Multidrug resistant Acinetobacter baumannii is a serious healthcare threat. In fact, the Center for Disease Control recently reported that carbapenem-resistant A. baumannii is responsible for more than 8,500 infections, 700 deaths, and $281 million in healthcare costs annually in the United States with few, if any, treatment options available, leading to its designation as a pathogen of urgent concern and a priority for novel antimicrobial development. It is hypothesized that biofilms are, at least in part, responsible for the high prevalence of A. baumannii nosocomial and recurrent infections because they frequently contaminate hospital surfaces and patient indwelling devices; therefore, there has been a recent push for mechanistic understanding of biofilm formation, maturation and dispersal. However, most research has focused on A. baumannii pneumonia and bloodstream infections, despite a recent retrospective study showing that 17.1% of A. baumannii isolates compiled from clinical studies over the last two decades were obtained from urinary samples. This highlights that A. baumannii is an underappreciated uropathogen. The following minireview will examine our current understanding of A. baumannii biofilm formation and how this influences urinary tract colonization and pathogenesis.

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Insights Into Mechanisms of Biofilm Formation in Acinetobacter baumannii and Implications for Uropathogenesis.

Malaria remains a major public health problem in South America, mostly in the Amazon region. Among newly proposed ways of controlling malaria transmission to humans, paratransgenesis is a promising alternative. Paratransgenesis aims to inhibit the development of parasites within the vector through the action of genetically modified bacteria. The first step towards successful paratransgenesis in the Amazon is the identification of Anopheles darlingi symbiotic bacteria, which are transmitted vertically among mosquitoes, and are not pathogenic to humans. Culturable bacteria associated with An. darlingi and their breeding sites were isolated by conventional microbiological techniques. Isolated strains were transformed with a GFP expressing plasmid, pSPT-1-GFP, and reintroduced in mosquitoes by feeding. Their survival and persistence in the next generation was assessed by the isolation of fluorescent bacteria from eggs, larvae, pupae and adult homogenates. A total of 179 bacterial strains were isolated from samples from two locations, Coari and Manaus. The predominant genera identified in this study were Acinetobacter, Enterobacter, Klebsiella, Serratia, Bacillus, Elizabethkingia, Stenotrophomonas and Pantoea. Two isolated strains, Serratia-Adu40 and Pantoea-Ovo3, were successfully transformed with the pSPT-1-GFP plasmid and expressed GFP. The fluorescent bacteria fed to adult females were transferred to their eggs, which persisted in larvae and throughout metamorphosis, and were detected in adult mosquitoes of the next generation. Serratia-Adu40 and Pantoea-Ovo3 are promising candidates for paratransgenesis in An. darlingi. Further research is needed to determine if these bacteria are vertically transferred in nature.

/pdf/culturable-bacteria-associated-with-anopheles-darlingi-and-xvanov81vb.pdf

Culturable bacteria associated with Anopheles darlingi and their paratransgenesis potential.

Introduction: Antibiotic resistance and virulence are common among bacterial populations, posing a global clinical challenge. The bacterial species Acinetobacter pittii, an infectious agent in clinical environments, has shown increasing rates of antibiotic resistance. Viruses that integrate as prophages into A. pittii could be a potential cause of this pathogenicity, as they often contain antibiotic resistance or virulence factor gene sequences. Methods: In this study, we analyzed 25 A. pittii strains for potential prophages. Using virulence factor databases, we identified many common and virulent prophages in A. pittii. Results: The analysis also included a specific catalogue of the virulence factors and antibiotic resistance genes contributed by A. pittii prophages. Finally, our results illustrate multiple similarities between A. pittii and its bacterial relatives with regard to prophage integration sites and prevalence. Discussion: These findings provide a broader insight into prophage behavior that can be applied to future studies on similar species in the Acinetobacter calcoaceticus-baumannii complex.

Prophages Present in Acinetobacter pittii Influence Bacterial Virulence, Antibiotic Resistance, and Genomic Rearrangements.

Abstract Background: The first pathogen to be designated a “red-alert” human pathogen is Acinetobacter baumannii , which is on the list of infections that must be treated urgently with new antibiotics. Infections due to this bacterium are on the rise, especially in patients admitted to hospital intensive care units. It can create biofilms on both biotic and abiotic surfaces. Objectives: This study aimed to detect biofilm formation by A. baumannii phenotypically and genotypically. Materials and Methods: A total of 250 samples were subjected to bacterial identification using the VITEK-2 compact system, which showed 42 A. baumannii isolates. Biofilm formation was phenotypically investigated using the microtiter plate method. Results: The results revealed three stages of biofilm formation: 5 (11.6%) nonbiofilm, 13 (30.2%) weak biofilm, 15 (34.9%) moderate, and 10 (23.3%) strong biofilm formation. The isolates from intensive care unit (ICU) patients had strong, moderate, weak, and nonforming biofilm ability in higher rates of biofilm producers compared with the isolates from samples of hospital wards. The polymerase chain reaction (PCR) products showed genotypically positive results as follows: PapII 12 (31.5%), OmpA 11 (28.9%), and LuxR 8 (21%) out of 38 positive samples of A. baumannii for all genes. Conclusion: Isolates of A. baumannii appeared in different stages of biofilm formation with a higher percentage rate in the ICU compared with hospitalized patients. The PCR products for isolates of A. baumannii showed that PapII , OmpA , and LuxR showed positive results. 

Molecular Detection of Pap II, OmpA, and LuxR Genes Responsible for Biofilm Formation in Acinetobacter baumannii Isolated from Hospitalized Patients

Genomic Diversity and Antimicrobial Resistance of Acinetobacter sp.-A Pan Genome Analysis

Acinetobacter has emerged recently as one of the most challenging nosocomial pathogens because of its increased rate of antimicrobial resistance. The genetic complexity and genome diversity, as well as the lack of adequate knowledge on the pathogenic determinants of Acinetobacter strains often hinder with pathogenesis studies for the development of better therapeutics to tackle this nosocomial pathogen. In this study, we comparatively analyzed the whole genome sequence of a virulent Acinetobacternosocomialis strain NCTC 8102. The genomic DNA of A. nosocomialis NCTC 8102 was isolated and sequenced using PacBio RS II platform. The sequenced genome was functionally annotated and gene prediction was carried out using the program, Glimmer 3. The phylogenetic analysis of the genome was performed using Mega 6 program and the comparative genome analysis was carried out by BLAST (Basic Local Alignment Search Tool). The complete genome analysis depicted that the genome consists of a circular chromosome with an average G + C content of 38.7%. The genome comprises 3700 protein-coding genes, 96 RNA genes (18 rRNA, 74 tRNA and 4 ncRNA genes), and 91 pseudogenes. In addition, 6 prophage regions comprising 2 intact, 1 incomplete and 3 questionable ones and 18 genomic islands were identified in the genome, suggesting the possible occurrence of horizontal gene transfer in this strain. Comparative genome analysis of A. nosocomialis NCTC 8102 genome with the already sequenced A. nosocomialis strain SSA3 showed an average nucleotide identity of 99.0%. In addition, the number of prophages and genomic islands were higher in the A. nosocomialis NCTC 8102 genome compared to that of the strain SSA3. 14 of the genomic islands were unique to A. nosocomialis NCTC 8102 compared to strain SSA3 and they harbored genes which are involved in virulence, multidrug resistance, biofilm formation and bacterial pathogenesis. We sequenced the whole genome of A. nosocomialis strain NCTC 8102 followed by comparatively genome analysis. The study provides valuable information on the genetic features of A. nosocomialis strain and the data from this study would assist in further studies for the development of control measures for this nosocomial pathogen.

Complete genome sequence and phylogenetic analysis of nosocomial pathogen Acinetobacter nosocomialis strain NCTC 8102

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Complete genome sequence and phylogenetic analysis of nosocomial pathogen Acinetobacter nosocomialis strain NCTC 8102