Journal of Biosciences and Medicines, 2014, 2, 12-17
Published Online August 2014 in SciRes.
How to cite this paper: Minami, M., et al. (2014) Prevalence and Antimicrobial Susceptibility Pattern of Streptococcus
pneumoniae at General Hospital in the Central Region of Japan from December 2013 to February 2014. Journal of Bio-
sciences and Medicines, 2, 12-17.
Prevalence and Antimicrobial Susceptibility
Pattern of Streptococcus pneumoniae at
General Hospital in the Central Region of
Japan from December 2013 to February
Masaaki Minami1*, Ryoko Sakakibara2, Taichi Imura2, Hideo Morita2, Naoto Kanemaki3,
Michio Ohta4
1Department of Bacteriology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
2Department of Clinical Investigation, Daido Hospital, Nagoya, Japan
3Department of Gastroenterology, Daido Hospital, Nagoya, Japan
4School of Nursing, Sugiyama Jyogakuen University, Nagoya, Japan
Email: *mina mi@ med.n ago ya
Received June 2014
Streptococcus pneum on ia infection is important cause of morbidity and mortality. This study was
conducted to find out the prevalence and antimicrobial susceptibility pattern of Streptococcus
pneum on ia e isolates at general hospitalin the central region of Japan from December 2013 to
February 2014. Streptococcus pneumoniae was identified by standard laboratory procedure. An-
timicrobial susceptibility testing was performed by micro dilution assay according to CLSI rec-
ommend ati on. One hundred fifty-three Streptococcus pneumoniae were isolated among which 80
(52.2%) were males and 73 (47.8%) were females. Nasal discharge (134%/87.6%) contributed
more than other biological materials. The age incidence of (0 - 1) years, (1 - 10) years, (11 - 40)
years, (41 - 60) years and >60 years age groups were 26 (17.0%), 110 (71.9%), 3 (2.0%), 10
(6.5%), and 4 (2.6%) respectively. Positive samples were received mostly from the pediatrics
(137%/89.5%), respiratory medicine (12%/ 7.8%) and lowest from gastroenterology (1%/0.6%)
and neurology (1/ 0.6%) department. Vancomycin and rifampicin were the most active antibiotics
with 100% susceptibility rates. The next best were levofloxacin, penicillin G and ceftriaxone. Our
study revealed that 82 Streptococcus pneumonia isolates had multidrug resistant ability (53.6%).
Streptococcus pneumoniae infection spreads among community easily and inappropriate use of
antibiotics contributes to their resistance. Continuous antimicrobial susceptible surveys are es-
sential to guide policy on the adequate use of antibiotics to reduce the morbidity and mortality
and reduce the emergency of antimicrobial resistance.
Streptococcus pneumoniae, Susceptibility, Antimicrobial Resistance, Multi Drug Resistance
Corresponding author.
M. Minami et al.
1. Introduction
Streptococcus pneumoniae is one of the most common bacteria causing pneumonia, meningitis, bacteremia and
many other infections, and continues to be an important cause of morbidity and mortality in the world [1].
Globall y, an estimated 1.6 million people including 1 million children less than 5 years old die of invasive
pneumonia disease annually [2]. Its clinical burden is concentrated among the very old and very young [2]. De-
spite this high toll, the vast majority of Streptococcus pneumoniae are found in asymptomatic nasopharyngeal
carriage, the prevalence of which varies by age and region [3]. The carriage state is responsible for transmission,
and is the stage of Streptococcus pneumoniae life history at which interventions such as antibiotics and vaccines
exert their selective pressure [4].
The present study was conducted to find out the recent prevalence and antimicrobial susceptibility pattern of
Streptococcus pneumoniae isolates at general hospital in the central of Japan. Our result would be useful in es-
tablishing empiric therapy guidelines and to contribute to larger more extensive surveillance study.
2. Materials and Methods
2.1. Strains and Clinical Data Collection
A total of 153 Streptococcus pneumoniae were obtained from various clinical specimens at Daido Hospital from
December 2013 to February 2014. Daido Hospital is a 404-bed private general hospital in the central region of
Japan. We used medical records appended to clinical species for the analysis of clinical feature at Daido Hospit-
al. We considered several isolates from the same region of the same patient as one isolate per one patient for the
analysis in this study. All streptococcal isolates were identified by standard conventional biochemical methods
or the VITEK2 system (b ioMé rieux, Durham NC, USA). Our experimental design was approved by the ethics
committee at Daido hospital.
2.2. Antimicrobial Susceptibility Analysis
Streptococcus pneumoniae isolates were examined for 15 antibiotic susceptibilities as follows; PCG, penicillin
G; AMPC, amoxicillin; CTX, cefotaxime; CTRX, ceftriaxone; IPM, imipenem; MEPM, meropenem; LVFX,
levofloxacin; OFLX, ofloxacin; CAM, clarithromycin; EM, erythromycin; VCM, vancomycin; TC, tetracycline;
CP, chloramphenicol; RFP, rifampicin, ST, Trimethoprim-sulfamethoxazole. Minimal inhibitory concentration
(MICs) were determined at clinical laboratory in Daido Hospital using broth micro dilution methodology with
the VITEK2 system. MICs were calculated as MIC90 (MIC causing inhibition of 90% of isolates). Percentage
susceptibilities were calculated based on Clinical Laboratory Standard Institute (CLSI) break point [5]. We used
two separate interpretive breakpoints for meningeal and non-meningeal isolates to define penicillin. Multidrug
resistance (MDR) was defined as non-susceptibility to more than any three antimicrobial agents [6].
2.3. Statistical Analysis of the Dat a
We conducted the statistical analysis with the chi-squared test or Fishers exact test when appropriate. Differ-
ences were considered significant when p was <0.05.
3. Results
One hundred fifty-t hre e Streptococcus pneumoniae were isolated among which 80 (52.2%) were from male pa-
tient and 73 (47.8%) were from females. Nasal discharge 134 (87.6%) [male-69, female-65], sputum 15 (9.7%)
[ma le-9, female-6], tonsil 2(1.3%) [mal e-1, female-1], pharyngeal mucus 1(0.7%) [mal e-1, fema le -1], and blood
1 (0.7%) [male-1, female-1] were the source of Streptococcus pneumoniae isolates (Table 1). There was no sig-
nificant difference between male and female.
The age incidence among 0 - 1 years age group was 26 (17%) [ma le-17, female-9], among 1 - 10 years age
group, 110 (71.9%) [male-52, female-58] (p < 0.05), among 11 - 40 years age group, 3 (1.7%) [male-2, fe-
male -1], in 41-60 years it was 10 (6.5%) [male-8, female-2] and in >60 years age group it was 4 (2.6%) [male-2,
fema le -2] (Table 2). There was no significant difference between male and female.
Most of the Streptococcus pneumoniae isolates were from the pediatrics (137/89.5%) [male-69, female-68]
followed by respiratory medicine (12/7.8%) [male-9, Female-3], general medicine (2/1.3%) [male -1, female-1]
M. Minami et al.
and lowest from gastroenterology (1/0.6%) [mal e-0, femal e -1], and neurology department (1/0.6%) [male-1,
fema le -0] (Table 3). There was no significant difference between male and female.
The results of antimicrobial susceptibility of Streptococcus pneumoniae isolates to various antibiotics tested
in this study are shown in Table 4. Vancomycin and rifampicin were the most active antibiotics with 100%.
Table 1. Biological material wise distribution of Streptococcus pneumoniae isolates.
biological material nasal discharge sputum tonsil pharyngeal mucus blood
male 69 9 1 0 1
female 65 6 1 1 0
total 134 15 2 1 1
Table 2. Age wise distribution of Streptococcus pneumoniae isolates.
age groups (0 - 1) years (1 - 10) years (11 - 40) years (41 - 60) years >60 years
male 17 52 1 8 2
female 9 58 2 2 2
total 26 110 3 10 4
Table 3. Clinical department wise distribution of Streptococcus pneumoniae isolates.
clinical department pediatrics respiratory medicine
general medicine gastroenterology neurology
male 69 9 1 0 1
female 68 3 1 1 0
total 137 12 2 1 1
Table 4. Antimicrobial susceptibility of Streptococcus pneumoniae isolates.
antimicrobial agents MIC90 (mg/mL) range % susceptibility
PCG 2 ≤0.06 - 4 97.4
AMPC 2 ≤0.06 - 4 92.8
CTX 1 ≤0.06 - 4< 93.5
CTRX 1 ≤0.06 - 4< 96.1
IPM 0.25 <0.03 - 0.5 74.5
MEPM 1 ≤0.06 - 0.12 73.9
LVFX 2 ≤0.5 - 8≤ 98.7
OFLX 4 ≤1 - 8≤ 88.9
CAM 1≤ ≤0.25 - 1≤ 6.5
EM 1≤ ≤0.25 - 1≤ 7.2
VCM ≤1 ≤1 100.0
TC 16≤ ≤1 - 16≤ 8.5
CP 16 ≤2 - 32≤ 87.6
RFP ≤0.25 ≤0.25 100.0
ST 20 ≤10 - 80 79.7
M. Minami et al.
susceptibility rates. The next best antibiotics with over 95% susceptibility rates were levofloxacin (98.7%), pe-
nicillin G (97.4%), and ceftriaxone (96.1%). Significant resistant were observed in tetracycline (8.5%), eryt-
hromycin (7.2%), clarithromycin (6.5%).
Our study revealed that 82 Streptococcus pneumoniae isolates had multidrug resistant ability (53.6%). The
most common pattern of MDR was resistant to clarithromycin, tetracycline, and imipenem (25.5%), followed by
resistant to clarithromycin, tetracycline, and trimethoprim - sulfamethoxazole (16.3%). Most Streptococcus
pneumoniae isolates with MDR were resistant to at least one of the macrolides tested.
4. Discussion
In this study, we described the characteristics of Streptococcus pneumonia isolates from December 2013 to
February 2014 at general hospital in the central region of Japan.
With respect to gender group, Streptococcus pneumoniae were isolated more from female patients than male
patients. Although previous report showed that the number of male patient was significant greater than that of
female patient [7], our study showed the male to female ratio was about 1.1 time and there was no significant
differences among gender.
We clarified Streptococcus pneumoniae with age distribution. The present study reveals the prevalence of
Streptococcus pneumonia more in extremes of age group as seen in 0 - 1 years age group, it is 17%, increasing
to 71.9% in 1 - 10 years age group, diminishing to 2% in 11 - 40 years age group, again increasing to 6.5% in
41% - 60 years age group and finally diminished to 2.6% in more than 60 years age group. Although young pa-
tients under 10 years frequently caused Streptcococcus pneumoniae infection, the large numbers of Streptc o-
coccus pneumoniae were not isolated from over 60 years age patients in o ur study. Previous report showed that
high incidence of pneumonia in children and elder people in different parts of world [7] [8]. It is suggested to
decrease immunity in the extremes of age groups.
In the analysis of clinical departments, we found that department where most patients with Streptococcus
pneumoniae were detected was pediatrics. Streptococcus pneumoniae infection, especially acute pharyngitis and
tonsillitis, was usually popular as pediatric diseases [1].
The disease burden of Streptococcus pneumoniae infections has increased due to widespread emergence of
antimicrob ial resistance in many countries from 1990s [2]. Previous studies documented very high prevalence
rates of beta-lactam and macrolide resistance in Streptococcus pneumoniae in Asian countries [2] [9]-[13]. Par-
ticularly, macroride resistance has remarkably increased in many Asian countries, where over 70% of clinical
isolates were fully resistant [2] [9] [12] [13]. Antimicrobial susceptible analysis of Streptococcus pneumoniae
revealed that macrolide was no longer effective against these bacteria because macrolide resistant rates of
Streptococcus pneumoniae were more than 90%. Recently Clarithromycin and Azithromycin, which we call new
macrolide, have been used frequently against respiratory tract infectious disease. Thus, we need further antimi-
crobial surveillance to prevent the spread of new macroride resistant Streptococcus pneumoniae.
Streptococcus pneumoniae also had tetracycline - resistant pattern. This result implies that Streptococcus
possesses the same pathogenic island including both macrolide and tetracycline resistant genes [4]. We found a
low prevalence of penicillin resistance in non-meningeal isolates according to the revised CLSI breakpoints for
resista nce to parenteral penicillin, although penicillin MICs have increased in some countries such as China and
India compared with past investigation [9]. Most of the non-meningeal isolates from Asian countries were sus-
ceptible to parenteral penicillin, a finding consistent with other study worldwide (<7%) [2] [9] [13]. As the
emergence of penicillin resistant Streptococcus pneumoniae is low, our result showed that the prevalence of im-
ipenem non-susceptibility was not low in Japan. We need to focus on the carbapenem susceptible pattern in
Streptococcus pneumonia hereafter. The overall rates of resistance to fluoroquinolone in Streptococcus pneumo-
niae remained low in most countries including Japan [2] [9] [13]. Thus, given the popular use of respiratory flu-
oroquinlone in clinical practice, the emergency of these strains highly resistant to fluoroquinolone could be a
concern in the future in the treatment of Streptococcus pneumoniae pneumonia. In addition, MDR Streptococcus
pneumonia was also very prevalent in Asian countries (59.3%), particularly in China (83.3%), Vietnam (75.5%),
South Korea (63.9%), Hong Kong (62.2%), and Taiwan (59.7%) [9]. From our result, multi drug resistance was
53.6% in Japan. But this rate in Japan was much higher than those in other parts world such as 9% to 24% in
North America and 0% to 43% in Europe [2] [9] [14]. The emergence of MDR Streptococcus pneumonia in-
cluding macrolide, tetracycline, and carbapenem resistant strains will raise the serious problem in Asian coun-
M. Minami et al.
tries including Japan [13] [15 ].
5. Conclusions
Incidence of Streptococcus pneumoniae infection is increasing worldwide affecting the children and aged adult
population which may lead to severe invasive infection by dissemination to other organs of the body if not
treated adequately. The indiscriminate and inadvertent use of antibiotics has led to the emergence of multidrug
resistance among commonly used antibiotics.
Our investigation aims to guide medical officer on appropriate use of antibiotics. This aim is not only to re-
duce the morbidity and mortality in the patients but also to control the emergence and spread of resistance
among Streptococcus pneumoniae. Continuous surveillance of the use of antibiotics helps in preserving the ef-
fectiveness of antibiotics. The results from our study strongly emphasize the need for continuous epidemiologi-
cal monitoring of antibiotic resistant.
We thank Mr. Shoji Ishihara and Ms. Miwako Fujimura for special encouragement. This study was supported by
a grant-in-aid for research from the Nagoya City University, Japan.
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