The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

Abstract: INTRODUCTION: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. METHODS: Isolates identified over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. RESULTS: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like-positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. CONCLUSIONS: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

Identification and Antibiotic Susceptibility of the Bacteria from Non-odontogenic Infectious Lesions

The purpose of this study was to isolate and identify bacteria from the 4 patients with non-odontogenic infectious lesions (mucormycosis, chronic inflammation from wound infection, and two actinomycosis) and determine their antimicrobial susceptibility against eight antibiotics. Bacterial culture was performed under three culture conditions (anaerobic, CO2, and aerobic incubator). The bacterial strains were identified by 16S rRNA gene (16S rDNA) sequence comparison analysis method. For investigating the antimicrobial susceptibility of the bacteria against eight antibiotics, penicillin G, amoxicillin, tetracycline, cefuroxime, erythromycin, clindamycin, vancomycin, and Augmentin(R) (amoxicillin + clavulanic acid), minimum inhibitory concentration (MIC) measurement was performed using broth microdilution assay. Nosocomial pathogens such as Enterococcus faecalis, Klebsiella pneumoniae, Bacillus subtilis, and Neisseria flavescens were isolated from mucormycosis. Veillonella parvula, Enterobacter hormaechei, and Acinetobacter calcoaceticus were isolated from chronic inflammatory lesion. Actinomyces massiliensis was isolated from actinomycosis in parotid gland. Capnocytophaga ochracea was isolated from actinomycosis in buccal region in anaerobic condition. There was no susceptible antibiotic to all bacteria in mucormycosis. Tetracycline was susceptible to all bacteria in chronic inflammation. C. ochracea was resistant to vancomycin and penicillin G; and other antibiotics showed susceptibility to all bacteria in actinomycosis. The results indicated that the combined treatment of two or more antibiotics is better than single antibiotic treatment in mucormycosis, and penicillin is the first recommended antibiotic to treat actinomycosis.

Doripenem vs meropenem against Pseudomonas and Acinetobacter.

Recently, doripenem has been approved for the treatment of nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP). The E-test was performed to determine the MICs of doripenem and meropenem in 203 endotracheal aspirate isolates that consisted of 140 Acinetobacter calcoaceticus-Acinetobacter baumannii complexes and 63 Pseudomonas aeruginosa. Doripenem showed minimum concentration necessary for inhibition of 50% (MIC 50 ) of P. aeruginosa isolates at 0.38 mg/L which is several times (84.2 times) lower than the corresponding MIC 50 value of >32 mg/L for meropenem. The MIC 50 and MIC 90 were similar for both the drugs against A. baumannii. Thus, P. aeruginosa was consistently more susceptible than the A. baumannii.

Screening and characterization of a novel alkaline lipase from Acinetobacter calcoaceticus 1-7 isolated from Bohai Bay in China for detergent formulation

A novel alkaline lipase-producing strain 1-7 identified as Acinetobacter calcoaceticus was isolated from soil samples collected from Bohai Bay, China, using an olive oil alkaline plate, which contained olive oil as the sole carbon source. The lipase from strain 1-7 showed the maximum activity at pH 9.0 under 40ºC. One interesting feature of this enzyme is that it exhibits lipase activity over a broad range of temperatures and good stability. It is also stable at a broad range of pHs from 4.0 to 10.0 for 24 h. Its catalytic activity was highly enhanced in the presence of Ca2+, Mg2+ and K+, but partially inhibited by Cu2+, Al3+, Fe3+ , Ba2+and Zn2+. The fact that it displays marked stability and activity in the presence of TritonX-100, Tween-20, Tween-80, SDS, Hydrogen peroxide, Sodium perborate, Sodium hypochlorite, Sodium citrate, Sodium taurocholate, Glycerine and NaCl suggests that this lipase is suitable as an additive in detergent formulations.

Cellular fatty acids as chemical markers for differentiation of Acinetobacter baumannii and Acinetobacter calcoaceticus / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>Gas chromatography (GC) was used to investigate the cellular fatty acid (CFA) composition of 141 Acinetobacter baumannii and 32 A. calcoaceticus isolates from different locations in China and to find chemical markers to differentiate these two closely related bacteria.</p><p><b>METHODS</b>Whole cell fatty acid methyl esters (FAMEs) were obtained by saponification, methylation, and extraction for GC analysis, followed by a standardized Microbial Identification System (MIS) analysis.</p><p><b>RESULTS</b>All A. baumannii and A. calcoaceticus strains contained some major fatty acids, namely, 18:1 ω9c, 16:0, Sum In Feature 3, 12:0, 17:1ω8c, 3-OH-12:0, 17:0, Sum In Feature 2, 2-OH-12:0, and 18:0 compounds. Although most of the total CFAs are similar between A. baumannii and A. calcoaceticus strains, the ratios of two pairs of CFAs, i.e., Sum In Feature 3/18:1 ω9c versus 16:0/18:1 ω9c and Sum In Feature 3/18:1 ω9c versus unknown 12.484/18:1 ω9c fatty acids, could differentiate these two closely related bacteria. A. baumannii could be easily classified into two subgroups by plotting some ratios such as Sum In Feature 3/16:0 versus 17:0 and Sum In Feature 3/2-OH-12:0 versus 17:0 fatty acids.</p><p><b>CONCLUSION</b>The ratios of some CFAs could be used as chemical markers to distinguish A. baumannii from A. calcoaceticus.</p>

Sensibilidad de Acinetobacter a la colistina evaluada mediante los métodos de predifusión y de concentración inhibitoria mínima: Detección de aislamientos heterorresistentes / Comparative evaluation of the sensitivity of Acinetobacter to colistin, using the prediffusion and minimum inhibitory concentration methods: Detection of heteroresistant isolates

El objetivo de este estudio fue evaluar comparativamente los métodos de predifusión y de concentración inhibitoria mínima para establecer la sensibilidad de aislamientos del complejo Acinetobacter calcoaceticus-baumannii (ABC) a la colistina y detectar a aquellos que presenten heterorresistencia a dicho antibiótico. Se estudiaron 75 aislamientos de ABC recuperados de materiales clínicamente significativos. Se determinó su sensibilidad a la colistina por el método de predifusión y de concentración inhibitoria mínima. Todos los aislamientos resultaron sensibles, con CIM = 2 µg/ml y halos de inhibición en el ensayo de la predifusión = 20 mm. Mediante el método de eficiencia de plaqueo se evaluó la presencia de heterorresistencia a la colistina. Se encontraron 14 aislamientos que originaron colonias heterorresistentes; sus CIM aumentaron en algunos casos en más de 8 veces. Con estas colonias seleccionadas se repitió el ensayo de predifusión. Finalmente se confeccionaron los gráficos de dispersión y se realizaron los análisis de regresión lineal, tanto para el conjunto inicial de todos los aislamientos clínicos como para el subgrupo de los aislamientos resistentes generados durante la evaluación de la heterorresistencia. Se obtuvieron coeficientes de determinación (r²) de 0,2017 y 0,604, respectivamente, lo que indica correlación entre los métodos sólo al evaluar aislamientos preseleccionados por su resistencia a este agente.

The objective of this study is to perform a comparative evaluation of the prediffusion and minimum inhibitory concentration (MIC) methods for the detection of sensitivity to colistin, and to detect Acinetobacter baumanii-calcoaceticus complex (ABC) heteroresistant isolates to colistin. We studied 75 isolates of ABC recovered from clinically significant samples obtained from various centers. Sensitivity to colistin was determined by prediffusion as well as by MIC. All the isolates were sensitive to colistin, with MIC = 2µg/ml. The results were analyzed by dispersion graph and linear regression analysis, revealing that the prediffusion method did not correlate with the MIC values for isolates sensitive to colistin (r² = 0.2017). Detection of heteroresistance to colistin was determined by plaque efficiency of all the isolates with the same initial MICs of 2, 1, and 0.5 µg/ml, which resulted in 14 of them with a greater than 8-fold increase in the MIC in some cases. When the sensitivity of these resistant colonies was determined by prediffusion, the resulting dispersion graph and linear regression analysis yielded an r² = 0.604, which revealed a correlation between the methodologies used.

Caracterização molecular e fenotípica de amostras bacterianas pertencentes ao complexo Acinetobacter calcoaceticus-Acinetobacter baumannii / Molecular and phenotypic characterization of Acinetobacter calcoaceticus-Acinetobacter baumannii isolates

Nos últimos 30 anos, Acinetobacter tornou-se um dos patógenos de maior preocupação clínica pela falta de terapias eficazes em virtude do fenótipo de multirresistência frequentemente apresentado. Dentre as espécies do gênero Acinetobacter, A. baumannii, A. genoespécie 3 e A. genoespécie 13TU são as mais comumente encontradas a partir de amostras biológicas. Estas espécies ao lado de A. calcoaceticus constituem o complexo A. calcoaceticus-A. baumannii (ACB). Este estudo propõe um esquema composto de duas PCRs para a identificação das espécies de interesse médico que fazem parte do complexo ACB. O método é simples, rápido e, além de identificar as espécies, permite pesquisar a presença de genes de resistência. Foram identificadas 515 amostras do complexo ACB, isoladas de pacientes no período de janeiro de 2005 a dezembro de 2010. A identificação das espécies do complexo ACB foi realizada por esquema composto de duas reações de PCR. Foram avaliados os perfis de sensibilidade por disco difusão e a pesquisa da presença dos genes blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP, blaVIM, blaSIM, blaSPM e blaGIM foi realizada por PCR utilizando-se iniciadores específicos. No grupo de amostras estudas, 82,5% são A. baumannii (425), 11,5% A. genoespécie 13TU (59) e 6,0% A. genoespécie 3 (30), sendo A. baumannii mais isolado em pacientes internados em UTIs (p=0,0407) e A. genoespécie 13TU mais isolado em pacientes de outros ambientes hospitalares (p=0,0204). A. baumannii apresentou menor sensibilidade a todos os antimicrobianos quando comparado com A. genoespécie 13TU e A. genoespécie. 3 (p<0,05). Foi possível observar ao longo do período estudado o aumento significativo da resistência aos carbapenêmicos e da sensibilidade a gentamicina por A. baumannii entre os isolados de pacientes de UTIs (p<0.05). Nenhum dos genes codificadores para metalo-lactamases foi detectado nas amostras estudadas Dentre os cepas resistentes aos carbapenêmico...

The genus Acinetobacter has emerged as one of the most troublesome pathogens for health care institutions globally. Its clinical significance, especially over the last 15 years, has been driven by its remarkable ability to up regulate or acquire resistance determinants, making it one of the organisms threatening the current antibiotic era. A. baumannii, A. 3 and A. 13TU are the most commonly species found from biological samples. These species beside A. calcoaceticus are very closely related and difficult to distinguish from each other by phenotypic properties. Therefore, it has been proposed to refer to these species as the A.calcoaceticus-A. baumannii complex(ACB). In the period from 2005 to 2009, the most frequent bacterial isolates among the nosocomial infection at the HU-USP was ACB (18%). Due to the frequency with which species are involved in ACB outbreaks of infection in the HU-USP and the emergency clinic because of expression of the phenotype of resistance to several classes of antibiotics, this study aimed to identify and characterize the species of complex ACB by molecular methods, to study their mechanisms of resistance and to characterize the different clones from patients admitted to different hospital areas. Furthermore, the ability to characterize biofilm formation, adhesion to different cell lines as well as the mechanisms of cell-cell communication were analyzed. From the ACB complex, 515 samples were identified, isolated from patients from January 2005 to December 2010. The identification of clinical species of the ACB was performed by molecular methods that were developed and validated for identification of Acinetobacter sp. include two reactions of PCR. The profiles of sensibility were evaluated by disc diffusion and the detection of the presence of genes blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP, blaVIM, blaSIM, blaGIM, and blaSPM were performed using specific primers. Molecular typing was performed using...

Emulsan analysis produced by locally isolated bacteria and Acinetobacter calcoaceticus RAG-1

Growth of previously isolated bacteria from Iranian oil reservoirs on different carbon and energy sources and under varying conditions have been used to produce a class of extracellular microbial protein-associated lipopolysaccharides named emulsan.Several Bacteria were previously isolated from Iranian oil reservoirs and designated as; Ilam-1 and Paydar-4. In present study, the isolated strains were compared with standard sample of Acinetobacter calcoaceticus RAG-1 from Persian Type Culture Collection [PTCC 1641], IROST. Among the isolated strains, two strains were found to produce an extracellular, emulsifying agent when grown in Mineral Salt Medium containing soya oil, ethanol or local crude oil. The isolated bacteria were cultured and further analysed using protein estimation, reducing sugar analysis, hemolytic activity, surface tension and emulsification activity tests. The crude emulsifier of RAG-1, PAYDAR-4 and ILAM-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89g, 1.78g and 1.69g of bioemulsan respectively. Emulsifying activity was observed over the entire production process. These investigations showed that emulsan produced by isolated Iranian crude oil reservoir were comparable with Acinetobacter calcoaceticus RAG-1 which is made of carbohydrate backbone as its hydrophilic part [N-acetyl-D-galactoseamine, N-acetylgalactoseamine uronic acid, diamino-6-deoxy-D-glucose] and fatty acid chain as its hydrophobic portion

Perfil nosológico e microbiológico das úlceras de pressão em pacientes neurocirúrgicos / Nosologic and microbiological profile of pressure ulcers in the neurosurgical patients

Objetivos. Estudar a freqüência, os fatores de risco e perfil microbiológico das úlceras de pressão dos pacientes neurocirúgicos do Hospital de Base do Distrito Federal. Métodos. Estudo transversal, realizado de 7 a 11 de março de 2005, durante o qual realizou-se busca ativa de pacientes com úlceras de pressão entre os pacientes internados na Unidade de Neurocirurgia do Hospital de Base. Analisou-se, então, nos pacientes portadores de úlcera de pressão, os fatores de risco, a cultura e o antibiograma das amostras das lesões. Resultados. Dos 81 pacientes neurocirúrgicos restritos ao leito, 11 (13,5%) apresentaram úlceras de pressão. A unidade de terapia intensiva apresentou a maior freqüência entre os setores (33,3%). Os fatores de risco encontrados foram: anemia em oito pacientes e distúrbio nutricional em oito. Havia quatro pacientes com traumatismo cranioencefálico e três com traumatismo raquimedular. Apuraram-se 16 casos de úlceras, com maior prevalência nos pacientes com acometimento encefálico. Houve maior prevalência de Klebsiella pneumoniae, Acinetobacter baumannii e Pseudomonas aeruginosa nas culturas, com relevante resistência antimicrobiana a antibióticos de última geração. Conclusão. A freqüência das úlceras de pressão na Unidade de Neurocirurgia do Hospital de Base é semelhante aos descrito na literatura. Os pacientes mais susceptíveis são aqueles que têm comprometimento encefálico, passagem pela UTI, sobrepeso, longa internação e anemia. As bactérias mais freqüentes nas lesões foram Klebsiella pneumoniae, Acinetobacter baumannii e Pseudomonas aeruginosa.

Objective. To study the prevalence of the pressure ulcers, risk factors and microbiological profile of the neurosurgical patients at the Hospital de Base do Distrito Federal. Methods. It deals qith a transversal study, made from 2005 March 7 to 11 at the Department of Neurosurgery of Hospital Base (DNHB). There was na active search for patients with pressure ulcers. A number of patients were evaluated in relation to risk factors of pressure ulcers. Cultures and antibiograms were made from samples of the ulcers. Results. Among 81 bedridden neurosurgical patients, 11 showed pressure ulcers, with mean prevalence of 13.6% in the DNHB. The Intensive Care Unit showed the highest prevalence between de sectors (33,33%). Among the 11 patients with ulcer, 8 patients were anemic and 8 had a nutritional disturbance. Four patients had brain injury from trauma and 3 had spine injury from trauma. We studied 16 patients with ulcers, with the highest prevalence in patients with brain injury. The klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa were the most prevalent bactéria on cultures and they showed na important antimicrobial resistance for the last generation antibiotics. Conclusion. The pressure ulcers prevalence in the DNBH is compatible with the literature. The patiens more susceptible had brain injury, Intensive Care Unit admission, overweight, log hospitalization and anemia. The most prevalent bactéria were Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa.

Etiology and occurrence of bacterial meningitis in children in Najaf

226 cerebrospinal fluid [CSF] specimens were collected from children aged [1 day-10 years] admitted to of Al-Zahara children's Hospital in Najaf governorate from November 2001 to October 2004. The incidence of bacterial meningitis was [11.6%]. The following bacterial species were identified: Staphylococcus aureus, E.coli, Kiebsiella pneumoniae, Enterobacter spp Acinetobacter calcoaceticus, Haemophilus influenzae Streptococcus pneumoniae. The most common etiologic agents of pediatric meningitis were Staph aureus and Enterobacter spp, together were isolated from 64% of CSF collected samples. The incidence of bacterial meningitis in male [52%] while in female [48%]

Bioemulsan production by Iranian oil reservoirs microorganisms

The biosurfactants are believed to be surface active components that are shed into the surrounding medium during the growth of the microorganisms. The oil degrading microorganism Acinetobacter calcoaceticus RAG-1 produces a poly-anionic biosurfactant, hetero-polysaccharide bioemulsifier termed as emulsan which forms and stabilizes oil-water emulsions with a variety of hydrophobic substrates. In the present paper results of the possibility of biosurfactant [Emulsan] production by microorganisms isolated from Iranian oil reservoirs is presented. Fourthy three gram negative and gram positive, non fermentative, rod bacilli and coccobacilli shaped baceria were isolated from the oil wells of Bibi Hakimeh, Siri, Maroon, Ilam, East Paydar and West Paydar. Out of the isolated strains, 39 bacterial strains showed beta haemolytic activity, further screening revealed the emulsifying activity and surface tension. 11 out of 43 tested emulsifiers were identified as possible biosurfactant producers and two isolates produced large surface tension reduction, indicating the high probability of biosurfactant production. Further investigation revealed that, two gram negative, oxidase negative, aerobic and coccoid rods isolates were the best producers and hence designated as IL-1, PAY-4. Whole culture broth of isolates reduced surface tension from 68 mN /m to 30 and 29.1mN/m, respectively, and were stable during exposure to high salinity [10%NaCl] and elevated temperatures[120°C for 15 min]

Endophthalmitis caused by Acinetobacter calcoaceticus. A profile.

PURPOSE: To report the clinical and microbiological profile of endophthalmitis caused by Acinetobacter calcoaceticus. METHODS: A retrospective study of case series of Acinetobacter calcoaceticus endophthalmitis. Outcome measures included ability to sterilise the eye, anatomical result (clear media and attached retina) and visual recovery (visual acuity > 6/60). RESULTS: Of the 20 cases studied, 10 were cases of postoperative endophthalmitis, 3 were posttraumatic, 6 were endogenous and one was bleb-related endophthalmitis. Specific features of interest observed were relative chronicity of presentation and absence of any obvious predisposing factor in endogenous endophthalmitis cases. All cases could be sterilised except one, which needed evisceration. Cases with postoperative endophthalmitis had better anatomical outcome (7/10 with attached retina and clear media) and visual outcome (4/10 regained vision > 6/18). Higher smear positivity was seen in vitreous samples (72.2%) compared to aqueous samples (37.5%). Culture positivity was higher from the vitreous cavity compared to aqueous. The organism was sensitive to ciprofloxacin in a high percentage (88.9%) of cases. CONCLUSIONS: Visual recovery in Acinetobacter calcoaceticus endophthalmitis is modest. Ciprofloxacin is the antibiotic of choice.

Acinetobacter blood stream infection in a teaching hospital- Riyadh, Saudi Arabia

To study the clinical conditions of patients with blood stream infection [BSI] due to Acinetobacter species, the predisposing factors, the antimicrobial susceptibilities and the outcome of infection by these organisms. Settings: The study took place at King Khalid University Hospital, Riyadh, Saudi Arabia. Forty patients with blood stream infection due to Acinetobacter species were prospectively studied. Acinetobacter isolates were identified by API 20E. Antimicrobial susceptibility to 13 antimicrobial agents was performed by a disc comparative Stoke's method. For 23 isolates, susceptibility was also tested by minimum inhibitory concentration using E test [Abbiodisk, Solna, Sweden]. The predominant Acinetobacter isolate was Acinetobacter baumannii 24 [60%] followed by Acinetobacter baumannii complex 10 [25%] and six [15%] were other Acinetobacter species. Patients with Acinetobacter baumannii blood stream infection were more frequently managed in intensive care units. Nineteen of them [47.5%] had serious underlying illnesses predisposing to Acinetobacter blood stream infections including, cardiac, renal diseases, prematurity and severe burns with six [25%] having a fatal outcome. Risk factors for Acinetobacter baumannii blood stream infection included: intravascular catheters, mechanical ventilation, prior antibiotic use and colonization at other body sites. These factors were independently associated with Acinetobacter baumannii acquisition in these patients [P = > 0.05]. The results of anti microbial susceptibility tested by disc diffusion method were comparable to those of E test. Among the 13 anti microbial agents tested, imipenem was the most active agent against Acinetobacter baumannii as well as other Acinetobacter species. We concluded that Acinetobacter baumannii is the most common Acinetobacter species causing significant blood stream infections among patients in intensive care units with serious underlying illnesses. Risk factors studied were independently associated with the disease process of these patients. Imipenem is the most active anti microbial agent against clinically significant Acinetobacter baumannii blood stream infection

Characterization of nonfermenters from clinical samples.

OBJECTIVE: Nonfermenters are a group of aerobic non sporing gram-negative bacilli found primarily free in nature and as commensals, whose pathogenic potentials are well established. The current study was conducted to assess the role of these nonfermenters in various infections and to characterize these isolates. METHODS: One hundred nonfermenters isolated from various clinical specimens were grouped according to Weaver-Hollis scheme based on growth on MacConkeys agar, oxidase activity and oxidation/fermentation of glucose. Species level identification was attempted based on a battery of biochemical tests. All isolates were then subjected to antimicrobial sensitivity. RESULTS: Majority of the isolates were encountered from pus and urine (50%). These isolates belonged to six of the seven Weaver-Hollis groups. Fifty six per cent of the isolates belonged to genus Pseudomonas. Multidrug resistance with resistance to more than three antimicrobials was frequently seen. Amikacin and ciprofloxacin were found to be most effective. CONCLUSION: Nonfermenting gram negative organisms are responsible for variety of infective conditions. Amongst them genus Pseudomonas and Acinetobacter calcoaceticus were more frequently encountered. Amikacin or ciprofloxacin (for nonfermenters other than Pseudomonas) appears to be the drug of choice for treatment of such infections.

Genomic species identification of Acinetobacter calcoaceticus - Acinetobacter baumannii complex strains by amplified ribosomal DNA restriction analysis (ARDRA)

Members of the genus Acinetobacter are recognized as newer pathogens of the nosocomial infection with an increasing frequency in recent years. Strains that belonged to A. calcoaceticus-A. baumannii complex (genomic species 1, 2, 3, and 13TU) were major groups associated with nosocomial infection. Phenotypic identification was unreliable and laborious method to classify Acinetobacter strains into 19 genomic species. Rapid and reliable identification of clinical isolates is essential to diagnosis and epidemiology of Acinetobacter. We investigated the suitability of amplified ribosomal DNA restriction analysis (ARDRA) to identify genomic species of 131 Acinetobacter isolates. The 16S rRNA genes (ribosomal DNA) were enzymatically amplified and the amplified PCR products were restricted independently with the enzymes, AluI, CfoI, and MboI. Genomic species of Acinetobacter was classified by the combinations of restriction patterns. The analysis was showed that restriction profiles were characteristic for each genomic species. One hundred fourteen isolates were identified as A. baumannii, twelve were identified as genomic species 13TU, and one was identified as genomic species 3. Four isolates were found to be unknown organisms. All of the isolates which were identified to A. baumannii by phenotypic tests were completely discriminated into A. baumannii and genomic species 13TU by ARDRA. This study demonstrates that ARDRA is a rapid and simple techniques for the identification of Acinetobacter species according to the genomic species.

Acinetobacter meningitis following head trauma.

A case of acinetobacter meningitis following head injury in a patient who developed cerebrospinal fluid otorrhea, and did not have any neurosurgical procedure, is presented. Previously reported cases are cited, with a review of the literature. Pefloxacin monotherapy is associated with a poor clinical response.

Identification of Acinetobacter calcoaceticus - Acinetobacter baumannii Complex by Ribotyping

Acinetobacter species encounters frequently with clinical specimens and now accounts for a substantial proportion of endemic nosocomial infections in Korea. Recent trends indicate that the antimicrobial resistant strains of Acinetobacter species are increasing. Sixty-one strains were isolated from specimens of patients suspected of nosocomial infections during 1991 to 1996. At present, phenotypic identification of Acinetobacter using biochemical test may not be reliable and resulted in the difficulty to clarify the source of infections and epidemiological study of hospital-acquired infections. Aware of the importance of rational taxonomic proposal for these isolates, correct species identification of these organisms by molecular typing method was carried out. A total of fifty-four strains of A. calcoaceticus-A. baumannii complex species which were identified to genospecies 2 and 13 by biochemical characteristics was subjected to identify by ribotyping using restriction endonuclease EcoRI, ClaI, and SalI. Of fifty-four strains, twenty-five strains were identified as A. baumannii (genospecies 2) and twenty-one strains as genospecies 13, and six strains changed to genospecies 3, and the rest two strains were confirmed as A. haemolyticus (genospecies 4). This result suggests that the ribotyping may be of value for identification of genospecies and epidemiological information of Acinetobacter strains.