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Biological activity of macrofungi in South Africa against respiratory and lung disease
- Authors: Didloff, Jenske
- Date: 2018
- Subjects: Macrofungi , Microbiology , Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30138 , vital:30835
- Description: Macrofungi represent an untapped source of natural bioactive compounds for various diseases, which have been targeted as potential therapeutic agents. The medicinal uses of macrofungi discovered to date include anticancer, antidiabetic, antioxidant, antimicrobial, and immunomodulatory properties. The knowledge regarding the medicinal uses of macrofungi in Africa is limited; however, it is believed that Africa may contain a large number of unidentified species of macrofungi. The objectives of this study were to: (i) screen the macrofungal extracts for antimicrobial activity against microorganisms responsible for respiratory diseases (e.g. Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Mycobacterium tuberculosis, HIV-1), (ii) determine the effect of macrofungal extracts on bacterial morphology, (iii) investigate the cytotoxicity of macrofungal extracts against human lung carcinoma cells, and to elucidate the mechanism/s of action of cytotoxicity/anticancer activity. In vitro bioassays for antimicrobial activity included: ρ-iodonitrotetrazolium chloride assays and microplate alamar blue assay (MABA), while the HIV-1 reverse transcriptase colorimetric ELISA and HIV-1 protease fluorometric assay kits were used for anti-HIV activity. Cytotoxicity of the macrofungal species against A549 lung cancer cell line was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and the IC50 values determined for the most cytotoxic macrofungal spp. The mechanism of cytotoxicity was investigated by cell cycle analysis and fluorescent staining to observe morphological and biochemical changes (i.e. acridine orange, caspase activation). Ethanol extracts of Amanita foetidissima, Gymnopilus junonius, Pisolithus tinctorius, Fomitopsis lilacinogilva, Stereum hirsutum and Pycnoporus sanguineus showed higher antimicrobial activity against the Gram-positive bacteria than aqueous extracts, with S. pneumoniae being the most susceptible. The ethanol extracts of Agaricus campestris, Chlorophyllum molybdites, Gymnopilus penetrans, Pseudophaeolus baudonii and Laetiporus sulphureus exhibited anti-TB (tuberculosis) activity with minimum inhibitory concentrations (MICs) ranging between 500-1,000 μg/mL. C. molybdites ethanol extract inhibited HIV-1 protease activity (IC50: 49.7 μg/mL). The macrofungal extracts did not inhibit HIV-1 reverse transcriptase activity. Ethanol extracts of F. lilacinogilva, G. junonius, P. sanguineus and the aqueous extract iv of P. baudonii were cytotoxic against A549 lung cancer cells at IC50 values of 69.2±3.6, 57±5, 7.4±1.1 and 53.6±1.1 μg/mL, respectively. Cell cycle arrest was observed in the G2 phase for both P. sanguineus and P. baudonii, and G2/M and early M phases for G. junonius and F. lilacinogilva, respectively. Apoptosis induced by macrofungal extracts was confirmed by fluorescent staining. Morphological and biochemical changes included chromatin condensation, membrane blebbing, loss of cytoskeletal structure, caspase activation and phosphatidylserine translocation. This study demonstrates the biological activities of selected macrofungal extracts and their potential mechanisms of action. Isolation and identification of active compounds require further analysis.
- Full Text:
- Authors: Didloff, Jenske
- Date: 2018
- Subjects: Macrofungi , Microbiology , Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30138 , vital:30835
- Description: Macrofungi represent an untapped source of natural bioactive compounds for various diseases, which have been targeted as potential therapeutic agents. The medicinal uses of macrofungi discovered to date include anticancer, antidiabetic, antioxidant, antimicrobial, and immunomodulatory properties. The knowledge regarding the medicinal uses of macrofungi in Africa is limited; however, it is believed that Africa may contain a large number of unidentified species of macrofungi. The objectives of this study were to: (i) screen the macrofungal extracts for antimicrobial activity against microorganisms responsible for respiratory diseases (e.g. Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Mycobacterium tuberculosis, HIV-1), (ii) determine the effect of macrofungal extracts on bacterial morphology, (iii) investigate the cytotoxicity of macrofungal extracts against human lung carcinoma cells, and to elucidate the mechanism/s of action of cytotoxicity/anticancer activity. In vitro bioassays for antimicrobial activity included: ρ-iodonitrotetrazolium chloride assays and microplate alamar blue assay (MABA), while the HIV-1 reverse transcriptase colorimetric ELISA and HIV-1 protease fluorometric assay kits were used for anti-HIV activity. Cytotoxicity of the macrofungal species against A549 lung cancer cell line was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and the IC50 values determined for the most cytotoxic macrofungal spp. The mechanism of cytotoxicity was investigated by cell cycle analysis and fluorescent staining to observe morphological and biochemical changes (i.e. acridine orange, caspase activation). Ethanol extracts of Amanita foetidissima, Gymnopilus junonius, Pisolithus tinctorius, Fomitopsis lilacinogilva, Stereum hirsutum and Pycnoporus sanguineus showed higher antimicrobial activity against the Gram-positive bacteria than aqueous extracts, with S. pneumoniae being the most susceptible. The ethanol extracts of Agaricus campestris, Chlorophyllum molybdites, Gymnopilus penetrans, Pseudophaeolus baudonii and Laetiporus sulphureus exhibited anti-TB (tuberculosis) activity with minimum inhibitory concentrations (MICs) ranging between 500-1,000 μg/mL. C. molybdites ethanol extract inhibited HIV-1 protease activity (IC50: 49.7 μg/mL). The macrofungal extracts did not inhibit HIV-1 reverse transcriptase activity. Ethanol extracts of F. lilacinogilva, G. junonius, P. sanguineus and the aqueous extract iv of P. baudonii were cytotoxic against A549 lung cancer cells at IC50 values of 69.2±3.6, 57±5, 7.4±1.1 and 53.6±1.1 μg/mL, respectively. Cell cycle arrest was observed in the G2 phase for both P. sanguineus and P. baudonii, and G2/M and early M phases for G. junonius and F. lilacinogilva, respectively. Apoptosis induced by macrofungal extracts was confirmed by fluorescent staining. Morphological and biochemical changes included chromatin condensation, membrane blebbing, loss of cytoskeletal structure, caspase activation and phosphatidylserine translocation. This study demonstrates the biological activities of selected macrofungal extracts and their potential mechanisms of action. Isolation and identification of active compounds require further analysis.
- Full Text:
Dinoflagellate communities in Algoa Bay: abundance and dynamics
- Authors: Van Zyl, Hendrik Francois
- Date: 2017
- Subjects: Marine microbiology , Microbiology , Marine biology -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21218 , vital:29457
- Description: The contribution of dinoflagellates to the phytoplankton of Algoa Bay is largely unknown. This study aimed to address this, but additionally considered seasonal and spatial variation in the dinoflagellate communities of Algoa Bay. Phytoplankton abundance and the inorganic nutrients ammonium, total oxidized nitrogen, soluble reactive phosphorus and silicate were analysed. Diatoms dominated the phytoplankton community in most samples, with dinoflagellates only occasionally dominating the community. No seasonality could be detected in dinoflagellate abundance. Furthermore, no significant spatial patterns could be distinguished in dinoflagellate abundance, with the only exception being that the Port Elizabeth harbour waters contained significantly fewer dinoflagellate cells than the younger Ngqura harbour. Total phytoplankton abundance was correlated with inorganic nitrogen concentrations, but this was due to diatoms – dinoflagellate abundance did not correlate significantly with any nutrient measured. Both the common, historically bloom-forming Noctiluca scintilans, as well as the recently red tide-forming Lingulodinium polyhedra were recorded during the study, the latter almost exclusively from the harbours, which can be considered repositories of these toxic and harmful algal cells. The findings suggest that dinoflagellates in Algoa Bay are a robust phytoplankton group able to survive, and often thrive, in wide range of environmental conditions.
- Full Text:
- Authors: Van Zyl, Hendrik Francois
- Date: 2017
- Subjects: Marine microbiology , Microbiology , Marine biology -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21218 , vital:29457
- Description: The contribution of dinoflagellates to the phytoplankton of Algoa Bay is largely unknown. This study aimed to address this, but additionally considered seasonal and spatial variation in the dinoflagellate communities of Algoa Bay. Phytoplankton abundance and the inorganic nutrients ammonium, total oxidized nitrogen, soluble reactive phosphorus and silicate were analysed. Diatoms dominated the phytoplankton community in most samples, with dinoflagellates only occasionally dominating the community. No seasonality could be detected in dinoflagellate abundance. Furthermore, no significant spatial patterns could be distinguished in dinoflagellate abundance, with the only exception being that the Port Elizabeth harbour waters contained significantly fewer dinoflagellate cells than the younger Ngqura harbour. Total phytoplankton abundance was correlated with inorganic nitrogen concentrations, but this was due to diatoms – dinoflagellate abundance did not correlate significantly with any nutrient measured. Both the common, historically bloom-forming Noctiluca scintilans, as well as the recently red tide-forming Lingulodinium polyhedra were recorded during the study, the latter almost exclusively from the harbours, which can be considered repositories of these toxic and harmful algal cells. The findings suggest that dinoflagellates in Algoa Bay are a robust phytoplankton group able to survive, and often thrive, in wide range of environmental conditions.
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Incidence of bacterial infections and colonisation in patients admitted to a tuberculosis hospital
- Authors: Annear, Dale John
- Date: 2018
- Subjects: Medical microbiology , Microbiology , Bacteriology , Tuberculosis -- Hospitals -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21482 , vital:29526
- Description: Patients with drug resistant tuberculosis (TB) are treated with multiple antibiotics including moxifloxacin, linezolid, and meropenem, which puts them at greater risk for colonisation by multi-drug resistant (MDR) bacteria. The objectives of this study were to: (i) assess the antimicrobial prescribing patterns practiced within the hospital by retrospective patient file review; (ii) determine the spectrum of bacterial colonisation in TB patients upon admission and during hospitalisation; (iii) identify bacterial isolates and evaluate antimicrobial susceptibility profiles; (iv) detect antimicrobial resistance genes in the bacterial isolates by PCR and DNA sequencing; and (v) investigate genetic relatedness of Klebsiella pneumoniae isolates using Multi Locus Sequence Typing. Nasal, groin and rectal swabs [for the detection of extended spectrum beta lactamases (EBSLs), carbapenem-resistant Enterobacteriaceae (CRE), vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA)] were analysed from a cohort of patients (n=37) admitted either from the community (n = 28) or from other healthcare facilities (n=9) to a TB hospital. Swab samples were collected at admission and at four week intervals thereafter during hospitalization. Identification and antimicrobial susceptibility testing of bacterial isolates (n=62) were determined at the National Health Laboratory Services (NHLS) by the VITEK-MS and Vitek 2 systems respectively. Additional antimicrobial susceptibility testing was conducted by Sensititre Gram Negative Xtra (GNFX2) MIC plates. PCR and DNA sequencing were used for detection of resistance genes. Patients (n=13/37; 35%) were colonized by MDR bacteria (ESBLs [n=11], MRSA [n=2]) on admission. Colonization rates were lower in patients admitted from the community (9/28; 32%) compared to those transferred from other healthcare facilities (4/9; 44%). All admitted patients who did not exhibit colonization at baseline and who were resident within the hospital for longer than 4 weeks (17/37; 46% of total patients) became colonised by an ESBL-producing Enterobacteriaceae species. No patients acquired MRSA during hospitalisation. Among ESBL Enterobacteriaceae, Escherichia coli (41/62; 66%) and K. pneumoniae [14/62; 23%]) predominated. Nineteen percent (7/37) of patients demised during their hospitalization. Both the Vitek system and Sensititre Gram Negative Xtra (GNFX2) MIC plates susceptibilities were similar for most antimicrobials, however there were discrepancies for tigecycline susceptibility profiles. A high number of isolates exhibited resistance to aminoglycosides and fluoroquinolones. Genes encoding for ESBLs (CTX-M-14, CTX-M-15, SHV-28, OXA-1, and OXY-2-9) were detected among ESBL Enterobacteriaceae. Two Enterobacteriaceae isolates with reduced carbapenem susceptibility did not contain carbapenemase-encoding genes. MLST revealed unique sequence types and genetic diversity among the K. pneumoniae isolates from hospitalised patients. However, the source and colonization routes of these isolates could not be determined, which requires further investigation. This study provides insight into the spectrum of bacterial pathogen colonisation in hospitalised TB patients and suggests a review of infection control programs and practices at the TB hospital.
- Full Text:
- Authors: Annear, Dale John
- Date: 2018
- Subjects: Medical microbiology , Microbiology , Bacteriology , Tuberculosis -- Hospitals -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21482 , vital:29526
- Description: Patients with drug resistant tuberculosis (TB) are treated with multiple antibiotics including moxifloxacin, linezolid, and meropenem, which puts them at greater risk for colonisation by multi-drug resistant (MDR) bacteria. The objectives of this study were to: (i) assess the antimicrobial prescribing patterns practiced within the hospital by retrospective patient file review; (ii) determine the spectrum of bacterial colonisation in TB patients upon admission and during hospitalisation; (iii) identify bacterial isolates and evaluate antimicrobial susceptibility profiles; (iv) detect antimicrobial resistance genes in the bacterial isolates by PCR and DNA sequencing; and (v) investigate genetic relatedness of Klebsiella pneumoniae isolates using Multi Locus Sequence Typing. Nasal, groin and rectal swabs [for the detection of extended spectrum beta lactamases (EBSLs), carbapenem-resistant Enterobacteriaceae (CRE), vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA)] were analysed from a cohort of patients (n=37) admitted either from the community (n = 28) or from other healthcare facilities (n=9) to a TB hospital. Swab samples were collected at admission and at four week intervals thereafter during hospitalization. Identification and antimicrobial susceptibility testing of bacterial isolates (n=62) were determined at the National Health Laboratory Services (NHLS) by the VITEK-MS and Vitek 2 systems respectively. Additional antimicrobial susceptibility testing was conducted by Sensititre Gram Negative Xtra (GNFX2) MIC plates. PCR and DNA sequencing were used for detection of resistance genes. Patients (n=13/37; 35%) were colonized by MDR bacteria (ESBLs [n=11], MRSA [n=2]) on admission. Colonization rates were lower in patients admitted from the community (9/28; 32%) compared to those transferred from other healthcare facilities (4/9; 44%). All admitted patients who did not exhibit colonization at baseline and who were resident within the hospital for longer than 4 weeks (17/37; 46% of total patients) became colonised by an ESBL-producing Enterobacteriaceae species. No patients acquired MRSA during hospitalisation. Among ESBL Enterobacteriaceae, Escherichia coli (41/62; 66%) and K. pneumoniae [14/62; 23%]) predominated. Nineteen percent (7/37) of patients demised during their hospitalization. Both the Vitek system and Sensititre Gram Negative Xtra (GNFX2) MIC plates susceptibilities were similar for most antimicrobials, however there were discrepancies for tigecycline susceptibility profiles. A high number of isolates exhibited resistance to aminoglycosides and fluoroquinolones. Genes encoding for ESBLs (CTX-M-14, CTX-M-15, SHV-28, OXA-1, and OXY-2-9) were detected among ESBL Enterobacteriaceae. Two Enterobacteriaceae isolates with reduced carbapenem susceptibility did not contain carbapenemase-encoding genes. MLST revealed unique sequence types and genetic diversity among the K. pneumoniae isolates from hospitalised patients. However, the source and colonization routes of these isolates could not be determined, which requires further investigation. This study provides insight into the spectrum of bacterial pathogen colonisation in hospitalised TB patients and suggests a review of infection control programs and practices at the TB hospital.
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The characterization of the interaction between Streptococcus pneumoniae PspC and Homo sapiens pIgR
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution , Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution , Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
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Molecular Detection of Antibiotic-Resistant Genes in Pseudomonas aeruginosa from Nonclinical Environment: Public Health Implications in Mthatha, Eastern Cape Province, South Africa
- Mojisola Clara Hosu, Sandeep Vasaikar, Grace Emily Okuthe, Teke Apalata
- Authors: Mojisola Clara Hosu , Sandeep Vasaikar , Grace Emily Okuthe , Teke Apalata
- Date: 5 January 2021
- Subjects: Microbiology
- Language: English
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/2417 , vital:41877
- Description: 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. .is 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%). .e 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 blaSHV, six isolates (40%) harbored blaTEM, and three isolates (20%) harbored blaCTX-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. .is 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.
- Full Text:
- Authors: Mojisola Clara Hosu , Sandeep Vasaikar , Grace Emily Okuthe , Teke Apalata
- Date: 5 January 2021
- Subjects: Microbiology
- Language: English
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/2417 , vital:41877
- Description: 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. .is 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%). .e 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 blaSHV, six isolates (40%) harbored blaTEM, and three isolates (20%) harbored blaCTX-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. .is 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.
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