Acinetobacter sp. isolates from emergency departments in two hospitals of South Korea

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1 Journal of Medical Microbiology (2014), 63, DOI /jmm Acinetobacter sp. isolates from emergency departments in two hospitals of South Korea Ji-Young Choi, 1 3 Eun Ah Ko, 2 3 Ki Tae Kwon, 3 Shinwon Lee, 3 Choel In Kang, 4 Doo-Ryeon Chung, 4 Kyong Ran Peck, 4 Jae-Hoon Song 4,5 and Kwan Soo Ko 1,5 Correspondence Kwan Soo Ko ksko@skku.edu 1 Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea 2 Korean Minjok Leadership Academy, Heongseong, Republic of Korea 3 Division of Infectious Diseases, Daegu Fatima Hospital, Daegu, Republic of Korea 4 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea 5 Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, Republic of Korea Received 6 March 2014 Accepted 25 July 2014 A total of 114 Acinetobacter sp. isolates were collected from patients in the emergency departments (EDs) of two Korean hospitals. Most isolates belonged to the Acinetobacter baumannii complex (105 isolates, 92.1 %). Imipenem resistance was found in 39 isolates (34.2 %) of the Acinetobacter sp. isolates, and 6 colistin-resistant isolates were also identified. Species distribution and antimicrobial-resistance rates were different between the two hospitals. In addition, two main clones were identified in the imipenem-resistant A. baumannii isolates from hospital B, but very diverse and novel genotypes were found in those from hospital A. Many Acinetobacter sp. isolates, including the imipenem-resistant A. baumannii, are considered to be associated with the community. The evidence of high antimicrobial resistance and different features in these Acinetobacter sp. isolates between the two EDs suggests the need for continuous testing to monitor changes in epidemiology. INTRODUCTION Until the 1980s, Acinetobacter spp. were considered as merely colonizers and were often neglected in the clinical setting; however, this group has now become one of the most problematic healthcare-associated pathogens (Munoz- Price & Weinstein, 2008). In particular, the emergence of multidrug-resistant or even pandrug-resistant Acinetobacter baumannii isolates has become a serious clinical problem in many parts of the world. Although Acinetobacter spp. have been known to cause mainly nosocomial infections, particularly in immunocompromised patients and patients in intensive care units, their presence in reservoirs outside the hospital has been recently reported (Eveillard et al., 2013; Choi et al., 2012). In addition, community-acquired Acinetobacter infections, such as bacteraemia, pneumonia and cellulitis, which may usually be associated with a detrimental patient s condition or comorbidity, have been repeatedly reported (Henao-Martínez et al., 2012; Gaillard et al., 2012; 3These authors contributed equally to this work. Abbreviations: AGS, Acinetobacter genomic species; CLSI Clinical and Laboratory Standards Institute; ED, emergency department; MLST, multilocus sequence typing; ST, sequence type. Leung et al., 2006; Peng et al., 2012). More frequently, community-onset infections by antimicrobial-resistant Acinetobacter spp. have been identified, and Acinetobacter spp. are now becoming a challenge for clinicians in emergency departments (EDs) (Kang et al., 2012a, b). However, the study of Acinetobacter sp. characteristics using ED isolates has rarely been performed. In this study, we investigated species distribution, antimicrobial resistance and genotypes to identify differences in the epidemiology of Acinetobacter sp. isolates between the EDs of two hospitals in Korea. The two hospitals that participated in this study showed different features. While one hospital (hospital A) is located in Seoul, the capital of Korea, another hospital (hospital B) is located in Daegu, which is approximately 300 km away from Seoul. In addition, while hospital A is a tertiary-care hospital, hospital B is a secondary-care hospital. We identified some different characteristics of the Acinetobacter sp. isolates from the EDs between the two hospitals. METHODS Bacterial isolates and species identification. A total of 114 Acinetobacter sp. isolates from patients were collected from May G 2014 The Authors Printed in Great Britain 1363

2 J.-Y. Choi and others to May 2013 from two EDs in Korean hospitals: one (hospital A) is a tertiary care hospital located in Seoul, the capital of Korea (91 isolates), and the other (hospital B) is a secondary hospital located in the province of Daegu (23 isolates). The isolation sources are listed in Table 1. Only the first isolate from each patient was included in this study. Preliminary species identification as Acinetobacter sp. isolates was performed using the VITEK-2 system. Acinetobacter spp. were determined based on partial rpob gene sequences (468 bp), as described elsewhere (Ko et al., 2007; La Scola et al., 2006). In vitro antimicrobial-susceptibility testing. In vitro antimicrobial-susceptibility testing was performed with all Acinetobacter sp. isolates by measuring MIC using the broth microdilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines (CLSI, 2013). Eleven antimicrobial agents were tested: imipenem, colistin, ampicillin/sulbactam, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, rifampicin, trimethoprim/sulfamethoxazole, tetracycline and tigecycline. CLSI susceptibility interpretive criteria were used (CLSI, 2013). Because no breakpoints for rifampicin and tigecycline are available in the CLSI guidelines, the CLSI criteria recommended for staphylococci were applied for rifampicin (resistant 4 mgl 21 ) (CLSI, 2013), and the criteria of the United States Food and Drug Administration for Enterobacteriaceae were used for tigecycline (intermediate 4 mg l 21 and resistant 8 mgl 21 ). Escherichia coli ATCC 25922, Staphylococcus aureus ATCC and Pseudomonas aeruginosa ATCC were used as control strains. Multilocus sequence typing (MLST), PFGE and antimicrobialresistance genes. MLST was performed for 28 imipenem-resistant A. baumannii isolates, as described elsewhere (Bartual et al., 2005). All MLST data, including newly identified alleles and sequence types (STs), were submitted to the A. baumannii MLST database ( pubmlst.org/abaumannii). A phylogenetic tree was reconstructed based on concatenated sequences of seven housekeeping genes using the neighbour-joining method. For PFGE, genomic DNA was digested using the ApaI restriction enzyme. The restriction fragments were separated by PFGE using a temperature-controlled CHEF DR III system (Bio-Rad). For the 39 imipenem-resistant Acinetobacter sp. isolates, resistance genes, including bla IMP, bla VIM, bla GIM, bla SIM, bla KPC, bla NDM-1 and bla OXA-48, as well as bla OXA-23-like, bla OXA-24-like, bla OXA-51-like and bla OXA-58-like, were also detected by PCR, as described elsewhere (Lee et al., 2005). RESULTS A total of 105 out of 114 Acinetobacter sp. isolates from the EDs belonged to the A. baumannii complex [or Acinetobacter calcoaceticus A. baumannii (Acb) complex], including A. baumannii, A. pittii, A. nosocomialis, Acinetobacter genomic species (AGS) close to 13TU and A. calcoaceticus (105 isolates, 92.1 %) (Table 1). Of these, A. baumannii was the most frequently isolated species (72 isolates, 63.2 %), and it was more frequently isolated in hospital B (20 out of 23 isolates, 87.0 %) than in hospital A (52 out of 91 isolates, 57.1 %). A. pittii was the second most common species (14 isolates, 12.3 %), followed by A. nosocomialis (11 isolates, 9.6 %), A. calcoaceticus (5 isolates, 4.4 %), A. soli (5 isolates, 4.4 %) and AGS close to 13TU (3 isolates, 2.6 %). Other species (Acinetobacter johnsonii, A. junii, A. ursingii and AGS 9) were represented by one isolate. A. pittii, A. soli, A. johnsonii, A. junii, A. ursingii and AGS 9 were identified only in hospital A. Among the 18 Acinetobacter sp. blood isolates, only six isolates (33.3 %) were classified as A. baumannii (Table 1). The imipenem-resistance rate was 34.2 % (39 isolates) among the Acinetobacter sp. isolates (Table 2). It was lower in A. pittii (2 out of 14 isolates, 14.3 %) than in other species. Six colistin-resistant Acinetobacter sp. isolates were identified: three belonged to A. baumannii, and one each to A. nosocomialis, A. calcoaceticus and A. soli. Resistance rates to the other antimicrobial agents among the Acinetobacter sp. isolates ranged from 22.8 to 53.3 %: 38.6 % for ampicillin/sulbactam, 42.1 % for cefotaxime, 53.5 % for ceftazidime, 48.2 % for ciprofloxacin, 43.9 % for gentamicin, 50.9 % for rifampicin and 43.0 % for trimethoprim/ sulfamethoxazole (Table 2). For tigecycline, 16 isolates (14.0 %) of Acinetobacter sp. and 13 isolates (18.1 %) of A. baumannii showed tigecycline intermediate susceptibility or were resistant (MIC 4 mgl 21 ) (Table 2). Of these, Table 1. Species and sources of Acinetobacter sp. isolates from the EDs of two Korean hospitals Species No. (%) Source SP BL UR Bile Pus TA DS PTF CSF AB OS PF UK A. baumannii 72 (63.2) A. pittii 14 (12.3) A. nosocomialis 11 (9.6) A. calcoaceticus 5 (4.4) AGS close to 13TU 3 (2.6) A. soli 5 (4.4) A. johnsonii 1 (0.9) 1 A. junii 1 (0.9) 1 A. ursingii 1 (0.9) 1 AGS 9 1 (0.9) 1 Total 114 (100) AB, Abscess; BL, blood; CSF, cerebrospinal fluid; DS, dialysate; OS, oral swab; PF, pleural fluid; PTF, peritoneal fluid; SP, sputum; TA, tracheal aspirate; UK, unknown; UR, urine Journal of Medical Microbiology 63

3 Acinetobacter from emergency departments Table 2. Antimicrobial-resistance rates in Acinetobacter sp. isolates from the EDs of two Korean hospitals Species (no. of isolates) Resistance rate (%) Hospital A Hospital B IMI CL A/S CTX CAZ CIP GEN RIF SXT TET TIG* IMI CL A/S CTX CAZ CIP GEN RIF SXT TET TIG* Total (A, 91; B, 23) A. baumannii complex (A, 82; B, 23) A. baumannii (A, 52; B, 20) A. pittii (A, 14; B, 0) A. nosocomialis (A, 10; B, 1) A. calcoaceticus (A, 4; B, 1) A. soli (A, 5; B, 0) A/S, Ampicillin/sulbactam; CAZ, ceftazidime; CIP, ciprofloxacin; CL, colistin; CTX, cefotaxime; GEN, gentamicin; IMI, imipenem; RIF, rifampicin; SXT, trimethoprim/sulfamethoxazole; TET, tetracycline; TIG, tigecycline. *For tigecycline, nonsusceptibility (resistance and intermediate susceptibility) is shown. five isolates (four A. baumannii and one A. pittii) were resistant to tigecycline (MIC 8 mgl 21 ). Antimicrobial-resistance rates differed between Acinetobacter sp. isolates from hospitals A and B. While 16 out of 23 of Acinetobacter sp. isolates (69.6 %) from hospital B were resistant to imipenem, only 23 out of 91 isolates (25.3 %) from hospital A were imipenem-resistant. For colistin, 4.4 and 8.7 % Acinetobacter sp. isolates from hospitals A and B were resistant, respectively. While Acinetobacter sp. isolates from hospital A showed low resistance rates for ampicillin/sulbactam, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, rifampicin, trimethoprim/sulbactam and tetracycline, those from hospital B showed higher resistance rates for them. While 12.1 % of Acinetobacter sp. isolates from hospital A were nonsusceptible to tigecycline, 21.7 % from hospital B were tigecycline nonsusceptible. The presence of antimicrobial-resistance genes was tested for the 39 imipenem-resistant Acinetobacter sp. isolates. Although the bla OXA-51-like gene and its upstream insertion element, ISAba1, were identified in all imipenem-resistant A. baumannii isolates, they were also found in one imipenem-resistant A. calcoaceticus pus isolate from hospital A. The bla OXA-23-like gene was found only in A. baumannii isolates. Among the 28 imipenem-resistant A. baumannii isolates, the bla OXA-23-like gene was identified in 19 isolates (67.9 %). While all 15 imipenem-resistant A. baumannii isolates from hospital B contained the bla OXA-23-like gene, the bla OXA-23-like gene was found in only 3 out of 13 imipenem-resistant A. baumannii isolates from hospital A (23.1 %). The other resistance genes tested in this study were not identified in any imipenem-resistant Acinetobacter sp. isolates. In imipenem-resistant A. baumannii isolates, in which the carbapenemase genes were not detected except for bla OXA-51-like, it is expected that efflux pumps may play a role in imipenem resistance. In addition, the bla OXA-51-like gene may also contribute the imipenem resistance because all isolates have ISAba1 elements upstream of bla OXA-51-like. In MLST analysis, 15 STs were identified among the 28 imipenem-resistant A. baumannii isolates (Table 3). Of these, 11 STs were newly identified in this study. CC92 including six STs was identified, and ST767 and ST774 comprised a CC. However, the other STs constituted singletons. ST357 and ST138 were represented by eight and seven isolates, respectively, but the other 13 STs were represented by only one isolate. All but one of the isolates belonging to ST357 and ST138 were from hospital B. Thus, all but one imipenem-resistant A. baumannii isolates from hospital B belonged to at least one of two main STs. ST357 and ST138 imipenem-resistant A. baumannii isolates showed different restriction fragment patterns in PFGE analysis from each other, but a very similar PFGE pattern was found within the same ST (data not shown). In contrast, no imipenem-resistant A. baumannii isolates from hospital A were represented by the same ST. In

4 J.-Y. Choi and others Table 3. Genotypes of imipenem-resistant A. baumannii isolates in MLST analysis Genotype Allelic profile* No. of isolates addition, 13 different STs from hospital A showed multiple nucleotide differences, and a phylogenetic tree from concatenated nucleotide sequences of the 7 gene fragments confirmed multiple origins of the imipenem-resistant A. baumannii isolates from hospital A (Fig. 1). DISCUSSION Hospital A (n513) Hospital B (n515) CC92 ST ST ST ST ST ST Others ST ST ST ST ST ST ST ST ST *glta-gyrb-gdhb-reca-cpn60-gpi-rpod. Several recent studies have reported community-onset Acinetobacter infections (Henao-Martínez et al., 2012; Gaillard et al., 2012; Leung et al., 2006; Peng et al., 2012), and have suggested the association of community-based A. baumannii isolates with these infections rather than nosocomial strains (Eveillard et al., 2013; Choi et al., 2012). In addition, clinical features of A. baumannii infections in patients admitted to EDs have been investigated in Korea (Kang et al., 2012a, b). In this study, we collected Acinetobacter sp. isolates from two EDs in Korea, and their characteristics were investigated. Although the different number of isolates and different locality of the two hospitals would be a limitation of this study, we identified that A. baumannii is the most prevalent species in the EDs, as in nosocomial infections. In our previous studies, A. baumannii constituted % of Acinetobacter sp. isolates in Korea (Ko et al., 2007; Park et al., 2012). However, the identification of A. soli had not been reported in the previous studies. A. soli was recently characterized as a novel species in Korea (Kim et al., 2008). Although it was first identified and isolated from forest soil, it has been reported to cause bloodstream infections, and carbapenem-resistant A. soli isolates have been identified (Pellegrino et al., 2011; Endo et al., 2012). In this study, we identified five A. soli isolates from one ED. Of these, two were isolated from the blood, and two were highly resistant to imipenem (MICs.64 mg l 21 ). In particular, one A. soli dialysate isolate (SMC ) was resistant to colistin and susceptible only to tigecycline. It is considered that antimicrobial-resistant A. soli, which is ubiquitous in the environment, can cause human infection, and thus should be included as an antimicrobial-resistant human pathogen. It is noted that many Acinetobacter sp. isolates were antimicrobial resistant. In particular, one-third of the Acinetobacter sp. isolates were resistant to imipenem. In a previous study on Acinetobacter sp. isolates collected in two hospitals from 2002 to 2006 in Korea, only 8.3 % were imipenem resistant (Ko et al., 2007). We have reported a drastic increase in imipenem resistance in Acinetobacter sp. isolates causing bloodstream infections in Korea from 15.9 % in to 77.6 % in (Park et al., 2012). Our results in this study are consistent with the increase of imipenem-resistant Acinetobacter sp. isolates in hospitals. In addition, we identified six colistin-resistant isolates, and the tigecycline-nonsusceptibility rate was 14.0 %. Thus, antimicrobial resistance should be not ignored in Acinetobacter sp. isolates from EDs in Korea. However, it should be noted that species distribution and antimicrobial-resistance rates were significantly different between the two hospitals. While most Acinetobacter sp. isolates belonged to A. baumannii and only three nonbaumannii Acinetobacter sp. isolates were identified in hospital B, ten species were identified and 57.1 % of isolates from the ED were classified as A. baumannii in hospital A. Resistance rates for most antimicrobial agents were higher in Acinetobacter sp. isolates from hospital B than in those from hospital A. In addition, clonality of the imipenemresistant A. baumannii isolates was also different between the two hospitals. While all but one of the imipenemresistant A. baumannii isolates from hospital B belonged to the ST138 and ST357 clones, no clonality was identified among the imipenem-resistant A. baumannii isolates from hospital A. In addition, most of the bla OXA-23-like genes, which are commonly related to carbapenem resistance worldwide, were identified in imipenem-resistant A. baumannii isolates from hospital B located in the Daegu province. That is, clonal A. baumannii isolates with high antimicrobial resistance might be brought into the hospital through the ED in hospital B, but not in hospital A. Such differences may be due to the features of the hospitals. Differences in region and hospital level may affect the features of the EDs and their patients, resulting in a difference in pathogens. Thus, understanding the characteristics of pathogens in each hospital will be important for the prevention, control and treatment of infections. ST357, one of the main clones identified in hospital B, was not identified in A. baumannii isolates causing nosocomial 1366 Journal of Medical Microbiology 63

5 Acinetobacter from emergency departments ST779 (07AC-343) ST778 (SMC ) ST768 (10AC-023) ST75 (07AC-306) ST773 (SMC ) ST780 (FA434) CC92 ST138 (SMC , FA127, FA330, FA336, FA475, FA763, FA789) ST769 (SMC ) ST770 (SMC ) ST357 (FA425, FA426, FA765, FA593, FA790, FA833, FA890, FA947) ST598 (07AC-256) ST774 (SMC ) ST767 (07AC-369) ST766 (07AC-018) ST771 (SMC ) Fig. 1. Unrooted phylogenetic tree of 28 imipenem-resistant A. baumannii isolates (15 STs) as reconstructed based on concatenated sequences of 7 housekeeping genes used in MLST. The tree was generated by the neighbour-joining method. Isolates from hospital A are underlined, and CC92 is also represented. Bar indicates 1 substitution per 1000 nt. infections in Korea (Park et al., 2012). It was speculated that new antimicrobial-resistant A. baumannii clones may be imported into the hospital from the community and can then spread within the hospital. In addition, most of the imipenem-resistant A. baumannii isolate genotypes from hospital A have not been previously identified. Thus, these isolates may also be imported from the community, but have not been spread within the hospital. However, identification of ST138, which belonged to CC92 or the global clone 2 distributed in Korea (Kim et al., 2013), as a main clone of imipenem-resistant A. baumannii in the ED suggests different implications. In our study, we identified that ST138 increased recently in a Korean hospital (Park et al., 2012). The ST138 clone identified from the ED in this study may be not be community based or may disperse into the community due to the blurred boundary between the hospital and the community. In this study, we identified antimicrobial-resistant Acinetobacter sp. isolates from two EDs in Korea. The two hospitals showed different characteristics of Acinetobacter sp. isolates, such as species distribution, antimicrobial resistance and clonality of imipenem-resistant A. baumannii isolates. Thus, initial antimicrobial coverage of Acinetobacter infections in EDs should be considered in each hospital. In addition, many Acinetobacter sp. isolates including imipenem-resistant A. baumannii are supposed to be associated with the community. Continuous surveillance studies are warranted to monitor changes in the epidemiology of hospital and community-onset Acinetobacter sp. infections. ACKNOWLEDGEMENTS This study was performed partly by E. A. Ko as her internship program at Sungkyunkwan University School of Medicine. This research was supported in part by the Basic Science Program through the National Research Foundation of Korea (NRF) and was funded by the Ministry of Science, ICT and Future Planning (NRF-2013R1A2A2A ). REFERENCES Bartual, S. G., Seifert, H., Hippler, C., Luzon, M. A., Wisplinghoff, H. & Rodríguez-Valera, F. (2005). Development of a multilocus sequence typing scheme for characterization of clinical isolates of Acinetobacter baumannii. J Clin Microbiol 43,

6 J.-Y. Choi and others Choi, J. Y., Kim, Y., Ko, E. A., Park, Y. K., Jheong, W. H., Ko, G. P. & Ko, K. S. (2012). Acinetobacter species isolates from a range of environments: species survey and observations of antimicrobial resistance. Diagn Microbiol Infect Dis 74, CLSI (2013). Performance Standards for Antimicrobial Susceptibility Testing; 23rd Informational Supplement M100 S23. Wayne, PA: Clinical and Laboratory Standards Institute. Endo, S., Sasano, M., Yano, H., Arai, K., Aoyagi, T., Hatta, M., Gu, Y., Yamada, M., Tokuda, K. & other authors (2012). First carbapenemresistant isolates of Acinetobacter soli in Japan. Antimicrob Agents Chemother 56, Eveillard, M., Kempf, M., Belmonte, O., Pailhoriès, H. & Joly-Guillou, M. L. (2013). Reservoirs of Acinetobacter baumannii outside the hospital and potential involvement in emerging human communityacquired infections. Int J Infect Dis 17, e802 e805. Gaillard, T., Darles, C., Pons, S., Martinaud, C., Soler, C. & Brisou, P. (2012). Acinetobacter parvus bacteraemia community-acquired. Int J Med Microbiol 302, Henao-Martínez, A. F., González-Fontal, G. R. & Johnson, S. (2012). A case of community-acquired Acinetobacter junii-johnsonii cellulitis. Biomedica 32, Kang, C.-I., Chung, D. R., Peck, K. R., Song, J.-H. & Korean Network for Study on Infectious Diseases (KONSID) (2012a). Clinical predictors of Pseudomonas aeruginosa or Acinetobacter baumannii bacteremia in patients admitted to the ED. Am J Emerg Med 30, Kang, S. J., Kang, C.-I., Park, S. Y., Ha, Y. E., Joo, E.-J., Chung, D. R., Peck, K. R., Lee, N. Y. & Song, J.-H. (2012b). Epidemiology and clinical features of community-onset Acinetobacter baumannii infections. Infect Control Hosp Epidemiol 33, Kim, D., Baik, K. S., Kim, M. S., Park, S. C., Kim, S. S., Rhee, M. S., Kwak, Y. S. & Seong, C. N. (2008). Acinetobacter soli sp. nov., isolated from forest soil. J Microbiol 46, Kim, D. H., Choi, J. Y., Kim, H. W., Kim, S. H., Chung, D. R., Peck, K. R., Thamlikitkul, V., So, T. M. K., Yasin, R. M. D. & other authors (2013). Spread of carbapenem-resistant Acinetobacter baumannii global clone 2 in Asia and AbaR-type resistance islands. Antimicrob Agents Chemother 57, Ko, K. S., Suh, J. Y., Kwon, K. T., Jung, S. I., Park, K. H., Kang, C. I., Chung, D. R., Peck, K. R. & Song, J.-H. (2007). High rates of resistance to colistin and polymyxin B in subgroups of Acinetobacter baumannii isolates from Korea. J Antimicrob Chemother 60, La Scola, B., Gundi, V. A., Khamis, A. & Raoult, D. (2006). Sequencing of the rpob gene and flanking spacers for molecular identification of Acinetobacter species. J Clin Microbiol 44, Lee, K., Yum, J. H., Yong, D., Lee, H. M., Kim, H. D., Docquier, J. D., Rossolini, G. M. & Chong, Y. (2005). Novel acquired metallo-blactamase gene, bla SIM-1, in a class 1 integron from Acinetobacter baumannii clinical isolates from Korea. Antimicrob Agents Chemother 49, Leung, W. S., Chu, C. M., Tsang, K. Y., Lo, F. H., Lo, K. F. & Ho, P. L. (2006). Fulminant community-acquired Acinetobacter baumannii pneumonia as a distinct clinical syndrome. Chest 129, Munoz-Price, L. S. & Weinstein, R. A. (2008). Acinetobacter infection. N Engl J Med 358, Park, Y. K., Jung, S. I., Park, K. H., Kim, D. H., Choi, J. Y., Kim, S. H. & Ko, K. S. (2012). Changes in antimicrobial susceptibility and major clones of Acinetobacter calcoaceticus-baumannii complex isolates from a single hospital in Korea over 7 years. J Med Microbiol 61, Pellegrino, F. L., Vieira, V. V., Baio, P. V., dos Santos, R. M., dos Santos, A.L.,Santos,N.G.,Meohas,M.M.,Santos,R.T.,deSouza,T.C.&other authors (2011). Acinetobacter soli as a cause of bloodstream infection in a neonatal intensive care unit. J Clin Microbiol 49, Peng, C., Zong, Z. & Fan, H. (2012). Acinetobacter baumannii isolates associated with community-acquired pneumonia in West China. Clin Microbiol Infect 18, E491 E Journal of Medical Microbiology 63