Upsala Journal of Medical Sciences. 2012; Early Online, 1–3

ORIGINAL ARTICLE

Microorganisms causing pyogenic spondylitis: Comparisonof community and hospital-acquired types

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TATSURO SASAJI, NOBORU YAMADA & KAZUO IWAI
Department of Orthopedic Surgery, Fukushima Rosai Hospital, 3-Numajiri, Tsuzura-machi, Uchigo, Iwaki 973-8403,
Japan

Abstract
Pyogenic spondylitis is a common infectious disease caused by various microorganisms. It is difﬁcult to predict the infecting
micro organism at the time of initiation of treatment. Pneumonia is generally clariﬁed into community or hospitalacquired types based on where the infection was acquired, and the infecting microorganisms are different for each type.
We retrospectively analyzed 20 cases of pyogenic spondylitis treated in our hospital and categorized the cases into communityand hospital-acquired types. We also identiﬁed the infecting microorganisms and the rate of sepsis in each type. There were
12 cases of community-acquired and 8 of hospital-acquired infection. The major infecting microorganisms responsible for thecommunity-acquired type were Gram-positive cocci, and those responsible for the hospital-acquired type were methicillinresistant Staphylococcus aureus and Gram-negative bacilli. The rate of sepsis was signiﬁcantly different for both groups: 16% for
the community-acquired type and 75% for the hospital-acquired type. The classiﬁcation of pyogenic spondylitis based onwhere the infection was acquired may be useful for predicting which microorganisms are responsible for the disease.

Key words: Classiﬁcation, infecting micro-organism, pyogenic spondylitis, sepsis

Introduction
Pyogenic spondylitis is a common orthopedic infectious disease. The incidence of pyogenic spondylitis isincreasing in Japan, which is an aging society (1).
Treatment of pyogenic spondylitis is generally
conservative and comprises of antibiotics, bed rest,and immobilization (2). Antibiotics should be selectedaccording to the sensitivity of the infecting microorganisms. The recommended ﬁrst-line antibiotics
include ﬁrst and second generation cephalosporins
and penicillin, to which Gram-positive cocci are sensitive. However, the infecting microorganisms are
sometimes bacteria other than Gram-positive cocci;
in such cases, other antibiotics are required. No reportson the classiﬁcation of pyogenic spondylitis basedon the infecting microorganisms are available.

For example, pneumonia is generally divided into
community and hospital-acquired types based onwhere the infection was acquired, because the infecting
microorganisms are different in each group (3,4).
Therefore, we hypothesized that the microorganisms
causing pyogenic spondylitis would also differ based onwhere the infection is acquired, namely, whether theinfection is community or hospital-acquired. We retrospectively analyzed the microorganisms causing pyogenic spondylitis among the cases treated in ourhospital. The purpose of the present study was toclarify the usefulness of a classiﬁcation based on wherethe infection was acquired.
Patients and methods
All patients were informed that the data from theircases would be used for the study.

Correspondence: Tatsuro Sasaji, Department of Orthopedic Surgery, Fukushima Rosai Hospital, 3-Numajiri, Tsuzura-machi, Uchigo, Iwaki 973-8403, Japan.
Fax: +81-246-26-1322. E-mail: taturosasaji@hotmail.com(Received 9 April 2012; accepted 17 April 2012)ISSN 0300-9734 print/ISSN 2000-1967 online  2012 Informa Healthcare
DOI: 10.3109/03009734.2012.687406

2T. Sasaji et al.

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Subjects
The subjects of this study included 20 patients who weretreated conservatively for pyogenic spondylitis in ourhospital between 2007 and 2011. Eleven patients withpyogenic spondylitis caused by unidentiﬁed microorganisms were excluded. We treated no case of pyogenic spondylitis surgically. The diagnosis of pyogenic
spondylitis was established by culture of the infectedintervertebral disc, laboratory data, including whiteblood cell count and C-reactive protein level, and magnetic resonance imaging. We analyzed age, sex, theinfecting microorganisms, the rate of sepsis, and divided
the patients into two types: community-acquired type ofpyogenic spondylitis and hospital-acquired type. We
analyzed the associated disease in the hospitalacquired type of pyogenic spondylitis. According to
the Surviving Sepsis Campaign guideline, the mortality
rate of sepsis within the ﬁrst month of diagnosis was
30% (5). We thought that it was important whether
pyogenic spondylitis was accompanied with sepsis ornot. We analyzed the infecting microorganisms andmerger rate of sepsis in each type. We deﬁned thecommunity-acquired type of pyogenic spondylitis as
the disease that occurred in patients at home and thehospital-acquired type as the disease that occurred inpatients treated and hospitalized in other departments.
Sepsis was deﬁned as a systemic inﬂammatory response
syndrome (SIRS) due to infection. SIRS was diagnosed
when two or more of the following criteria were present:high fever or hypothermia, tachycardia, tachypnea, andabnormal white blood cell count (6).

of < 0.05 was considered signiﬁcant. Statisticalanalyses were performed using GraphPad Prism(GraphPad Software Inc., San Diego, CA, USA).
Results

For statistical purposes, the data were analyzed using
Fisher’s exact probability test to compare the merger
rate of sepsis between the types. A probability value

A total of 12 male and 8 female patients with a mean age of
70 years (range 16–82 years) were included in the study.
The infecting microorganisms were Staphylococcus aureus
in 5 cases, methicillin-resistant Staphylococcus aureus(MRSA) in 3, Streptococcus agalactiae in 3, coagulasenegative Staphylococcus in 2, Enterococcus faecalis in 2, andStaphylococcus intermedius, Pseudomonas aeruginosa, Bacillus cereus, Campylobacter species, and Escherichia coli in
1 each. Sepsis developed in 8 cases. The communityacquired type of pyogenic spondylitis occurred in12 cases
and the hospital-acquired type in 8. The infecting
microorganisms in the community-acquired type were
Staphylococcus aureus in 5 cases, Streptococcus agalactiae in2, coagulase-negative Staphylococcus in 2, and Staphylococcus intermedius, Escherichia coli, and Enterococcus faecalis
in 1 each. The infecting microorganisms in the hospitalacquired type were MRSA in 3 cases and Enterococcus
faecalis, Pseudomonas aeruginosa, Bacillus cereus, Campylobacter species, and Streptococcus agalactiae in 1 each(Table I). Gram-positive cocci were found in 10 casesof the community-acquired type. Gram-negative bacilli
were found in 4 cases and MRSA in 3 cases of thehospital-acquired type. Sepsis occurred in 2 (16%) casesof the community-acquired type and 6 (75%) cases of thehospital-acquired type (Table II). The rate of sepsis was
signiﬁcantly different between the two types (P = 0.019).
The associated diseases in the hospital-acquired type ofpyogenic spondylitis were alcoholic hepatitis in 3, chronic
renal failure treated with hemodialysis in 1, ileus in
1, lung abscess in 1, lumbar injection in another hospitalin 1, cardiopulmonary arrest treated in intensive careunit in 1.

Table I. Infecting organism in pyogenic spondylitis.

Discussion

Statistical analyses

Infecting micro organism
Community-acquired
type (12 cases)

Staphylococcus aureus
Streptococcus agalactiae
Coagulase-negative Staphylococcus
Staphylococcus intermedius
Escherichia coli
Enterococcus faecalis(Gram-positive coccus: 10 cases)

Hospital-acquired
type (8 cases)

Methicillin-resistant Staphylococcus
aureusEnterococcus faecalis
Pseudomonas aeruginosa
Bacillus cereus
Campylobacter species
Streptococcus agalactiae(MRSA: 3 cases; Gram-negative
bacilli: 4 cases)

The treatment of pyogenic spondylitis is generally
conservative and comprises of antibiotics, bed rest,and immobilization (2). Appropriate antibiotic selection
is important until the sensitivity of the infecting microorganism can be established by culture sensitivitytesting. Staphylococcus aureus is reportedly the mostTable II. Comparison of the rate of sepsis.

The merger rate ofsepsis (sepsis cases)

Community-acquired
type (12 cases)

Hospital-acquired
type (8 cases)

16% (2 cases)

75% (6 cases)

P = 0.019 compared with each type (Fisher’s exact probability test).

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Micro-organisms causing pyogenic spondylitis
common micro organism causing pyogenic spondylitis(2). On the other hand, microorganisms other than
Staphylococcus aureus have also been reported to cause
this infection (2). It was unclear what factor was responsible for the difference in infecting microorganisms.
We classiﬁed pyogenic spondylitis based on where theinfection was acquired in the present study. The major
infecting microorganisms were Gram-positive cocciin the community-acquired type and Gram-negative
bacilli and MRSA in the hospital-acquired type.
Thus, classiﬁcation based on where the infection wasacquired may be useful for predicting the identity of theinfecting microorganisms.
Since the development of chemotherapy, theprognosis of pyogenic spondylitis is generally good.
Generalized sepsis indicates a primary source of
infection other than the spine (2). However, sepsis
occurred in some cases in the present study. Mortalityassociated with sepsis is unacceptably high, and rapid
management is critical (5). In the present study, therate of sepsis was higher in the group with hospitalacquired type of pyogenic spondylitis. Immediateprescription of wide-spectrum antibiotics to which
Gram-negative bacilli and MRSA are sensitive isessential for the hospital-acquired type of pyogenic
spondylitis.
No reports on the classiﬁcation of pyogenic
spondylitis based on the infecting microorganisms
are available. On the basis of present study, we
assumed that classiﬁcation based on where theinfection was acquired was useful for predicting
the identity of the infecting micro organism and for3

selecting the appropriate ﬁrst-line antibiotics
therapy. However, the number of cases was small
in the present study. Further studies with a large
number of pyogenic spondylitis patients would benecessary to address this question.
Declaration of interest: The authors report noconﬂicts of interest. The authors alone are responsible
for the content and writing of the paper.

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