https://doi.org/10.53453/ms.2024.11.5
Antibiotic resistance of pathogens causing hospital–acquired
infections after surgical interventions in the hospital of Lithuanian
University of Health Sciences Kaunas Clinics
Gintarė Lukoševičiūtė
1
, Tautvydas Skripkauskas
1
, Valdemar Loiba
2
1
Faculty of Medicine, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
2
Department of Orthopaedics and Traumatology, Faculty of Medicine, Medical Academy, Lithuanian University
of Health Sciences, Kaunas, Lithuania
Abstract
Background. The global community is facing a significant and concerning rise in antibiotic–resistant infections.
In Lithuania, drug resistant pathogens are ranked as the fifth leading cause of death, underscoring the critical
nature of this issue. This is particularly relevant in the field of orthopaedics and traumatology, where the presence
of foreign bodies amplifies the risk of infection, necessitating strict interventions to combat antibiotic resistance.
Aim. The purpose of this study was to evaluate antibiotic resistance and infection risk factors in postoperative
infections in the department of orthopedics and traumatology of Kaunas Clinics.
Methods. The data of 104 patients from 2017 to 2021 were selected as the research object. All data were obtained
from hospital information database.
Results. This study, involving 104 patients, revealed a male predominance (66.3 %) with an average age of 53.43
± 2.029, statistically differing from females. Stratification into age groups showed middle–aged individuals
(62.5%) more prone to infections. S. aureus was the primary pathogen (48.1 %). While penicillin G resistance for
this pathogen was 66 %, sensitivity to gentamicin, rifampicin, trimethoprim/sulfamethoxazole, and vancomycin
was 100 %. Significant age and gender differences were found in S. aureus infections. Lower extremity surgeries
were more common (76 %) with S. aureus. Gender–dependent ciprofloxacin resistance distribution was observed.
Sensitive causative agents were more frequently found in males.
Conclusions. S. Aureus was the dominant gram–positive pathogen in this study. Its drug resistance pattern showed
that antibiotic resistance is a serious concern.
Keywords: drug resistance, nosocomial infections, orthopaedics, traumatology
Journal of Medical Sciences. 3 Nov, 2024 - Volume 12 | Issue 5. Electronic - ISSN: 2345-0592
Medical Sciences 2024 Vol. 12 (5), p. 47-53, https://doi.org/10.53453/ms.2024.11.5
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1. Background
Every year, microorganisms resistant to
antibiotics cause numerous infections, often
complicated by death. It has been estimated that
in 2019 alone, antibiotic–resistant pathogens
worldwide caused approximately 1.27 million
deaths [1]. In the same year, infections caused by
methicillin–resistant S. aureus killed more
United States (US) citizens than emphysema,
HIV, Parkinson's disease, and suicide combined
[2]. Additionally, the Centers for Disease
Control and Prevention (CDC) in the US has
calculated that infections caused by antibiotic–
resistant pathogens cost the US healthcare
system an additional $20 billion annually [3]. In
Europe, these infections incur an additional cost
of about €9 billion [4]. It is projected that these
numbers will continue to rise, and without urgent
actions to curb the spread of antibiotic–resistant
microorganisms, it is estimated that by 2050,
around 10 million people worldwide will die
from infections caused by antibiotic–resistant
pathogens [5]. In Lithuania, resistant pathogens
annually cause the death of 1900 people, ranking
as the fifth most common cause of death [6].
This issue is particularly relevant in orthopaedics
and traumatology, where various foreign bodies
such as endoprostheses or plates are often used
during surgeries. They increase the frequency of
postoperative infections by at least 10000 times,
as foreign bodies provide an excellent
environment for pathogens to multiply, requiring
very few of them to cause an infection [7].
Microorganisms that adhere to the foreign body
form biofilms, which are more resistant to the
immune response and antimicrobial drugs.
These infections are challenging to treat because
the causative agents are often of nosocomial
origin, making them significantly resistant to
antibiotics. It has been found that in endemic
areas, more than half of staphylococcus–related
postoperative infections were caused by
methicillin–resistant strains [8]. This poses
additional challenges in treating these patients,
as more potent antibiotics and even revision
surgeries are often required.
2. Methods
During the study, a retrospective analysis of the
medical documents of infected patients treated
between 2017–2021 in the department of
orthopedics and traumatology of Kaunas Clinics
was performed. 133 patients were selected based
on ICD codes M00 and T84.7 and after
excluding duplicates, 104 cases were used.
Subjects were divided into groups according to
infectious agents. Antibiotic resistance of
pathogens was evaluated, as well as the
dependence of the most causative agent – S.
aureus – and those infected with it on gender,
age, time of year, type of operation and operated
area. Subjects are divided into male and female
groups according to gender. According to the
World Health Organization (WHO), the subjects
were divided into three groups by age: patients
under 18, from 18 to 65 years. age and 65 years
age and older patients.
All clinical specimens, including wound
secretions (skin and tissue that were already
injured pre–surgery), incisional secretions (skin
and tissue intact pre–surgery), urine, blood, and
joint fluids, obtained from the orthopedics
department between January 2017 and
December 2021 were included in the analysis if
they tested positive for pathogens.
Statistical data analysis was performed using the
IBM SPSS Statistics 23.0 software. Research
data were processed using Chi–square (X²),
non–parametric – Mano Whitney was used to
compare two independent samples. The Kruskal
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Wallis non–parametric test was applied when
there were more than two study groups.
Differences were considered statistically
significant when the obtained p–value was lower
than the chosen significance level α=0.05.
3. Results
In the study, there were 104 infections after
surgical interventions in the orthopedics and
traumatology department, with 69 being male
patients (66.3 %) and 35 female patients
(33.7 %). The average age for females was 70.46
± 2.427, and for males – 53.43 ± 2.029.
According to the Mann–Whitney criterion, the
age of onset of infection statistically differed
between males and females (p < 0.05) – males
were prone to a higher infection risk at a younger
age than females.
The subjects were also divided into age groups:
up to 18 years (Group 1 – boys, girls), 18–65
(Group 2 – men, women), and 65+ (Group 3 –
seniors). The group of middle–aged individuals
consisted of 65 persons (62.5 %), while seniors
were 39 (37.5 %). In the middle–aged group of
65 patients, microorganisms did not grow in 14
samples (21.5 %), and in the senior group of 39,
8 samples (20.5 %). For a fifth of patients in each
age group, an infection diagnosis was recorded
without a positive culture result.
Out of 104 patients, microorganisms did not
grow for 22 individuals (21.2 %), and for the
remaining 82 (78.8 %), the most common
causative agents were Staphylococcus aureus
(60.9 %, 50/82), Staphylococcus epidermidis
(7.3 %, 6/82), Cutibacterium acnes (4.88 %,
4/82), Streptococcus agalactiae (6.09 %, 5/82),
and Enterobacter (6.09 %, 5/82).
It was observed in the study that the Gram–
positive bacterium S. aureus was the most
common causative agent of infections in the
orthopedics and traumatology department
(48.1 %, 50/104). The majority, 66 % (33/50),
were resistant to at least one of the tested
antibiotics (oxacillin, penicillin G, cipro-
floxacin, clindamycin, erythromycin, tetracyc-
line, gentamicin, rifampicin, trimetho-
prim/sulfamethoxazole, vancomycin), and 34 %
(17/50) were susceptible.
In 28 cases, S. aureus strains were identified
from joint fluid, 24 through biopsy, and 15 from
pus cultures. A statistically significant difference
between age and gender was found (p < 0.05). In
joint fluid samples, the average age for females
was 69.70 ± 17.3, for males – 50.78 ± 16.4. In
biopsy samples, the average age for females was
74.83 ± 15.2, for males – 56.44 ± 15.3. In pus
culture samples, it was 76.00 ± 14.0 for females,
and 59.91 ± 11.9 for males.
Out of 50 individuals with S. aureus caused
infections, the majority were males (70.0 %,
35/50), and the rest females (30%, 15/50). Most
individuals belonged to age group 2 (64.0 %,
32/50), while the older age group comprised
36 % (18/50). A statistically significant
difference was found between the age of
S. aureus infected males and females (p < 0.05)
– females more frequently fell into the 65+ age
group, with an average age of 72.27 ± 15.9,
while males were under 65, with an average age
of 54.66 ± 14.9 years.
Both middle–aged and older individuals more
frequently underwent lower extremities (76 %,
38/50) rather than upper extremities (24 %,
12/50) surgeries in the presence of S. aureus as
the causative agent (p < 0.05).
In cases of S. aureus caused infections, the most
frequently performed surgeries were debride-
ment (28.0 %, 14/50), osteotomy (22.0 %,
11/50), osteosynthesis (22.0 %, 11/50), and
revision surgeries for endoprosthesis (14.0 %,
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7/50). During debridement surgeries, it was
found that in half of the cases (50 %), S. aureus
strains were sensitive, and in the other half
(50 %), resistant to at least one of the tested
antibiotics. For osteotomy surgeries, 81.8% were
resistant to at least one of the tested antibiotics,
and 22.2 % were sensitive. Similarly, for
revision and osteosynthesis surgeries, the
majority (71.4 % and 60 %, respectively) of
S. aureus strains were resistant to at least one of
the tested antibiotics. No statistically significant
difference was found between S. aureus
sensitivity/resistance and the type of intervention
performed (p < 0.05). S. aureus and other
pathogen
S. aureus showed the highest resistance to
penicillin G (66 %, 33/50) and the lowest
resistance to gentamicin, rifampicin, trimetho-
prim/sulfamethoxazole, and vancomycin (100%,
50/50 sensitive). Analyzing the selected
antibiotics: oxacillin, penicillin G, ciprofloxacin,
clindamycin, erythromycin, gentamicin,
rifampicin, vancomycin, trimethoprim/sul-
famethoxazole – no statistically significant
dependence of S. aureus sensitivity/resistance on
time, age, gender, or area was found (p < 0.05).
There was a statistically significant difference in
the distribution of ciprofloxacin resistance/sen-
sitivity based on gender. Sensitive causative
agents were more frequently found in males,
while resistant ones in females (p < 0.05).
4. Discussion
4.1 Demographic insights
The observed increased susceptibility of men to
infections at younger ages is consistent with
previous studies showing sex differences in
infection risk. Gender–specific immunological
differences and hormonal influences contribute
to this discrepancy. After puberty, women are
initially less susceptible to infectious diseases
because of their increased ability to mobilize and
activate immune responses comparing to men.
Furthermore, testosterone in men has
immunosuppressive properties, which could
lead to the discrepancies [9].
The stratification of subjects into age groups
highlighted distinct infection patterns. Notably,
a significant proportion of infections occurred in
the middle–aged group rather than senior group.
Previous studies showed similar results. Biscoff
et al. found increasing age predicted increased
surgical site infection risk until age 65 years.
After 65 years of age, increasing age predicts
lower infection risk. The decreased
susceptibility to infection of senior population
may be influenced by a combination of factors,
including less frequent surgeries and “hardly
survivor“ effect [10]. Although these factors
remain controversial and further research is
needed.
4.2 Microbiological landscape and antibiotic
resistance
In our study, like several previous findings, the
most common pathogen causing nosocomial
infections was S. aureus (60.9 %) [11–14].
These microorganisms are part of the natural
skin microflora, however, when introduced into
a surgical wound, they can cause opportunistic
wound infections. This is particularly relevant in
orthopedics and traumatology, as foreign bodies
used in surgeries create an excellent
environment for pathogens to multiply [15].
Our study identified S. aureus as the
predominant Gram–positive bacterium, aligning
with its well–established role as a major
pathogen in orthopedic infections [16]. Of
particular concern is the high resistance
observed to penicillin G, reaching 66 % (33/50)
in our study. In contrast, a comprehensive study
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50
conducted by Latha et al. revealed a resistance
prevalence of only 57.3 % among Staphylo-
coccus aureus strains to penicillin. [17].
Currently, numerous medical practitioners
administer empirical antibiotics without
awaiting sensitivity reports [18,19]. Our
findings demonstrated a major problem with
antimicrobial resistance and necessitates a
cautious approach in selecting empirical
antibiotic therapies in the study hospital
Therefore, we strongly advise against the
empiric use of penicillin in orthopaedics and
traumatology department. In contrast, S. aureus
showed least resistance to gentamicin,
rifampicin, trimethoprim/sulfamethoxazole, and
vancomycin, suggesting that they can be safely
used in the clinic. However, in 2002, a report
emerged regarding the presence of a
vancomycin–resistant S. aureus isolate [20].
Thus, this antibiotic should be exclusively
administered in cases of severe infections that
are unresponsive to other antibiotics.
The intricate resistance patterns observed in S.
aureus strains underscore the challenges in
antibiotic management. The gender–dependent
distribution of ciprofloxacin resistance
highlights the need for nuanced considerations in
antibiotic selection, considering patient–specific
factors.
4.3 Clinical correlations
The type of surgery played a crucial role in S.
aureus infections, with lower extremity
surgeries being more frequently associated with
the bacterium. A study conducted by Onyekwelu
et al. demonstrated a significantly elevated risk
of surgical site infections in lower extremities
compared to upper extremity surgeries [21,22].
Various factors such as vascularity and
susceptibility to contamination may contribute to
this phenomenon, however, additional research
is needed to further study these mechanisms.
5. Conclusion
In this study, we found that S. aureus was the
dominant gram–positive pathogen responsible
for nosocomial infections in the department
orthopaedics and traumatology of Kaunas
Clinics. Drug resistance pattern of this pathogen
showed that antibiotic resistance is a serious
concern. Based on our results, we highly
recommend the implementation of thorough and
dynamic surveillance of antibiotic–resistant
bacteria, in addition to cautious utilization of
antibiotics, as an effective approach to
controlling the development of antimicrobial
resistance in pathogens.
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