Honghua Hu | Macquarie University (original) (raw)

Papers by Honghua Hu

Bioengineering, Sep 9, 2022

Research Square (Research Square), Feb 9, 2023

Journal of Infection and Public Health, May 1, 2018

Materials

Topical antiseptics are often used to treat chronic wounds with biofilm infections and during sal... more Topical antiseptics are often used to treat chronic wounds with biofilm infections and during salvage of biofilm contaminated implants, but their antibacterial efficacy is frequently only tested against non-aggregated planktonic or free-swimming organisms. This study evaluated the antibacterial and antibiofilm efficacy of four commercial surgical washes Bactisure, TorrenTX, minimally invasive lavage (MIS), and Betadine against six bacterial species: Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pyogenes, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli, which are commonly isolated from surgical site infections and chronic wound infections using different in vitro models. We determined minimum planktonic inhibitory and eradication concentration and minimum 1-day-old biofilm inhibition and eradication concentration of antiseptics in 96-well plates format with 24 h contact time. We also tested the efficacy of antiseptics at in-use concentration a...

International Journal of Molecular Sciences

The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic in... more The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic infections worldwide and is well-known for its biofilm formation ability. Recent findings of biofilms on dry hospital surfaces emphasise the failures in current cleaning practices and disinfection and the difficulty in removing these dry surface biofilms (DSBs). Many aspects of the formation of complex DSB biology on environmental surfaces in healthcare settings remains limited. In the present study, we aimed to determine how the protein component varied between DSBs and traditional hydrated biofilm. To do this, biofilms were grown in tryptic soy broth (TSB) on removable polycarbonate coupons in the CDC biofilm reactor over 12 days. Hydrated biofilm (50% TSB for 48 h, the media was then changed every 48 h with 20% TSB, at 37 °C with 130 rpm). DSB biofilm was produced in 5% TSB for 48 h at 35 °C followed by extended periods of dehydration (48, 66, 42 and 66 h at room temperature) interspers...

International Journal of Molecular Sciences

Staphylococcus aureus is a notorious biofilm-producing pathogen that is frequently isolated from ... more Staphylococcus aureus is a notorious biofilm-producing pathogen that is frequently isolated from implantable medical device infections. As biofilm ages, it becomes more tolerant to antimicrobial treatment leading to treatment failure and necessitating the costly removal of infected devices. In this study, we performed in-solution digestion followed by TMT-based high-throughput mass spectrometry and investigated what changes occur in the proteome of S. aureus biofilm grown for 3-days and 12-days in comparison with 24 h planktonic. It showed that proteins associated with biosynthetic processes, ABC transporter pathway, virulence proteins, and shikimate kinase pathway were significantly upregulated in a 3-day biofilm, while proteins associated with sugar transporter, degradation, and stress response were downregulated. Interestingly, in a 3-day biofilm, we observed numerous proteins involved in the central metabolism pathways which could lead to biofilm growth under diverse environment...

Infection, Disease & Health

Journal of Clinical Oncology

e18053 Background: Biofilm formation is a continuous process in oral cancer patients, despite pro... more e18053 Background: Biofilm formation is a continuous process in oral cancer patients, despite proper extirpation/elimination of a bacterial plaque via a surgical procedure or antibiotic treatment. Also, elimination of a bacterial plaque does not necessarily remove extant bacterial antigen-stimulated oral cancer cells. Therefore, combination drug treatment may be an appropriate approach to elucidate the confounding effects of bacterial antigens on anti-cancer drugs. Methods: Our drug combination strategy addressed both Gram-positive (Lipoteichoic acid [LTA]) and Gram-negative (Lipopolysaccharide [LPS]) bacterial antigens, to determine the effect of anti-cancer drugs on LPS/LTA/LPS+LTA-stimulated preclinical oral cancer models (SCC4, SCC9, SCC25, and Cal 27). The drug combination strategy was designed in six phases of treatment. In phase 1, plated cells were treated with different combinations of bacterial antigens in combination with anti-cancer drugs. In the phases 2 and 3, inhibito...

Journal of Hospital Infection

The efficacy of double manual cleaning (DMC) with enzymatic detergent followed by alkaline deterg... more The efficacy of double manual cleaning (DMC) with enzymatic detergent followed by alkaline detergent on biofilm removal on hinged surgical instruments was compared to automated cleaning. Biofilm covered haemostatic forceps were divided into four groups: positive control (soaked in sterile water); DMC; DMC plus extra brushing of the inner hinge; and automated cleaning. All DMC, DMC plus brushing the hinge and automated cleaning significantly (p < 0.001) reduced 94.8%, 99.8% and 100% viable bacteria and 82.3%, 93.8% and 95.1% residual protein respectively compared to positive control. DMC instruments had significantly more viable bacteria (p < 0.05) and residual protein (p < 0.01) than those in instruments subjected to DMC with hinge brushing and automated cleaning. However, there was no significant difference in residual protein between DMC with hinge brushing and automated cleaning. In sterilizing service units with no access to automated cleaning equipment, it is important to brush the inner hinge during manual cleaning, and DMC plus brushing the inner hinge could be considered a viable alternative for cleaning hinged surgical instruments.

32nd Lorne Cancer Conference 2020, 2020

Hernia, 2022

Purpose The purpose of this study was to investigate the link between bacterial biofilms and nega... more Purpose The purpose of this study was to investigate the link between bacterial biofilms and negative outcomes of hernia repair surgery. As biofilms are known to play a role in mesh-related infections, we investigated the presence of biofilms on hernia meshes, which had to be explanted due to mesh failure without showing signs of bacterial infection. Methods In this retrospective observational study, 20 paraffin-embedded tissue sections from explanted groin hernia meshes were analysed. Meshes have been removed due to chronic pain, hernia recurrence or mesh shrinkage. The presence and bacterial composition of biofilms were determined. First, specimens were stained with fluorescence in situ hybridisation (FISH) probes, specific for Staphylococcus aureus and coagulase-negative staphylococci, and visualised by confocal laser scanning microscopy. Second, DNA was extracted from tissue and identified by S. aureus and S. epidermidis specific PCR. Results Confocal microscopy showed evidence ...

International Journal of Molecular Sciences, 2021

The bacterial antigen, lipopolysaccharide (LPS) and disruptions in calcium channels are independe... more The bacterial antigen, lipopolysaccharide (LPS) and disruptions in calcium channels are independently known to influence oral cancer progression. Previously, we found that bacterial antigens, LPS and lipoteichoic acid (LTA) act as confounders during the action of capsaicin on Cal 27 oral cancer proliferation. As calcium channel drugs may affect oral cancer cell proliferation, we investigated the effect of ML218 HCl, a T-type voltage-gated calcium channel blocker, on the proliferation of Cal 27 oral cancer cells. We hypothesized that ML218 HCl could effectively reduce LPS-induced oral cancer cell proliferation. LPS and LTA antigens were added to Cal 27 oral cancer cells either prior to and/or concurrently with ML218 HCl treatment, and the efficacy of the treatment was evaluated by measuring Cal 27 proliferation, cell death and apoptosis. ML218 HCl inhibited oral cancer cell proliferation, increased apoptosis and cell death, but their efficacy was significantly reduced in the presence...

Infection, Disease & Health, 2022

BACKGROUND Acquisition of surgical instruments (SI) and implants by loaner system is a worldwide ... more BACKGROUND Acquisition of surgical instruments (SI) and implants by loaner system is a worldwide practice. Although quality of device reprocessing has been reported to be lower in low and middle-income countries compared with higher income countries, few investigations have been conducted on the management and reprocessing of loaned devices. Thus, in this study we evaluate the practices of management and reprocessing of loaner SI and non-sterile implants (NSI) in a high (Australia) and a middle-income (Brazil) country. METHODS Cross-sectional surveys (hardcopy or online form) was self-administered by sterilising service unit's personnel of Brazilian and Australian hospitals. Only those units that sourced orthopaedic surgical instruments and non-sterile loaned implants from independent companies were eligible. RESULTS A total of 65 questionnaires from Australia and 168 from Brazil were analysed. Quality indicators regarding structure and work process for the management and reprocessing of loaned SI and NSI was of a higher standard in Australia than in Brazil. However, failures were detected in both countries, for instance delivery delays and improper point-of-use pre-cleaning practices. CONCLUSION There are key challenges inherent of the multifaceted reusable medical devices loaner system in both countries, such as communication failures, implementation of non-recommended practices, reprocessing of NSI, and other related to structure and process quality indicators, that must be faced. Initial and ongoing education and training should be provided and should embrace the themes of technical proficiency, effective communication and teamwork, and should include all personnel involved in this process, even loaner company staff.

14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020), 2020

We develop europium complexes with distinguishable luminescence lifetimes in the microsecond-to-m... more We develop europium complexes with distinguishable luminescence lifetimes in the microsecond-to-millisecond region as new multiplexing probes for luminescence in situ hybridisation, and apply them to multiplexed detection and lifetime imaging of bacterial species.

Dental Oral Biology and Craniofacial Research, 2021

Oral biofilms harbour gram-negative bacterial antigen lipopolysaccharide (LPS) involved in oral c... more Oral biofilms harbour gram-negative bacterial antigen lipopolysaccharide (LPS) involved in oral cancer progression and gram-positive bacterial surface-associated adhesive, lipoteichoic acid (LTA). Thus, we hypothesised that LPS and LTA together would increase the proliferation of cancer cells compared to stimulation by LPS alone. Oral cancer cell lines SCC4, SCC9, SCC25, Cal 27 and the normal oral cell line, OKF6, were studied. The bacterial antigen stimulation indices were determined using the MT Glo assay. Cell proliferation after bacterial antigen stimulation was validated by clonogenic assays. Phosphokinase array, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Western blot were employed to study proliferative and apoptotic pathways in bacterial antigen-stimulated cells. Bacterial antigens significantly stimulated Cal 27 (p ≤ 0.001) alone. SCC4 and SCC9 showed negligible stimulation with either antigen, while SCC25 results were comparable to OKF6. The...

Infection, Disease & Health, 2018

BMC Microbiology, 2020

Background Health-care professionals need to collect wound samples to identify potential pathogen... more Background Health-care professionals need to collect wound samples to identify potential pathogens that contribute to wound infection. Obtaining appropriate samples from diabetic foot ulcers (DFUs) where there is a suspicion of infection is of high importance. Paired swabs and tissue biopsies were collected from DFUs and both sampling techniques were compared using 16S rRNA gene sequencing. Results Mean bacterial abundance determined using quantitative polymerase chain reaction (qPCR) was significantly lower in tissue biopsies (p = 0.03). The mean number of reads across all samples was significantly higher in wound swabs Big(overlineX\Big(\overline{X}Big(overlineX(X¯ = 32,014) compared to tissue (overlineX\overline{X}overlineXX¯ = 15,256, p = 0.001). Tissue biopsies exhibited greater overall diversity of bacteria relative to swabs (Shannon’s H diversity p = 0.009). However, based on a presence/absence analysis of all paired samples, the frequency of occurrence of bacteria from genera of known and potential pathoge...

Bioengineering, Sep 9, 2022

Research Square (Research Square), Feb 9, 2023

Journal of Infection and Public Health, May 1, 2018

Materials

Topical antiseptics are often used to treat chronic wounds with biofilm infections and during sal... more Topical antiseptics are often used to treat chronic wounds with biofilm infections and during salvage of biofilm contaminated implants, but their antibacterial efficacy is frequently only tested against non-aggregated planktonic or free-swimming organisms. This study evaluated the antibacterial and antibiofilm efficacy of four commercial surgical washes Bactisure, TorrenTX, minimally invasive lavage (MIS), and Betadine against six bacterial species: Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pyogenes, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli, which are commonly isolated from surgical site infections and chronic wound infections using different in vitro models. We determined minimum planktonic inhibitory and eradication concentration and minimum 1-day-old biofilm inhibition and eradication concentration of antiseptics in 96-well plates format with 24 h contact time. We also tested the efficacy of antiseptics at in-use concentration a...

International Journal of Molecular Sciences

The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic in... more The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic infections worldwide and is well-known for its biofilm formation ability. Recent findings of biofilms on dry hospital surfaces emphasise the failures in current cleaning practices and disinfection and the difficulty in removing these dry surface biofilms (DSBs). Many aspects of the formation of complex DSB biology on environmental surfaces in healthcare settings remains limited. In the present study, we aimed to determine how the protein component varied between DSBs and traditional hydrated biofilm. To do this, biofilms were grown in tryptic soy broth (TSB) on removable polycarbonate coupons in the CDC biofilm reactor over 12 days. Hydrated biofilm (50% TSB for 48 h, the media was then changed every 48 h with 20% TSB, at 37 °C with 130 rpm). DSB biofilm was produced in 5% TSB for 48 h at 35 °C followed by extended periods of dehydration (48, 66, 42 and 66 h at room temperature) interspers...

International Journal of Molecular Sciences

Staphylococcus aureus is a notorious biofilm-producing pathogen that is frequently isolated from ... more Staphylococcus aureus is a notorious biofilm-producing pathogen that is frequently isolated from implantable medical device infections. As biofilm ages, it becomes more tolerant to antimicrobial treatment leading to treatment failure and necessitating the costly removal of infected devices. In this study, we performed in-solution digestion followed by TMT-based high-throughput mass spectrometry and investigated what changes occur in the proteome of S. aureus biofilm grown for 3-days and 12-days in comparison with 24 h planktonic. It showed that proteins associated with biosynthetic processes, ABC transporter pathway, virulence proteins, and shikimate kinase pathway were significantly upregulated in a 3-day biofilm, while proteins associated with sugar transporter, degradation, and stress response were downregulated. Interestingly, in a 3-day biofilm, we observed numerous proteins involved in the central metabolism pathways which could lead to biofilm growth under diverse environment...

Infection, Disease & Health

Journal of Clinical Oncology

e18053 Background: Biofilm formation is a continuous process in oral cancer patients, despite pro... more e18053 Background: Biofilm formation is a continuous process in oral cancer patients, despite proper extirpation/elimination of a bacterial plaque via a surgical procedure or antibiotic treatment. Also, elimination of a bacterial plaque does not necessarily remove extant bacterial antigen-stimulated oral cancer cells. Therefore, combination drug treatment may be an appropriate approach to elucidate the confounding effects of bacterial antigens on anti-cancer drugs. Methods: Our drug combination strategy addressed both Gram-positive (Lipoteichoic acid [LTA]) and Gram-negative (Lipopolysaccharide [LPS]) bacterial antigens, to determine the effect of anti-cancer drugs on LPS/LTA/LPS+LTA-stimulated preclinical oral cancer models (SCC4, SCC9, SCC25, and Cal 27). The drug combination strategy was designed in six phases of treatment. In phase 1, plated cells were treated with different combinations of bacterial antigens in combination with anti-cancer drugs. In the phases 2 and 3, inhibito...

Journal of Hospital Infection

The efficacy of double manual cleaning (DMC) with enzymatic detergent followed by alkaline deterg... more The efficacy of double manual cleaning (DMC) with enzymatic detergent followed by alkaline detergent on biofilm removal on hinged surgical instruments was compared to automated cleaning. Biofilm covered haemostatic forceps were divided into four groups: positive control (soaked in sterile water); DMC; DMC plus extra brushing of the inner hinge; and automated cleaning. All DMC, DMC plus brushing the hinge and automated cleaning significantly (p < 0.001) reduced 94.8%, 99.8% and 100% viable bacteria and 82.3%, 93.8% and 95.1% residual protein respectively compared to positive control. DMC instruments had significantly more viable bacteria (p < 0.05) and residual protein (p < 0.01) than those in instruments subjected to DMC with hinge brushing and automated cleaning. However, there was no significant difference in residual protein between DMC with hinge brushing and automated cleaning. In sterilizing service units with no access to automated cleaning equipment, it is important to brush the inner hinge during manual cleaning, and DMC plus brushing the inner hinge could be considered a viable alternative for cleaning hinged surgical instruments.

32nd Lorne Cancer Conference 2020, 2020

Hernia, 2022

Purpose The purpose of this study was to investigate the link between bacterial biofilms and nega... more Purpose The purpose of this study was to investigate the link between bacterial biofilms and negative outcomes of hernia repair surgery. As biofilms are known to play a role in mesh-related infections, we investigated the presence of biofilms on hernia meshes, which had to be explanted due to mesh failure without showing signs of bacterial infection. Methods In this retrospective observational study, 20 paraffin-embedded tissue sections from explanted groin hernia meshes were analysed. Meshes have been removed due to chronic pain, hernia recurrence or mesh shrinkage. The presence and bacterial composition of biofilms were determined. First, specimens were stained with fluorescence in situ hybridisation (FISH) probes, specific for Staphylococcus aureus and coagulase-negative staphylococci, and visualised by confocal laser scanning microscopy. Second, DNA was extracted from tissue and identified by S. aureus and S. epidermidis specific PCR. Results Confocal microscopy showed evidence ...

International Journal of Molecular Sciences, 2021

The bacterial antigen, lipopolysaccharide (LPS) and disruptions in calcium channels are independe... more The bacterial antigen, lipopolysaccharide (LPS) and disruptions in calcium channels are independently known to influence oral cancer progression. Previously, we found that bacterial antigens, LPS and lipoteichoic acid (LTA) act as confounders during the action of capsaicin on Cal 27 oral cancer proliferation. As calcium channel drugs may affect oral cancer cell proliferation, we investigated the effect of ML218 HCl, a T-type voltage-gated calcium channel blocker, on the proliferation of Cal 27 oral cancer cells. We hypothesized that ML218 HCl could effectively reduce LPS-induced oral cancer cell proliferation. LPS and LTA antigens were added to Cal 27 oral cancer cells either prior to and/or concurrently with ML218 HCl treatment, and the efficacy of the treatment was evaluated by measuring Cal 27 proliferation, cell death and apoptosis. ML218 HCl inhibited oral cancer cell proliferation, increased apoptosis and cell death, but their efficacy was significantly reduced in the presence...

Infection, Disease & Health, 2022

BACKGROUND Acquisition of surgical instruments (SI) and implants by loaner system is a worldwide ... more BACKGROUND Acquisition of surgical instruments (SI) and implants by loaner system is a worldwide practice. Although quality of device reprocessing has been reported to be lower in low and middle-income countries compared with higher income countries, few investigations have been conducted on the management and reprocessing of loaned devices. Thus, in this study we evaluate the practices of management and reprocessing of loaner SI and non-sterile implants (NSI) in a high (Australia) and a middle-income (Brazil) country. METHODS Cross-sectional surveys (hardcopy or online form) was self-administered by sterilising service unit's personnel of Brazilian and Australian hospitals. Only those units that sourced orthopaedic surgical instruments and non-sterile loaned implants from independent companies were eligible. RESULTS A total of 65 questionnaires from Australia and 168 from Brazil were analysed. Quality indicators regarding structure and work process for the management and reprocessing of loaned SI and NSI was of a higher standard in Australia than in Brazil. However, failures were detected in both countries, for instance delivery delays and improper point-of-use pre-cleaning practices. CONCLUSION There are key challenges inherent of the multifaceted reusable medical devices loaner system in both countries, such as communication failures, implementation of non-recommended practices, reprocessing of NSI, and other related to structure and process quality indicators, that must be faced. Initial and ongoing education and training should be provided and should embrace the themes of technical proficiency, effective communication and teamwork, and should include all personnel involved in this process, even loaner company staff.

14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020), 2020

We develop europium complexes with distinguishable luminescence lifetimes in the microsecond-to-m... more We develop europium complexes with distinguishable luminescence lifetimes in the microsecond-to-millisecond region as new multiplexing probes for luminescence in situ hybridisation, and apply them to multiplexed detection and lifetime imaging of bacterial species.

Dental Oral Biology and Craniofacial Research, 2021

Oral biofilms harbour gram-negative bacterial antigen lipopolysaccharide (LPS) involved in oral c... more Oral biofilms harbour gram-negative bacterial antigen lipopolysaccharide (LPS) involved in oral cancer progression and gram-positive bacterial surface-associated adhesive, lipoteichoic acid (LTA). Thus, we hypothesised that LPS and LTA together would increase the proliferation of cancer cells compared to stimulation by LPS alone. Oral cancer cell lines SCC4, SCC9, SCC25, Cal 27 and the normal oral cell line, OKF6, were studied. The bacterial antigen stimulation indices were determined using the MT Glo assay. Cell proliferation after bacterial antigen stimulation was validated by clonogenic assays. Phosphokinase array, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Western blot were employed to study proliferative and apoptotic pathways in bacterial antigen-stimulated cells. Bacterial antigens significantly stimulated Cal 27 (p ≤ 0.001) alone. SCC4 and SCC9 showed negligible stimulation with either antigen, while SCC25 results were comparable to OKF6. The...

Infection, Disease & Health, 2018

BMC Microbiology, 2020

Background Health-care professionals need to collect wound samples to identify potential pathogen... more Background Health-care professionals need to collect wound samples to identify potential pathogens that contribute to wound infection. Obtaining appropriate samples from diabetic foot ulcers (DFUs) where there is a suspicion of infection is of high importance. Paired swabs and tissue biopsies were collected from DFUs and both sampling techniques were compared using 16S rRNA gene sequencing. Results Mean bacterial abundance determined using quantitative polymerase chain reaction (qPCR) was significantly lower in tissue biopsies (p = 0.03). The mean number of reads across all samples was significantly higher in wound swabs Big(overlineX\Big(\overline{X}Big(overlineX(X¯ = 32,014) compared to tissue (overlineX\overline{X}overlineXX¯ = 15,256, p = 0.001). Tissue biopsies exhibited greater overall diversity of bacteria relative to swabs (Shannon’s H diversity p = 0.009). However, based on a presence/absence analysis of all paired samples, the frequency of occurrence of bacteria from genera of known and potential pathoge...