Plastics and Micro/Nano-Plastics (MNPs) in the Environment: Occurrence, Impact, and Toxicity.

Plastics, due to their varied properties, find use in different sectors such as agriculture, packaging, pharmaceuticals, textiles, and construction, to mention a few. Excessive use of plastics results in a lot of plastic waste buildup. Poorly managed plastic waste (as shown by heaps of plastic waste on dumpsites, in free spaces, along roads, and in marine systems) and the plastic in landfills, are just a fraction of the plastic waste in the environment. A complete picture should include the micro and nano-plastics (MNPs) in the hydrosphere, biosphere, lithosphere, and atmosphere, as the current extreme weather conditions (which are effects of climate change), wear and tear, and other factors promote MNP formation. MNPs pose a threat to the environment more than their pristine counterparts. This review highlights the entry and occurrence of primary and secondary MNPs in the soil, water and air, together with their aging. Furthermore, the uptake and internalization, by plants, animals, and humans are discussed, together with their toxicity effects. Finally, the future perspective and conclusion are given. The material utilized in this work was acquired from published articles and the internet using keywords such as plastic waste, degradation, microplastic, aging, internalization, and toxicity.

Molecular Detection of Antibiotic-Resistant Genes in Pseudomonas aeruginosa from Nonclinical Environment: Public Health Implications in Mthatha, Eastern Cape Province, South Africa.

Evaluation of resistant profiles and detection of antimicrobial-resistant genes of bacterial pathogens in the nonclinical milieu is imperative to assess the probable risk of dissemination of resistant genes in the environment. This paper sought to identify antibiotic-resistant genes in Pseudomonas aeruginosa from nonclinical sources in Mthatha, Eastern Cape, and evaluate its public health implications. Samples collected from abattoir wastewater and aquatic environment were processed by membrane filtration and cultured on CHROMagarTM Pseudomonas medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL). Molecular characterization of the isolates was confirmed using real-time polymerase chain reaction (rPCR) and selected isolates were further screened for the possibility of harboring antimicrobial resistance genes. Fifty-one Pseudomonas species were recovered from abattoir wastewater and surface water samples, out of which thirty-six strains were Pseudomonas aeruginosa (70.6%). The P. aeruginosa isolates demonstrated resistance to aztreonam (86.1%), ceftazidime (63.9%), piperacillin (58.3%), cefepime (55.6%), imipenem (50%), piperacillin/tazobactam (47.2%), meropenem (41.7%), and levofloxacin (30.6%). Twenty out of thirty-six P. aeruginosa displayed multidrug resistance profiles and were classified as multidrug-resistant (MDR) (55.6%). Most of the bacterial isolates exhibited a high Multiple Antibiotic Resistance (MAR) Index ranging from 0.08 to 0.69 with a mean MAR index of 0.38. In the rPCR analysis of fifteen P. aeruginosa isolates, 14 isolates (93.3%) were detected harboring bla SHV, six isolates (40%) harbored bla TEM, and three isolates (20%) harbored bla CTX-M, being the least occurring ESBL. Results of the current study revealed that P. aeruginosa isolates recovered from nonclinical milieu are resistant to frontline clinically relevant antipseudomonal drugs. This is concerning as it poses a risk to the environment and constitutes a public health threat. Given the public health relevance, the paper recommends monitoring of multidrug-resistant pathogens in effluent environments.

Molecular Detection of Carbapenemase-Encoding Genes in Multidrug-Resistant Acinetobacter baumannii Clinical Isolates in South Africa.

INTRODUCTION: Carbapenem-resistant Acinetobacter baumannii has been responsible for an increasing number of hospital-acquired infections globally. The study investigated the prevalence of carbapenemase-encoding genes in clinical multidrug-resistant A. baumannii strains. MATERIALS AND METHODS: A total of 100 nonduplicate multidrug-resistant A. baumannii strains were cultured from clinical samples obtained from healthcare facilities in the O. R. Tambo district. The strains were confirmed by detecting the intrinsic bla OXA-51-like gene. Antimicrobial susceptibility testing was performed by VITEK® 2 and autoSCAN-4 systems. The MIC of imipenem and meropenem was rechecked by E-test. Colistin MIC was confirmed by the broth microdilution method. Real-time PCR was performed to investigate the presence of carbapenemase-encoding genes. RESULTS: Most strains showed high resistance rates (>80%) to the antibiotics tested. Resistance to amikacin, tetracycline, and tigecycline were 50%, 64%, and 48%, respectively. All strains were fully susceptible to colistin. The bla OXA-51-like was detected in all strains whilst bla OXA-23-like, bla OXA-58-like, bla OXA-24-like, bla IMP-1, bla VIM, and bla NDM-1 were found in 70%, 8%, 5%, 4%, 3%, and 2% of strains, respectively. None of the tested strains harboured the genes bla SIM and bla AmpC. The coexistence of bla OXA-23-like, and bla IMP-1 or bla OXA-58-like was detected in 1% and 2% strains, respectively. A distinct feature of our findings was the coharbouring of the genes bla OXA-23-like, bla OXA-58-like, and bla IMP-1 in 2% strains, and this is the first report in the Eastern Cape Province, South Africa. The intI1 was carried in 80% of tested strains whilst ISAba1/bla OXA-51-like and ISAba1/bla OXA-23-like were detected in 15% and 40% of the strains, respectively. The detection of bla OXA-23-like, ISAba1/bla OXA-51-like, ISAba1/bla OXA-23-like, and bla OXA-23-like, bla OXA-58-like, and bla IMP-1 carbapenemases in strains had a significant effect on both imipenem and meropenem MICs. CONCLUSIONS: Results showed a high level of oxacillinases producing A. baumannii circulating in our study setting, highlighting the need for local molecular surveillance to inform appropriate management and prevention strategies.

In vitro antimicrobial photodynamic inactivation of multidrug-resistant Acinetobacter baumannii biofilm using Protoporphyrin IX and Methylene blue.

BACKGROUND: Acinetobacter baumannii is a challenging pathogen due to the rapid development of antimicrobial resistance and biofilm formation. The objective of this study was to evaluate the effect of antimicrobial photodynamic inactivation against biofilms of multidrug-resistant A. baumannii isolated from clinical, abattoir and aquatic sources. METHODS: The isolates were tested for susceptibility to imipenem, meropenem, tigecycline and colistin using autoSCAN-4 automated system and rechecked by the E-test. Methylene blue, Protoporphyrin IX, and a halogen lamp were used in the in vitro assay against biofilms of the isolates. The antimicrobial photodynamic inactivation was assessed by counting colony-forming units (CFU). RESULTS: The isolates from abattoir and aquatic sources were resistant to carbapenems (>64 µg/mL) but susceptible to tigecycline (2 µg/mL) and colistin (Abattoir, 0.35 µg/mL and Aquatic, 0.24 µg/mL), whereas the clinical isolate was susceptible to only colistin (0.5 µg/mL) using the E-test. The log survival percentages of the control group at a concentration of 20 µM were 5 × 10-6 % for Protoporphyrin IX and 2 × 10-6 % for Methylene blue. Therefore, Methylene blue showed higher bacterial reduction of 7.0 log10 colony forming units than 6.0 log10 for Protoporphyrin IX. No significant difference was observed with respect to the origin of isolates and the minimum inhibitory concentrations. CONCLUSION: The results indicate that antimicrobial photodynamic inactivation could be an alternative strategy for the control of infections caused by multi-drug resistant A. baumannii by significantly reducing biofilm growth at a sub-lethal concentrations.

Prevalence and molecular analysis of multidrug-resistant Acinetobacter baumannii in the extra-hospital environment in Mthatha, South Africa

ABSTRACT Introduction: The presence of Acinetobacter baumannii outside hospitals remains unclear. This study aimed to determine the prevalence of multidrug-resistance (MDR) A. baumannii in the extra-hospital environment in Mthatha, South Africa and to investigate the frequency of carbapenemase-encoding genes. Material and Methods: From August 2016 to July 2017 a total of 598 abattoir samples and 689 aquatic samples were collected and analyzed presumptively by cultural methods for the presence of A. baumannii using CHROMagar™ Acinetobacter medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL) and confirmed by the detection of their intrinsic blaOXA-51 gene. Confirmed MDR A. baumannii isolates were screened for the presence of carbapenemase-encoding genes, ISAba1 insertion sequence and integrase intI1. Results: In total, 248 (19.3%) Acinetobacter species were isolated. Acinetobacter. baumannii was detected in 183 (73.8%) of which 85 (46.4%) and 98 (53.6%) were recovered from abattoir and aquatic respectively. MDR A. baumannii was detected in 56.5% (48/85) abattoir isolates and 53.1% (52/98) aquatic isolates. Isolates showed high resistance to antimicrobials most frequently used to treat Acinetobacter infections such as piperacillin/tazobactam; abattoir (98% of isolates resistant), aquatic (94% of isolates resistant), ceftazidime (84%, 83%), ciprofloxacin (71%, 70%), amikacin (41%, 42%), imipenem (75%, 73%), and meropenem (74%, 71%). All the isolates were susceptible to tigecycline and colistin. All the isolates carried blaOXA-51-like. The blaOXA-23 was detected in 32 (66.7%) abattoir isolates and 11 (21.2%) aquatic isolates. The blaOXA-58-like was positive in 7 (14.6%) and 4 (7.7%) abattoir and aquatic isolates, respectively. Both groups of isolates lacked blaOXA-24-like, blaIMP-type, blaVIM-type, blaNDM-1, blaSIM, blaAmpC, ISAba1 and inI1. Isolates showed high level of Multiple Antibiotic Resistance Index (MARI) ranging from 0.20-0.52. Conclusion: Extra-hospital sources such as abattoir and aquatic environments may be a vehicle of spread of MDR A. baumannii strains in the community and hospital settings.

Prevalence and molecular analysis of multidrug-resistant Acinetobacter baumannii in the extra-hospital environment in Mthatha, South Africa.

INTRODUCTION: The presence of Acinetobacter baumannii outside hospitals remains unclear. This study aimed to determine the prevalence of multidrug-resistance (MDR) A. baumannii in the extra-hospital environment in Mthatha, South Africa and to investigate the frequency of carbapenemase-encoding genes. MATERIAL AND METHODS: From August 2016 to July 2017 a total of 598 abattoir samples and 689 aquatic samples were collected and analyzed presumptively by cultural methods for the presence of A. baumannii using CHROMagar™ Acinetobacter medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL) and confirmed by the detection of their intrinsic blaOXA-51 gene. Confirmed MDR A. baumannii isolates were screened for the presence of carbapenemase-encoding genes, ISAba1 insertion sequence and integrase intI1. RESULTS: In total, 248 (19.3%) Acinetobacter species were isolated. Acinetobacter. baumannii was detected in 183 (73.8%) of which 85 (46.4%) and 98 (53.6%) were recovered from abattoir and aquatic respectively. MDR A. baumannii was detected in 56.5% (48/85) abattoir isolates and 53.1% (52/98) aquatic isolates. Isolates showed high resistance to antimicrobials most frequently used to treat Acinetobacter infections such as piperacillin/tazobactam; abattoir (98% of isolates resistant), aquatic (94% of isolates resistant), ceftazidime (84%, 83%), ciprofloxacin (71%, 70%), amikacin (41%, 42%), imipenem (75%, 73%), and meropenem (74%, 71%). All the isolates were susceptible to tigecycline and colistin. All the isolates carried blaOXA-51-like. The blaOXA-23 was detected in 32 (66.7%) abattoir isolates and 11 (21.2%) aquatic isolates. The blaOXA-58-like was positive in 7 (14.6%) and 4 (7.7%) abattoir and aquatic isolates, respectively. Both groups of isolates lacked blaOXA-24-like, blaIMP-type, blaVIM-type, blaNDM-1,blaSIM, blaAmpC, ISAba1 and inI1. Isolates showed high level of Multiple Antibiotic Resistance Index (MARI) ranging from 0.20-0.52. CONCLUSION: Extra-hospital sources such as abattoir and aquatic environments may be a vehicle of spread of MDR A. baumannii strains in the community and hospital settings.

DNA and RNA pattern of staining during oogenesis in zebrafish (Danio rerio): a confocal microscopy study.

Oogenesis involves a sequence of cellular divisions and developmental changes leading to the formation of oocytes, whose role in development is to transfer genomic information to the next generation. During this process, the gene expression pattern changes considerably concomitant with genome remodeling, while genomic information is maintained. The development of the gonad in zebrafish is unique in that it goes through an initial ovarian phase and subsequently into either ovarian or testicular phases. How the germ cells choose to commit to an oogenic fate and enter meiosis or alternatively not to enter meiosis and commit to a spermatogenetic fate remains a key question in development. Lack of suitable markers has hampered the understanding of the principles controlling sex differentiation in zebrafish. The current study was aimed at finding substantive cytochemical markers to identify specific oocyte stages primarily focusing on the DNA and RNA component of cells, using fluorescent dyes: acridine orange and propidium iodide. The pattern of synthesis and appearance of nucleoli was stage specific and may be used to identify stages of oogenesis. A distinguishing and possibly diagnostic feature of the staining pattern observed was the low level of chromatin staining compared to other cellular structures. This may be related to the more diffuse state of chromatin that occurs prior to thickening of chromosomes from the pachytene stage onwards. Although the fluorescent dyes may be useful in determining the localization of nucleic acids in tissue sections, it was not possible to quantify the relative contribution of the DNA and RNA components of specific stages of oocyte growth.

Spectrin labeling during oogenesis in zebrafish (Danio rerio).

Progression through mitosis and meiosis during early zebrafish ovarian development is accompanied by highly regulated series of transformations in the architecture of oocytes. These cytoskeletal-dependent membrane events may be assumed to be brought about by deployment of proteins. While the cytoskeleton and its associated proteins play a pivotal role in each of these developmental transitions, it remains unclear how specific cytoskeletal proteins participate in regulating diverse processes of oocyte development in zebrafish. Results from this study show that a pool of spectrin accumulates during oogenesis and parallels an increase in volume of oocytes at pre-vitellogenic stages of development. Spectrin labeling is restricted to the surface of oogonia, the cortex of post-pachytene oocytes and later accumulates on the cytoplasm of pre-vitellogenic and vitellogenic oocytes. Results here suggest a correlation between spectrin labeling, increased cytoplasm volume of oocytes, an increase in the number of nucleoli and accumulation of cytoplasmic organelles. Overall, these results suggest that synthesis and storage of spectrin during pre-vitellogenic stages of oogenesis primes the egg with a pre-established pool of membrane-cytoskeletal precursors for use during embryogenesis, and that the presence of spectrin at the oocyte sub-cortex is essential for maintaining oocyte structure.