Characteristics of Microorganisms Isolated from Blood Cultures at Nine University Hospitals in Korea during 2009

Hee-Jung Kim; Nam Yong Lee; Sunjoo Kim; Jeong Hwan Shin; Mi-Na Kim; Eui-Chong Kim; Sun Hoi Koo; Nam Hee Ryoo; Jae-Seok Kim; Ji-Hyun Cho

doi:10.5145/KJCM.2011.14.2.48

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Kim, Lee, Kim, Shin, Kim, Kim, Koo, Ryoo, Kim, and Cho: Characteristics of Microorganisms Isolated from Blood Cultures at Nine University Hospitals in Korea during 2009

Original Article

Korean J Clin Microbiol 2011;14(2):48-54.

Published online: 21 June 2011

DOI: https://doi.org/10.5145/KJCM.2011.14.2.48

Characteristics of Microorganisms Isolated from Blood Cultures at Nine University Hospitals in Korea during 2009

Hee-Jung Kim¹, Nam Yong Lee¹, Sunjoo Kim^2,³, Jeong Hwan Shin^4,⁵, Mi-Na Kim⁶, Eui-Chong Kim⁷, Sun Hoi Koo⁸, Nam Hee Ryoo⁹, Jae-Seok Kim¹⁰, Ji-Hyun Cho¹¹

¹Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

²Department of Laboratory Medicine, Jinju, Korea

³Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea

⁴Department of Laboratory Medicine, Seoul, Korea

⁵Paik Institute for Clinical Research, Inje University College of Medicine, Busan, Department of Laboratory Medicine, Seoul, Korea

⁶Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea

⁷Seoul National University Hospital, Seoul, Korea

⁸College of Medicine, Chungnam National University, Daejeon, Korea

⁹School of Medicine, Keimyung University, Daegu, Korea

¹⁰Hallym University College of Medicine, Seoul, Korea

¹¹College of Medicine, Wonkwang University, Iksan, Korea

Correspondence: Nam Yong Lee, Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-gu, Seoul 135-710, Korea. (Tel) 82-2-3410-2706, (Fax) 82-2-3410-2719, (E-mail) micro.lee@samsung.com

Received 1 December 2010 Revised 3 March 2011 Accepted 27 April 2011

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Blood culture is important for determining the etiologic agents of bacteremia and fungemia. Analyses of blood culture results and antimicrobial susceptibility can provide clinicians with relevant information for the empirical treatment of patients. The present study was conducted to assess the frequencies and antimicrobial resistance patterns of clinically important microorganisms from nine hospitals.

Methods

Data including microbiological isolates and corresponding antimicrobial susceptibility test results were collected during 2009 from nine and five university hospitals, respectively. Microorganism identification was based on conventional methods. Antimicrobial susceptibility was tested using the VITEK II system or the Clinical and Laboratory Standards Institute disk diffusion method.

Results

Of 397,602 blood specimens cultured from nine hospitals, 34,708 (8.7%) were positive for microorganisms. Excluding coagulase-negative Staphylococci (CoNS), Escherichia coli was the most common isolate (13.5%), followed by Staphylococcus aureus (11.5%), Klebsiella pneumoniae (6.5%) and Enterococcus faecium (3.4%). The isolation rate of CoNS was 23.6%, while that of ceftazidime-resistant E. coli showed geographic differences ranging from 11% to 28%. Among the Gram-negative isolates, A. baumannii displayed the highest levels of resistance. The total isolation rate of the Candida species increased compared to the previous reported rate in Korea.

Conclusion

Among the isolates, CoNS was the most common, followed by E. coli and S. aureus. The gradual increase in the prevalence of extended-spectrum β-lactamase (ESBL) producers has contributed to the increase in multidrug resistance among bacterial isolates from bloodstream infections.

Keywords: Blood culture, Bacteremia, Antimicrobial susceptibility, Fungemia

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Fig. 1.

The isolation frequencies of common bacteria from 9 hospitals. A, Asan Medical Center; B, Samsung Medical Center; C, Seoul National University Hospital; D, Gyeongsang National University Hospital; E, Inje University Paik Hospital; F, Chungnam National University Hospital; G, Dongsan Medical Hospital; H, Wonkwang University Hospital; I, Kangdong Sacred Heart Hospital.

Fig. 2.

The isolation frequencies of common yeasts from 9 hospitals. See Fig. 2 for designations for each hospital (A∼H).

Table 1.

Rates of antibiotic resistance among the most common Gram-positive bacteria causing bloodstream infections from 5 Korean hospitals in 2009

	Staphylococcus aureus		Staphylococcus epidermidis		Enterococcus faecium		Enterococcus faecalis		Streptococcus pneumoniae
	N	% resistance	N	% resistance	N	% resistance	N	% resistance	N	% resistance
Ampicillin	ND	NA	ND	NA	336	91.2	186	14.2	ND	NA
Penicillin	1121	95.4	1032	96.8	336	92.1	186	15.7	49	20.9
Clindamycin	1121	63.8	1032	65.9	ND	NA	ND	NA	ND	NA
Oxacillin	1072	69.8	1032	84.7	ND	NA	ND	NA	ND	NA
QNP-DFP	1072	0.2	1032	0.1	ND	NA	ND	NA	ND	NA
Cefotaxime^∗	ND	NA	ND	NA	ND	NA	ND	NA	52	7.3
Cefotaxime^†	ND	NA	ND	NA	ND	NA	ND	NA	52	5.4
Erythromycin	1121	61.0	1032	71.3	ND	NA	ND	NA	59	61.5
Ciprofloxacin	1121	56.4	1032	58.8	ND	NA	ND	NA	ND	NA
Levofloxacin	731	62.4	656	26.2	ND	NA	ND	NA	59	7.9
Gentamicin	947	61.4	1032	63.7	ND	NA	ND	NA	ND	NA
HL Gentamicin	ND	NA	ND	NA	325	49.2	186	37.9	ND	NA
HL Streptomycin	ND	NA	ND	NA	325	8.0	186	16.9	ND	NA
Rifampin	502	2.8	1032	16.2	ND	NA	ND	NA	ND	NA
Tetracycline	1121	55.8	1032	22.9	ND	NA	ND	NA	59	68.1
TMP-SMX	502	7.3	522	49.7	ND	NA	ND	NA	34	24.6
Vancomycin	1072	0.0	1032	0.0	336	28.6	186	0.0	52	0.0

^∗ Meningitis, CLSI-recommended resistant MIC breakpoint 2≥ µg/mL

^† Non-meningitis, CLSI-recommended resistant MIC breakpoint 4≥ µg/mL.

Abbreviations: ND, not done; NA, not applicable; QNP-DFP, quinupristin-dalfopristin; HL, high-level; TMP-SMX, trimethoprim-sulfamethoxazole.

Table 2.

Rates of antibiotic resistance among the most common Gram-negative rods causing bloodstream infections from 5 Korean hospitals in 2009

	Escherichia coli		Klebsiella pneumoniae		Acinetobacter baumannii		Pseudomonas aeruginosa
	N	% resistance	N	% resistance	N	% resistance	N	% resistance
Ampicillin	1537	63.4	702	96.8	ND	NA	ND	NA
Amoxicillin-Clavulanate	ND	NA	702	17.8	ND	NA	ND	NA
Piperacillin	721	44.2	597	71.5	200	57.2	263	26.2
Piperacillin-Tazobactam	1129	10.2	736	12.5	200	49.9	263	20.6
Ticarcillin	ND	NA	ND	NA	ND	NA	250	32.9
Ticarcilin-Clavulanate	ND	NA	ND	NA	151	53.1	ND	NA
Cefazolin	832	23.9	394	30.4	ND	NA	ND	NA
Cefoxitin	ND	NA	736	14.0	ND	NA	ND	NA
Cefotaxime	1537	19.1	736	27.2	ND	NA	ND	NA
Ceftazidime	1129	19.9	736	24.2	226	56.4	250	21.5
Cefepime	1113	19.7	736	26.7	226	55.8	263	18.1
Imipenem	1456	0.2	702	0.4	226	34.2	250	25.0
Meropenem	1456	0.1	702	0.7	226	54.4	250	19.0
Aztreonam	ND	NA	736	28.0	ND	NA	250	20.9
Ciprofloxacin	913	36.6	394	17.5	207	62.0	263	18.8
Levofloxacin	ND	NA	394	13.4	226	43.4	157	32.5
Gentamicin	1537	27.0	736	19.4	226	61.2	263	13.3
Amikacin	ND	NA	736	13.7	ND	NA	263	6.7
Tobramycin	1537	14.0	736	19.8	226	47.2	263	11.4
TMP-SMX	1032	37.0	509	23.3	ND	NA	126	98.4

Abbreviations: See Table 1.

Table 3.

Rank order of microorganisms or microorganism groups most frequently isolated from blood samples

Rank	Study (period)
Rank	This study (2009)	Kang et al [13] (2003∼2007)	Ahn et al [14] (2002∼2005)	Koh et al [12] (1994∼2003)	Weinstein et al [22] (1990s)	Cockerill et al [15] (1996∼1997)
1	CoNS	CoNS	CoNS	CoNS	S. aureus	S. aureus
2	E. coli	E. coli	E. coli	E. coli	E. coli	E. coli
3	S. aureus	S. aureus	S. aureus	S. aureus	CoNS	CoNS
4	K. pneumoniae	K. pneumoniae	S. maltophilia	SVG	K. pneumoniae	Enterococci
5	E. faecium	S. pneumoniae	S. marcescens	Enterococci	Enterococci	C. albicans

Abbreviations: CoNS, coagulase-negative staphylococci; S. aureus, Staphylococcus aureus; E. coli, Escherichia coli; K. pneumoniae, Klebsiella pneumoniae; S. maltophilia, Stenotrophomonas maltophilia; SVG, Streptococcus viridans group; E. faecium, Enterococcus faecium; S. marcescens, Serratia marcescens; C. albicans, Candida albicans.

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