Bacterial communities associated with anthracnose symptomatic and asymptomatic leaves of guarana, an endogenous tropical crop, and their pathogen antagonistic effects.

Plants are colonized by diverse microorganisms that can substantially impact their health and growth. Understanding bacterial diversity and the relationships between bacteria and phytopathogens may be key to finding effective biocontrol agents. We evaluated the bacterial community associated with anthracnose symptomatic and asymptomatic leaves of guarana, a typical tropical crop. Bacterial communities were assessed through culture-independent techniques based on extensive 16S rRNA sequencing, and cultured bacterial strains were evaluated for their ability to inhibit the growth of Colletotrichum sp. as well as for enzyme and siderophore production. The culture-independent method revealed that Proteobacteria was the most abundant phylum, but many sequences were unclassified. The emergence of anthracnose disease did not significantly affect the bacterial community, but the abundance of the genera Acinetobacter, Pseudomonas and Klebsiella were significantly higher in the symptomatic leaves. In vitro growth of Colletotrichum sp. was inhibited by 11.38% of the cultured bacterial strains, and bacteria with the highest inhibition rates were isolated from symptomatic leaves, while asymptomatic leaves hosted significantly more bacteria that produced amylase and polygalacturonase. The bacterial isolate Bacillus sp. EpD2-5 demonstrated the highest inhibition rate against Colletotrichum sp., whereas the isolates EpD2-12 and FD5-12 from the same genus also had high inhibition rates. These isolates were also able to produce several hydrolytic enzymes and siderophores, indicating that they may be good candidates for the biocontrol of anthracnose. Our work demonstrated the importance of using a polyphasic approach to study microbial communities from plant diseases, and future work should focus on elucidating the roles of culture-independent bacterial communities in guarana anthracnose disease.

Crude Oil Degrading Fingerprint and the Overexpression of Oxidase and Invasive Genes for n-hexadecane and Crude Oil Degradation in the Acinetobacter pittii H9-3 Strain.

A crude oil-degrading bacterium named strain H9-3 was isolated from crude oil contaminated soil in the Northeastern area of China. Based on its morphological characteristics and 16S rDNA sequence analysis, strain H9-3 is affiliated to Acinetobacter pittii in the group of Gammaproteobacteria. The strain was efficient in removing 36.8% of the initial 10 g·L - 1 of crude oil within 21 days. GC-MS was performed and a preference was shown for n-C10, n-C11, i-C14, i-C17, i-C34, n-C12, n-C13, n-C14, n-C27, n-C32 and i-C13, over n-C16, n-C18⁻C22, n-C24⁻n-C31, and n-C36. This can be regarded as the specific fingerprint for crude oil degradation by strain H9-3 of Acinetobacter pittii. In addition to crude oil, it was shown that soybean oil and phenols can be utilized as carbon sources by strain H9-3. It was also shown that aniline and α -naphthol cannot be utilized for growth, but they can be tolerated by strain H9-3. Methylbenzene was neither utilized nor tolerated by strain H9-3. Although n-hexadecane was not preferentially consumed by strain H9-3, during culture with crude oil, it could be utilized for growth when it is the sole carbon source. The degradation of some branched alkanes (i-C14, i-C17 and i-C34) and the preferential degradation of crude oil over phenols could be used as a reference for distinguishing A. pittii from A. calcoaceticus. The difference in gene expression was very significant and was induced by diverse carbon sources, as shown in the qRT-PCR results. The oxidation and adhesion events occurred at high frequency during alkane degration by Acinetobacter pittii strain H9-3 cells.

Production, characterization, and applications of bioemulsifiers (BE) and biosurfactants (BS) produced by Acinetobacter spp.: A review.

Bioemulsifiers (BE) and biosurfactants (BS) are considered as multifunctional biomolecules of 21st century because of their functional abilities and eco-friendly properties. They are produced by various microorganisms under versatile and extreme environmental conditions. They have tremendous applications in various industries such as petroleum, food, medicine, pharmaceutical, chemical, paper & pulp, textile, and cosmetics. Currently, they are also considered as "green molecules" because of their wide applications in bioremediation of soil. Their importance has been increasing day by day in the global market as they are the natural resources with high-aggregate value. Although, there are numerous reports on BE and BS production by different bacteria, Acinetobacter spp. acquired special attention among all. This is because it is the earliest member known for the production of bioemulsifier. Emulsan and Alasan are the best examples of the commercially used BE produced by Acinetobacter spp. These BE are mainly used in microbial enhanced oil recovery and biodegradation of toxic compounds. This review is focused on BE and BS produced by Acinetobacter spp., their characterization and applications in different fields. This is the first review on genus Acinetobacter which defines independently about different types of BE and BS produced by it. It will also address the need of exploration of these molecules from various sources and their applications for the benefit of mankind and sustainable environment.

Genomic and phenotypic characterization of the species Acinetobacter venetianus.

Crude oil is a complex mixture of hydrocarbons and other organic compounds that can produce serious environmental problems and whose removal is highly demanding in terms of human and technological resources. The potential use of microbes as bioremediation agents is one of the most promising fields in this area. Members of the species Acinetobacter venetianus have been previously characterized for their capability to degrade n-alkanes and thus may represent interesting model systems to implement this process. Although a preliminary experimental characterization of the overall hydrocarbon degradation capability has been performed for five of them, to date, the genetic/genomic features underlying such molecular processes have not been identified. Here we have integrated genomic and phenotypic information for six A. venetianus strains, i.e. VE-C3, RAG-1(T), LUH 13518, LUH 7437, LUH 5627 and LUH 8758. Besides providing a thorough description of the A. venetianus species, these data were exploited to infer the genetic features (presence/absence patterns of genes) and the short-term evolutionary events possibly responsible for the variability in n-alkane degradation efficiency of these strains, including the mechanisms of interaction with the fuel droplet and the subsequent catabolism of this pollutant.

Description of Acinetobacter populi sp. nov. isolated from symptomatic bark of Populus x euramericana canker.

Five Gram-negative, non-motile, rod-shaped bacterial strains were isolated from cankers of Populus x euramericana collected from different locations in Puyang city, Henan Province, China. The five strains were characterized by nutritional and physiological testing and DNA sequence analysis. Haemolysis was not observed on agar media supplemented with sheep erythrocytes. The strains could be distinguished from members of most species of the genus Acinetobacter by their inability to assimilate L-arginine and benzoate. The five strains formed a single branch in phylogenetic trees based on 16S rRNA, gyrB and rpoB individual gene sequence analysis,indicating that they all belonged to a single taxon within the genus Acinetobacter. DNA-DNA hybridization results indicated that the five isolates represented to a single species that was separate from Acinetobacter puyangensis. On the basis of the phenotypic, genotypic and phylogenetic characteristics, the five strains are considered to represent a novel species of the genus Acinetobacter, for which the name Acinetobacter populi sp. nov. is proposed. The typestrain of A. populi sp. nov. is PBJ7T (CFCC 11170T=KCTC 42272T).

Risk factors and outcome for colistin-resistant Acinetobacter nosocomialis bacteraemia in patients without previous colistin exposure.

The clinical characteristics of patients with colistin-resistant Acinetobacter baumannii bacteraemia have been documented, but those of patients with bacteraemia caused by other Acinetobacter species remain unknown. Previous exposure to colistin has been shown to be associated with the emergence of colistin resistance, but may be not the only predisposing factor. In the current study, we highlight the risk and outcome of patients without previous exposure to colistin who acquired colistin-resistant Acinetobacter nosocomialis (ColRAN) bacteraemia. This 11-year single-centre retrospective study analysed 58 patients with ColRAN bacteraemia and 213 patients with colistin-susceptible A. nosocomialis (ColSAN) bacteraemia. Antimicrobial susceptibilities were determined with an agar dilution method. The clonal relationship of ColRAN isolates was determined with pulsed-field gel electrophoresis. A conjugation mating-out assay was conducted to delineate the potential transfer of colistin resistance genes. Multivariable analysis was performed to evaluate the risk factors for ColRAN bacteraemia. Chronic obstructive pulmonary disease (COPD) was independently associated with ColRAN bacteraemia (OR 3.04; 95% CI 1.45-6.37; p 0.003). Patients with ColRAN bacteraemia had higher APACHE II scores, but the two groups showed no significant differences in 14-day mortality (10.3% vs. 10.3%) or 28-day mortality (15.5% vs. 15.0%). ColRAN isolates had greater resistance than ColSAN isolates to all antimicrobial agents except for ciprofloxacin (0% vs. 6.6%). There were 16 different ColRAN pulsotypes, and two major clones were found. Colistin resistance did not transfer to colistin-susceptible A. baumannii or A. nosocomialis. These results show that COPD is an independent risk factor for acquisition of ColRAN bacteraemia. The mortality rates were similar between patients with ColRAN and ColSAN bacteraemia.

Acinetobacter puyangensis sp. nov., isolated from the healthy and diseased part of Populus xeuramericana canker bark.

Two Gram-negative, non-motile, rod-shaped strains, BQ4-1(T) and NHI3-2, isolated respectively from the healthy and diseased part of Populus ×euramericana canker bark, were characterized using a polyphasic approach. Chemotaxonomic characterization supported the inclusion of the two strains in the genus Acinetobacter, with genomic DNA G+C contents (42.5-43 mol%) within the range observed for this genus (38-47 mol%) and 9-octadecenoic acid (C18 : 1ω9c, 39.87 %), hexadecanoic acid (C16 : 0, 11.26 %) and summed feature 3 (comprising C16 : 1ω7c/C16 : 1ω6c, 18.90 %) as major fatty acids. Phylogenetic analysis based on 16S rRNA, rpoB and gyrB gene sequences revealed that strains BQ4-1(T) and NHI3 did not cluster with any species with validly published names, and formed a distinct cluster with 99-100 % bootstrap support on three phylogenetic trees within the genus Acinetobacter. Acid was not produced from d-glucose, and haemolysis was not observed on agar media supplemented with sheep erythrocytes. On the basis of phenotypic, genotypic and phylogenetic characteristics, the two strains are considered to represent a novel species of the genus Acinetobacter, for which the name Acinetobacter puyangensis sp. nov. is proposed. The type strain is BQ4-1(T) (= CFCC 10780(T) = JCM 18011(T)).

Antimicrobial susceptibility pattern in nosocomial infections caused by Acinetobacter species in Asir Region, Saudi Arabia.

This study aimed at evaluating the sensitivity of antibiotics towards nosocomial infections caused by Acinetobacter species. The study took place during the period Dec. 2011- Dec. 2012 at Assir Central Hospital in collaboration with the department of microbiology, college of medicine, King Khalid University, Abha. A prospective study involving 150 patients presented with nosocomial infections due to Acinetobacter species detected by bacteriological tests; direct microscopy, culture in blood agar media, fermentation test in MacConkey media and MIC (minimum inhibitory concentration) for antibiotics sensitivity using Muller Hinton media and Chemical test using API 20. A 150 nosocomial infections in this study showed gram-negative coccobacilli, non motile, glucose-negative fermentor and oxidase negative. All isolates showed 100% sensitivity to: Imipramine, Meropenem, Colistin. From the rest of tested antibiotics the higher resistant ones were; Nitrofurantoin 87% and Cefoxitin 85%. The least resistant antibiotics; Imipenem 3% and Ticarcillin 7%. While variable resistance in the rest of tested antimicrobials. A 47 patients (31.3%) have used antibiotics prior to this study. The high rate of usage occurred in elder patients. The frequency of Acinetobacter calcoaceticus baumannii complex multi-drugs resistance ABCMDR is rising including almost all commonly used antibiotics. Only few antibiotics exert 100% sensitivity towards these bacteria.

Antibacterial effects on acinetobacter species of commonly employed antineoplastic agents used in the treatment of haematological malignancies: an in vitro laboratory evaluation.

Although about 75-80% of neutropenic fevers are thought to be caused by infections, a causal organism can be confirmed microbiologically or suspected clinically in only 30-50%, and even fewer of these cases (16%) have a documented bacteraemia. The cause of neutropenic fever in the remaining cases remains elusive. The reasons for this failure may be due to the difficulty in recovering low numbers of organisms, fastidious organisms which fail to grow using conventional culture media, the presence of non-culturable organisms, or the presence of inhibitory substances in specimens. Previously, the authors showed the presence of Acinetobacter in peripheral blood of febrile neutropenic patients with a haematological malignancy, using 16S rDNA polymerase chain reaction (PCR) and sequencing techniques. However, conventional culture was unable to detect these organisms. Hence, it was felt necessary to examine the antibacterial properties of four antineoplastic agents used in the treatment of haematological malignancy, namely bleomycin, cisplatin, doxorubicin and vincristine. A total of 56 wild-type Acinetobacter including seven species (A. calcoaceticus [n=17], A. septicus [n=11], A. baumannii [n=10], A. johnsonii [n=7], A. lwoffii [n=8] A. haemolyticus [n=2] and A. radioresistens [n=1]) were examined for their susceptibility to the four antineoplastic agents at therapeutic concentration. No inhibition was observed, but inhibition was seen at higher concentrations of both bleomycin and doxorubicin. Time to detection of blood culture bottles containing separate antineoplastic agents (i.e., bleomycin and doxorubicin) was compared to that containing saline using a paired t-test. Samples containing doxorubicin at 1 pg/mL were shown to have a mean time to detection of 21.8 h (range: 15.6-31.4 h). Bottles containing saline had a mean time to detection of 22.9 h (range: 18.2-31.3 h). Statistical analysis showed no significant difference (P=0.3361) between time to detection for blood culture bottles containing doxorubicin at achievable plasma concentration and corresponding negative controls. With regard to bleomycin (300 miu/mL), the mean time to detection was 27.29 h (range: 20.2-38.4 h) in the test bottles, with mean time to detection in the saline negative controls of 22.56 h (range: 17.0-30.1 h). Paired t-test gave P=0.000451, hence a significant difference in time to detection for blood cultures containing therapeutic levels of bleomycin. Overall, the antineoplastic agents vincristine, cisplatin or doxorubicin did not have any inhibitory effects on the Acinetobacter organisms examined. At worst, therapeutic concentrations of bleomycin may delay automated detection of an Acinetobacter bacteraemia by a mean time of 5.9 h.

DNA-based stable isotope probing enables the identification of active bacterial endophytes in potatoes.

A (13)CO2 (99 atom-%, 350 ppm) incubation experiment was performed to identify active bacterial endophytes in two cultivars of Solanum tuberosum, cultivars Desirée and Merkur. We showed that after the assimilation and photosynthetic transformation of (13)CO2 into (13)C-labeled metabolites by the plant, the most directly active, cultivar specific heterotrophic endophytic bacteria that consume these labeled metabolite scan be identified by DNA stable isotope probing (DNA-SIP).Density-resolved DNA fractions obtained from SIP were subjected to 16S rRNA gene-based community analysis using terminal restriction fragment length polymorphism analysis and sequencing of generated gene libraries.Community profiling revealed community compositions that were dominated by plant chloroplast and mitochondrial 16S rRNA genes for the 'light' fractions of (13)CO2-incubated potato cultivars and of potato cultivars not incubated with (13)CO2. In the 'heavy' fractions of the (13)CO2-incubated endophyte DNA, a bacterial 492-bp terminal restriction fragment became abundant, which could be clearly identified as Acinetobacter and Acidovorax spp. in cultivars Merkur and Desirée,respectively, indicating cultivar-dependent distinctions in (13)C-label flow. These two species represent two common potato endophytes with known plant-beneficial activities.The approach demonstrated the successful detection of active bacterial endophytes in potato. DNA-SIP therefore offers new opportunities for exploring the complex nature of plant-microbe interactions and plant-dependent microbial metabolisms within the endosphere.

Cyanuric acid biodegradation by a mixed bacterial culture of Agrobacterium tumefaciens and Acinetobacter sp. in a packed bed biofilm reactor.

Cyanuric acid (1,3,5-triazine-2,4,6-triol [OOOT]) is a common biodegradation byproduct of triazinic herbicides, frequently accumulated in soils or water when supplementary carbon sources are absent. A binary bacterial culture able to degrade OOOT was selected through a continuous selection process accomplished in a chemostat fed with a mineral salt (MS) medium containing cyanuric acid as the sole carbon and nitrogen source. By sequence comparison of their 16S rDNA amplicons, bacterial strains were identified as Agrobacterium tumefaciens, and Acinetobacter sp. When the binary culture immobilized in a packed bed reactor (PBR) was fed with MS medium containing OOOT (50 mg L(-1)), its removal efficiencies were about 95%; when it was fed with OOOT plus glucose (120 mg L(-1)) as a supplementary carbon source, its removal efficiencies were closer to 100%. From sessile cells, attached to PBR porous support, or free cells present in the outflowing medium, DNA was extracted and used for Random Amplification of Polymorphic DNA analysis. Electrophoretic patterns obtained were compared to those of pure bacterial strains, a clear predominance of A. tumefaciens in PBR was observed. Although in continuous suspended cell culture, a stable binary community could be maintained, the attachment capability of A. tumefaciens represented a selective advantage over Acinetobacter sp. in the biofilm reactor, favoring its predominance in the porous stone support.

A double kill gene cassette for the positive selection of transforming non-selective DNA segments in Acinetobacter baylyi BD413.

Natural transformation has been widely used for the monitoring of DNA in biological and environmental samples. These assays depended on selectable traits on the tested DNA. We have now developed a transformation assay system in which recombinational removal of a cassette with two conditional kill genes (hok and sacB) from the recipient genome provides positive selection for non-selective DNA. The cassette was integrated into the Acinetobacter baylyi BD413 chromosome within trpE and was flanked by two segments of non-selective test DNA, which in this study were from a T-DNA construct previously used to generate a transgenic potato. Genes for tetracycline and spectinomycin/streptomycin resistance located at the sides of the cassette allowed to maintain selection pressure against spontaneous loss of the cassette. Plasmid DNA containing the T-DNA gave transformation frequencies ranging linearly from 10(-4) per recipient (at 1 mug DNA ml(-1)) down to 10(-7) (1 ng DNA ml(-1)) by selecting for survivors after activation of both kill functions. Transformation depended on the two flanking homologous segments for recombinational exchange. DNA of the transgenic potato also gave positive scores in spite of the about 10(5)-fold dilution of T-DNA by potato DNA. False positives having a spontaneous deletion of hok and sacB occurred at a frequency of 1.8x10(-9) per cell but could be distinguished by PCR from real transformants. Thus, the system is suitable for detection of transformation frequencies down to about 10(-9). Hok and sacB as well as the regulatory system used (LacI-lac operator and T5 promoter) are known to function in many organisms suggesting wide applicability of the cassette for positive selection.

Improvements in lipase production and recovery from Acinetobacter radioresistens in presence of polypropylene powders filled with carbon sources.

Polypropylene powders as the adsorbent for organic solution containing n-hexadecane and olive oil were employed as the carbon source for producing an alkaline lipase from Acinetobacter radioresistens. The best volumetric ratio of n-hexadecane to olive oil around 5 for lipase production was determined from shake-flask and fermentation cultivations. The existence of a maximum time course lipase activity of the aqueous phase was attributed to the compensation effects of olive oil on cell growth and lipase production, repression of lipase synthesis by oleic acid, and lipase adsorption on the supports. A linear relationship between the average cell growth rate in the exponential phase and the ratio of surface areas of the supports was found. The benefits of using the present fermentation process include less foaming and emulsion of the broth, less organic phase used, higher lipase production, and easy recovery of the lipase in the centrifugation step.

RAPD-PCR typing of Acinetobacter isolates from activated sludge systems designed to remove phosphorus microbiologically.

AIMS: This study investigated whether there were differences in RAPD fingerprints between already described genomic species of Acinetobacter and those from activated sludge systems. Whether plant-specific populations of acinetobacters exist was also examined. METHODS AND RESULTS: Fifty-two isolates of Acinetobacter from four biological phosphorus removal (EBPR) systems of different configurations, and the known genomic species, were characterized using RAPD-PCR, and fragments separated on agarose gels. Patterns were analysed using Gel Pro software and data analysed numerically. RAPD-PCR produced patterns suggesting that many environmental isolates differ from known genomic species. In two cases, strains from individual plants clustered closely enough together to imply that there may be plant-specific populations of acinetobacters. CONCLUSION: The data suggest that current understanding of the taxonomic status of Acinetobacter may need modifying to accommodate non-clinical isolates, as many of the clusters emerging after numerical analysis of RAPD-PCR fragments from activated sludge isolates were quite separate from the clusters containing the already described genomic species. Some evidence was also obtained from the clusters generated to support a view that particular populations of Acinetobacter may occur in individual activated sludge plants. SIGNIFICANCE AND IMPACT OF THE STUDY: These data suggest that the current understanding of the systematics of Acinetobacter, based as it is almost exclusively on clinical isolates, may need drastic revision to accommodate environmental strains. They also suggest that a re-examination of the importance and role of Acinetobacter in the activated sludge process may be appropriate.

Phenotypic characterization and antibiotic resistance of Acinetobacter spp. isolated from aquatic sources.

A total of 99 Acinetobacter isolates from sewage, freshwater aquaculture habitats, trout intestinal contents and frozen shrimps was characterized phenotypically and antibiotic susceptibility patterns determined. One group of genomic species, including Ac. johnsonii, Ac. lwoffi and spp. 15TU, was detected in all sample types and represented the majority of the isolates (n = 54). Isolates belonging to the Acb complex (Ac. calcoaceticus, Ac. baumannii and genomic species 3) were detected in sewage (n = 6) and frozen shrimps (n = 1), Ac. haemolyticus in frozen shrimps (n = 6) and trout intestinal contents (n = 2) and genomic species 11 in freshwater aquaculture habitats (n = 6) and trout intestinal contents (n = 1). Acinetobacter junii (n = 5), genomic species 10 (n = 2), 14BJ (n = 8) and 16BJ (n = 4) were only isolated from sewage. Acinetobacter isolates from sewage were generally more biochemically reactive and resistant to antimicrobial agents compared with isolates from other sample types. Different strains, often belonging to different genomic species, were isolated from sites situated upstream and downstream of the discharge point of a pharmaceutical plant. This finding supported the hypothesis that the waste effluent from the pharmaceutical plant was likely to cause a change in the distribution of Acinetobacter spp. by selecting and/or introducing antibiotic-resistant strains into the recipient sewers.

Antibiotic resistance in Acinetobacter spp. isolated from sewers receiving waste effluent from a hospital and a pharmaceutical plant.

The possible increase of antibiotic-resistant bacteria in sewage associated with the discharge of wastewater from a hospital and a pharmaceutical plant was investigated by using Acinetobacter species as environmental bacterial indicators. The level of susceptibility to six antimicrobial agents was determined in 385 Acinetobacter strains isolated from samples collected upstream and downstream from the discharge points of the hospital and the pharmaceutical plant. Results indicated that while the hospital waste effluent affected only the prevalence of oxytetracycline resistance, the discharge of wastewater from the pharmaceutical plant was associated with an increase in the prevalence of both single- and multiple-antibiotic resistance among Acinetobacter species in the sewers.

Clinical and molecular epidemiology of acinetobacter infections sensitive only to polymyxin B and sulbactam.

A nosocomial outbreak of infections due to imipenem-resistant Acinetobacter baumannii occurred in a New York hospital after increased use of imipenem for cephalosporin-resistant klebsiella infections. We identified all A baumannii isolates over 12 months, reviewed corresponding patient records, and compared strains with different antibiotic susceptibility patterns by restriction endonuclease analysis. Environmental surveillance cultures were done before and after institution of control measures. 59 patients harboured imipenem-resistant A baumannii, and 18 were infected. Isolates from patients were resistant to all routinely tested antibiotics, including imipenem. Further studies showed susceptibility to polymyxin B and sulbactam. These isolates were identical by restriction endonuclease analysis to A baumannii isolates susceptible to imipenem alone, or to imipenem and amikacin, but differed from broadly susceptible isolates. Surveillance cultures showed hand and environmental colonisation by imipenem-resistant strains. Infection and colonisation were eliminated by intensive infection control measures, and irrigation of wounds with polymyxin B. Increased use of imipenem against cephalosporin-resistant klebsiella may lead to imipenem resistance among other species, particularly acinetobacter. Such resistance appears to derive from a prior multi-resistant clone, in contrast to one which retains susceptibility to several antibiotics.

Application of gas-liquid chromatography to the routine identification of nonfermenting gram-negative bacteria in clinical specimens.

A total of 430 strains of glucose-nonfermenting gram-negative bacteria representing 35 species were analyzed for their cellular fatty acid composition by gas-liquid chromatography (GLC). On the basis of qualitative differences in their cellular fatty acid composition, these bacteria could be divided into 19 distinct chromatographic groups. Eight Pseudomonas species, Achromobacter xylosoxidans, group Vd, and Agrobacterium radiobacter were identified from their fatty acid compositions alone. The other glucose-nonfermenting gram-negative bacterial species studied here, classified within nine distinct GLC groups, were easily recognized by using the GLC fatty acid analysis supplemented with a limited number of conventional biochemical tests. The results support the hypothesis that bacterial fatty acid composition is rather specific and that qualitative GLC fatty acid analysis can be adapted in the clinical laboratory either to provide additional criteria for differentiation of closely related groups or to serve as a rapid and highly reproducible method for their routine identification.

Comparison of the API 20E and Oxi/Ferm systems in identification of nonfermentative and oxidase-positive fermentative bacteria.

The API 20E and Oxi/Ferm systems were tested in parallel to identify nonfermentative bacteria and oxidase-positive fermentative bacteria. Test strains consisted of consecutive clinical isolates, with stock cultures used to supplement those species infrequently recovered. The two microsystems, as well as tubes of triple sugar iron, motility, cetrimide, and oxidative glucose media, were inoculated by each worker for each organism. Identification of each isolate was by the protocol of the manufacturers, with supplemental tests and flagella stains performed when necessary. Concurrent identification was undertaken with a conventional system against which the results of the two systems were compared for accuracy. There was a 95.3% accuracy in identification by the Oxi-Ferm system and 88.9% by the API system. Almost one-fourth of all identification attempts with the API required computer assistance, and most of these were for oxidase positive bacteria. Because of this, and because the API system showed greater accuracy in identification of the oxidase-negative bacteria, it seems best suited for identification of these organisms (P. maltophilia, A. anitratus, and A. lwoffi). The Oxi/Ferm system is technically less cumbersome than the API and is well suited for both groups of organisms.