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Fulltext Antimicrobial resistance: Prevalence, economic burden, mechanisms of resistance and strategies to overcome

Pulingam T, Parumasivam T, Gazzali AM, Sulaiman AM, Chee JY, Lakshmanan M, et al.

Eur J Pharm Sci, 2022 Mar 01;170:106103.
PMID: 34936936 DOI: 10.1016/j.ejps.2021.106103

Antibiotic resistance is a major health concern globally and has been estimated to cause 10 million deaths worldwide by year 2050 if the current trend of inappropriate and excessive use of antibiotics continues. Although, the discovery of antibiotics has saved countless of lives for the past 80 years, increasing levels of bacterial resistance to antibiotics would jeopardize the progress in clinical and agricultural sectors and may cause life-threatening situations even for previously treatable bacterial infections. Antibiotic resistance would increase the levels of poverty of low-middle income countries mostly due to extended hospital stays, higher cost of treatment and untimely deaths that directly affect the total productivity rate. Recent incidences of antibiotic resistance have been gradually increasing globally and this may potentiate horizontal transmission of the resistant gene and have been linked with cross-resistance to other antibiotic families as well. This review summarizes the global burden of antibiotic resistance from the economic viewpoint, highlights the recent incidences of antibiotic resistance mainly related to Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Salmonella spp. and Staphylococcus aureus, describes the common mechanistic actions of antibiotic resistance and potential strategies to overcome antibiotic resistance.

Matched MeSH terms: Acinetobacter baumannii*
Fulltext Acinetobacter spp. infections in Malaysia: a review of antimicrobial resistance trends, mechanisms and epidemiology

Mohd Rani F, A Rahman NI, Ismail S, Alattraqchi AG, Cleary DW, Clarke SC, et al.

Front Microbiol, 2017;8:2479.
PMID: 29312188 DOI: 10.3389/fmicb.2017.02479

Acinetobacter spp. are important nosocomial pathogens, in particular the Acinetobacter baumannii-calcoaceticus complex, which have become a global public health threat due to increasing resistance to carbapenems and almost all other antimicrobial compounds. High rates of resistance have been reported among countries in Southeast Asia, including Malaysia. In this review, we examine the antimicrobial resistance profiles of Acinetobacter spp. hospital isolates from Malaysia over a period of nearly three decades (1987-2016) with data obtained from various peer-reviewed publications as well as the Malaysian National Surveillance on Antibiotic Resistance (NSAR). NSAR data indicated that for most antimicrobial compounds, including carbapenems, the peak resistance rates were reached around 2008-2009 and thereafter, rates have remained fairly constant (e.g., 50-60% for carbapenems). Individual reports from various hospitals in Peninsular Malaysia do not always reflect the nationwide resistance rates and often showed higher rates of resistance. We also reviewed the epidemiology and mechanisms of resistance that have been investigated in Malaysian Acinetobacter spp. isolates, particularly carbapenem resistance and found that blaOXA-23 is the most prevalent acquired carbapenemase-encoding gene. From the very few published reports and whole genome sequences that are available, most of the Acinetobacter spp. isolates from Malaysia belonged to the Global Clone 2 (GC2) CC92 group with ST195 being the predominant sequence type. The quality of data and analysis in the national surveillance reports could be improved and more molecular epidemiology and genomics studies need to be carried out for further in-depth understanding of Malaysian Acinetobacter spp. isolates.

Matched MeSH terms: Acinetobacter Infections*
Global Metabolic Analyses of Acinetobacter baumannii

Mahamad Maifiah MH, Velkov T, Creek DJ, Li J

Methods Mol Biol, 2019;1946:321-328.
PMID: 30798566 DOI: 10.1007/978-1-4939-9118-1_28

Acinetobacter baumannii is rapidly emerging as a multidrug-resistant pathogen responsible for nosocomial infections including pneumonia, bacteremia, wound infections, urinary tract infections, and meningitis. Metabolomics provides a powerful tool to gain a system-wide snapshot of cellular biochemical networks under defined conditions and has been increasingly applied to bacterial physiology and drug discovery. Here we describe an optimized sample preparation method for untargeted metabolomics studies in A. baumannii. Our method provides a significant recovery of intracellular metabolites to demonstrate substantial differences in global metabolic profiles among A. baumannii strains.

Matched MeSH terms: Acinetobacter baumannii/drug effects; Acinetobacter baumannii/metabolism*
Hexavalent molybdenum reduction to Mo-blue by Acinetobacter calcoaceticus

Shukor MY, Rahman MF, Suhaili Z, Shamaan NA, Syed MA

Folia Microbiol (Praha), 2010 Mar;55(2):137-43.
PMID: 20490756 DOI: 10.1007/s12223-010-0021-x

A local molybdenum-reducing bacterium was isolated and tentatively identified as Acinetobacter calcoaceticus strain Dr.Y12 based on carbon utilization profiles using Biolog GN plates and 16S rDNA comparative analysis. Molybdate reduction was optimized under conditions of low dissolved oxygen (37 degrees C and pH 6.5). Of the electron donors tested, glucose, fructose, maltose and sucrose supported molybdate reduction after 1 d of incubation, glucose and fructose supporting the highest Mo-blue production. Optimum Mo-blue production was reached at 20 mmol/L molybdate and 5 mmol/L phosphate; increasing the phosphate concentrations inhibited the production. An increase in an overall absorption profiles, especially at peak maximum at 865 nm and the shoulder at 700 nm, was observed in direct correlation with the increased in Mo-blue amounts. Metal ions, such as chromium, cadmium, copper, mercury and lead (2 mmol/L final concentration) caused approximately 88, 53, 80, 100, and 20 % inhibition, respectively. Respiratory inhibitors, such as antimycin A, rotenone, sodium azide and cyanide showed in this bacterium no inhibition of the Mo-blue production, suggesting that the electron transport system is not a site of molybdate reduction.

Matched MeSH terms: Acinetobacter calcoaceticus/genetics; Acinetobacter calcoaceticus/isolation & purification; Acinetobacter calcoaceticus/metabolism*
Fulltext Genomic and phenotypic characterization of Acinetobacter colistiniresistens isolated from the feces of a healthy member of the community

Muzahid NH, Md Zoqratt MZH, Ten KE, Hussain MH, Su TT, Ayub Q, et al.

Sci Rep, 2023 Aug 03;13(1):12596.
PMID: 37537198 DOI: 10.1038/s41598-023-39642-0

Acinetobacter species are widely known opportunistic pathogens causing severe community and healthcare-associated infections. One such emerging pathogen, Acinetobacter colistiniresistens, is known to exhibit intrinsic resistance to colistin. We investigated the molecular characteristics of A. colistiniresistens strain C-214, isolated from the fecal sample of a healthy community member, as part of a cohort study being conducted in Segamat, Malaysia. Comparison of the whole genome sequence of C-214 with other A. colistiniresistens sequences retrieved from the NCBI database showed 95% sequence identity or more with many of the genome sequences representing that species. Use of the Galleria mellonella killing assay showed that C-214 was pathogenic in this model infection system. The strain C-214 had a colistin and polymyxin B MIC of 32 and 16 mg/L, respectively. Besides, it was resistant to cefotaxime, amikacin, and tetracycline and showed moderate biofilm-producing ability. Different genes associated with virulence or resistance to major classes of antibiotics were detected. We observed mutations in lpxA/C/D in C-214 and other A. colistiniresistens strains as probable causes of colistin resistance, but the biological effects of these mutations require further investigation. This study provides genomic insights into A. colistiniresistens, a potentially pathogenic bacterium isolated from a community member and notes the public health threat it may pose.

Matched MeSH terms: Acinetobacter*; Acinetobacter baumannii*
Green synthesis of silver nanoparticles using Ocimum sanctum Linn. and its antibacterial activity against multidrug resistant Acinetobacter baumannii

Gautam D, Dolma KG, Khandelwal B, Gupta M, Singh M, Mahboob T, et al.

PeerJ, 2023;11:e15590.
PMID: 37529215 DOI: 10.7717/peerj.15590

The biosynthesis of nanoparticles using the green route is an effective strategy in nanotechnology that provides a cost-effective and environmentally friendly alternative to physical and chemical methods. This study aims to prepare an aqueous extract of Ocimum sanctum (O. sanctum)-based silver nanoparticles (AgNPs) through the green route and test their antibacterial activity. The biosynthesized silver nanoparticles were characterised by colour change, UV spectrometric analysis, FTIR, and particle shape and size morphology by SEM and TEM images. The nanoparticles are almost spherical to oval or rod-shaped with smooth surfaces and have a mean particle size in the range of 55 nm with a zeta potential of -2.7 mV. The antibacterial activities of AgNPs evaluated against clinically isolated multidrug-resistant Acinetobacter baumannii (A. baumannii) showed that the AgNPs from O. sanctum are effective in inhibiting A. baumannii growth with a zone of inhibition of 15 mm in the agar well diffusion method and MIC and MBC of 32 µg/mL and 64 µg/mL, respectively. The SEM images of A. baumannii treated with AgNPs revealed damage and rupture in bacterial cells. The time-killing assay by spectrophotometry revealed the time- and dose-dependent killing action of AgNPs against A. baumannii, and the assay at various concentrations and time intervals indicated a statistically significant result in comparison with the positive control colistin at 2 µg/mL (P

Matched MeSH terms: Acinetobacter calcoaceticus*; Acinetobacter baumannii*
Comparison of the antiseptic effectiveness of octenidine dihydrochloride with povidone-iodine for Acinetobacter baumannii contaminated wounds in Wistar rat

Pramana IGAN, Hariani L, Zarasade L

Med J Malaysia, 2023 Jul;78(4):484-487.
PMID: 37518916

INTRODUCTION: Effective antiseptic use is essential in healthcare settings to prevent the spread of diseases, especially in areas with high patient traffic and exposure to various pathogens. One essential pathogenic germ is Acinetobacter baumannii. Octenidine and povidone-iodine have been demonstrated to be effective against A. baumannii in vitro. This study will compare octenidine dihydrochloride and povidone-iodine as wound-cleansing solutions for wounds contaminated with A. baumannii in vivo.
MATERIALS AND METHODS: Twenty-four rats were divided into three groups: normal saline, octenidine dihydrochloride and povidone-iodine. Wounds were made on the rats' backs, and A. baumannii germs were inoculated into the wounds. After 3 hours, the wound was irrigated with wound cleansing solution according to the group for 30 seconds. Each wound was taken swab culture before and after wound irrigation and tissue culture 5 hours after wound irrigation.
RESULTS: All specimens showed bacterial colony growth with a median value of 1.22 × 105 CFU before irrigation. Wound irrigation with normal saline did not reduce colony counts, while there was a 3-log reduction to 5-log reduction in the octenidine and povidone-iodine groups. Statistically, there was no significant difference in the mean number of colonies between the octenidine and povidone-iodine groups after irrigation (p = 0.535). However, 3 hours after irrigation, all specimens that experienced 3-log reduction showed regrowth to more than 1 × 105 CFU. In contrast, specimens subjected to 5-log reduction did not exhibit any regrowth.
CONCLUSION: The antiseptic effectiveness of octenidine dihydrochloride is equivalent to povidone-iodine in eradicating A. baumannii colonies in wounds in vivo.

Matched MeSH terms: Acinetobacter baumannii*
The global prevalence of multidrug-resistance among Acinetobacter baumannii causing hospital-acquired and ventilator-associated pneumonia and its associated mortality: A systematic review and meta-analysis

Mohd Sazlly Lim S, Zainal Abidin A, Liew SM, Roberts JA, Sime FB

J Infect, 2019 12;79(6):593-600.
PMID: 31580871 DOI: 10.1016/j.jinf.2019.09.012

OBJECTIVE: The objective of this works was to assess the global prevalence of multidrug-resistance among A. baumannii causing hospital-acquired (HAP) and ventilator-associated pneumonia (VAP), and describe its associated mortality.
METHODS: We performed a systematic search of four databases for relevant studies. Meta-analysis was done based on United Nations geoscheme regions, individual countries and study period. We used a random-effects model to calculate pooled prevalence and mortality estimates with 95% confidence intervals (CIs), weighted by study size.
RESULTS: Among 6445 reports screened, we identified 126 relevant studies, comprising data from 29 countries. The overall prevalence of multidrug-resistance among A. baumannii causing HAP and VAP pooled from 114 studies was 79.9% (95% CI 73.9-85.4%). Central America (100%) and Latin America and the Caribbean (100%) had the highest prevalence, whereas Eastern Asia had the lowest (64.6%; 95% CI, 50.2-77.6%). The overall mortality estimate pooled from 27 studies was 42.6% (95% CI, 37.2-48.1%).
CONCLUSIONS: We observed large amounts of variation in the prevalence of multidrug-resistance among A. baumannii causing HAP and VAP and its mortality rate among regions and lack of data from many countries. Data from this review can be used in the development of customized strategies for infection control and antimicrobial stewardship.

Matched MeSH terms: Acinetobacter Infections/microbiology*; Acinetobacter Infections/mortality*; Acinetobacter baumannii/drug effects*; Acinetobacter baumannii/isolation & purification
Emergence of ST119 Acinetobacter pittii co-harbouring NDM-1 and OXA-58 in Malaysia

Ang GY, Yu CY, Cheong YM, Yin WF, Chan KG

Int J Antimicrob Agents, 2016 Feb;47(2):168-9.
PMID: 26742728 DOI: 10.1016/j.ijantimicag.2015.11.008
Matched MeSH terms: Acinetobacter/enzymology*; Acinetobacter/genetics*; Acinetobacter Infections/diagnosis*; Acinetobacter Infections/microbiology*
Fulltext Complete Genome Sequencing of Acinetobacter baumannii AC1633 and Acinetobacter nosocomialis AC1530 Unveils a Large Multidrug-Resistant Plasmid Encoding the NDM-1 and OXA-58 Carbapenemases

Alattraqchi AG, Mohd Rani F, A Rahman NI, Ismail S, Cleary DW, Clarke SC, et al.

mSphere, 2021 Jan 27;6(1).
PMID: 33504662 DOI: 10.1128/mSphere.01076-20

Carbapenem-resistant Acinetobacter spp. are considered priority drug-resistant human-pathogenic bacteria. The genomes of two carbapenem-resistant Acinetobacter spp. clinical isolates obtained from the same tertiary hospital in Terengganu, Malaysia, namely, A. baumannii AC1633 and A. nosocomialis AC1530, were sequenced. Both isolates were found to harbor the carbapenemase genes blaNDM-1 and blaOXA-58 in a large (ca. 170 kb) plasmid designated pAC1633-1 and pAC1530, respectively, that also encodes genes that confer resistance to aminoglycosides, sulfonamides, and macrolides. The two plasmids were almost identical except for the insertion of ISAba11 and an IS4 family element in pAC1633-1, and ISAba11 along with relBE toxin-antitoxin genes flanked by inversely orientated pdif (XerC/XerD) recombination sites in pAC1530. The blaNDM-1 gene was encoded in a Tn125 composite transposon structure flanked by ISAba125, whereas blaOXA-58 was flanked by ISAba11 and ISAba3 downstream and a partial ISAba3 element upstream within a pdif module. The presence of conjugative genes in plasmids pAC1633-1/pAC1530 and their discovery in two distinct species of Acinetobacter from the same hospital are suggestive of conjugative transfer, but mating experiments failed to demonstrate transmissibility under standard laboratory conditions. Comparative sequence analysis strongly inferred that pAC1633-1/pAC1530 was derived from two separate plasmids in an IS1006-mediated recombination or transposition event. A. baumannii AC1633 also harbored three other plasmids designated pAC1633-2, pAC1633-3, and pAC1633-4. Both pAC1633-3 and pAC1633-4 are cryptic plasmids, whereas pAC1633-2 is a 12,651-bp plasmid of the GR8/GR23 Rep3-superfamily group that encodes the tetA(39) tetracycline resistance determinant in a pdif module.IMPORTANCE Bacteria of the genus Acinetobacter are important hospital-acquired pathogens, with carbapenem-resistant A. baumannii listed by the World Health Organization as the one of the top priority pathogens. Whole-genome sequencing of carbapenem-resistant A. baumannii AC1633 and A. nosocomialis AC1530, which were isolated from the main tertiary hospital in Terengganu, Malaysia, led to the discovery of a large, ca. 170-kb plasmid that harbored genes encoding the New Delhi metallo-β-lactamase-1 (NDM-1) and OXA-58 carbapenemases alongside genes that conferred resistance to aminoglycosides, macrolides, and sulfonamides. The plasmid was a patchwork of multiple mobile genetic elements and comparative sequence analysis indicated that it may have been derived from two separate plasmids through an IS1006-mediated recombination or transposition event. The presence of such a potentially transmissible plasmid encoding resistance to multiple antimicrobials warrants vigilance, as its spread to susceptible strains would lead to increasing incidences of antimicrobial resistance.

Matched MeSH terms: Acinetobacter/drug effects; Acinetobacter/genetics*; Acinetobacter baumannii/drug effects; Acinetobacter baumannii/genetics*
Prevalence and antimicrobial susceptibilities of Acinetobacter baumannii and non-baumannii Acinetobacters from Terengganu, Malaysia and their carriage of carbapenemase genes

Mohd Rani F, A Rahman NI, Ismail S, Abdullah FH, Othman N, Alattraqchi AG, et al.

J Med Microbiol, 2018 Nov;67(11):1538-1543.
PMID: 30251951 DOI: 10.1099/jmm.0.000844

A total of 153 non-repeat Acinetobacter spp. clinical isolates obtained in 2015 from Hospital Sultanah Nur Zahirah (HSNZ) in Terengganu, Malaysia, were characterized. Identification of the isolates at species level was performed by ribosomal DNA restriction analysis (ARDRA) followed by sequencing of the rpoB gene. The majority of the isolates (n=128; 83.7 %) were A. baumannii while the rest were identified as A. nosocomialis (n=16), A. calcoaceticus (n=5), A. soli (n=2), A. berezeniae (n=1) and A. variabilis (n=1). Multidrug resistance (MDR) was most prevalent in A. baumannnii (66.4 %) whereas only one non-baumannii isolate (A. nosocomialis) was MDR. The blaOXA-23 gene was the predominant acquired carbapenemase gene (56.2 %) and was significantly associated (P<0.001) with carbapenem resistance. However, no significant association was found for carbapenem resistance and isolates that contained the ISAba1-blaOXA-51 configuration.

Matched MeSH terms: Acinetobacter/drug effects*; Acinetobacter/enzymology; Acinetobacter/genetics; Acinetobacter Infections/microbiology; Acinetobacter Infections/epidemiology*; Acinetobacter calcoaceticus/drug effects; Acinetobacter calcoaceticus/enzymology; Acinetobacter calcoaceticus/genetics; Acinetobacter baumannii/drug effects*; Acinetobacter baumannii/enzymology; Acinetobacter baumannii/genetics
In vitro activity of tigecycline against Acinetobacter baumannii isolates from a teaching hospital in Malaysia

Dhabaan GN, AbuBakar S, Shorman MA, Hassan H

J Chemother, 2012 Apr;24(2):87-92.
PMID: 22546763 DOI: 10.1179/1120009X12Z.00000000017

The In vitro susceptibility of clinical and environmental isolates of Acinetobacter baumannii to tigecycline and other antibiotics was determined by disk diffusion method. The E-test was used to determine the minimum inhibitory concentration (MIC). The growth curves of tigecycline treated environmental and clinical strains were established. Fifty-seven percent and 75% of the clinical and environmental isolates were MDR strains, respectively. Ninety-five percent of the clinical isolates were susceptible to tigecycline and 5% showed intermediate resistance with MIC ranging between 0.032 and 3 mg/l. Tigecycline susceptible and intermediate resistance among the environmental isolates were 40% and 60%, respectively, with a significantly lower MIC range of 0.5-4 mg/l. The bacterial growth curves demonstrated the higher ability of the environmental strains to tolerate the antibiotic effects than the clinical strains. The relatively high resistance profile among the environmental isolate suggests an insidious emergence of tigecycline resistance amongst A. baumannii. Strict infection control procedures are imperative to prevent the dissemination of tigecycline-resistant A. baumannii strains in the hospital environment.

Matched MeSH terms: Acinetobacter Infections/drug therapy*; Acinetobacter Infections/microbiology; Acinetobacter baumannii/drug effects*; Acinetobacter baumannii/growth & development; Acinetobacter baumannii/isolation & purification
Fulltext Extremely high prevalence of antiseptic resistant Quaternary Ammonium Compound E gene among clinical isolates of multiple drug resistant Acinetobacter baumannii in Malaysia

Babaei M, Sulong A, Hamat R, Nordin S, Neela V

Ann Clin Microbiol Antimicrob, 2015;14:11.
PMID: 25858356 DOI: 10.1186/s12941-015-0071-7

Antiseptics are commonly used for the management of MDR (multiple drug resistance) pathogens in hospitals. They play crucial roles in the infection control practices. Antiseptics are often used for skin antisepsis, gauze dressing, preparation of anatomical sites for surgical procedure, hand sterilization before in contact with an infected person, before an invasive procedure and as surgical scrub.

Matched MeSH terms: Acinetobacter Infections/microbiology*; Acinetobacter Infections/epidemiology; Acinetobacter baumannii/drug effects*; Acinetobacter baumannii/genetics; Acinetobacter baumannii/isolation & purification
An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation

Mea HJ, Yong PVC, Wong EH

Microbiol Res, 2021 Jun;247:126722.
PMID: 33618061 DOI: 10.1016/j.micres.2021.126722

The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.

Matched MeSH terms: Acinetobacter Infections/microbiology*; Acinetobacter baumannii/drug effects; Acinetobacter baumannii/genetics; Acinetobacter baumannii/metabolism*; Acinetobacter baumannii/pathogenicity*
Antibiotic susceptibility and REP-PCR fingerprints of Acinetobacter spp. isolated from a hospital ten years apart

Misbah S, AbuBakar S, Hassan H, Hanifah YA, Yusof MY

J Hosp Infect, 2004 Dec;58(4):254-61.
PMID: 15564001

The antibiotic susceptibility profiles and the repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR)-determined genotypes of 109 Acinetobacter strains collected from the University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia, in 1987 (N=21) and 1996-1998 (N=88) were established. Twelve antibiotic susceptibility profiles of antibiotics used at the UMMC were obtained. In descending order of effectiveness, imipenem, amikacin and ciprofloxacin were the most effective against the Acinetobacter strains. Compared with 1987 isolates, the isolates obtained in 1996-1998 had decreased susceptibility to these antibiotics and were tolerant to the antibiotics up to an MIC90 of > or =256 mg/L. REP-PCR DNA fingerprints of all the isolates revealed the presence of four Acinetobacter spp. lineages; 92% of all the isolates belonged to two dominant lineages (genotypes 1 and 4). Genotype 4 isolates predominant in 1987 showed increased resistance and antibiotic tolerance to imipenem, amikacin and ciprofloxacin compared with the 1996-1998 isolates. In contrast, genotype 1 isolates from 1996-1998 were mainly sensitive to these antibiotics. These findings demonstrate the presence of at least two independent Acinetobacter spp. lineages in the same hospital, and suggest the possibility that genotype 4 Acinetobacter spp. acquired the resistance phenotype in situ, whereas most of the genotype 1 isolates were probably introduced to the hospital in recent years.

Matched MeSH terms: Acinetobacter/classification; Acinetobacter/drug effects*; Acinetobacter Infections/microbiology*; Acinetobacter Infections/epidemiology; Acinetobacter Infections/prevention & control
Fulltext Spread of carbapenem-resistant Acinetobacter baumannii global clone 2 in Asia and AbaR-type resistance islands

Kim DH, Choi JY, Kim HW, Kim SH, Chung DR, Peck KR, et al.

Antimicrob Agents Chemother, 2013 Nov;57(11):5239-46.
PMID: 23939892 DOI: 10.1128/AAC.00633-13

In this surveillance study, we identified the genotypes, carbapenem resistance determinants, and structural variations of AbaR-type resistance islands among carbapenem-resistant Acinetobacter baumannii (CRAB) isolates from nine Asian locales. Clonal complex 92 (CC92), corresponding to global clone 2 (GC2), was the most prevalent in most Asian locales (83/108 isolates; 76.9%). CC108, or GC1, was a predominant clone in India. OXA-23 oxacillinase was detected in CRAB isolates from most Asian locales except Taiwan. blaOXA-24 was found in CRAB isolates from Taiwan. AbaR4-type resistance islands, which were divided into six subtypes, were identified in most CRAB isolates investigated. Five isolates from India, Malaysia, Singapore, and Hong Kong contained AbaR3-type resistance islands. Of these, three isolates harbored both AbaR3- and AbaR4-type resistance islands simultaneously. In this study, GC2 was revealed as a prevalent clone in most Asian locales, with the AbaR4-type resistance island predominant, with diverse variants. The significance of this study lies in identifying the spread of global clones of carbapenem-resistant A. baumannii in Asia.

Matched MeSH terms: Acinetobacter Infections/drug therapy; Acinetobacter Infections/microbiology; Acinetobacter Infections/epidemiology*; Acinetobacter baumannii/classification; Acinetobacter baumannii/enzymology; Acinetobacter baumannii/genetics*; Acinetobacter baumannii/isolation & purification
Enhanced phenol degradation by immobilized Acinetobacter sp. strain AQ5NOL 1

Ahmad SA, Shamaan NA, Arif NM, Koon GB, Shukor MY, Syed MA

World J Microbiol Biotechnol, 2012 Jan;28(1):347-52.
PMID: 22806810 DOI: 10.1007/s11274-011-0826-z

A locally isolated Acinetobacter sp. Strain AQ5NOL 1 was encapsulated in gellan gum and its ability to degrade phenol was compared with the free cells. Optimal phenol degradation was achieved at gellan gum concentration of 0.75% (w/v), bead size of 3 mm diameter (estimated surface area of 28.26 mm(2)) and bead number of 300 per 100 ml medium. At phenol concentration of 100 mg l(-1), both free and immobilized bacteria exhibited similar rates of phenol degradation but at higher phenol concentrations, the immobilized bacteria exhibited a higher rate of degradation of phenol. The immobilized cells completely degrade phenol within 108, 216 and 240 h at 1,100, 1,500 and 1,900 mg l(-1) phenol, respectively, whereas free cells took 240 h to completely degrade phenol at 1,100 mg l(-1). However, the free cells were unable to completely degrade phenol at higher concentrations. Overall, the rates of phenol degradation by both immobilized and free bacteria decreased gradually as the phenol concentration was increased. The immobilized cells showed no loss in phenol degrading activity after being used repeatedly for 45 cycles of 18 h cycle. However, phenol degrading activity of the immobilized bacteria experienced 10 and 38% losses after the 46 and 47th cycles, respectively. The study has shown an increased efficiency of phenol degradation when the cells are encapsulated in gellan gum.

Matched MeSH terms: Acinetobacter/isolation & purification; Acinetobacter/metabolism*
The mazEF toxin-antitoxin system as a novel antibacterial target in Acinetobacter baumannii

Ghafourian S, Good L, Sekawi Z, Hamat RA, Soheili S, Sadeghifard N, et al.

Mem Inst Oswaldo Cruz, 2014 Jul;109(4):502-5.
PMID: 25004148

Although analysis of toxin-antitoxin (TA) systems can be instructive, to date, there is no information on the prevalence and identity of TA systems based on a large panel of Acinetobacter baumannii clinical isolates. The aim of the current study was to screen for functional TA systems among clinical isolates of A. baumannii and to identify the systems' locations. For this purpose, we screened 85 A. baumannii isolates collected from different clinical sources for the presence of the mazEF, relBE and higBA TA genes. The results revealed that the genes coding for the mazEF TA system were commonly present in all clinical isolates of A. baumannii. Reverse transcriptase-polymerase chain reaction analysis showed that transcripts were produced in the clinical isolates. Our findings showed that TA genes are prevalent, harboured by chromosomes and transcribed within A. baumannii. Hence, activation of the toxin proteins in the mazEF TA system should be investigated further as an effective antibacterial strategy against this bacterium.

Matched MeSH terms: Acinetobacter baumannii/genetics; Acinetobacter baumannii/metabolism*
Fulltext Whole-genome sequence of N-acylhomoserine lactone-synthesizing and -degrading Acinetobacter sp. strain GG2

Hong KW, Koh CL, Sam CK, Yin WF, Chan KG

J Bacteriol, 2012 Nov;194(22):6318.
PMID: 23105061 DOI: 10.1128/JB.01579-12

Acinetobacter sp. strain GG2 is a quorum-sensing and quorum-quenching bacterium isolated from the ginger rhizosphere. It degrades a broad range of N-acylhomoserine lactone molecules via lactonase. The genome sequence of strain GG2 may provide insights on the regulation of quorum-sensing and quorum-quenching mechanisms in this bacterium.

Matched MeSH terms: Acinetobacter/classification*; Acinetobacter/genetics*
Clinico-epidemiological nature and antibiotic susceptibility profile of Acinetobacter species

Biglari S, Hanafiah A, Ramli R, Mostafizur Rahman M, Mohd Nizam Khaithir T

Pak J Med Sci, 2013 Apr;29(2):469-73.
PMID: 24353558

Acinetobacter spp. has emerged as an important opportunistic pathogen responsible for nosocomial infections in many health-care settings worldwide. The study describes the clinico-epidemiology and antimicrobial susceptibility of Acinetobacter spp. in a tertiary health-care institution. Methodology : Acinetobacter spp. were isolated from 141 specimens of the patients who reported to Universiti Kebangsaan Medical Centre (UKMMC). The sources of specimens were wound, skin and soft tissue, respiratory and urinary tract from patients in various wards. Clinio-epidemiological features of patients infected with Acinetobacter spp. were recorded. Standard bacteriological techniques with API 20NE kits and disk diffusion method were followed for identification and antibiotic sensitivity of the organisms.

Matched MeSH terms: Acinetobacter; Acinetobacter Infections

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