Lwoffii Strains Research Articles

Corrosion resistance and antibacterial activity of 2-mercaptobenzothiazole for 7B04 aluminium alloy in 3.5%NaCl solution

In this paper, the inhibition effect of 2-mercaptobenzothiazole (MBT) on microorganisms in the fuel system and corrosion inhibition of 7B04 aluminum alloy are studied, and the mechanism is discussed. The antibacterial activity of MBT is studied by microbial experiments. The agar diffusion test demonstrates the significant antibacterial efficacy of MBT against Lysinibacillus sphaericus (L. sphaericus) and Acinetobacter lwoffii (A. lwoffii) strains isolated from aircraft fuel systems, and the bacteriostatic effect on L. sphaericus is better. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PDP) results show that MBT inhibits the corrosion of 7B04 aluminum alloy by forming a protective film on the aluminum alloy surface and inhibiting the cathode reaction. In this study, the most effective corrosion inhibition concentration of MBT is 200 mg∙L−1, with a maximum corrosion inhibition rate of 99.27%. Langmuir adsorption isotherm results further indicate that MBT acts on the aluminum alloy surface by physical adsorption and chemical adsorption. The scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) results confirm that MBT form a protective adsorption film on the aluminum alloy surface, which effectively shield the corrosive media on the surface. Furthermore, density functional theory (DFT), Monte Carlo simulation (MC), and molecular dynamics simulation (MD) are employed to identify the active sites of MBT as N and S atoms and to demonstrate that MBT adsorb onto the aluminum alloy surface in a horizontal orientation.

Hetero-antagonism of avibactam and sulbactam with cefiderocol in carbapenem-resistant Acinetobacter spp.

Cefiderocol, a siderophore-cephalosporine conjugate antibiotic, shows promise as a therapeutic option for carbapenem-resistant (CR) Acinetobacter infections. While resistance has already been reported in A. baumannii, combination therapies with avibactam or sulbactam reduce MICs of cefiderocol, extending its efficacy. However, careful consideration is necessary when using these combinations. In our experiments, exposure of A. baumannii and A. lwoffii to cefiderocol and sulbactam or avibactam led to the selection of cefiderocol-resistant strains. Three of those were subjected to whole genome sequencing and transcriptomic analysis. The strains all possessed synonymous and non-synonymous substitutions and short deletions. The most significant mutations affected efflux pumps, transcriptional regulators, and iron homeostasis genes. Transcriptomics showed significant alterations in expression levels of outer membrane proteins, iron homeostasis, and β-lactamases, suggesting adaptive responses to selective pressure. This study underscores the importance of carefully assessing drug synergies, as they may inadvertently foster the selection of resistant variants and complicate the management of CR Acinetobacter infections.IMPORTANCEThe emergence of carbapenem-resistant Acinetobacter strains as a serious global health threat underscores the urgent need for effective treatment options. Although few drugs show promise against CR Acinetobacter infections, resistance to both drugs has been reported. In this study, the molecular characterization of spontaneous cefiderocol-resistant variants, a CR A. baumannii strain with antagonism to sulbactam, and an A. lwoffii strain with antagonism to avibactam, provides valuable insights into the mechanisms of resistance to cefiderocol. Some mechanisms observed are associated with mutations affecting efflux pumps, regulators, and iron homeostasis genes. These findings highlight the importance of understanding resistance mechanisms to optimize treatment options. They also emphasize the importance of early evaluation of drug synergies to address the challenges of antimicrobial resistance in Acinetobacter infections.

Four novel Acinetobacter lwoffii strains isolated from the milk of cows in China with subclinical mastitis

BackgroundAcinetobacter lwoffii (A. lwoffii) is a Gram-negative bacteria common in the environment, and it is the normal flora in human respiratory and digestive tracts. The bacteria is a zoonotic and opportunistic pathogen that causes various infections, including nosocomial infections. The aim of this study was to identify A. lwoffii strains isolated from bovine milk with subclinical mastitis in China and get a better understanding of its antimicrobial susceptibility and resistance profile. This is the first study to analyze the drug resistance spectrum and corresponding mechanisms of A. lwoffii isolated in raw milk.ResultsFour A. lwoffii strains were isolated by PCR method. Genetic evolution analysis using the neighbor-joining method showed that the four strains had a high homology with Acinetobacter lwoffii. The strains were resistant to several antibiotics and carried 17 drug-resistance genes across them. Specifically, among 23 antibiotics, the strains were completely susceptible to 6 antibiotics, including doxycycline, erythromycin, polymyxin, clindamycin, imipenem, and meropenem. In addition, the strains showed variable resistance patterns. A total of 17 resistance genes, including plasmid-mediated resistance genes, were detected across the four strains. These genes mediated resistance to 5 classes of antimicrobials, including beta-lactam, aminoglycosides, fluoroquinolones, tetracycline, sulfonamides, and chloramphenicol.ConclusionThese findings indicated that multi-drug resistant Acinetobacter lwoffii strains exist in raw milk of bovine with subclinical mastitis. Acinetobacter lwoffii are widespread in natural environmental samples, including water, soil, bathtub, soap box, skin, pharynx, conjunctiva, saliva, gastrointestinal tract, and vaginal secretions. The strains carry resistance genes in mobile genetic elements to enhance the spread of these genes. Therefore, more attention should be paid to epidemiological surveillance and drug resistant A. lwoffii.

Identification of an Acinetobacter lwoffii strain isolated from diseased hybrid sturgeon (Acipenser baerii♀× Acipenser schrenckii♂)

Members of the genus Acinetobacter are important opportunistic pathogens responsible for various nosocomial infections. However, Acinetobacter spp. are rarely isolated from fish. In this study, we isolated a dominant bacterial strain named I-702 from diseased hybrid sturgeons (Acipenser baerii♀ × Acipenser schrenckii♂) bred at a farm in Yichang City, Hubei Province, China. We identified the strain as Acinetobacter lwoffii based on morphological, physiological and biochemical, and 16S rRNA gene sequence analyses. Regression infection experiments using strain I-702 showed that the symptoms of the artificially infected fish were the same as those of natural diseased sturgeons, such as abdominal congestion and redness and swelling of cloaca. We calculated that the median lethal dose (LD50) of strain I-702 for hybrid sturgeons was 1.22 × 102 ± 0.11 colony forming units/g fish. We also compared the proportion of different leukocytes between healthy and diseased fish; the proportion of neutrophils (30.89%) and monocytes (36.68%) in infected fish increased significantly, whereas that of lymphocytes (30.17%) decreased. Histopathological examination revealed that strain I-702 caused damage to the liver, and intestine tissues of sturgeons. Gut microbial analysis revealed that I-702 infection caused dysbiosis in sturgeons. The relative abundance of Acinetobacter in the diseased group (54.4%) was significantly higher than that in the healthy group (10.7%), whereas the relative abundance of Cetobacterium decreased significantly (healthy sturgeon: 25.6%, diseased sturgeon: 1.5%). Strain I-702 was susceptible to aminoglycosides (neomycin sulfate, amikacin, and gentamycin) and tetracyclines (minocycline and doxycycline). These results suggest that A. lwoffii is an important pathogen of sturgeons. Moreover, the study provides a scientific basis for the control and prevention of A. lwoffii infection in fish.

Screening for extracellular synthesis of silver nanoparticles by bacteria isolated from Al-Halfaya oil field reservoirs in Missan province, Iraq

Abstract. Alshami HGA, Al-Tamimi WH, Hateet RR. 2022. Screening for extracellular synthesis of silver nanoparticles by bacteria isolated from Al-Halfaya oil field reservoirs in Missan province, Iraq. Biodiversitas 23: 3462-3470. Microorganisms that live in deep environments are thought to be adapted to the conditions of these environments and possess enzymatic systems that can be useful in scientific and commercial applications. The study aimed to isolate, identify, and screening of silver nanoparticles (AgNPs)-producing bacteria from five samples of produced water of the Al-Halfaya oil field reservoirs in Missan governorate, Iraq. The results revealed a total of 22 bacterial isolates were isolated and identified by morphological features and amplification of the 16S rDNA gene. The isolates are belonging to nine species, including Bacillus cereus strain DBA1.1, Bacillus thuringiensis strain MSP51, Neobacillus drentensis strain ROA042, Enterococcus faecalis strain 2674, Exiguobacterium mexicanum strain AB201, Klebsiella quasipneumoniae strain KP18-31, Klebsiella quasipneumoniae subsp. similipneumoniae strain 2437, Klebsiella pneumoniae strain IOB-L, and Acinetobacter lwoffii strain K34. The Gram-positive bacteria were the most dominant (55.56%), and the most frequent isolate was Klebsiella quasipneumoniae strain KP18-31 (63.64%). Six species out of nine species were recognized as AgNPs producing bacteria and B. cereus strain DBA1 was the best and most potent isolate in the synthesis of AgNPs. The phylogenetic tree was constructed depending on 16S rDNA gene sequences to determine the evolutionary relationship among the isolated bacteria.

Genome Analysis of Acinetobacter lwoffii Strains Isolated from Permafrost Soils Aged from 15 Thousand to 1.8 Million Years Revealed Their Close Relationships with Present-Day Environmental and Clinical Isolates.

Simple SummaryArctic ecosystems are an extreme habitat characterized by a negative average annual temperature and the presence of permafrost that occupies about 25% of the land. Permafrost can retain viable microorganisms for several million years and therefore it is a source of unique “ancient” microbes. Acinetobacter lwoffii are aerobic chemoorganotrophic bacteria widespread in a variety of natural and artificial environments, and have been reported as hospital pathogens associated with nosocomial infections. Here, we carried out a genome-wide analysis of five strains of A. lwoffii isolated from permafrost aged from 15 thousand to 1.8 million years. Surprisingly, we did not reveal genetic determinants that distinguish them from modern clinical and environmental A. lwoffii isolates. On the phylogenetic tree permafrost strains do not form a separate cluster, but are related to various clinical isolates. The genomes of clinical and permafrost strains contain similar mobile elements and prophages, which indicates an intense horizontal gene transfer. Like clinical isolates, permafrost strains harbored antibiotic resistance genes, although plasmids from the modern strains are enriched with antibiotic resistance genes compared to permafrost ones. The obtained results indicate that thawing of permafrost caused by global warming could release new potentially pathogenic strains of Acinetobacter into the modern biosphere.Microbial life can be supported at subzero temperatures in permafrost up to several million years old. Genome analysis of strains isolated from permafrost provides a unique opportunity to study microorganisms that have not previously come into contact with the human population. Acinetobacter lwoffii is a typical soil bacterium that has been increasingly reported as hospital pathogens associated with bacteremia. In order to identify the specific genetic characteristics of ancient permafrost-conserved strains of A. lwoffii and their differences from present-day clinical isolates, we carried out a genome-wide analysis of five strains of A. lwoffii isolated from permafrost aged from 15 thousand to 1.8 million years. Surprisingly, we did not identify chromosomal genetic determinants that distinguish permafrost strains from clinical A. lwoffii isolates and strains from other natural habitats. Phylogenetic analysis based on whole genome sequences showed that permafrost strains do not form a separate cluster and some of them are most closely related to clinical isolates. The genomes of clinical and permafrost strains contain similar mobile elements and prophages, which indicates an intense horizontal transfer of genetic material. Comparison of plasmids of modern and permafrost strains showed that plasmids from the modern strains are enriched with antibiotic resistance genes, while the content of genes for resistance to heavy metals and arsenic is nearly the same. The thawing of permafrost caused by global warming could release new potentially pathogenic strains of Acinetobacter.

Antibiotic Resistance Profile of Acinetobacter Species Isolated from Blood Cultures of Inpatients in Harran University Hospital

Objectives: Acinetobacter baumannii causes serious blood stream infections especially in immunocompromised and hospitalized patients. In this study, the distribution of antibacterial resistance among 92 A. baumannii isolates and 5 A. lwoffii isolates from blood cultures collected at Harran University Hospital (Urfa, Turkey) from 2017 to 2019 was investigated. Methods: Blood cultures were followed up in Versa-TREK (Trek Diagnostic System, USA) device; Passages were made to 5% blood agar and eosin methylene blue (EMB) agar. Passaged bacteria colonies were identified by MALDI-TOF MS (Bruker, Germany) and VITEK 2 compact system (bioMérieux, France). Sensitivities of Acinetobacter strains to meropenem, ciprofloxacin, amikacin, gentamicin, tobramycin, tigecycline and trimethoprim-sulfamethoxazole were tested by VITEK 2 compact system (bioMérieux, France). The results were evaluated by VITEK 2 device based on EUCAST's guide. Results: The antibiotic resistance rates of A. baumannii strains are as follows; ciprofloxacin 92%, imipenem %88, meropenem 88%, gentamicin 74%, tobramycin 67%, trimethoprim-sulfamethoxazole 63%, amikacin 53%, and tigecycline 10%. The resistance ratio of A. lwoffii strains are ciprofloxacin (40%), gentamicin 40%, amikacin 40%, tobramycin 40%, trimethoprim sulfamethoxazole 20%, imipenem %20, meropenem 20% and tigecycline 20%. Conclusions: Our study suggests A. baumannii strains have high resistance ratios to available antibiotics. A. lwoffii also has an increasing resistance profile. Tigecycline is the most sensitive antibiotic, followed by amikacin and tobramycin. New antibiotics, rapid access to antibiotic sensitivity results and correct selection of empiric antibiotics has clinical importance.

Acinetobacter Plasmids: Diversity and Development of Classification Strategies.

Bacteria of the genus Acinetobacter, with their numerous species common in various habitats, play a significant role as pathogens. Their ability to adapt to different living conditions is largely due to the presence of numerous plasmids containing the necessary adaptive genes. At the same time the diversity of Acinetobacter plasmids and their evolutionary dynamics have not been sufficiently studied. Here, we characterized 44 plasmids isolated from five permafrost Acinetobacter lwoffii strains, examined their relationship with plasmids of modern Acinetobacter strains and identified groups of related plasmids. For this purpose, we have developed a combined approach for classifying all known Acinetobacter plasmids. The classification took into account the size of plasmids, the presence and structure of the rep and mob genes, as well as the structure of their backbone and accessory regions. Based on the analysis, 19 major groups (lineages) of plasmids were identified, of which more than half were small plasmids. The plasmids of each group have common features of the organization of the backbone region with a DNA identity level of at least 80%. In addition, plasmids of the same group have similarities in the organization of accessory regions. We also described a number of plasmids with a unique structure. The presence of plasmids in clinical strains that are closely related to those of environmental permafrost strains provides evidence of the origin of the former from the latter.

Plasmidome of an environmental Acinetobacter lwoffii strain originating from a former gold and arsenic mine

Emerging important Acinetobacter strains commonly accommodate a plethora of mobile elements including plasmids of different size. Plasmids, apart from encoding modules enabling their self-replication and/or transmission, can carry a diverse number of genes, allowing the host cell to survive in an environment that would otherwise be lethal or restrictive for growth. The present study characterizes the plasmidome generated from an arsenic-resistant strain named ZS207, classified as Acinetobacter lwoffii. Sequencing effort revealed the presence of nine plasmids in the size between 4.3 and 38.4 kb as well as one 186.6 kb megaplasmid. All plasmids, except the megaplasmid, do apparently not confer distinguishing phenotypic features. In contrast, the megaplasmid carries arsenic and heavy metals resistance regions similar to those found in permafrost A. lwoffii strains. In-depth in silico analyses have shown a significant similarity between the regions from these plasmids, especially concerning multiple transposable elements, transfer and mobilization genes, and toxin-antitoxin systems.Since ars genes encode proteins of major significance in terms of potential use in bioremediation, arsenic resistance level of ZS207 was determined and the functionality of selected ars genes was examined. Additionally, we checked the functionality of plasmid-encoded toxin-antitoxin systems and their impact on the formation of persister cells.

Abundance of mobile genetic elements in an Acinetobacter lwoffii strain isolated from Transylvanian honey sample

Based on phylogenetic analyses, strain M2a isolated from honey, an unexpected source of acinetobacters, was classified as Acinetobacter lwoffii. The genome of this strain is strikingly crowded with mobile genetic elements. It harbours more than 250 IS elements of 15 IS-families, several unit and compound transposons and 15 different plasmids. These IS elements, including 30 newly identified ones, could be classified into at least 53 IS species. Regarding the plasmids, 13 of the 15 belong to the Rep-3 superfamily and only one plasmid, belonging to the “Low-GC” family, possesses a seemingly complete conjugative system. The other plasmids, with one exception, have a mobilization region of common pattern, consisting of the divergent mobA/mobL-family and mobS-, mobC- or traD-like genes separated by an oriT-like sequence. Although two plasmids of M2a are almost identical to those of A. lwoffi strains isolated from gold mine or Pleistocene sediments, most of them have no close relatives. The presence of numerous plasmid-borne and chromosomal metal resistance determinants suggests that M2a previously has also evolved in a metal-polluted environment. The numerous, possibly transferable, plasmids and the outstanding number of transposable elements may reflect the high potential of M2a for rapid evolution.

Crude Oil Biodegradation by Newly Isolated Bacterial Strains and Their Consortium Under Soil Microcosm Experiment.

Bioremediation has been attracting researchers' attention to develop as a technique to remove the pollution of crude oil in the environment. However, more or stronger novel strains capable of crude oil removal are still required. In this study, the potential of five newly isolated bacterial strains for crude oil abatement was evaluated in the liquid medium and contaminated soil individually and as a mixed consortium. Raoultella ornithinolytica strain PS exhibited the highest ability and degraded up to 83.5% of crude oil. Whereas Bacillus subtilis strain BJ11 degraded 81.1%, Acinetobacter lwoffii strain BJ10 degraded 75.8%, Acinetobacter pittii strain BJ6 degraded 74.9%, and Serratia marcescens strain PL degraded only 70.0% of crude oil in the liquid media. The consortium comprising the above five strains degraded more than 94.0% of crude oil after 10days of incubation in the liquid medium. The consortium degraded more than 65.0% of crude oil after 40days incubation even in the contaminated soil. The five crude oil degrading strains, especially their consortium, exhibited a high capability to break down a wide range of compounds in crude oil including straight-chain alkanes, branched alkanes, and aromatic hydrocarbons. These strains, especially as consortia, have good potential of application in the remediation of crude oil-contaminated environments.

Antimicrobial effect of copper alloys on Acinetobacter species isolated from infections and hospital environment

BackgroundAn increased proportion of Gram-negative bacteria have recently been reported among etiologic agents of infection. In Poland, Acinetobacter baumannii is a big problem for hospitals, especially intensive care units. Touch surfaces made from materials with antimicrobial properties, especially copper alloys, are recommended as a supplementary method of increasing biological safety in the hospital environment.Aim of the studyThe objective of this study is to determine the susceptibility to selected copper alloys of three clinical Acinetobacter baumannii strains, one Acinetobacter lwoffi and an A. pittii strain isolated from the hospital environment.Material and methodThe modification of the Japanese Standard, which the ISO 22196:2011 norm was used for testing antimicrobial properties of CuZn37, CuSn6 and CuNi18Zn20 and Cu-ETP and stainless steel as positive and negative control, respectively.ResultsThe highest cidal efficiency, expressed as both time and the degree of reduction of the initial suspension density, against all of the tested Acinetobacter strains was found for ETP copper. But, the results of our study also confirmed effective activity (bacteriocidal or bacteriostatic) of copper alloys selected for the study, contrary to the stainless steel. The reduction in bacterial suspension density is significantly different depending on the strain and copper alloy composition.ConslusionsThe results of our study confirmed the effective antibacterial activity of copper and its selected alloys against clinical Acinetobacter baumannii and Acinetobacter lwoffii strains, and Acinetobacter pittii strain isolated from the hospital environment.

Multi-drug resistance in Acinetobacter baumannii strains isolated from the clinical specimens of three hospitals in Tehran-Iran

The aim of this study is to investigate multi-drug resistance in A. baumannii strains that was isolated from clinical samples of three highly large hospitals in Tehran-Iran. This descriptive-cross sectional study was performed in three large hospitals in Tehran on 70 samples of Acinetobacter which were isolated from patients during April to November 2010. After identifying the species level by using culture and biochemical methods, in order to determine sensitivity of 50 isolates of A. baumannii to 13 antibiotics, standard methods according to CLSI guidelines were performed. In this study, resistance to three or more of three classes of antibiotics multidrug resistance was defined. In this study, 50 A. baumannii strains, 12 A. lwoffii strains and other Acinetobacter species were isolated from patients. The majority of isolates were from blood specimens. Isolates of A. baumannii showed the highest resistance to cefepime, ceftazidime, aztreonam, norfloxacin, ofloxacin, ciprofloxacin and amikacin. Tobramycin and meropenem considered as effective drugs in this study. Multi-drug resistance in these strains was respectively 55.4%. Multi-drug resistant Acinetobacters are growing and considered as important threat for hospitalized patients, so change in consumption patterns of antibiotics and control of hospital infections seems to be necessary.

Multi-drug resistance in Acinetobacter baumannii strains isolated from clinical specimens from three hospitals in Tehran-Iran

The aim of this study is to investigate multi-drug resistance in A. baumannii strains that was isolated from clinical samples of three highly large hospitals in Tehran-Iran. This descriptive-cross sectional study was performed in three large hospitals in Tehran on 70 samples of Acinetobacter which were isolated from patients during April to November 2010. After identifying the species level by using culture and biochemical methods, in order to determine sensitivity of 50 isolates of A. baumannii to 13 antibiotics, standard methods according to CLSI guidelines were performed. In this study, resistance to three or more of three classes of antibiotics multidrug resistance was defined. In this study, 50 A. baumannii strains, 12 A. lwoffii strains and other Acinetobacter species were isolated from patients. The majority of isolates were from blood specimens. Isolates of A. baumannii showed the highest resistance to cefepime, ceftazidime, aztreonam, norfloxacin, ofloxacin, ciprofloxacin and amikacin. Tobramycin and meropenem considered as effective drugs in this study. Multi-drug resistance in these strains was respectively 55.4%. Multi-drug resistant Acinetobacters are growing and considered as important threat for hospitalized patients, so change in consumption patterns of antibiotics and control of hospital infections seems to be necessary.

Carbon source-dependent modulation of NADP-glutamate dehydrogenases in isophthalate-degrading Pseudomonas aeruginosa strain PP4, Pseudomonas strain PPD and Acinetobacter lwoffii strain ISP4

Acinetobacter lwoffii strain ISP4 metabolizes isophthalate rapidly compared with Pseudomonas aeruginosa strain PP4 and Pseudomonas strain PPD. Isophthalate has been reported to be a potent competitive inhibitor of glutamate dehydrogenase (GDH). Exogenous supplementation of isophthalate with glutamate or alpha-ketoglutarate at 1 mM concentration caused strains PP4 and PPD to grow faster than in the presence of isophthalate alone; however, no such effect was observed in strain ISP4. When grown on isophthalate, all strains showed activity of NADP-dependent GDH (NADP-GDH), while cells grown on glucose, 2x yeast extract-tryptone broth (2YT) or glutamate showed activities of both NAD-dependent GDH (NAD-GDH) and NADP-GDH. Activity staining, inhibition and thermal stability studies indicated the carbon source-dependent presence of two (GDH(I) and GDH(II)), three (GDH(A), GDH(B) and GDH(C)) and one (GDH(P)) forms of NADP-GDH in strains PP4, PPD and ISP4, respectively. The results demonstrate the carbon source-dependent modulation of different forms of NADP-GDH in these bacterial strains. This modulation may help the efficient utilization of isophthalate as a carbon source by overcoming the inhibitory effect on GDH.

Acinetobacter lwoffii and Lactococcus lactis strains isolated from farm cowsheds possess strong allergy-protective properties

Children who grow up in a farming environment show lower levels of atopic sensitization, hay fever, and asthma than children of the same age not living in such an environment. A number of investigations provided good evidence that this is due to an early-life contact with cowsheds, farm animals, and/or consumption of products like raw milk. Also, it had been indicated that microorganisms might have an important effect on the development of allergies, and thus the question arose of which farm microbial organisms, their products, or both might induce or influence allergy-protective mechanisms. We sought to gain further insight into the potential allergy-protective properties of microbes isolated from the farming environment. Of a number of bacterial species identified in cowsheds of farms, 2 were selected, isolated, and characterized, namely Acinetobacter lwoffii F78 and Lactococcus lactis G121. The isolates were investigated with regard to their activation of pattern-recognition receptors, the maturation of human monocyte-derived dendritic cells, the upregulation of inflammatory cytokines, the T(H)1-polarizing Notch ligand expression, and their influence on the allergic phenotype. It is shown that both bacterial isolates were able to reduce allergic reactions in mice, to activate mammalian cells in vitro, and to induce a T(H)1-polarizing program in dendritic cells. Our data strongly support the hygiene hypothesis, which states that an environment rich in microbiologic structures, such as a farming environment, might protect against the development of allergies. This work provides the first data on a potential application of cowshed bacteria in allergy protection.

Catheter-related Bacteremia and Multidrug-resistantAcinetobacter lwoffii

To the Editor: Acinetobacter species are ubiquitous in the environment. In recent years, some species, particularly A. baumannii, have emerged as important nosocomial pathogens because of their persistence in the hospital environment and broad antimicrobial drug resistance patterns (1,2). They are often associated with clinical illness including bacteremia, pneumonia, meningitis, peritonitis, endocarditis, and infections of the urinary tract and skin (3). These conditions are more frequently found in immunocompromised patients, in those admitted to intensive care units, or in those who have intravenous catheters, and those who are receiving mechanical ventilation (4,5). The role of A. baumannii in nosocomial infections has been documented (2), but the clinical effect of other Acinetobacter species has not been investigated. A. lwoffii (formerly A. calcoaceticus var. lwoffii) is a commensal organism of human skin, oropharynx, and perineum that shows tropism for urinary tract mucosa (6). Few cases of A. lwoffii bacteremia have been reported (3,5–7). We report a 4-year (2002–2005) retrospective study of 10 patients with A. lwoffii bacteremia admitted to a 600-bed teaching hospital in central Italy. All 10 patients were immunocompromised; 8 had used an intravascular catheter (peripheral or central) and 2 had used a urinary catheter. Blood cultures of the patients were analyzed with the BacT/ALERT 3D system (bioMerieux, Marcy l’Etoile, France). Isolates were identified as A. lwoffii by using the Vitek 2 system and the API 20NE system (both from bioMerieux). Susceptibilities of 10 A. lwoffii isolates to 18 antimicrobial drugs were determined by the broth microdilution method, according to Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) guidelines (8). The drugs tested were amikacin, ampicillin-sulbactam, aztreonam, cefepime, cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, levofloxacin, meropenem, ofloxacin, piperacillin, piperacillin-tazobactam, tetracycline, tobramycin, and trimethoprim-sulfamethoxazole. MIC was defined as the lowest drug concentration that prevented visible bacterial growth. Interpretative criteria for each drug tested were as in CLSI guidelines (8). A. lwoffii resistant to >4 classes of drugs were defined as multidrug-resistant (MDR) isolates. A. lwoffii isolates were genotyped by pulsed-field gel electrophoresis (PFGE) to determine their epidemiologic relatedness. Chromosomal DNA was digested with SmaI (9) and analyzed with a CHEF DR II apparatus (Bio-Rad Laboratories, Hercules, CA, USA). PFGE patterns were classified as identical, similar (differed by 1–3 bands), or distinct (differed by >4 bands) (10). Among the 10 A. lwoffii isolates, 6 were susceptible to all drugs except cephalosporins (cefepime, cefotaxime, ceftazidime, and ceftriaxone) and aztreonam. The other 4 isolates were MDR: 3 were susceptible only to imipenem (MICs 1–4 μg/mL), meropenem (MICs 1–2 μg/mL), and amikacin (MICs 2–4 μg/mL). The fourth MDR strain was susceptible to imipenem (MIC 2 μg/mL), meropenem (MIC 2 μg/mL), amikacin (MIC 4 μg/mL), and ciprofloxacin (MIC 1 μg/mL). Seven antimicrobial drug resistance profiles were detected (Table). Table Antimicrobial drug susceptibility and pulsed-field gel electrophoresis (PFGE) patterns of 10 Acinetobacter lwoffii strains, Italy, 2002–2005 Macrorestriction analysis of the A. lwoffii isolates identified 8 distinct PFGE types. Two MDR strains (strains 2 and 3 in the Table), which were isolated from patients in different wards, and 2 non-MDR strains (strains 8 and 9), which were isolated from patients in the same ward, had similar PFGE patterns and identical resistance phenotypes. These findings suggest nosocomial transmission. Nine of the 10 patients survived after catheter removal or treatment with appropriate antimicrobial drugs. These results confirm that catheter-related A. lwoffii bacteremia in immunocompromised hosts is associated with a low risk for death (4,6). This study identified A. lwoffii MDR strains that cause bacteremia in immunocompromised catheterized patients. Our data are consistent with those of previous reports on the role of catheters as the principal source of A. lwoffii infections.

Evaluation of the ability of a commercial system to identify Acinetobacter genomic species.

A collection of 130 Acinetobacter strains identified by DNA hybridization to 18 different genomic species was used to assess the ability of the API 20NE system (bioMérieux, France) to identify Acinetobacter genomic species and to determine its accuracy. Fifty-eight (87%) of the 67 strains of genomic species defined in the database (version 5.1) were identified to the appropriate genomic species. The Acinetobacter baumannii strains and the Acinetobacter haemolyticus strains were all identified correctly. Three of five Acinetobacter junii strains, three of eight Acinetobacter johnsonii strains, and 11 of 13 Acinetobacter lwoffii strains were also identified correctly. The 58 correctly identified strains represented 45% of the total 130 strains. Thirty-six of the 72 inappropriately identified strains were designated Acinetobacter baumannii. Thirty-one of these 36 strains belonged to genomic species 1 (Acinetobacter calcoaceticus), 3, or 13TU. Analysis of the profiles showed that the API system does not discriminate between genomic species 1, 2, 3, and 13TU. Lumping of these groups into the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in the API 20NE database would make the system considerably more accurate. Incorporation of these data into the database may improve identification of the remaining genomic species, including some that are not defined. However, the discriminative power of the tests in the API galleries is insufficient for correct identification of all Acinetobacter genomic species.

Acinetobacter in Denmark: I. Taxonomy, antibiotic susceptibility, and pathogenicity of 112 clinical strains.

One hundred and twelve clinical strains of Acinetobacter were collected during a 7-month period in 1990-1991 from Danish clinical microbiology departments. According to the old notation, 37 strains were biovar anitratus and 75 b.lwoffii. Using the newest terminology, 35 strains were unambiguously identified as the species A. haemolyticus, A. johnsonii, A. radioresistens, and as the unnamed phenons 6, 10, and 14, by a numerical approach using a simplified phenotypical identification scheme. Most of the remaining strains were identified to the genotypically heterogeneous A. calcoaceticus-A. baumannii complex and the A. lwoffii phenotype. Sixteen strains (14%) were left unidentified. Eight A. lwoffii strains were glucose-oxidizing and were thus classified as b. anitratus using the old terminology. The strains were tested for susceptibility to ampicillin, piperacillin, ticarcillin, cefotaxime, ceftazidime, imipenem, gentamicin, tetracycline, sulphonamide, and nalidixic acid. All strains were susceptible to imipenem. The susceptibility to the remaining beta-lactams was variable, the A. lwoffii isolates being the most and the A. calcoaceticus-A. baumannii complex strains the least susceptible. All non-A. calcoaceticus-A. baumannii complex strains were susceptible to all other antibiotics tested, except for one A. lwoffii strain that was sulphonamide resistant. Twenty-two percent of the strains in the A. calcoaceticus-A. baumannii complex showed reduced susceptibility or resistance to gentamicin, but only sporadic resistance to sulphonamides, tetracyclines, and nalidixic acid. Eight infections were recorded: three cases of septicaemia, three cases of peritonitis related to continuous ambulatory peritoneal dialysis, and two cases of recurrent urinary tract infection. No epidemics were detected.

Overall similarity and DNA base composition of some Acinetobacter strains.

Six namedAcinetobacter anitratus and 23 namedA. lwoffii strains, most of them isolated in Hungary, were numerically analyzed. A set of 56 selected, distinctive features was used. All features giving an identical response were omitted. There are three interrelated groups. One group contains all of theA. anitratus and one of theA. lwoffii strains; it is largely glucidolytic and nearly all strains have 42.5±0-5 % GC. The second group consists ofA. lwoffii strains with % GC values below 43. The third and largest group containsA. lwoffii strains with % GC between 44.5 and 47. There are no sharp boundaries between the three groups.