201
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Xiong W, Sun Y, Zhang T, Ding X, Li Y, Wang M, Zeng Z. Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China. MICROBIAL ECOLOGY 2015; 70:425-32. [PMID: 25753824 DOI: 10.1007/s00248-015-0583-x] [Citation(s) in RCA: 244] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/12/2015] [Indexed: 05/22/2023]
Abstract
Environmental antibiotic resistance has drawn increasing attention due to its great threat to human health. In this study, we investigated concentrations of antibiotics (tetracyclines, sulfonamides and (fluoro)quinolones) and abundances of antibiotic resistance genes (ARGs), including tetracycline resistance genes, sulfonamide resistance genes, and plasmid-mediated quinolone resistance genes, and analyzed bacterial community composition in aquaculture environment in Guangdong, China. The concentrations of sulfametoxydiazine, sulfamethazine, sulfamethoxazole, oxytetracycline, chlorotetracycline, doxycycline, ciprofloxacin, norfloxacin, and enrofloxacin were as high as 446 μg kg(-1) and 98.6 ng L(-1) in sediment and water samples, respectively. The relative abundances (ARG copies/16S ribosomal RNA (rRNA) gene copies) of ARGs (sul1, sul2, sul3, tetM, tetO, tetW, tetS, tetQ, tetX, tetB/P, qepA, oqxA, oqxB, aac(6')-Ib, and qnrS) were as high as 2.8 × 10(-2). The dominant phyla were Proteobacteria, Bacteroidetes, and Firmicutes in sediment samples and Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The genera associated with pathogens were also observed, such as Acinetobacter, Arcobacter, and Clostridium. This study comprehensively investigated antibiotics, ARGs, and bacterial community composition in aquaculture environment in China. The results indicated that fish ponds are reservoirs of ARGs and the presence of potential resistant and pathogen-associated taxonomic groups in fish ponds might imply the potential risk to human health.
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Affiliation(s)
- Wenguang Xiong
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China
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202
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Caldeira SM, Cunha ARD, Akazawa RT, Moreira RG, Souza LDRD, Fortaleza CMCB. Weather parameters and nosocomial bloodstream infection: a case-referent study. Rev Saude Publica 2015; 49:19. [PMID: 25830871 PMCID: PMC4390072 DOI: 10.1590/s0034-8910.2015049005438] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 10/20/2014] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE To evaluate if temperature and humidity influenced the etiology of bloodstream infections in a hospital from 2005 to 2010. METHODS The study had a case-referent design. Individual cases of bloodstream infections caused by specific groups or pathogens were compared with several references. In the first analysis, average temperature and humidity values for the seven days preceding collection of blood cultures were compared with an overall “seven-days moving average” for the study period. The second analysis included only patients with bloodstream infections. Several logistic regression models were used to compare different pathogens and groups with respect to the immediate weather parameters, adjusting for demographics, time, and unit of admission. RESULTS Higher temperatures and humidity were related to the recovery of bacteria as a whole (versus fungi) and of gram-negative bacilli. In the multivariable models, temperature was positively associated with the recovery of gram-negative bacilli (OR = 1.14; 95%CI 1.10;1.19) or Acinetobacter baumannii (OR = 1.26; 95%CI 1.16;1.37), even after adjustment for demographic and admission data. An inverse association was identified for humidity. CONCLUSIONS The study documented the impact of temperature and humidity on the incidence and etiology of bloodstream infections. The results correspond with those from ecological studies, indicating a higher incidence of gram-negative bacilli during warm seasons. These findings should guide policies directed at preventing and controlling healthcare-associated infections.
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203
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Xiong W, Sun Y, Ding X, Wang M, Zeng Z. Selective pressure of antibiotics on ARGs and bacterial communities in manure-polluted freshwater-sediment microcosms. Front Microbiol 2015; 6:194. [PMID: 25814986 PMCID: PMC4356103 DOI: 10.3389/fmicb.2015.00194] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/23/2015] [Indexed: 01/22/2023] Open
Abstract
The aim of this study was to investigate selective pressure of antibiotics on antibiotic resistance genes (ARGs) and bacterial communities in manure-polluted aquatic environment. Three treatment groups were set up in freshwater-sediment microcosms: tetracyclines group, sulfonamides group and fluoroquinolones group. Sediment and water samples were collected on day 14 after treatment. Antibiotic concentrations, ARGs abundances and bacterial community composition were analyzed. Antibiotic concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by real time quantitative PCR. Bacterial community composition was analyzed based on amplicon sequencing. Of the three classes of antibiotics analyzed in the treatment groups, accumulation amounts were tetracyclines> fluoroquinolone> sulfonamides in the sediment samples, while they were sulfonamides> fluoroquinolone> tetracyclines in the water samples. In the treatment groups, the relative abundances of some tet resistance genes [tet(W) and tet(X)] and plasmid-mediated quinolone resistance (PMQR) genes [oqx(B) and aac(6′)-Ib] in sediment samples were significantly higher than those in the paired water samples. Tetracyclines significantly selected the bacterial classes including Gammaproteobacteria, Clostridia, and the genera including Salmonella, Escherichia/Shigella, Clostridium, Stenotrophomonas in sediment samples. The significant selection on bacterial communities posed by sulfonamides and fluoroquinolones was also observed. The results indicated that sediment may supply an ideal setting for maintenance and persistence of tet resistance genes [tet(W) and tet(X)] and PMQR genes [oqx(B) and aac(6′)-Ib] under antibiotic pollution. The results also highlighted that antibiotics significantly selected specific bacterial communities including the taxa associated with opportunistic pathogens.
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Affiliation(s)
- Wenguang Xiong
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University Guangzhou, China
| | - Yongxue Sun
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University Guangzhou, China
| | - Xueyao Ding
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University Guangzhou, China
| | - Mianzhi Wang
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University Guangzhou, China
| | - Zhenling Zeng
- National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, College of Veterinary Medicine, South China Agricultural University Guangzhou, China
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204
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Pittaway P, Herzig M, Stuckey N, Larsen K. Biodegradation of artificial monolayers applied to water storages to reduce evaporative loss. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2015; 72:1334-1340. [PMID: 26465303 DOI: 10.2166/wst.2015.348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Repeat applications of an artificial monolayer to the interfacial boundary layer of large agricultural water storages during periods of high evaporative demand remains the most commercially feasible water conservation strategy. However, the interfacial boundary layer (or microlayer) is ecologically distinct from subsurface water, and repeat monolayer applications may adversely affect microlayer processes. In this study, the natural cleansing mechanisms operating within the microlayer were investigated to compare the biodegradability of two fatty alcohol (C16OH and C18OH) and one glycol ether (C18E1) monolayer compound. The C16OH and C18OH compounds were more susceptible to microbial degradation, but the C18E1 compound was most susceptible to indirect photodegradation. On clean water the surface pressure and evaporation reduction achieved with a compressed C18E1 monolayer was superior to the C18OH monolayer, but on brown water the surface pressure dropped rapidly. These results suggest artificial monolayers are readily degraded by the synergy between photo and microbial degradation. The residence time of C18OH and C18E1 monolayers on clear water is sufficient for cost-effective water conservation. However, the susceptibility of C18E1 to photodegradation indicates the application of this monolayer to brown water may not be cost-effective.
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Affiliation(s)
- P Pittaway
- National Centre for Engineering in Agriculture, University of Southern Queensland, West St, Toowoomba, 4350 Australia E-mail:
| | - M Herzig
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland, 4072 Australia
| | - N Stuckey
- National Centre for Engineering in Agriculture, University of Southern Queensland, West St, Toowoomba, 4350 Australia E-mail:
| | - K Larsen
- Faculty of Sciences, University of Southern Queensland, Toowoomba, 4350 Australia
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205
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Bruhn KW, Pantapalangkoor P, Nielsen T, Tan B, Junus J, Hujer KM, Wright MS, Bonomo RA, Adams MD, Chen W, Spellberg B. Host fate is rapidly determined by innate effector-microbial interactions during Acinetobacter baumannii bacteremia. J Infect Dis 2014; 211:1296-305. [PMID: 25378635 DOI: 10.1093/infdis/jiu593] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Acinetobacter baumannii is one of the most antibiotic-resistant pathogens. Defining mechanisms driving pathogenesis is critical to enable new therapeutic approaches. METHODS We studied virulence differences across a diverse panel of A. baumannii clinical isolates during murine bacteremia to elucidate host-microbe interactions that drive outcome. RESULTS We identified hypervirulent strains that were lethal at low intravenous inocula and achieved very high early, and persistent, blood bacterial densities. Virulent strains were nonlethal at low inocula but lethal at 2.5-fold higher inocula. Finally, relatively avirulent (hypovirulent) strains were nonlethal at 20-fold higher inocula and were efficiently cleared by early time points. In vivo virulence correlated with in vitro resistance to complement and macrophage uptake. Depletion of complement, macrophages, and neutrophils each independently increased bacterial density of the hypovirulent strain but insufficiently to change lethality. However, disruption of all 3 effector mechanisms enabled early bacterial densities similar to hypervirulent strains, rendering infection 100% fatal. CONCLUSIONS The lethality of A. baumannii strains depends on distinct stages. Strains resistant to early innate effectors are able to establish very high early bacterial blood density, and subsequent sustained bacteremia leads to Toll-like receptor 4-mediated hyperinflammation and lethality. These results have important implications for translational efforts to develop therapies that modulate host-microbe interactions.
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Affiliation(s)
| | | | | | - Brandon Tan
- Department of Molecular Microbiology and Immunology
| | - Justin Junus
- Department of Molecular Microbiology and Immunology
| | - Kristine M Hujer
- Department of Medicine Department of Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Ohio
| | | | - Robert A Bonomo
- Department of Medicine Department of Pharmacology Department of Molecular Biology and Microbiology, Case Western Reserve University Department of Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Ohio
| | - Mark D Adams
- Department of J. Craig Venter Institute, La Jolla, California
| | - Wangxue Chen
- Department of Human Health Therapeutics, National Research Council Canada, Ottawa, Ontario
| | - Brad Spellberg
- Department of Medicine, Division of Infectious Diseases, Keck School of Medicine, University of Southern California, Los Angeles
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206
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Mohr EL, Berhane A, Zora JG, Suchdev PS. Acinetobacter baumannii neonatal mastitis: a case report. J Med Case Rep 2014; 8:318. [PMID: 25256141 PMCID: PMC4181466 DOI: 10.1186/1752-1947-8-318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/04/2014] [Indexed: 11/25/2022] Open
Abstract
Introduction Neonatal mastitis is a rare infection. When it does occur, infants younger than 2 months of age are typically affected and the majority of cases are caused by Staphylococcus aureus. We present the first reported case of neonatal mastitis caused by Acinetobacter baumannii, an unusual organism for this type of infection. Case presentation A 15-day-old full-term Caucasian male neonate presented to our emergency room following fever at home and was admitted for routine neonatal sepsis evaluation. After admission, he developed purulent drainage from his right nipple, was diagnosed with mastitis, and was started on empiric therapy with clindamycin and cefotaxime with presumed coverage for S. aureus. Drainage culture identified pan-susceptible Acinetobacter baumannii/haemolyticus and antibiotic therapy was changed to ceftazidime. He was discharged after 5 days of ceftazidime with complete resolution of his symptoms. Conclusions This case illustrates the importance of obtaining drainage cultures in mastitis cases because of the possibility of organisms besides S. aureus causing infection. Acinetobacter baumannii is considered part of the normal human flora and is associated with serious infections in intensive care units. This is the first case report describing Acinetobacter baumannii as an etiologic agent of neonatal mastitis and highlights the importance of including unusual organisms in the differential for infectious etiologies for general practitioners.
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Affiliation(s)
| | | | | | - Parminder S Suchdev
- Department of Pediatrics, Emory University, 1405 Clifton Rd, Atlanta, GA 30322, USA.
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207
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Yang CW, Chang YT, Chao WL, Shiung II, Lin HS, Chen H, Ho SH, Lu MJ, Lee PH, Fan SN. An investigation of total bacterial communities, culturable antibiotic-resistant bacterial communities and integrons in the river water environments of Taipei city. JOURNAL OF HAZARDOUS MATERIALS 2014; 277:159-168. [PMID: 24411460 DOI: 10.1016/j.jhazmat.2013.12.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/03/2013] [Accepted: 12/20/2013] [Indexed: 06/03/2023]
Abstract
The intensive use of antibiotics may accelerate the development of antibiotic-resistant bacteria (ARB). The global geographical distribution of environmental ARB has been indicated by many studies. However, the ARB in the water environments of Taiwan has not been extensively investigated. The objective of this study was to investigate the communities of ARB in Huanghsi Stream, which presents a natural acidic (pH 4) water environment. Waishuanghsi Stream provides a neutral (pH 7) water environment and was thus also monitored to allow comparison. The plate counts of culturable bacteria in eight antibiotics indicate that the numbers of culturable carbenicillin- and vancomycin-resistant bacteria in both Huanghsi and Waishuanghsi Streams are greater than the numbers of culturable bacteria resistant to the other antibiotics tested. Using a 16S rDNA sequencing approach, both the antibiotic-resistant bacterial communities (culture-based) and the total bacterial communities (metagenome-based) in Waishuanghsi Stream exhibit a higher diversity than those in Huanghsi Stream were observed. Of the three classes of integron, only class I integrons were identified in Waishuanghsi Stream. Our results suggest that an acidic (pH 4) water environment may not only affect the community composition of antibiotic-resistant bacteria but also the horizontal gene transfer mediated by integrons.
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Affiliation(s)
- Chu-Wen Yang
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC.
| | - Yi-Tang Chang
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Wei-Liang Chao
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Iau-Iun Shiung
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Han-Sheng Lin
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Hsuan Chen
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Szu-Han Ho
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Min-Jheng Lu
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Pin-Hsuan Lee
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
| | - Shao-Ning Fan
- Department of Microbiology, Soochow University, Shih-Lin, Taipei 111, Taiwan, ROC
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208
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da Silva PSL, Lipinski RW. Hemolytic uremic syndrome associated withAcinetobacter hemolyticus. Ren Fail 2014; 36:1122-4. [DOI: 10.3109/0886022x.2014.917575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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209
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Identification, genotypic relation, and clinical features of colistin-resistant isolates of Acinetobacter genomic species 13BJ/14TU from bloodstreams of patients in a university hospital. J Clin Microbiol 2014; 52:931-9. [PMID: 24403305 DOI: 10.1128/jcm.02868-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Colistin resistance remains rare among clinical isolates of Acinetobacter species. We noted the emergence of colistin-resistant bloodstream isolates of the Acinetobacter genomic species (GS) 13BJ/14TU from patients at a university hospital between 2003 and 2011. We report here, for the first time, the microbiological and molecular characteristics of these isolates, with clinical features of Acinetobacter GS 13BJ/14TU bacteremia. All 11 available patient isolates were correctly identified as Acinetobacter GS 13BJ/14TU using partial rpoB gene sequencing but were misidentified using the phenotypic methods Vitek 2 (mostly as Acinetobacter baumannii), MicroScan (mostly as A. baumannii/Acinetobacter haemolyticus), and the API 20 NE system (all as A. haemolyticus). Most isolates were susceptible to commonly used antibiotics, including carbapenems, but all were resistant to colistin, for which it is unknown whether the resistance is acquired or intrinsic. However, the fact that none of the patients had a history of colistin therapy strongly suggests that Acinetobacter GS 13BJ/14TU is innately resistant to colistin. The phylogenetic tree of multilocus sequence typing (MLST) showed that all 11 isolates formed a separate cluster from other Acinetobacter species and yielded five sequence types. However, pulsed-field gel electrophoresis (PFGE) revealed 11 distinct patterns, suggesting that the bacteremia had occurred sporadically. Four patients showed persistent bacteremia (6 to 17 days), and all 11 patients had excellent outcomes with cleared bacteremia, suggesting that patients with Acinetobacter GS 13BJ/14TU-associated bacteremia show a favorable outcome. These results emphasize the importance of precise species identification, especially regarding colistin resistance in Acinetobacter species. In addition, MLST offers another approach to the identification of Acinetobacter GS 13BJ/14TU, whereas PFGE is useful for genotyping for this species.
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210
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Chang P, Gerhardt KE, Huang XD, Yu XM, Glick BR, Gerwing PD, Greenberg BM. Plant growth-promoting bacteria facilitate the growth of barley and oats in salt-impacted soil: implications for phytoremediation of saline soils. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2014; 16:1133-47. [PMID: 24933907 DOI: 10.1080/15226514.2013.821447] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Plant growth-promoting bacteria (PGPB) strains that contain the enzyme 1-amino-cyclopropane-1-carboxylate (ACC) deaminase can lower stress ethylene levels and improve plant growth. In this study, ACC deaminase-producing bacteria were isolated from a ) salt-impacted ( 50 dS/m) farm field, and their ability to promote plant growth of barley 1): and oats in saline soil was investigated in pouch assays (1% NaCI), greenhouse trials (9.4 dS/m), and field trials (6-24 dS/m). A mix of previously isolated PGPB strains UW3 (Pseudomonas sp.) and UW4 (P. sp.) was also tested for comparison. Rhizobacterial isolate CMH3 (P. corrugata) and UW3+UW4 partially alleviated plant salt stress in growth pouch assays. In greenhouse trials, CMH3 enhanced root biomass of barley and oats by 200% and 50%, respectively. UW3+UW4, CMH3 and isolate CMH2 also enhanced barley and oat shoot growth by 100%-150%. In field tests, shoot biomass of oats tripled when treated with UW3+UW4 and doubled with CHM3 compared with that of untreated plants. PGPB treatment did not affect salt uptake on a per mass basis; higher plant biomass led to greater salt uptake, resulting in decreased soil salinity. This study demonstrates a method for improving plant growth in marginal saline soils. Associated implications for salt
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211
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Heintzman PD, Elias SA, Moore K, Paszkiewicz K, Barnes I. Characterizing DNA preservation in degraded specimens of Amara alpina (Carabidae: Coleoptera). Mol Ecol Resour 2013; 14:606-15. [PMID: 24266987 DOI: 10.1111/1755-0998.12205] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 01/08/2023]
Abstract
DNA preserved in degraded beetle (Coleoptera) specimens, including those derived from dry-stored museum and ancient permafrost-preserved environments, could provide a valuable resource for researchers interested in species and population histories over timescales from decades to millenia. However, the potential of these samples as genetic resources is currently unassessed. Here, using Sanger and Illumina shotgun sequence data, we explored DNA preservation in specimens of the ground beetle Amara alpina, from both museum and ancient environments. Nearly all museum specimens had amplifiable DNA, with the maximum amplifiable fragment length decreasing with age. Amplification of DNA was only possible in 45% of ancient specimens. Preserved mitochondrial DNA fragments were significantly longer than those of nuclear DNA in both museum and ancient specimens. Metagenomic characterization of extracted DNA demonstrated that parasite-derived sequences, including Wolbachia and Spiroplasma, are recoverable from museum beetle specimens. Ancient DNA extracts contained beetle DNA in amounts comparable to museum specimens. Overall, our data demonstrate that there is great potential for both museum and ancient specimens of beetles in future genetic studies, and we see no reason why this would not be the case for other orders of insect.
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Affiliation(s)
- Peter D Heintzman
- School of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
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212
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Zhang W, Wu YG, Qi XM, Dai H, Lu W, Zhao M. Peritoneal dialysis-related peritonitis with Acinetobacter baumannii: a review of seven cases. Perit Dial Int 2013; 34:317-21. [PMID: 24293662 DOI: 10.3747/pdi.2012.00198] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Peritonitis is still known as an important complication of continuous ambulatory peritoneal dialysis (CAPD). Multi-drug resistant (MDR) Acinetobacter baumannii is an increasing problem worldwide. Moreover, the increasing reports of carbapenem-resistant A. baumannii strains is common. Although peritoneal dialysis-related peritonitis with MDR A. baumannii is rarely reported, infection with this organism always results in serious peritonitis and increases the possibility of dropout or mortality. Here, we present 7 cases of peritonitis caused by A. baumannii species. Among those 7 cases, 2 involved MDR A. baumannii, and 1 involved a carbapenem-resistant strain. All the MDR bacterial infections failed treatment. We also review the literature about Acinetobacter peritonitis and current treatment protocols.
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Affiliation(s)
- Wei Zhang
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
| | - Yong-Gui Wu
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
| | - Xiang-Ming Qi
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
| | - Hong Dai
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
| | - Wen Lu
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
| | - Min Zhao
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Anhui, PR China
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213
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Erdem H, Dizbay M, Karabey S, Kaya S, Demirdal T, Koksal I, Inan A, Erayman I, Ak O, Ulu-Kilic A, Karasahin O, Akbulut A, Elaldi N, Yilmaz G, Candevir A, Gul HC, Gonen I, Oncul O, Aslan T, Azak E, Tekin R, Kocak Tufan Z, Yenilmez E, Arda B, Gungor G, Cetin B, Kose S, Turan H, Akalin H, Karabay O, Dogan-Celik A, Albayrak A, Guven T, Celebi G, Ozgunes N, Ersoy Y, Sirmatel F, Oztoprak N, Balkan II, Bayazit FN, Ucmak H, Oncu S, Ozdemir D, Ozturk-Engin D, Bitirgen M, Tabak F, Akata F, Willke A, Gorenek L, Ahmed SS, Tasova Y, Ulcay A, Dayan S, Esen S, Leblebicioglu H, Altun B, Unal S. Withdrawal of Staphylococcus aureus from intensive care units in Turkey. Am J Infect Control 2013; 41:1053-8. [PMID: 23663858 DOI: 10.1016/j.ajic.2013.01.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/23/2013] [Accepted: 01/24/2013] [Indexed: 11/16/2022]
Abstract
BACKGROUND In the past, Staphylococcus aureus infections have displayed various patterns of epidemiologic curves in hospitals, particularly in intensive care units (ICUs). This study aimed to characterize the current trend in a nationwide survey of ICUs in Turkey. METHODS A total of 88 ICUs from 36 Turkish tertiary hospitals were included in this retrospective study, which was performed during the first 3 months of both 2008 (period [P] 1) and 2011 (P2). A P value ≤.01 was considered significant. RESULTS Although overall rates of hospital-acquired infection (HAI) and device-associated infection densities were similar in P1 and P2, the densities of HAIs due to S aureus and methicillin-resistant S aureus (MRSA) were significantly lower in P2 (P < .0001). However, the proportion of HAIs due to Acinetobacter was significantly higher in P2 (P < .0001). CONCLUSIONS The incidence of S aureus infections is declining rapidly in Turkish ICUs, with potential impacts on empirical treatment strategies in these ICUs.
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Affiliation(s)
- Hakan Erdem
- Department of Infectious Diseases and Clinical Microbiology, GATA Haydarpasa Training Hospital, Istanbul, Turkey.
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Sunu Kumari AM, Routray A, Yadav D, Madhavan R. Imipenem resistance and biofilm production in Acinetobacter. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.dit.2013.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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215
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Lazarević K, Stojanović D, Bogdanović DC, Dolićanin ZĆ. Hygiene Training of Food Handlers in Hospital Settings: Important Factor in the Prevention of Nosocomial Infections. Cent Eur J Public Health 2013; 21:146-9. [DOI: 10.21101/cejph.a3843] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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216
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Álvarez-Pérez S, Lievens B, Jacquemyn H, Herrera CM. Acinetobacter nectaris sp. nov. and Acinetobacter boissieri sp. nov., isolated from floral nectar of wild Mediterranean insect-pollinated plants. Int J Syst Evol Microbiol 2013; 63:1532-1539. [DOI: 10.1099/ijs.0.043489-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The taxonomic status of 14 strains of members of the genus
Acinetobacter
isolated from floral nectar of wild Mediterranean insect-pollinated plants, which did not belong to any previously described species within this genus, was investigated following a polyphasic approach. Confirmation that these strains formed two separate lineages within the genus
Acinetobacter
was obtained from comparative analysis of the partial sequences of the 16S rRNA gene and the gene encoding the β-subunit of RNA polymerase (rpoB), DNA–DNA reassociation data, determination of the DNA G+C content and physiological tests. The names Acinetobacter nectaris sp. nov. and Acinetobacter boissieri sp. nov. are proposed. The type strain of A. nectaris sp. nov. is SAP 763.2T ( = LMG 26958T = CECT 8127T) and that of A. boissieri sp. nov. is SAP 284.1T ( = LMG 26959T = CECT 8128T).
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Affiliation(s)
- Sergio Álvarez-Pérez
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio, E-41092 Sevilla, Spain
| | - Bart Lievens
- Scientia Terrae Research Institute, B-2860 Sint-Katelijne-Waver, Belgium
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Lessius University College, De Nayer Campus, Consortium for Industrial Microbiology and Biotechnology (CIMB), Department of Microbial and Molecular Systems (M2S), KU Leuven Association, B-2860 Sint-Katelijne-Waver, Belgium
| | - Hans Jacquemyn
- Division of Plant Ecology and Systematics, Biology Department, KU Leuven, B-3001 Heverlee, Belgium
| | - Carlos M. Herrera
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio, E-41092 Sevilla, Spain
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217
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Golic A, Vaneechoutte M, Nemec A, Viale AM, Actis LA, Mussi MA. Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter. PLoS One 2013; 8:e55059. [PMID: 23358859 PMCID: PMC3554667 DOI: 10.1371/journal.pone.0055059] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 12/23/2012] [Indexed: 11/28/2022] Open
Abstract
We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.
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Affiliation(s)
- Adrián Golic
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Mario Vaneechoutte
- Laboratory for Bacteriology Research, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - Alexandr Nemec
- Laboratory of Bacterial Genetics, National Institute of Public Health, Prague, Czech Republic
| | - Alejandro M. Viale
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - María Alejandra Mussi
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
- * E-mail:
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218
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Streptomycin inhibits quorum sensing in Acinetobacter baumannii. Antimicrob Agents Chemother 2013; 57:1926-9. [PMID: 23318804 DOI: 10.1128/aac.02161-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptomycin at subinhibitory concentrations was found to inhibit quorum sensing in Acinetobacter baumannii. Conditioned medium prepared by growth of A. baumannii in the presence of subinhibitory concentrations of streptomycin exhibited reduced activation of two quorum-sensing-regulated genes, abaI, encoding an autoinducer synthase, and A1S_0112. The reduced expression of AbaI resulted in greatly decreased levels of 3-OH-C(12)-HSL as confirmed by direct analysis using thin-layer chromatography. The effect on acyl-homoserine lactone (AHL) signal production was specific to streptomycin, as gentamicin and myomycin had no significant effect at subinhibitory levels.
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219
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Kim CH, Jeong YJ, Lee J, Jeon SJ, Park SR, Kang MJ, Park JH, Park JH. Essential role of toll-like receptor 4 in Acinetobacter baumannii-induced immune responses in immune cells. Microb Pathog 2012; 54:20-5. [PMID: 22982140 DOI: 10.1016/j.micpath.2012.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
Abstract
TLR4 is a membrane sensor for lipopolysaccharide (LPS), a major cell wall component of gram-negative bacteria. In this study, we investigated the role of TLR4 on innate immune responses in immune cells against Acinetobacter baumannii. Bone marrow-derived macrophages (BMDMs) and dendritic cells (BMDCs) were isolated from WT and TLR4-deficient mice and infected with A. baumannii ATCC 15150. ELISA assay revealed that the production of IL-6 and TNF-α by A. baumannii was impaired in TLR4-deficient macrophages. However, absence of TLR2 did not affect A. baumannii-induced cytokines production in BMDMs. In addition, TLR4 was required for the optimal production of IL-6, TNF-α, and IL-12 in BMDCs in response to A. baumannii. Western blot analysis showed that A. baumannii leads to the activation of NF-κB and MAPKs (p38, ERK, and JNK) in macrophages via TLR4-dependent pathway. mRNA expression of iNOS and NO production was elicited in WT BMDMs in response to A. baumannii, which was abolished in TLR4-deficienct cells. Bacterial killing ability against A. baumannii was impaired in TLR4-deficient BMDMs. In addition, A. baumannii induced apoptosis in BMDMs via TLR4-independent pathway. Our results demonstrate that TLR4 is essential for initiating innate immune response of macrophages against A. baumannii infection.
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Affiliation(s)
- Chang-Hwan Kim
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-742, Republic of Korea
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220
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Minard G, Tran FH, Raharimalala FN, Hellard E, Ravelonandro P, Mavingui P, Valiente Moro C. Prevalence, genomic and metabolic profiles of Acinetobacter and Asaia associated with field-caught Aedes albopictus from Madagascar. FEMS Microbiol Ecol 2012; 83:63-73. [PMID: 22808994 DOI: 10.1111/j.1574-6941.2012.01455.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 06/26/2012] [Accepted: 07/06/2012] [Indexed: 11/29/2022] Open
Abstract
The presence of cultivable bacteria Acinetobacter and Asaia was recently demonstrated in the mosquito vector Aedes albopictus. However, it is not known how prevalent these bacteria are in field populations. Here, the presence of these bacteria in Ae. albopictus populations from Madagascar was diagnosed by amplification of 16S rRNA gene fragments. Both genera were detected at relatively high frequencies, 46% for Asaia and 74% for Acinetobacter. The prevalence of Acinetobacter correlated significantly with mosquito gender, and the prevalence of Asaia with the interaction between mosquito gender and the sampling site. For each bacterial genus, more male than female mosquitoes were infected. Using pulse field gel electrophoresis, no significant difference in genome size was found between Acinetobacter isolates from mosquitoes compared with free-living Acinetobacter. However, a great diversity was observed in plasmid numbers (from 1 to 12) and sizes (from < 8 to 690 kb). Mosquito isolates utilized fewer substrates than free-living isolates, but some substrates known as blood or plant components were specifically utilized by mosquito isolates. Therefore it is likely that a specific subpopulation of Acinetobacter is selected by Ae. albopictus. Overall, this study emphasizes the need to gain a global view on the bacterial partners in mosquito vectors.
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Affiliation(s)
- Guillaume Minard
- Université de Lyon, UMR5557 Ecologie Microbienne, CNRS, USC1190 INRA, VetAgro Sup, Université Lyon 1, Villeurbanne, France
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221
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Mukhopadhyay J, Braig HR, Rowton ED, Ghosh K. Naturally occurring culturable aerobic gut flora of adult Phlebotomus papatasi, vector of Leishmania major in the Old World. PLoS One 2012; 7:e35748. [PMID: 22629302 PMCID: PMC3358311 DOI: 10.1371/journal.pone.0035748] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 03/23/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Cutaneous leishmaniasis is a neglected, vector-borne parasitic disease and is responsible for persistent, often disfiguring lesions and other associated complications. Leishmania, causing zoonotic cutaneous leishmaniasis (ZCL) in the Old World are mainly transmitted by the predominant sand fly vector, Phlebotomus papatasi. To date, there is no efficient control measure or vaccine available for this widespread insect-borne infectious disease. METHODOLOGY/PRINCIPAL FINDINGS A survey was carried out to study the abundance of different natural gut flora in P. papatasi, with the long-term goal of generating a paratransgenic sand fly that can potentially block the development of Leishmania in the sand fly gut, thereby preventing transmission of leishmania in endemic disease foci. Sand flies, in particular, P. papatasi were captured from different habitats of various parts of the world. Gut microbes were cultured and identified using 16S ribosomal DNA analysis and a phylogenetic tree was constructed. We found variation in the species and abundance of gut flora in flies collected from different habitats. However, a few Gram-positive, nonpathogenic bacteria including Bacillus flexus and B. pumilus were common in most of the sites examined. CONCLUSION/SIGNIFICANCE Our results indicate that there is a wide range of variation of aerobic gut flora inhabiting sand fly guts, which possibly reflect the ecological condition of the habitat where the fly breeds. Also, some species of bacteria (B. pumilus, and B. flexus) were found from most of the habitats. Important from an applied perspective of dissemination, our results support a link between oviposition induction and adult gut flora.
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Affiliation(s)
- Jaba Mukhopadhyay
- Division of Entomology, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Henk R. Braig
- School of Biological Sciences, Bangor University, Bangor, Wales, United Kingdom
| | - Edgar D. Rowton
- Division of Entomology, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Kashinath Ghosh
- Division of Entomology, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
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O'Shea MK. Acinetobacter in modern warfare. Int J Antimicrob Agents 2012; 39:363-75. [PMID: 22459899 DOI: 10.1016/j.ijantimicag.2012.01.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 01/24/2012] [Indexed: 10/28/2022]
Abstract
Increasing appreciation of the role of Acinetobacter baumannii in the aetiology of severe nosocomial infections, together with its ability to employ several mechanisms to rapidly develop resistance to multiple classes of antimicrobial agents, has led to growing interest in this organism over recent years. Recognition and subsequent investigation of the significance of pathogenic Acinetobacter infections in military personnel sustaining injuries during the conflicts in Afghanistan and Iraq has provided an important contribution to the epidemiology of infections with Acinetobacter spp. The following review examines this recent military experience.
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Affiliation(s)
- M K O'Shea
- Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK.
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223
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Figueiredo S, Bonnin RA, Poirel L, Duranteau J, Nordmann P. Identification of the naturally occurring genes encoding carbapenem-hydrolysing oxacillinases from Acinetobacter haemolyticus, Acinetobacter johnsonii, and Acinetobacter calcoaceticus. Clin Microbiol Infect 2011; 18:907-13. [PMID: 22128805 DOI: 10.1111/j.1469-0691.2011.03708.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Carbapenem resistance is increasingly being reported among Acinetobacter species, and results mostly from the expression of acquired carbapenem-hydrolysing oxacillinases (CHDLs). Several Acinetobacter species intrinsically possess chromosomal CHDL genes: Acinetobacter baumannii (bla(OXA-51) ), Acinetobacter radioresistens (bla(OXA-23) ), and Acinetobacter lwoffii (bla(OXA-134) ). We aimed to identify the progenitors of novel CHDL-encoding genes for identification of potential reservoirs. We performed PCR screening using degenerated internal primers designed from a sequence alignment of the known CHDLs (OXA-23, OXA-40, OXA-51, OXA-58, OXA-134, and OXA-143) applied to a collection of 50 Acinetobacter strains belonging to 23 different species. Two strains of Acinetobacter johnsonii, one strain of Acinetobacter calcoaceticus and two strains of Acinetobacter haemolyticus were found to harbour, respectively, the totally novel bla(OXA-211) -like, bla(OXA-213) -like and bla(OXA-214) -like genes. In addition, the complete genomes of those three species available in GenBank, i.e. one A. johnsonii genome, four A. calcoaceticus genomes, and one A. haemolyticus genome, were analysed and found to be positive for the presence of bla(OXA211) -like, bla(OXA-213) -like and bla(OXA-214) -like genes, respectively. The β-lactamases OXA-211, OXA-213 and OXA-214 are diverse, with amino acid identities ranging from 53% to 76%, as compared with the naturally occurring OXA-51-like CHDL from A. baumannii. These β-lactamases showed a peculiar hydrolysis profile, including mostly penicillins and carbapenems. Regarding bla(OXA-23) in A. radioresistens and bla(OXA-134) in A. lwoffii, these genes were not expressed (or expressed at a non-significant level) in their host. Detection of these β-lactamase genes might be used as a useful tool for accurate identification of these Acinetobacter species.
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Affiliation(s)
- S Figueiredo
- Service de Bactériologie-Virologie, INSERM U914 Emerging Resistance to Antibiotics, Département Anesthésie-Réanimation, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine et Université Paris-Sud, K.-Bicêtre, France
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Acinetobacter insertion sequence ISAba11 belongs to a novel family that encodes transposases with a signature HHEK motif. Appl Environ Microbiol 2011; 78:471-80. [PMID: 22081580 DOI: 10.1128/aem.05663-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Experimental and in silico PCR analysis targeting ISAba11 and TnAbaR islands in 196 epidemiologically unrelated Acinetobacter strains representative of ≥19 species were performed. The first two Acinetobacter baumannii ISAba11 elements identified had been found to map to the same site on TnAbaR transposons. However, no further evidence of physical linkage between the two elements was demonstrated. Indeed, examination of 25 definite or putative insertion sites suggested limited sequence specificity. Importantly, an aacC1-tagged version of ISAba11 was shown to actively transpose in A. baumannii. Similarity searches identified nine iso-ISAba11 elements in Acinetobacter and one in Enhydrobacter and single representatives of four distant homologs in bacteria belonging to the phyla "Cyanobacteria" and Proteobacteria. Phylogenetic, sequence, and structural analyses of ISAba11 and/or its associated transposase (Tnp(ISAba11)) suggested that these elements be assigned to a new family. All five homologs encode transposases with a shared extended signature comprising 16 invariant residues within the N2, N3, and C1 regions, four of which constituted the cardinal ISAba11 family HHEK motif that is substituted for the YREK DNA binding motif conserved in the IS4 family. Additionally, ISAba11 family members were associated with either no flanking direct repeat (DR) or an ISAba11-typical 5-bp DR and possessed variable-length terminal inverted repeats that exhibited extensive intrafamily sequence identity. Given the limited pairwise identity among Tnp(ISAba11) homologs and the observed restricted distribution of ISAba11, we propose that substantial gaps persist in the evolutionary record of ISAba11 and that this element represents a recent though potentially highly significant entrant into the A. baumannii gene pool.
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