Acinetobacter
Acinetobacter is a
They are important
Description
Species of the genus Acinetobacter are
The morphology of Acinetobacter species can be quite variable in Gram-stained human clinical specimens, and cannot be used to differentiate Acinetobacter from other common causes of infection.[citation needed]
Most strains of Acinetobacter, except some of the A. lwoffii strain, grow well on MacConkey agar (without salt). Although officially classified as not lactose-fermenting, they are often partially lactose-fermenting when grown on MacConkey agar. They are oxidase-negative, catalase-positive, indole-negative, nonmotile, and usually nitrate-negative.[citation needed]
Bacteria of the genus Acinetobacter are known to form intracellular inclusions of polyhydroxyalkanoates under certain environmental conditions (e.g. lack of elements such as phosphorus, nitrogen, or oxygen combined with an excessive supply of carbon sources).[citation needed]
Etymology
Acinetobacter is a compound word from scientific Greek [α + κίνητο + βακτηρ(ία)], meaning nonmotile rod. The first element acineto- appears as a somewhat baroque rendering of the Greek morpheme ακίνητο-, commonly transliterated in English is akineto-, but actually stems from the French cinetique and was adopted directly into English.[citation needed] Nevertheless, the French word also originates from the Greek privative α + κίνησις (motion) confirming the same origin from a different path.
Taxonomy
The genus Acinetobacter comprises 38 validly named species.[8]
Identification
Identification of Acinetobacter species is complicated by lack of standard identification techniques. Initially, identification was based on phenotypic characteristics such as growth temperature,
Because routine identification in the clinical microbiology laboratory is not yet possible, Acinetobacter isolates are divided and grouped into three main complexes:[citation needed]
- Acinetobacter calcoaceticus-baumannii complex: glucose-oxidising nonhemolytic (A. baumannii can be identified by OXA-51 typing)
- Acinetobacter lwoffii: glucose-negative nonhemolytic
- Acinetobacter haemolyticus: hemolytic
Different species of bacteria in this genus can be identified using fluorescence-lactose-denitrification to find the amount of acid produced by
Some of the molecular methods used in species identification are repetitive extragenic palindromic sequence-based PCR, ribotyping, pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA, amplified fragment length polymorphism (AFLP), restriction and sequence analysis of tRNA and 16S-23S rRNA gene spacers and amplified 16S ribosomal DNA restriction analysis (ARDRA). PFGE, AFLP, and ARDRA are validated common methods in use today because of their discriminative ability. However, most recent methods include multilocus sequence typing and multilocus PCR and electrospray ionization mass spectrometry, which are based on amplification of highly conserved housekeeping genes and can be used to study the genetic relatedness between different isolates.[10]
Habitat
Acinetobacter species are widely distributed in nature, and commonly occur in soil and water.[11] Their ability to survive on moist and dry surfaces, as well as to survive exposure to various common disinfectants, allows some Acinetobacter species to survive in a hospital environment.[11] Furthermore, Acinetobacter species can grow at a broad range of temperatures, allowing them to survive in a broad array of environments.[11]
Clinical significance
Acinetobacter is frequently isolated in
Of the Acinetobacter, A. baumannii is the greatest cause of human disease, having been implicated in a number of hospital-acquired infections such as bacteremia, urinary tract infections (UTIs), secondary meningitis, infective endocarditis, and wound and burn infections.[12] In particular, A. baumannii is frequently isolated as the cause of hospital-acquired pneumonia among patients admitted to the intensive care unit. Risk factors include long-term intubation and tracheal or lung aspiration. In most cases of ventilator-associated pneumonia, the equipment used for artificial ventilation such as endotracheal tubes or bronchoscopes serve as the source of infection and result in the colonization of the lower respiratory tract by A. baumannii. In some cases, the bacteria can go on to enter the bloodstream, resulting in bacteremia with mortality rates ranging from 32% to 52%. UTIs caused by A. baumannii appear to be associated with continuous catheterization, as well as antibiotic therapy. A. baumannii has also been reported to infect skin and soft tissue in traumatic injuries and postsurgical wounds. A. baumannii commonly infect burns and may result in complications owing to difficulty in treatment and eradication. Though less common, some evidence also links this bacterium to meningitis, most often following invasive surgery, and, in very rare cases, to community-acquired primary meningitis wherein the majority of the victims were children.[13] Case reports also link A. baumannii to endocarditis, keratitis, peritonitis, and very rarely fatal neonatal sepsis.[14]
The clinical significance of A. baumannii is partially due to its capacity to develop resistance against many available antibiotics. Reports indicate that it possesses resistance against broad-spectrum
In healthy individuals, Acinetobacter colonies on the skin correlate with low incidence of
Treatment
Acinetobacter species are innately resistant to many classes of antibiotics, including
In November 2004, the CDC reported an increasing number of A. baumannii bloodstream infections in patients at military medical facilities in which service members injured in the
Reports suggest this bacterium is susceptible to phage therapy.[26]
Gene-silencing antisense oligomers in a form called peptide-conjugated phosphorodiamidate morpholino oligomers have also been reported to inhibit growth in tests carried out in animals infected with antibiotic-resistant A. baumannii.[27][28]
Sulbactam/durlobactam (Xacduro) was approved for medical use in the United States in May 2023.[29]
Aseptic technique
The frequency of
Natural transformation
Bacterial transformation involves the transfer of DNA from a donor to a recipient bacterium through the intervening liquid medium. Recipient bacteria must first enter a special physiological state termed competence to receive donor DNA. A. calcoaceticus is induced to become competent for natural transformation by dilution of a stationary culture into fresh nutrient medium.[31] Competence is gradually lost during prolonged exponential growth and for a period after entrance into the stationary state. The DNA taken up may be used to repair DNA damage or as a means to exchange genetic information by horizontal gene transfer.[31] Natural transformation in A. calcoaceticus may protect against exposure to DNA-damaging conditions in the natural environment of these bacteria, as appears to be the case for other bacterial species capable of transformation.[32]
References
- ^ LPSN.
- ^ "Acinetobacter oryzae ANC 4261 - Project". Genomes OnLine Database (GOLD). Joint Genome Institute (JGI). Retrieved 2021-05-06.
- ^ "Info - Acinetobacter oryzae ANC 4261". Joint Genome Institute Genome Portal. Retrieved 2021-05-06.
- NCBI Taxonomy Browser. Retrieved 2021-05-06.
- Deutsche Sammlung von Mikroorganismen und Zellkulturen). Retrieved 2021-05-06.
- ^ [2][3][4][5]
- S2CID 42820743.
- S2CID 45593914.
- PMID 21715961.
- ^ Antibiotic resistance is a major risk factor for epidemic behavior of Acinetobacter baumannii. Infect Control Hosp Epidemiol 2001; 22:284–288.
- ^ PMID 21502736.
- PMID 20609238.
- PMID 8286623.
- S2CID 25898468.
- S2CID 10955468.
- PMID 16447117.
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- S2CID 28194712.
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- .
- PMID 28427887.
- S2CID 8107934.
- ^ Geller BL, Marshall-Batty K, Schnell FJ, et al. (October 2013). "Gene-Silencing Antisense Oligomers Inhibit Acinetobacter Growth In Vitro and In Vivo. J. Infect. Diseases".
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(help) - ^ "Beyond antibiotics: PPMOs offer new approach to bacterial infection". 2013-10-15. Retrieved October 15, 2013.
- ^ "FDA Approves New Treatment for Pneumonia Caused by Certain Difficult-to-Treat Bacteria". U.S. Food and Drug Administration (Press release). 24 May 2023. Retrieved 24 May 2023.
This article incorporates text from this source, which is in the public domain.
- ^ "Air ionizers wipe out hospital infections". The New Scientist. Retrieved 2006-08-30.
- ^ PMID 8436948.
Further reading
- K.J. Towner; E. Bergogne-Bérézin; C.A. Fewson (30 June 1991). The Biology of Acinetobacter: Taxonomy, Clinical Importance, Molecular Biology, Physiology, Industrial Relevance (F.E.M.S. Symposium Series). Springer. ISBN 0306439026.
- Dongyou Liu (13 April 2011). Molecular Detection of Human Bacterial Pathogens (1 ed.). Crc Pr Inc. ISBN 978-1439812389.
- Dongyou Liu (1 March 2013). Microbiology of Waterborne Diseases: Microbiological Aspects and Risks (2 ed.). Academic Press. ISBN 978-0124158467.
- Narciso-Da-Rocha, C.; Vaz-Moreira, I.; Svensson-Stadler, L.; Moore, E. R. B.; Manaia, C. L. M. (2012). "Diversity and antibiotic resistance of Acinetobacter spp. in water from the source to the tap". Applied Microbiology and Biotechnology. 97 (1): 329–340. S2CID 323861.
External links
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