Understanding the antimicrobial activity of selected disinfectants against methicillin-resistant Staphylococcus aureus (MRSA)

Effectiveness of Extended Infection Control Measures on Methicillin-Resistant Staphylococcus aureus Infection Among Orthopaedic Patients

Purpose

The purpose of the study was to find the effectiveness of Extended Infection Control Measures (EICM) in reducing the rate of methicillin-resistant Staphylococcus aureus (MRSA) infection among orthopaedic surgery patients.

Methods

The study adopted a quasi-experimental design and was conducted in the orthopaedic units of a tertiary care hospital. This study recruited 168 orthopaedic patients and 154 healthcare professionals (HCPs). EICM included hand hygiene, decolonizing the patients and HCPS, staff education, feedback of surveillance data, treatment of high-risk and MRSA-infected patients, having separate equipment for MRSA-infected patients, and appropriate cleaning of patient's unit.

Results

The EICM effectively reduced MRSA infection from 21.2 to 6% (p < 0.001). It also resulted in improving the knowledge of HCPs in the prevention and management of MRSA infection (p < 0.001), and all colonized HCPs were successfully (100%) decolonized.

Conclusion

EICM is a promising intervention to combat MRSA infection among orthopaedic wards. Hence, it can be executed in orthopaedic wards, thereby improving the treatment quality and reducing the infection-related consequences.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-022-00713-5.

Surface disinfection with silver loaded pencil graphite prepared with green UV photoreduction technique

Carbon-based materials have been studied for their antimicrobial properties. Previously, most antimicrobial studies are investigated with suspended nanoparticles in a liquid medium. Most works are often carried out with highly ordered pyrolytic graphite. These materials are expensive and are not viable for mass use on high-touch surfaces. Additionally, highly antimicrobial silver nanoparticles are often incorporated onto substrates by chemical reduction. At times, harmful chemicals are used. In this work, low-cost graphite pencils are mechanically exfoliated and transferred onto Si substrates. The sparsely-covered graphite flakes are treated by either plasma O₂or UV irradiation. Subsequently, Ag is photo reduced in the presence of UV onto selected graphite flake samples. It is found that graphite flake surface topography and defects are dependent on the treatment process. High surface roughness and (defects density,I_D/I_G) are induced by plasma O₂follows by UV and pristine graphite flake as follows: 6.45 nm (0.62), 4.96 nm (0.5), 3.79 nm (0.47). Antimicrobial tests withE. colireveal high killing efficiency by photoreduced Ag-on-graphite flake. The reversible effect of Ag leaching can be compensated by repeating the photoreduction process. This work proposes that UV treatment is a promising technique over that of plasma O₂in view that the latter treated surface could repel bacteria resulting in lower bacteria-killing efficiency.

Development of low-cost edible coatings based on polysaccharides with active lactic acid bacteria for the protection of fresh produce modeled using fresh cut apples

The loss of fresh produce along the supply chain represents a significant contributor to environmental and economic burden. Although technological advances in distribution and storage have provided a means to reduce the loss of fresh produce, in resource-limited settings, these technologies may not be available. One attractive approach to help address this limitation is to use edible coatings to protect fresh produce from biotic and abiotic factors that cause food deterioration. Here, we developed edible coatings from materials that are cheap and easy to prepare: maize starch, κ-carrageenan, and agar as the matrix; glycerol as the plasticizer; and Lactobacillus plantarum TPB21.12 as the active ingredient. Using fresh cut apples as a model substrate, we found that maize starch coating retained color, agar coating delayed browning, and κ-carrageenan coating decreased mass shrinkage of the fresh cut apples. L. plantarum TPB21.12 remained viable in the edible coating suspensions during storage and was active against Escherichia coli TPB21.8, a model bacterium for biotic factor that causes food spoilage. The simplicity of the edible coating formulation and preparation method offers an attractive approach for applications to help protect fresh produce from deterioration and reduce food loss and waste generation.

Reduced Susceptibility and Increased Resistance of Bacteria against Disinfectants: A Systematic Review

Disinfectants are used to reduce the concentration of pathogenic microorganisms to a safe level and help to prevent the transmission of infectious diseases. However, bacteria have a tremendous ability to respond to chemical stress caused by biocides, where overuse and improper use of disinfectants can be reflected in a reduced susceptibility of microorganisms. This review aims to describe whether mutations and thus decreased susceptibility to disinfectants occur in bacteria during disinfectant exposure. A systematic literature review following PRISMA guidelines was conducted with the databases PubMed, Science Direct and Web of Science. For the final analysis, 28 sources that remained of interest were included. Articles describing reduced susceptibility or the resistance of bacteria against seven different disinfectants were identified. The important deviation of the minimum inhibitory concentration was observed in multiple studies for disinfectants based on triclosan and chlorhexidine. A reduced susceptibility to disinfectants and potentially related problems with antibiotic resistance in clinically important bacterial strains are increasing. Since the use of disinfectants in the community is rising, it is clear that reasonable use of available and effective disinfectants is needed. It is necessary to develop and adopt strategies to control disinfectant resistance.

Disinfectant and Antimicrobial Susceptibility Studies of Staphylococcus aureus Strains and ST398-MRSA and ST5-MRSA Strains from Swine Mandibular Lymph Node Tissue, Commercial Pork Sausage Meat and Swine Feces

Staphylococcus aureus (S. aureus) causes gastrointestinal illness worldwide. Disinfectants are used throughout the food chain for pathogenic bacteria control. We investigated S. aureus bioavailability in swine Mandibular lymph node tissue (MLT) and pork sausage meat (PSM), established susceptibility values for S. aureus to disinfectants, and determined the multilocus sequence type of MRSA strains. Antimicrobial and disinfectant susceptibility profiles were determined for 164 S. aureus strains isolated from swine feces (n = 63), MLT (n = 49) and PSM (n = 52). No antimicrobial resistance (AMR) was detected to daptomycin, nitrofurantoin, linezolid, and tigecycline, while high AMR prevalence was determined to erythromycin (50.6%), tylosin tartrate (42.7%), penicillin (72%), and tetracycline (68.9%). Methicillin-resistant S. aureus (MRSA) strains, ST398 (n = 6) and ST5 (n = 1), were found in the MLT and PSM, 4 MRSA in MLT and 3 MRSA strains in the PSM. About 17.5% of feces strains and 41.6% of MLT and PSM strains were resistant to chlorhexidine. All strains were susceptible to triclosan and benzalkonium chloride, with no cross-resistance between antimicrobials and disinfectants. Six MRSA strains had elevated susceptibilities to 18 disinfectants. The use of formaldehyde and tris(hydroxylmethyl)nitromethane in DC&R was not effective, which can add chemicals to the environment. Didecyldimethylammonium chloride and benzyldimethylhexadecylammonium chloride were equally effective disinfectants. ST398 and ST5 MRSA strains had elevated susceptibilities to 75% of the disinfectants tested. This study establishes susceptibility values for S. aureus strains from swine feces, mandibular lymph node tissue, and commercial pork sausage against 24 disinfectants. Since it was demonstrated that S. aureus and MRSA strains can be found deep within swine lymph node tissue, it may be beneficial for the consumer if raw swine lymph node tissue is not used in uncooked food products and pork sausage.

Pulsed blue light inactivates two strains of human coronavirus

Emerging evidence suggests that blue light has the potential to inactivate viruses. Therefore, we investigated the effect of 405 nm, 410 nm, 425 nm and 450 nm pulsed blue light (PBL) on human alpha coronavirus HCoV-229 E and human beta coronavirus HCoV-OC43, using Qubit fluorometry and RT-LAMP to quantitate the amount of nucleic acid in irradiated and control samples. Like SARS-CoV-2, HCoV-229E and HCoV-OC43 are single stranded RNA viruses transmitted by air and direct contact; they have similar genomic sizes as SARS-CoV-2, and are used as surrogates for SARS-CoV-2. Irradiation was carried out either at 32.4 J cm^-2 using 3 mW cm^-2 irradiance or at 130 J cm^-2 using 12 mW cm^-2 irradiance. Results: (1) At each wavelength tested, PBL was antiviral against both coronaviruses. (2) 405 nm light gave the best result, yielding 52.3% (2.37 log₁₀) inactivation against HCoV-OC43 (p < .0001), and a significant 1.46 log ₁₀ (44%) inactivation of HCoV-229E (p < .01). HCoV-OC43, which like SARS-CoV-2 is a beta coronavirus, was more susceptible to PBL irradiation than alpha coronavirus HCoV-229E. The latter finding suggests that PBL is potentially antiviral against multiple coronavirus strains, and that, while its potency may vary from one virus to another, it seems more antiviral against beta coronaviruses, such as HCoV-OC43. (3) Further, the antiviral effect of PBL was better at a higher irradiance than a lower irradiance, and this indicates that with further refinement, a protocol capable of yielding 100% inactivation of viruses is attainable.

Potential application of novel technology developed for instant decontamination of personal protective equipment before the doffing step

The use of personal protective equipment (PPE) has been considered the most effective way to avoid the contamination of healthcare workers by different microorganisms, including SARS-CoV-2. A spray disinfection technology (chamber) was developed, and its efficacy in instant decontamination of previously contaminated surfaces was evaluated in two exposure times. Seven test microorganisms were prepared and inoculated on the surface of seven types of PPE (respirator mask, face shield, shoe, glove, cap, safety glasses and lab coat). The tests were performed on previously contaminated PPE using a manikin with a motion device for exposure to the chamber with biocidal agent (sodium hypochlorite) for 10 and 30s. In 96.93% of the experimental conditions analyzed, the percentage reduction was >99% (the number of viable cells found on the surface ranged from 4.3x106 to <10 CFU/mL). The samples of E. faecalis collected from the glove showed the lowest percentages reduction, with 86.000 and 86.500% for exposure times of 10 and 30 s, respectively. The log10 reduction values varied between 0.85 log10 (E. faecalis at 30 s in glove surface) and 9.69 log10 (E. coli at 10 and 30 s in lab coat surface). In general, E. coli, S. aureus, C. freundii, P. mirabilis, C. albicans and C. parapsilosis showed susceptibility to the biocidal agent under the tested conditions, with >99% reduction after 10 and 30s, while E. faecalis and P. aeruginosa showed a lower susceptibility. The 30s exposure time was more effective for the inactivation of the tested microorganisms. The results show that the spray disinfection technology has the potential for instant decontamination of PPE, which can contribute to an additional barrier for infection control of healthcare workers in the hospital environment.

Value-added switchgrass extractives for reduction of Escherichia coli O157:H7 and Salmonella Typhimurium populations on Formica coupons

Recurring outbreaks linked to Escherichia coli O157:H7-contaminated lettuce and Salmonella enterica-contaminated sprouts highlight the need for improved food safety measures. The aim of this study was to determine the ability of a bio-based antimicrobial extract prepared from switchgrass, a dedicated energy crop, to reduce E. coli O157:H7 and S. Typhimurium populations on Formica coupons, a model food-contact surface. Overnight cultures of ~7 log CFU/mL E. coli O157:H7 and S. Typhimurium, air-dried on Formica coupons were treated with 0.625% NaClO, 70% ethanol, sterile water or different batches of switchgrass extractives (SE1, SE2, and SE3) for up to 30 min. E. coli O157:H7 was reduced by 4.43 log CFU/mL after 1 min by SE3, and to non-detectable levels after 1 min by all other treatments. Populations of S. Typhimurium LT2 (15-min drying) were reduced by 3.30 log CFU/mL with 70% ethanol, 5.38 log CFU/mL with SE1, and to non-detectable levels with 0.625% NaClO after 1 min, while S. Typhimurium ATCC 23564 (1-h drying) was non-detectable after 1 min by all treatments. Under soiled conditions, 10-min treatment with SE1 and 70% ethanol reduced both bacteria to non-detectable levels. Studies with concentrated switchgrass extractives combined with various other natural disinfectants or in hurdle approaches warrant further investigation.

Borderline resistance to oxacillin in Staphylococcus aureus after treatment with sub-lethal sodium hypochlorite concentrations

Surface disinfectants are regularly used in prophylactic and infection control measures. Concern has been raised whether residues of sub-inhibitory disinfectant concentrations may constitute a selective pressure and could contribute to the development of strains which are tolerant and/or resistant to biocides including antibiotics. The current study investigated whether Staphylococcus (S.) aureus ATCC® 29213™ and ATCC® 6538™ would change their growth characteristics and antimicrobial susceptibility profiles after prolonged treatment with sub-inhibitory concentrations of sodium hypochlorite (NaOCl). NaOCl is a fast-acting disinfectant with a broad-spectrum activity, inexpensive and widely used in healthcare and the food production industry. Minimum inhibitory concentration (MIC) for NaOCl was determined by broth macrodilution according to the guidelines for disinfectant efficacy testing provided by the German Veterinary Medical Society. Serial passages after 24 h and 72 h, respectively, in defined sub-inhibitory concentrations of NaOCl resulted in a number of phenotypic variants. Two of these variants, derived from S. aureus ATCC® 29213™, showed elevated MICs of oxacillin and were considered as in vitro-generated borderline oxacillin-resistant S. aureus (BORSA). Transmission electron microscopy revealed a significantly thickened cell wall in these isolates, a phenomenon that has also been described for Listeria monocytogenes after low-level exposure to NaOCl. Whole genome sequencing revealed an early stop codon in the gene coding for the GdpP protein and thereby abolishing the function of this gene. GdpP represents a phosphodiesterase that regulates gene expression, and loss of function of the GdpP protein has been described in association with borderline oxacillin resistance. Our findings suggest that a mutation in the GdpP protein gene and morphological changes of the cell wall were induced by repeated exposure to sub-lethal NaOCl concentrations, and most likely accounted for a BORSA phenotype in two variants derived from S. aureus ATCC® 29213™.

Reduction of Health Care-Associated Infections (HAIs) with Antimicrobial Inorganic Nanoparticles Incorporated in Medical Textiles: An Economic Assessment

Health care-associated infections (HAIs) affect millions of patients annually with up to 80,000 affected in Europe on any given day. This represents a significant societal and economic burden. Staff training, hand hygiene, patient identification and isolation and controlled antibiotic use are some of the standard ways to reduce HAI incidence but this is time consuming and subject and subject to rigorous implementation. In addition, the lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Textiles are an attractive substrate for pathogens because of contact with the human body with the attendant warmth and moisture. Textiles and surfaces coated with engineered nanomaterials (ENMs) have shown considerable promise in reducing the microbial burden on those surfaces. Studies have also shown that this antimicrobial affect can reduce the incidence of HAIs. For all of the promising research, there has been an absence of study on the economic effectiveness of ENM coated materials in a healthcare setting. This article examines the relative economic efficacy of ENM coated materials against an antiseptic approach. The goal is to establish the economic efficacy of the widespread usage of ENM coated materials in a healthcare setting. In the absence of detailed and segregated costs, benefits and control variables over at least cross sectional data or time series, an aggregated approach is warranted. This approach, while relying on some supposition allows for a comparison with similar data regarding standard treatment to reduce HAIs and provides a reasonable economic comparison. We find that while, relative to antiseptics, ENM coated textiles represent a significant clinical advantage, they can also offer considerable cost savings.

Light as a potential treatment for pandemic coronavirus infections: A perspective

The recent outbreak of COVID-19, which continues to ravage communities with high death tolls and untold psychosocial and catastrophic economic consequences, is a vivid reminder of nature's capacity to defy contemporary healthcare. The pandemic calls for rapid mobilization of every potential clinical tool, including phototherapy—one of the most effective treatments used to reduce the impact of the 1918 “Spanish influenza” pandemic. This paper cites several studies showing that phototherapy has immense potential to reduce the impact of coronavirus diseases, and offers suggested ways that the healthcare industry can integrate modern light technologies in the fight against COVID-19 and other infections. The evidence shows that violet/blue (400–470 nm) light is antimicrobial against numerous bacteria, and that it accounts for Niels Ryberg Finsen's Nobel-winning treatment of tuberculosis. Further evidence shows that blue light inactivates several viruses, including the common flu coronavirus, and that in experimental animals, red and near infrared light reduce respiratory disorders, similar to those complications associated with coronavirus infection. Moreover, in patients, red light has been shown to alleviate chronic obstructive lung disease and bronchial asthma. These findings call for urgent efforts to further explore the clinical value of light, and not wait for another pandemic to serve as a reminder. The ubiquity of inexpensive light emitting lasers and light emitting diodes (LEDs), makes it relatively easy to develop safe low-cost light-based devices with the potential to reduce infections, sanitize equipment, hospital facilities, emergency care vehicles, homes, and the general environment as pilot studies have shown.

Pulsed 450 nm blue light significantly inactivates Propionibacterium acnes more than continuous wave blue light

Infection with Propionibacterium acnes is ubiquitous, and drug resistant strains have been on the rise as the use of pharmaceutical antimicrobials continues to engender the emergence of further resistant strains. In previous studies, we showed that treatment with blue light serves as an alternative to pharmaceutical intervention. As a part of our ongoing effort to improve the antimicrobial efficacy of blue light, we studied the effect of pulsed 450 nm light on P. acnes in vitro and compared two pulsed rates with continuous wave irradiation. We irradiated cultures of P. acnes at various irradiances and radiant energies either singly or repeatedly at various time intervals, using printed micro-LEDs, with the goal of finding the lowest combination of irradiance and radiant energy that would yield 100% bacterial suppression. Our results show that treatment with 33% pulsed light gave the best result compared to 20% pulsed wave or continuous wave. Timing irradiation to coincide with the replication cycle of P. acnes produced a significantly better antimicrobial effect. Furthermore, repeated irradiation at 3-h or 4-h interval enabled significant bacterial suppression even at lower irradiances; thus, making single irradiation at high irradiances unnecessary. Moreover, combining repeated irradiation with appropriate duration of treatment and 33% irradiation pulse rate gave optimal 100% [7 log₁₀] bacterial suppression.

Pulsed 450 nm blue light suppresses MRSA and Propionibacterium acnes in planktonic cultures and bacterial biofilms

In our recent study, we showed that pulsed blue light (PBL) suppresses the growth of Propionibacterium acnes more than continuous wave (CW) blue light in vitro, but it is not known that other bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), respond similarly to PBL. The high potency of PBL relative to CW blue light makes it a suitable antimicrobial for suppressing bacterial growth in biofilms as well. Therefore, we determined if MRSA-a deadly bacterium of global concern-is susceptible to 450 nm PBL irradiation in vitro, and ascertained whether the bactericidal effect of PBL on planktonic P. acnes culture can be replicated in biofilms of P. acnes and MRSA. In three series of experiments, we irradiated P. acnes and MRSA respectively, either in planktonic cultures, forming biofilms or formed biofilms. Compared to controls, the results showed 100% bacterial suppression in planktonic cultures of MRSA irradiated with 3 mW/cm² irradiance and 7.6 J/cm² radiant exposure three times at 30-minute intervals, and also in P. acnes cultures irradiated with 2 mW/cm² irradiance 5 J/cm² radiant exposure thrice daily during each of 3 days. Irradiation of biofilms with the same irradiances and radiant exposures that gave 100% bacterial suppression in planktonic cultures resulted in disruption and disassembly of the architecture of MRSA and P. acnes biofilms, more so in forming biofilms than formed biofilms. The antimicrobial effect on each bacterium was minimal in forming biofilms, and even less in formed biofilms. Increasing radiant exposure slightly from 7.6 J/cm² to 10.8 J/cm² without changing any other parameter, yielded more disruption of the biofilm and fewer live MRSA and P. acnes, suggesting that 100% bacterial suppression is possible with further refinement of the protocol. In both planktonic cultures and biofilms, PBL suppressed MRSA more than P. acnes.

Molecular mechanism of antimicrobial activity of chlorhexidine against carbapenem-resistant Acinetobacter baumannii

Acinetobacter baumannii causes hospital-acquired infections, especially in those with impaired immune function. Biocides or disinfectants are widely used antibacterial agents used to eradicate the effect of A. baumannii on inanimate objects and health care environments. In the current study, the antimicrobial activity of chlorhexidine has been investigated against carbapenem-resistant (RS-307, RS-7434, RS-6694, and RS-122), and sensitive (ATCC-19606 and RS-10953) strains of A. baumannii. We have determined growth kinetics, antimicrobial susceptibility, ROS production, lipid peroxidation, cell viability using flow cytometry assay (FACS), and membrane integrity by scanning electron microscope (SEM). The effect of chlorhexidine on the bacterial membrane has also been investigated using Fourier transform infrared (FTIR) spectroscopy. The present study showed that 32μg/ml chlorhexidine treatment results in the decreased bacterial growth, CFU count and cell viability. The antibacterial activity of chlorhexidine is due to the elevated ROS production and higher lipid peroxidation. These biochemical changes result in the membrane damage and alteration in the membrane proteins, phospholipids, carbohydrates, nucleic acids as evident from the FTIR and SEM data. Therefore, chlorhexidine has the potential to be used in the hospital setups to remove the spread of A. baumannii.

A phenotypic screening bioassay for Escherichia coli stress and antibiotic responses based on Fourier-transform infrared (FTIR) spectroscopy and multivariate analysis

AIMS

To develop and optimize a Fourier-transform infrared spectroscopy (FTIRS) phenotypic screening bioassay for stress responses, regarding the effect of nutrient content, bacterial growth phase and stress agent exposure time.

METHODS AND RESULTS

A high-throughput FTIRS bioassay was developed to distinguish the stress responses of Escherichia coli to sodium hydroxide, hydrochloric acid, sodium chloride, sodium hypochlorite and ethanol. Principal component analysis and hierarchical clustering were used to quantify the effect of each parameter on bioassay performance, namely its reproducibility and metabolic resolution. Bioassay performance varied greatly, ranging from poor to very good. Spectra were partitioned into biologically relevant regions to evaluate their contributions to bioassay performance, but further improvements were not observed. Bioassay optimization was validated against empirical parameters, which confirmed a closer representation of known mechanisms on the antibiotic-induced stress responses.

CONCLUSIONS

The optimized bioassay used standard nutrient content, cells in the late-stationary growth phase and a one-shift exposure duration. Only the optimized bioassay adequately and reproducibly distinguished the E. coli stress and antibiotic responses. The absence of performance improvements using partitioned spectra indicated that stress responses are imprinted on the whole-spectra metabolic signature.

SIGNIFICANCE AND IMPACT OF THE STUDY

Highly optimized FTIRS bioassay parameters are vital in capturing whole-spectra metabolic signatures that can be used for satisfactory and reproducible phenotypic screening of stress and antibiotic responses.

An assessment of antibacterial mode of action of chitosan on Listeria innocua cells using real-time HATR-FTIR spectroscopy

The antibacterial mode of action of chitosan using real-time, horizontal attenuated total reflectance, Fourier-transform infrared (HATR-FTIR) spectroscopy and transmission electron microscopy (TEM) was investigated. Listeria innocua was treated with chitosan solution. HATR-FTIR revealed an increased lethality and substantially metabolomics response on cell components. The main changes in FTIR and their 2nd derivative spectra were at 1045 cm^-1 (carbohydrates in cell wall). Principal component analysis clearly segregated untreated and treated cells. Loadings plot revealed the functional groups in cell wall, cell membrane, phospholipid and protein regions of spectrum that are responsible for the classification of treated and control spectra. Kinetic traces of the metabolomics change suggested that cell wall and cell membrane seemed to be the initial target of the antimicrobial mechanism of chitosan. In agreement with the TEM images, which showed breakage of cell wall integrity. The cell wall, cell membrane, phospholipids, proteins and nucleic acids of FTIR spectral data recorded during the cell inactivation were shown to be linked to the metabolomics cell response in the lethality rate and structure of the cells. This work clearly showed, using HATR-FTIR spectroscopy, how bacteria can change their metabolomics response substantially during the first 45 min of contact time.

Fluorescence microscopy to monitor wine malolactic fermentation

Malolactic fermentation (MLF) is a natural and biological deacidification of wines and a required step for making premium red wines. MLF is carried out by lactic acid bacteria (LAB) that are present in the fermenting wines. Currently, real-time control of MLF is an issue of great interest as the classical plate count technique for assessing bacterial populations requires long incubation times that are not compatible with a tight control of MLF. The aim of this study was to apply fluorescence microscopy and the bacteria staining kit Live/Dead BacLight™ to quantify viable LAB populations in red wines undergoing MLF. This method proved to be a fast and reliable culture-independent method to monitor wine MLF. Moreover, comparison of bacterial population data obtained by fluorescence microscopy and classical plate counts of LAB populations allowed discriminating a population of fully active and culturable cells, from total viable cells that include cells in an intermediate unculturable state.

In vitroantibacterial activity of oxide and non-oxide bioceramics for arthroplastic devices: II. Fourier transform infrared spectroscopy

The metabolic response of Gram-positiveStaphylococcus epidermidisbacteria to bioceramic substrates was probed by Fourier transform infrared spectroscopy.