Comparing antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa from environmental and clinical settings.

Antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa, isolated from water sources collected in informal settlements, were compared to clinical counterparts. Cluster analysis using repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR) indicated that, for each respective species, low genetic relatedness was observed between most of the clinical and environmental isolates, with only one clinical P. aeruginosa (PAO1) and one clinical K. pneumoniae (P2) exhibiting high genetic similarity to the environmental strains. Based on the antibiograms, the clinical E. faecium Ef CD1 was extensively drug resistant (XDR); all K. pneumoniae isolates (n = 12) (except K. pneumoniae ATCC 13883) were multidrug resistant (MDR), while the P. aeruginosa (n = 16) isolates exhibited higher susceptibility profiles. The tetM gene (tetracycline resistance) was identified in 47.4 % (n = 6 environmental; n = 3 clinical) of the E. faecium isolates, while the blaKPC gene (carbapenem resistance) was detected in 52.6 % (n = 7 environmental; n = 3 clinical) and 15.4 % (n = 2 environmental) of the E. faecium and K. pneumoniae isolates, respectively. The E. faecium isolates were predominantly poor biofilm formers, the K. pneumoniae isolates were moderate biofilm formers, while the P. aeruginosa isolates were strong biofilm formers. All E. faecium and K. pneumoniae isolates were gamma (γ)-haemolytic, non-gelatinase producing (E. faecium only), and non-hypermucoviscous (K. pneumoniae only), while the P. aeruginosa isolates exhibited beta (ß)-haemolysis and produced gelatinase. The fimH (type 1 fimbriae adhesion) and ugE (uridine diphosphate galacturonate 4-epimerase synthesis) virulence genes were detected in the K. pneumoniae isolates, while the P. aeruginosa isolates possessed the phzM (phenazine production) and algD (alginate biosynthesis) genes. Similarities in antibiotic resistance and virulence profiles of environmental and clinical E. faecium, K. pneumoniae, and P. aeruginosa, thus highlights the potential health risks posed by using environmental water sources for daily water needs in low-and-middle-income countries.

The Acinetobacter baumannii website (Ab-web): a multidisciplinary knowledge hub, communication platform, and workspace.

Acinetobacter baumannii is a Gram-negative bacterium increasingly implicated in hospital-acquired infections and outbreaks. Effective prevention and control of such infections are commonly challenged by the frequent emergence of multidrug-resistant strains. Here we introduce Ab-web (https://www.acinetobacterbaumannii.no), the first online platform for sharing expertise on A. baumannii. Ab-web is a species-centric knowledge hub, initially with 10 articles organized into two main sections, 'Overview' and 'Topics', and three themes, 'epidemiology', 'antibiotic resistance', and 'virulence'. The 'workspace' section provides a spot for colleagues to collaborate, build, and manage joint projects. Ab-web is a community-driven initiative amenable to constructive feedback and new ideas.

Genotypic and phenotypic comparison of clinical and environmental Acinetobacter baumannii strains.

The genotypic and phenotypic characteristics and antibiotic resistance (antibiogram) profiles of clinical (n = 13) and environmental (n = 7) Acinetobacter baumannii isolates were compared. Based on the Repetitive Extragenic Palindromic Sequence-based PCR (REP-PCR) analysis, the clinical and environmental A. baumannii isolates shared low genetic relatedness (∼60%). Multilocus sequence typing (MLST, Oxford scheme) indicated that the clinical A. baumannii were assigned to three sequence types (ST231, ST945 and ST848), while the environmental A. baumannii (excluding AB 14) were categorised into the novel ST2520. The majority of the clinical (excluding AB 5, CAB 11, CAC 37) and environmental (excluding AB 14 and AB 16) A. baumannii strains were then capable of phase variation with both the translucent (71.4%; 15/21) and opaque (95.2%; 20/21) colony phenotypes detected. The clinical isolates however, exhibited significantly (p < 0.05) higher biofilm formation capabilities (OD570: 2.094 ± 0.497). Moreover, the clinical isolates exhibited significantly (p < 0.05) higher resistance to first line antibiotics, with 92.3% (12/13) characterised as extensively drug resistant (XDR), whereas environmental A. baumannii exhibited increased antibiotic susceptibility with only 57.1% (4/7) characterised as multidrug resistant (MDR). The environmental isolate AB 14 was however, characterised as XDR. In addition, only five clinical A. baumannii isolates exhibited colistin resistance (38.5%; 5/13). The current study highlighted the differences in the genotypic, phenotypic, and antibiotic resistance profiles of clinical and environmental A. baumannii. Moreover, the environmental strains were assigned to the novel ST2520, which substantiates the existence of this opportunistic pathogen in extra-hospital reservoirs.

Prevalence of ESKAPE pathogens in the environment: Antibiotic resistance status, community-acquired infection and risk to human health.

The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens are characterised by increased levels of resistance towards multiple classes of first line and last-resort antibiotics. Although these pathogens are frequently isolated from clinical environments and are implicated in a variety of life-threatening, hospital-associated infections; antibiotic resistant ESKAPE strains have been isolated from environmental reservoirs such as surface water, wastewater, food, and soil. Literature on the persistence and subsequent health risks posed by the ESKAPE isolates in extra-hospital settings is however, limited and the current review aims to elucidate the primary reservoirs of these pathogens in the environment, their antibiotic resistance profiles, and the link to community-acquired infections. Additionally, information on the current state of research regarding health-risk assessments linked to exposure of the ESKAPE pathogens in the natural environment, is outlined.

Biological Control of Acinetobacter baumannii: In Vitro and In Vivo Activity, Limitations, and Combination Therapies.

The survival, proliferation, and epidemic spread of Acinetobacter baumannii (A. baumannii) in hospital settings is associated with several characteristics, including resistance to many commercially available antibiotics as well as the expression of multiple virulence mechanisms. This severely limits therapeutic options, with increased mortality and morbidity rates recorded worldwide. The World Health Organisation, thus, recognises A. baumannii as one of the critical pathogens that need to be prioritised for the development of new antibiotics or treatment. The current review will thus provide a brief overview of the antibiotic resistance and virulence mechanisms associated with A. baumannii's "persist and resist strategy". Thereafter, the potential of biological control agents including secondary metabolites such as biosurfactants [lipopeptides (surfactin and serrawettin) and glycolipids (rhamnolipid)] as well as predatory bacteria (Bdellovibrio bacteriovorus) and bacteriophages to directly target A. baumannii, will be discussed in terms of their in vitro and in vivo activity. In addition, limitations and corresponding mitigations strategies will be outlined, including curtailing resistance development using combination therapies, product stabilisation, and large-scale (up-scaling) production.

Insights into Bdellovibrio spp. mechanisms of action and potential applications.

Recent studies investigating Bdellovibrio spp. have found that although this predator predominantly preys on Gram-negative organisms, under certain conditions (nutrient/prey limitation), it will adapt to survive and grow axenically (without prey) or in the presence of Gram-positive bacterial prey. These advances in the understanding of predatory bacteria have stimulated a renewed interest in these organisms and the potential applications of Bdellovibrio spp. to the benefit of society. Early studies primarily focused on the application of predatory bacteria as "live antibiotics" in the medical field, probiotics in aquaculture and veterinary medicine and their use in agriculture. Additionally, studies have investigated their prevalence in wastewater and environmental sources. However, comprehending that Bdellovibrio spp. may also prey on and target Gram-positive organisms, implies that these predators could specifically be applied for the bioremediation or removal of mixed bacterial communities. Recent studies have also indicated that Bdellovibrio spp. may be useful in controlling food spoilage organisms and subsequently decrease our reliance on food additives. This review will thus highlight recent developments in understanding Bdellovibrio spp. predation strategies and focus on potential new applications of these organisms for water treatment, food preservation, enhancement of industrial processes, and in combination therapies with bacteriophages and/or antibiotics to combat multi-drug resistant organisms.

Exploring the antimicrobial resistance profiles of WHO critical priority list bacterial strains.

BACKGROUND: The antimicrobial resistance of clinical, environmental and control strains of the WHO "Priority 1: Critical group" organisms, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa to various classes of antibiotics, colistin and surfactin (biosurfactant) was determined. METHODS: Acinetobacter baumannii was isolated from environmental samples and antibiotic resistance profiling was performed to classify the test organisms [A. baumannii (n = 6), P. aeruginosa (n = 5), E. coli (n = 7) and K. pneumoniae (n = 7)] as multidrug resistant (MDR) or extreme drug resistant (XDR). All the bacterial isolates (n = 25) were screened for colistin resistance and the mobilised colistin resistance (mcr) genes. Biosurfactants produced by Bacillus amyloliquefaciens ST34 were solvent extracted and characterised using ultra-performance liquid chromatography (UPLC) coupled to electrospray ionisation mass spectrometry (ESI-MS). The susceptibility of strains, exhibiting antibiotic and colistin resistance, to the crude surfactin extract (cell-free supernatant) was then determined. RESULTS: Antibiotic resistance profiling classified four A. baumannii (67%), one K. pneumoniae (15%) and one P. aeruginosa (20%) isolate as XDR, with one E. coli (15%) and three K. pneumoniae (43%) strains classified as MDR. Many of the isolates [A. baumannii (25%), E. coli (80%), K. pneumoniae (100%) and P. aeruginosa (100%)] exhibited colistin resistance [minimum inhibitory concentrations (MICs) ≥ 4 mg/L]; however, only one E. coli strain isolated from a clinical environment harboured the mcr-1 gene. UPLC-MS analysis then indicated that the B. amyloliquefaciens ST34 produced C13-16 surfactin analogues, which were identified as Srf1 to Srf5. The crude surfactin extract (10.00 mg/mL) retained antimicrobial activity (100%) against the MDR, XDR and colistin resistant A. baumannii, P. aeruginosa, E. coli and K. pneumoniae strains. CONCLUSION: Clinical, environmental and control strains of A. baumannii, P. aeruginosa, E. coli and K. pneumoniae exhibiting MDR and XDR profiles and colistin resistance, were susceptible to surfactin analogues, confirming that this lipopeptide shows promise for application in clinical settings.