by sampling of
surfaces as described below. Additionally, health care
workers were educated on diagnosis, treatment and
prevention of CDI and provided with an antibiotic risk
checklist which groups of antibiotics in 3 risk categories
(low risk: linezolid, vancomycin, metronidazole,
tetracycline, trimethoprim/sulfamethoxazole, fosfomycin;
daptomycin, medium risk: all beta-lactam-antibiotics with the
exception of third generation cephalosporins; high risk;
clindamycin, third generation cephalosporins,
fluoroquinolones). Physicians were instructed to follow the
inhouse guidelines for antibiotic therapy and
microbiological diagnostic of osteoarticular infections and to
avoid the prescription of high risk antibiotics for
therapy. In quarter 3/2015 an intensified antibiotic
stewardship program was implemented which included a weekly
review of all antibiotic prescriptions by an orthopedic
surgeon and a clinical microbiologist trained in
antibiotic stewardship. The organization of the team was
not changed since the beginning of the intervention. If
possible antibiotic therapy was adjusted in order to avoid
CDI high risk antibiotics as described above.
In order to control the impact of infection control
measures and antibiotic stewardship the CDI incidence
was monitored as number of cases per 1,000 hospital
bed days per quarter.
In addition the impact of the antibiotic stewardship
intervention was controlled by quarterly monitoring of
antibiotic consumption on the septic ward. Antibiotic
consumption was calculated as defined daily doses
(DDD) per 100 hospital bed days according to WHO
Diagnostic specimens and CDI laboratory diagnostic
Diagnostic stool specimens were collected from 63 adult
patients showing symptoms of diarrhea between June
2014 and December 2015. Stool diagnostic was
performed as part of the routine microbiological diagnostic
in a two-step algorithm.
First, clinical samples were primarily screened with a
Clostridium glutamate dehydrogenase (GDH)-specific
enzyme-linked immunosorbent assay (RIDASCREEN®
Clostridium difficile GDH, R-Biopharm, Darmstadt,
Germany) using the protocol provided by the
manufacturer. In case of positive results (n = 29) DNA was
extracted from the original stool sample. In brief, 100 μl
stool in 900 μl sample buffer were used, followed by
centrifugation at 1,000 x g for 5 min. Subsequently
400 μl supernatant was transferred into Precellys® Soil
grinding SK38 tubes (Bertin Technologies, USA) and
homogenized by centrifugation (5,000 x g for 75 sec)
using the MagNA Lyser System (Roche Diagnostics,
Mannheim, Germany). The lysate was clarified by
centrifugation at 1,000 x g for 5 min and subsequent
incubated for 10 min at 70 °C in a thermoshaker.
DNAextraction was performed using the QIAamp® DNA Mini
Kit (Qiagen, Hilden, Germany) according to
Second, purified DNA samples were tested for the
presence of C. difficile DNA using two commercially
available real-time PCR test systems. C. difficile toxins A
(tcdA) and B (tcdB) genes were detected using the
RealStar® Clostridium difficile PCR Kit 1.0 (altona
Diagnostics, Hamburg, Germany). The binary toxin gene
and the Δ117 deletion in the tcdC gene were detected
using Xpert® C. difficile/Epi PCR assay (GeneXpert,
Cepheid, Sunnyvale, CA, USA). All tests were performed
according to manufacturer’s protocol.
Multilocus sequence typing (MLST)
MLST was performed with DNA either isolated from
feces (n = 10) or from isolated strains (n = 16). The
MLST was performed as described before , targeting
7 housekeeping genes of C. difficile: adk, atpA, dxr, glyA,
recA, sod and tpi. The sequencing reactions were run on
a 3130xl Genetic Analyzer (Applied Biosystems). Editing,
alignment, and phylogenetic analysis of sequences were
performed with the program MEGA 6.0 . DNA
sequences were uploaded to the MLST database and
C. difficile sequence types (ST) were received from
the website .
Clostridium difficile culture and susceptibility testing
Clostridium difficile was cultured form GDH-positive
stools (n = 16) using a chromogenic medium (chromID™
C. difficile, bioMérieux, Marcy l’Etoile, France). The
medium was inoculated with 10 μl feces and incubated
anaerobically at 35 ± 1 °C for 7 days. Presumptive C.
difficile colonies were confirmed by MALDI-TOF MS
(VITEK® MS, bioMérieux).
The minimal inhibitory concentrations (MIC) of
metronidazole, vancomycin, rifampicin, levofloxacin, and
clindamycin were determined by gradient strip test
(Etest, bioMérieux) on Brucella blood agar (Becton
Dickinson, Heidelberg, Germany) inoculated with 100 μl
solution of a 1.0 McFarland suspension of C. difficile in
saline as described previously . Agar plates were
incubated under anaerobic conditions at 35 ± 1 °C for
48 h. For the interpretation of MIC the EUCAST
epidemiological cut off values (ECOFF) were used for
metronidazole (>2 mg/L), vancomycin (>2 mg/L), rifampicin
(>0.004 mg/L). No ECOFF are available for clindamycin
Enviromental sampling of inpatient environment
Sampling of the inpatient environment for the presence
of C. difficile was performed as described . Briefly,
surface samples were taken using 25 cm2 sponge swabs
pre-moistened with neutralizing solution (Lab M Ltd,
Heywood, United Kingdom). Frequent contact surfaces
of the patient room (head/foot-end boards of patient
beds, bed rail, bedside table, nurse call button, patients
telephone) and the en-suite bathroom (toilet seat, toilet
assist handle) were sampled. After sampling sponge swabs
were placed aseptically into the sterile sample transport
bag prefilled with 10 ml neutralizing solution. The
laboratory bags were opened and supplemented with 40 ml
sterile phosphate-buffered saline (Becton Dickinson,
Heidelberg, Germany) to yield a final volume of 50 ml.
Sponge bags were resealed and homogenized manually by
massaging the bag for 1 min. After 10 min. incubation at
room temperature the whole volume was passed through
a 45 μm membrane filter (Pall GmbH Laboratory,
Dreieich, Germany). Filters were aseptically put onto
Brazier's CCEY agar (Oxoid, Wesel, Germany) and
incubated 48 h in an anaerobic atmosphere at 35 ± 1 °C. After
48 h, suspected C. difficile colonies were further analysed
by MALDI-TOF MS. Confirmed C. difficile isolates were
tested for toxin production and typed by MLST.
Ribotyping and multiple-locus variable-number tandem
repeat analysis (MLVA)
Ribotyping and MLVA analysis of 11 ST1 isolates was
performed by the National Consultant Laboratory for
C. difficile in Homburg/Saar (University of Saarland
Medical Center, Homburg, Germany). PCR-ribotyping
was performed for each isolate according the standard
protocol (European harmonized diagnostic procedures
ECDIS; http://www.ecdisnet.eu) as described earlier 
which included capillary gel electrophoresis of fluorescent
labelled fragments (Beckmann Coulter, Brea, California
USA) and ribotype assignment to an institutional
databank by an automated software tool (BioNumerics
version 7.1, Applied Math, Sint-Martens-Latem, Belgium).
MLVA was carried out as described previously  with
BioNumerics as automated software (version 7.1, Applied
Math, Sint-Martens-Latem, Belgium). The definition of
clonality was based upon previous studies with a genetic
difference of less than 3 repeats while a clonal cluster was
defined by ≤2 repeat differences and genetic related
isolates by ≤10 repeat differences .
Statistical analyses were performed using the Fisher’s
exact Test for bivariate analysis of C. difficile risk factors
(non RT027 CDI versus RT027 associated CDI) and the
two-sample independent t Test for the means of
antibiotic consumption data before and after intervention
with a significance level of p values <0.05. The Microsoft
Excel statistic tool, OpenEpi (http://www.openepi.com)
was used to analyze the data. The upper and lower
statistical boundaries were defined as the mean CDI
incidence of the four previous quarters plus/minus standard
deviation (MA ± SD).
Clustering of CDI cases
Retrospective analysis showed that already in the third
quarter of 2014 the CDI incidence (1.41 cases per 1,000
hospital bed days) on the septic ward, a special unit for
treatment of patients with osteoarticular infections was
significantly above average incidence of the whole
department (0.64 cases per 1,000 hospital bed days,
p = 0.036). Orthopedic infections in our patient cohort
were associated with endoprosthesis (19/26; 65.5%), soft
tissue/wound infections (4/26; 15.4%), septic spondylitis
(2/26; 7.7%), and osteomyelitis (1/26; 3.8%).
In quarter 3/2014 the CDI incidence was above the
mean CDI incidence of the 4 previous quarters plus
SD (Fig. 1). The mean CDI incidence on the septic
ward increased significantly from 0.33 infections per
1,000 hospital bed days (SD 0.25) in the period from
quarter 1/2013 to 2/2014 to 2.3 infections per 1,000
hospital bed days (SD 0.98) in quarters 1/2015 to 4/2015
(p = 7.2 x 10−7). After implementation of an
intensified antibiotic stewardship program in quarter 3/2015
the CDI incidence dropped in the first quarter 2016
to no case per quarter which was significantly below
the mean CDI incidence of the 4 previous quarters
minus SD of 2.13 infections per 1,000 hospital bed
days (Fig. 1). Also in the second quarter 2016 no CDI
case was monitored.
From June 1st 2014 to December 31th 2015 a total
number of 63 patients with gastrointestinal disorders
were tested for the presence of C. difficile. GDH-positive
samples from 29 patients were further tested for the
presence of toxin genes by PCR. CDI was confirmed by
PCR in 26 patients, which also demonstrated the clinical
symptoms of CDI. With exception of two samples,
sequence types were determined by MLST from toxin
gene-positive samples, 15 samples (57.7%) were typed as
ST1 and were further identified as RT027 by
CEribotyping. The following sequence types were identified:
ST3 (n = 2), ST6 (n = 2), ST14 (n = 2), ST8 (n = 1), ST15
(n = 1), and ST92 (n = 1). In all samples both toxin
encoding genes were detectable, whereas the binary toxin
gene and the Δ117 in the tcdC gene were only present
in samples typed as ST1.
The time between admission of patients to the septic
ward and diagnosis of CDI ranged from 2 to 72 days.
Characteristics and co-morbidities of patients were
summarized from patients records (Table 1). Renal
insufficiency, treatment with gastric acid suppressors and
Fig. 1 Incidence of C. difficile infections during the study period. The CDI incidence rates (number of cases per 1000 hospital bed days per
quarter) for the whole department of orthopedic surgery (diamonds) and the septic ward only (squares) are shown. For every quarter the moving
average (MA) of the previous four quarters was calculated. For CDI surveillance upper (MA + SD, upper dotted line) and lower (MA-SD, lower
dotted line) boundaries were defined. An increase or decrease of the CDI incidence was considered significant if the actual CDI incidence crossed
the upper or lower boundaries, respectively
treatment with CDI high risk antibiotics were the most
frequent risk factors but were not significantly different
among patients infected with C. difficile RT027 (ST1)
and non-RT027 strains. The only significant risk factor
for CDI caused by RT027 was a patient’s stay on the
Outcome of CDI
Non-severe CDI was initially diagnosed in 18 from 26
patients (69.2%) and in 6 from 15 patients (40.0%)
infected with RT027. Treatment of CDI was initiated in all
cases according to current European Society of Clinical
Microbiology and Infectious Diseases guidelines .
After primary CDI treatment 15 (57.7%) patients
recovered, among them 6 (40%) patients with RT027.
Recurrences were observed in 10 (38.5%) patients. The
mortality of 15.4% (4/26) within 6 months after
diagnosis of CDI was exclusively attributable to CDI due to
C. difficile RT027.
Infection control and antibiotic stewardship
After clustering of CDI cases was first recognized in the
quarter 1/2015 a primary infection control and antibiotic
stewardship bundle was implemented (see methods
Orthopedic infections generally require a long-term
(≥6 weeks) antibiotic treatment [22–24]. In most cases,
antibiotic therapy of the primary orthopedic infection
consisted of two or more antibiotics. The most frequently
prescribed classes of antibiotics were fluoroquinolones
(34.6%), cephalosporins (50.0%), clindamycin (26.9%),
rifampicin (50.0%), and the penicillin/betalactamase
inhibitor combinations ampicillin/clavulanic acid (15.4%)
and piperacillin/tazobactam (23.1%) (Table 1).
Initial review of antibiotic prescription data indicated
an overuse of CDI high risk antibiotics (Table 2)
although an in-house guideline for antibiotic therapy and
infectious disease diagnostics had been in use for several
years. The primary antibiotic stewardship intervention
focused on information of medical doctors, who were
provided with an antibiotic risk checklist which groups
of antibiotics in 3 risk categories. Physicians were
instructed to follow the in-house guidelines for antibiotic
therapy and microbiological diagnostic of osteoarticular
infections and to avoid the prescription of high risk
antibiotics for therapy. An intensified antibiotic stewardship
program was implemented during quarter 3/2015 which
included a weekly review of all antibiotic prescriptions
by a clinical microbiologist.
The quarterly analysis of antibiotic consumption
between quarters 1/2013 and 2/2016 shows that
fluoroquinolones, 1st and 2nd generation cephalosporins and
clindamycin were the most prescribed antibiotics on the
septic ward, even after the initial recommendation to
avoid these antibiotics after recognition of the enhanced
CDI incidence in quarter 1/2015 (Table 2).
Significant reduction of antibiotic consumption of
C. difficile high risk antibiotics was achieved after the
intensified antibiotic stewardship program for septic
orthopedic patients was initiated in quarter 3/2015.
This intervention led to a significant reduction (p values
<0.05, Table 2, Fig. 2) of the consumption of
fluoroquinolones, clindamycin, and 1st and 2nd generation
cephalosporins and increased use of narrow spectrum
Table 2 Antibiotic consumption in the septic ward during quarters 1/2013 to 2/2016
Narrow spectrum penicillinsb
Broad spectrum penicillinsc
Cephalosprins 1st and 2nd gen. 12.2
Cephalosprins 3rd gen.
Antibiotic consumption (DDD/100 hospital bed days)
Q1 Q2 Q3 Q4 Q1 Q2 Q3
8.8 20.8 16.5 26.3 6.8 11.3 8.3
125.6 132.3 150.6 106.9 129.7 157.3 122.7 113.1 133.0 141.6 122.1 133.5 103.5 150.2 0.348
Fig. 2 Antibiotic prescription for patients of the septic ward before and after implementation of the intensified antibiotic stewardship program in
quarter 3/2015. Bars indicate the mean antibiotic consumption calculated as defined daily doses (DDD) per 100 hospital bed days. For the major
classes of antibiotics the mean antibiotic consumption and standard deviations were calculated for quarters 1/2013 to 2/2015 before intervention
and quarters 3/2015 to 2/2016 after intervention. Narrow spectrum penicillins include benzylpenicillin, flucloxacillin, and aminopenicillins; broad
spectrum penicllins include piperacillin and piperacillin/tazobactam. Asterisks indicate a significant (p values <0.05) difference of antibiotic
consumption before and after intervention
penicillins (benzylpenicillin and flucloxacillin, +110%),
linezolid (+111%), and rifampicin (+41%). The total
average antibiotic consumption before intervention
was 131.3 DDD per 100 hospital bed days and after
intervention 127.3 DDD per 100 hospital bed days,
respectively. Thus, although consumption of high risk
antimicrobials was significantly lowered total
antibiotic consumption remained on a high level after the
Antibiotic susceptibility testing of C. difficile isolates
In vitro antibiotic susceptibility tests were performed
with 16 C. difficile isolates (ST1 (n = 11), ST6 (n = 2),
ST8 (n = 1), ST14 (n = 1), and ST92 (n = 1) (Table 3). All
ST1 (RT027) isolates showed an elevated MIC for
multiple antibiotics including levofloxacin (MIC ≥32 mg/L),
and rifampicin (MIC ≥32 mg/L). Also the MIC of
clindamycin was elevated among the majority of RT027
isolates. All non-RT027 strains showed a low MIC for
rifampicin (<0.002 mg/L) and the MIC of clindamycin
(2.0–8.0 mg/L) was under the epidemiological cut-off
value of 16.0 mg/L. The MIC of levofloxacin was
6.0 mg/L (ECOFF not available).
The inquiry by infection control personal yielded no
noticeable epidemiological association among patients
with identical non-RT027 strains (data not shown). In
order to confirm a possible epidemiological
association of RT027 isolates form the septic ward
subtyping by MLVA was performed. The typing of 11
RT027 isolates revealed two genetically related
clusters (defined as ≤10 repeat differences). The larger
cluster comprised 9 isolates (isolates 1–4 and 7–11)
and the minor cluster 2 isolates (isolates 5 and 6)
(Fig. 3). Only three isolates (1, 3, and 4) showed
clonal relatedness (defined as ≤2 repeat differences).
A fourth isolate (# 3) showing three repeat differences
was also closely related to this cluster. We further
analyzed the possible epidemiological association of the
four patients from which these genetically closely
related strains (repeat differences ≤3) were isolated. A
detailed inquiry of possible contacts, however, did not
reveal any direct or indirect contacts of inpatients
infected within these related RT027 isolates. As shown
in Fig. 4, there were no overlaps of admission and
discharge data of excluding direct contact.
Table 3 MLST types and MICs for selected antibiotics of C. difficile isolates
n.d. not determined
In order to further exclude a remnant reservoir of
viable C. difficile RT027 in patient rooms after discharge
of the patient and cleaning of the room, environmental
investigations of surfaces of patient rooms were
performed. Among 60 environmental samples taken in
August 2015, December 2015, and January 2016 C.
difficile RT027 was isolated from only one sample from the
telephone set of an inpatient infected with RT027,
without any transmissions of this particular strain to other
inpatients up to now. Thus indicating that cleaning
procedures were adequate and a persistent
environmental C. difficile reservoir in patient rooms was highly
Here we report an increased incidence of CDI mainly
caused by C. difficile RT027 with an elevated MIC for
rifampicin among patients suffering from osteoarticular
infections and the successful control of CDI by
implementation of an antibiotic stewardship program focused
on this difficult to treat group of patients.
The dominance of C. difficile RT027 among patients
with orthopedic infections observed in the current study
could be due to a number of different reasons. During
the primary outbreak analysis, the investigation focused
on a possible common source of C. difficile RT027
isolates. The only risk factor for CDI caused by RT027 was
a patient’s stay on the septic ward neither molecular
epidemiological analysis, nor analysis of inpatient contacts,
nor environmental sampling suggested a possible
common source of RT027 isolates. Probably, CDI was mainly
restricted to the septic ward due to the higher exposure
of inpatients to CDI high risk antibiotics required for
the treatment of osteoarticular infections. Antibiotic
consumption of high risk antibiotics on the septic ward
was 2 to 3-fold higher compared to the other wards of
Fig. 3 MLVA minimum spanning tree of 11 RT027 isolates
the orthopedic department (data not shown). The
majority of complications was associated with RT027, however
due to the low number of patients the observed
differences between patients infected with RT027 and
nonRT027 were not significant.
The bundle of optimized antibiotic treatment,
environmental cleaning procedures and education of health care
workers effectively controlled nosocomial CDI thus
corroborating previously published studies [10, 25–27].
Implementation of infection control measures alone,
however, did not reduce the incidence of CDI, which
was only achieved after drastic reduction of the
consumption of C. difficile high risk antibiotics. The
incidence of CDI was significantly reduced only after
implementation of an intensified antibiotic stewardship
program which lowered the prescription of
fluoroquinolones, clindamycin, and cephalosporins in favor of low
risks antibiotics such as penicillins and linezolid.
Average total antibiotic consumption before
intervention was 131 DDD/100 hospital bed days and after
intervention 127 DDD/100 hospital bed days. The antibiotic
stewardship intervention shifted antibiotic therapy
towards the use of narrow spectrum penicillins
(benzylpenicillin and flucloxacillin, +110%), linezolid (+111%), and
rifampicin (+41%). The DDD of benzylpenicillin is 3.6 g.
Treatment of serious infections, however, generally
Fig. 4 Admission and discharge data (month and year) of CDI cases from which genetically related C. difficile were isolated
requires a dose of 12 g or even higher. Thus calculating
DDD while using much higher therapeutic doses results
in an overestimation of the prescribed doses . If
correcting this by using recommended daily doses (RDD)
 for the calculation of antibiotic consumption the
antibiotic consumption before intervention was 99.0
RDD/100 hospital bed days and after intervention 86.1
RDD/100 hospital bed days, indicating that the number
of prescribed doses on the septic ward was reduced
roughly 13%. Total antibiotic consumption on the septic
ward, however, remained significantly above the available
national benchmark data for surgical departments other
than general surgery (75% quantile 56 RDD/100 hospital
bed days) [28, 29]. To our knowledge no benchmark
data are available for units specialized on septic
orthopedic surgery like the septic ward studied here. On the
septic ward inpatients often require high-dose antibiotic
combination therapies which explain the significantly
higher antibiotic consumption compared to general
The average consumption of fluoroquinolones was
34.5 DDD (33.3 RDD) per 100 hospital bed days before
and 11.5 DDD (10.3 RDD) per 100 hospital bed days
after implementation of intensified antibiotic
stewardship program. Despite after the intervention roughly
70% less quinolones were used overall quinolone
consumption was still significantly above the national
benchmark (75% quantile 6.9 RDD/100 patient days)
[28, 29]. The consumption of first and second generation
cephalosporins was reduced roughly 30% by replacing
them with flucloxacillin for the therapy of susceptible
staphylococci and by avoiding prolonged perioperative
In Germany regionally between 5.3% and 33.5% of
CDI are caused by RT027 [30, 31]. In our study 66% of
CDI on the septic ward were caused by RT027,
suggesting selection of this particular strain. Because for the
study region no data are available for the rate of
asymptomatic RT027 carriers, we cannot judge the degree of
selection of RT027 among our patient group.
Antimicrobial therapy of osteoarticular infections
often requires prolonged antibiotic treatment for 6 to
12 weeks [22–24]. According to current guidelines an
initial parenteral therapy with beta-lactam antibiotics is
often followed by oral therapy with antibiotics such as
fluoroquinolones and rifampicin with good
bioavailability, effective tissue and bone penetration, and biofilm
activity [22–24]. Nevertheless, reports indicating an
enhanced CDI incidence among patients with prosthetic
joint infections are scarce . Our current working
hypothesis is that cephalosporins, quinolones and
clindamycin as high risk antibiotics trigger CDI and
concurrent treatment with rifampicin protects patients from
CDI caused by rifampicin-susceptible C. difficile. Thus
the reduced susceptibility of RT027 to rifampicin might
increase the risk of CDI among patients treated with
rifampicin [5, 32, 33]. However, rifampicin alone probably
did not trigger CDI because less prescription of high risk
antimicrobials even without reduction of the
consumption of rifampicin significantly lowered the CDI
incidence. The ClosER (Clostridium difficile European
Resistance) study reported elevated MICs of C. difficile
for fluoroquinolones and clindamycin among various
ribotypes, whereas elevated rifampicin MICs were
mainly associated with a few ribotypes such as RT027,
RT018, and RT356 which are more common in South
Eastern Europe . It has also been shown before that
long-term rifampicin treatment may result in the
selection of C. difficile strains with an elevated rifampicin
MIC [32–34]. In view of the low rifampicin MIC of the
majority of C. difficile strains, it has been hypothesized
that rifampicin might prevent CDI in osteoarticular
Our study has a number of limitations. Firstly, because
culture-based diagnostic of C. difficile was initiated by
the laboratory after recognition of the epidemic situation
in May 2015 the initial epidemiological analysis was
performed based on PCR and MLST only. Sequence type 1
(ST1) can correspond to several ribotypes in particular
RT176 , and the GeneXpert cannot differentiate
between RT027 and RT176 [35, 36]. In Germany, however,
RT176 is rather uncommon [37, 38], and ribotyping of
11 isolates confirmed that all ST1 belong to RT027.
Because the discriminatory power of MLST alone is not
sufficient for the analysis of the molecular epidemiology
of C. difficile in outbreaks  MLVA analysis of 11
RT027 isolates was performed. The results indicated the
presence of a very closely related strain in only four out
of 11 patients, making a clonal outbreak caused by a
common source in the hospital unlikely.
Secondly, the initially increased incidence of CDI in
quarter 3/2014 correlated with the introduction of a new
diagnostic test for the detection of C. difficile, which was
switched from a toxin-specific enzyme-linked
immunosorbent assay to primary screening with a GDH-specific
ELISA followed by a toxin gen-specific PCR test. Thus,
initially the increased number of patients with positive
C. difficile tests was interpreted as result of the improved
sensitivity of the new diagnostic test. Gould et al.
reported an increase of the CDI incidence ranging from
43% to 67% after switching from toxin enzyme
immunoassays to PCR-based C. difficile diagnostic tests .
Beginning with the third quarter 2014 the incidence of
recurrent and severe CDI increased compared to the
period before. Among all cases of CDI 28.6% of patients
and among the cases of CDI caused by RT027 38,5% of
patients had at least one criterion of severe CDI at
the time point of laboratory diagnosis. In accordance
with reported data, the CDI-associated mortality rate
within 6 months was 15.4% for all CDI cases and
26.7% for RT027 cases, respectively. Severe CDI
occurred mostly among elderly patients with multiple
co-morbidities [10, 25, 27, 34, 41].
Third, despite the analysis of patient to patient
contacts did not reveal a direct connection of our
patients from which highly related RT027 were isolated
we cannot strictly exclude a possible epidemiological
connection. We could not exclude possible patient
contacts outside the hospital and environmental
screening was performed after cleaning and, therefore,
the environment cannot be strictly excluded as source
of infection. Also, screening of health care workers
and asymptomatic patients was not performed which
have been reported to act as vector for nosocomial
transmission of C. difficile [42, 43].
To our knowledge, this is the first report of an enhanced
incidence of CDI caused by C. difficile RT027 with
elevated MICs for rifampicin among patients with
osteoarticular infections. The successful reduction of the CDI
incidence demonstrates the importance of antibiotic
stewardship programs focused on patients treated for
osteoarticular infections. The impact of antibiotic
stewardship on the restriction of C. difficile high risk
antimicrobials should be tightly monitored in order to
ensure that antibiotic stewardship recommendations are
CDI: Clostridium difficile infection; ClosER: Clostridium difficile European
resistance study; DDD: Defined daily doses; ECOFFs: Epidemiological cut-off
value; ELISA: Enzyme-linked immunosorbent assay; GDH: Clostridium
glutamate dehydrogenase; MA+/− SD: Moving average plus/minus standard
deviation; MIC: Minimum inhibitory concentration; MLST: Multilocus
sequence typing; MLVA: Multiple locus variable-number tandem repeat
analysis; n.d.: Not determined; Q1-4: Quarter 1–4; RT027: C. difficile ribotype 027;
ST: Sequence type; WHO: World Health Organization
JF and GG conceived the study, participated in its design and coordination
and drafted the manuscript. JF, KB, FB, BG, LM, DS collected and compiled
microbiological data. SI and CHL collected and compiled clinical data. CG,
SZ, GG collected and compiled antibiotic consumption data. All authors read
and approved the final manuscript.
The authors declare that they have no competing interests
Consent for publication
Ethics approval and consent to participate
The research protocol was approved by the Institutional Review Board of the
Otto-von-Guericke University of Magdeburg (No. 71/16).
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