Microorganisms attach to surfaces and develop biofilms. Biofilm-associated cells can be differentiated from their suspended counterparts by generation of an extracellular polymeric substance (EPS) matrix, reduced growth rates, and the up- and down- regulation of specific genes. Attachment is a complex process regulated by diverse characteristics of the growth medium, substratum, and cell surface. An established biofilm structure comprises microbial cells and EPS, has a defined architecture, and provides an optimal environment for the exchange of genetic material between cells. Cells may also communicate via quorum sensing, which may in turn affect biofilm processes such as detachment. Biofilms have great importance for public health because of their role in certain infectious diseases and importance in a variety of device-related infections. A greater understanding of biofilm processes should lead to novel, effective control strategies for biofilm control and a resulting improvement in patient management.

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Biofilms: microbial life on surfaces.

Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactant-producing microorganisms and evaluation of their activity have been developed. Genes involved in rhamnolipid synthesis (rhlAB) and regulation (rhlI and rhlR) in Pseudomonas aeruginosa are characterized, and expression of rhlAB in heterologous hosts is discussed. Genes for surfactin production (sfp, srfA, and comA) in Bacillus spp. are also characterized. Fermentative production of biosurfactants depends primarily on the microbial strain, source of carbon and nitrogen, pH, temperature, and concentration of oxygen and metal ions. Addition of water-immiscible substrates to media and nitrogen and iron limitations in the media result in an overproduction of some biosurfactants. Other important advances are the use of water-soluble substrates and agroindustrial wastes for production, development of continuous recovery processes, and production through biotransformation. Commercialization of biosurfactants in the cosmetic, food, health care, pulp- and paper-processing, coal, ceramic, and metal industries has been proposed. However, the most promising applications are cleaning of oil-contaminated tankers, oil spill management, transportation of heavy crude oil, enhanced oil recovery, recovery of crude oil from sludge, and bioremediation of sites contaminated with hydrocarbons, heavy metals, and other pollutants. Perspectives for future research and applications are also discussed.

Microbial production of surfactants and their commercial potential.

INTRODUCTION 149 TAXONOMY 149 Historical Features 149 Current Taxonomic Status 149 Delineation of Species 149 Species of Clinical Importance 150 LABORATORY IDENTIFICATION 150 Isolation from Clinical Specimens 150 Morphological, Cultural, and Metabolic Characteristics 151 Species Identification 151 NOSOCOMIAL INFECTIONS CAUSED BY ACINETOBACTER SPP. 152 Overview 152 Respiratory Infection 152 Bacteremia 153 Meningitis 153 Urinary Tract Infection 154 Other Miscellaneous Infections 154 PATHOGENESIS OF ACINETOBACTER INFECTIONS 154 Predisposing Factors 154 Virulence of Acinetobacter spp. 154 EPIDEMIOLOGY 155 Human Carriage 155 Persistence in the Hospital Environment 155 TYPING SYSTEMS 156 Biotyping 156 Antibiograms 156 Serotyping 156 Phage Typing 157 Bacteriocin Typing 157 Protein Profiles 157 Multilocus Enzyme Electrophoretic Typing 157 Plasmid Profiles 157 Analysis by Pulsed-Field Gel Electrophoresis 157 Ribotyping 157 PCR-Based Methods 158 CLINICAL ANTIBIOTIC RESISTANCE 158 BIOCHEMICAL AND GENETIC MECHANISMS OF ANTIBIOTIC RESISTANCE 158 Genetics of Resistance 158 b-Lactams 159 Aminoglycosides 159 Quinolones 160 Other Antibiotics 160 THERAPY OF ACINETOBACTER INFECTIONS 160 CONCLUSIONS 160 ACKNOWLEDGMENTS 161 REFERENCES 161

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Acinetobacter spp. as nosocomial pathogens: microbiological, clinical, and epidemiological features.

Surfactants are surface-active compounds capable of reducing surface and interfacial tension at the interfaces between liquids, solids and gases, thereby allowing them to mix or disperse readily as emulsions in water or other liquids. The enormous market demand for surfactants is currently met by numerous synthetic, mainly petroleum-based, chemical surfactants. These compounds are usually toxic to the environment and non-biodegradable. They may bio-accumulate and their production, processes and by-products can be environmentally hazardous. Tightening environmental regulations and increasing awareness for the need to protect the ecosystem have effectively resulted in an increasing interest in biosurfactants as possible alternatives to chemical surfactants. Biosurfactants are amphiphilic compounds of microbial origin with considerable potential in commercial applications within various industries. They have advantages over their chemical counterparts in biodegradability and effectiveness at extreme temperature or pH and in having lower toxicity. Biosurfactants are beginning to acquire a status as potential performance-effective molecules in various fields. At present biosurfactants are mainly used in studies on enhanced oil recovery and hydrocarbon bioremediation. The solubilization and emulsification of toxic chemicals by biosurfactants have also been reported. Biosurfactants also have potential applications in agriculture, cosmetics, pharmaceuticals, detergents, personal care products, food processing, textile manufacturing, laundry supplies, metal treatment and processing, pulp and paper processing and paint industries. Their uses and potential commercial applications in these fields are reviewed.

Potential commercial applications of microbial surfactants.

Research and development of antimicrobial materials for food applications such as packaging and other food contact surfaces is expected to grow in the next decade with the advent of new polymer materials and antimicrobials. This article reviews the different types of antimicrobial polymers developed for food contact, commercial applications, testing methods, regulations and future trends. Special emphasis will be on the advantages/disadvantages of each technology.

Review of antimicrobial food packaging

ADA guidelines stipulate that organoleptic/hedonic odour judges are the ‘Gold Standard’ whereas instrumental (e.g. gas chromatography) and microbiological analyses of oral malodour are considered secondary tests.

1. Why is instrumental measurement considered 2nd best to odour judges?

Comments of the participants included:

• Human judges are more commonly used. Gas chromatography (GC) is used to measure volatile sulphur compounds (VSCs), which are only part of the total breath mix.
• To what extent do VSCs contribute to breath odour? They correlate with odour scores but are not the only odour in breath.
• First, define other odorants in breath to produce simulated mixtures then compare these mixes to the real thing.
• There are probably different types of bad breath from different locations within the oral cavity.
• Methyl mercaptan is important, in determining the source of oral malodour.
• Butyric acid is odorous and present at high levels in saliva but does not play as important a role in breath odour.
• It is generally accepted that instrumental measures are not advanced or sophisticated enough to measure oral malodour.
• However, judges are subjective and there is a real need for ‘equipment’ that can be taken into the field.
• An inventory of the chemical constituents of bad breath must be completed because VSCs are not the only important component they are just the ‘easy’ route to measuring bad breath. Indole, skatole, butyric acid: Are they important?
• Use GC-MS and profile the breath of 1000 patients. This is not necessarily straightforward because it is possible to introduce false positive results by concentrating breath samples.
• Often, breath odour treatments can reduce the concentration of VSCs measured in a patients breath but the patient still has oral odour suggesting that other components are important.
• VSC levels in breath can be elevated by cysteine challenges, what components in breath are elevated after challenging with other amino acids?
• Microbiological techniques show increased numbers of Streptococcus salivarius in patients without oral odour, could this be the emergence of the ‘good guy’?
• There have been no long term microbiological studies looking at ecology shifts in patients with and without oral malodour.
• Would long term microbiological studies provide useful information given that many species in the oral cavity are non-culturable and many are unknown?
• J. Tonzetich examined different components of oral malodour before he focused on the GC measurement of VSCs.
• The Halimeter® has been demonstrated to have a correlation of about 0.5 with odour scores.
• BANA (benzoyl-dl-arginine-napthyamide) and other enzymatic test have been shown to correlate with odour scores.
• Correlations between odour judges and other techniques for assessing oral malodour do vary and this depends on the number of odour judges used.
• Quest International has designed a screening system to find flavour components that specifically eliminate VSCs. Reducing VSCs results in reduced odour in most subjects but there will always be exceptions.
• There are still studies that show the opposite effects for VSC and odour scores.
• Concentrated whole breath should be assessed – although alkanes have been shown to be present in oral odour, the odour index of alkanes is low.
• Do researchers actually look for other molecules in oral odour, other than VSCs?
• Colgate measure VSCs but are moving into the measurement of volatile fatty acids, indoles and amines using SPME.
• GC is a good predictor for the activity of potential odour reducing products. The hierarchical testing procedure for new products is usually as follows: in vitro to Halimeter to GC to organoleptic/hedonic odour assessments.
• What is the cost of using odour judges? Studies using odour judges are expensive, certainly more costly that using instrumental measures, and this could cause problems for smaller companies who do not have sufficient funding. 2. Will there be a day when an analytical measure is the ‘gold standard’ for assessing oral odour?
• Can we produce bad breath in a bottle?
• There is a difference between chronic and morning breath. The industry is geared towards treatment of morning breath. Do such treatments work for sufferers of chronic bad breath?
• There is no information correlating morning breath with mid-afternoon breath.
• How important will bacterial tests become? Have bacterial tests such as BANA been used in the professional field?
• Industry is driving the use of the Halimeter®. Maybe the BANA test should be marketed similarly to the Halimeter®.
• The BANA test needs money and marketing, as does the OK to KISS test.
• Is it possible to test odour treatments on bacteria, where the measurable end product is gaseous headspace? Caution must be exercised since bacterial metabolism will be effected by culturing conditions.
• Some microorganisms have been associated with oral odour, such as Porphyromonas gingivalis, Prevotella intermedius, however the problem is that a large percentage of the oral flora is non-culturable.
• What is the importance of postnasal drip in oral odour?
• How does tongue cleaning effect oral odour?
• Can amino acid mapping in the oral cavity be correlated with oral odour? (e.g. measuring the concentrations of methionine, cysteine, tryptophan at different locations in the mouth). 3. Will there ever be a ‘gizmo’ to measure oral odour with a 0.9 correlation with odour judges?
• Is this the promise of the electronic nose? Current problems with the electronic nose include moisture and must choose the right sensors. A researcher from University of Manchester Institute of Technology (UMIST) working with the electronic nose forecast that the technology would be ready by 2008!


General concensus 

• Odour judges ‘measure’ whole breath odour, which is why they are considered the gold standard measure of oral odour. However research has shown that the human nose exhibits a Log response to stimuli but the scales used to rate oral odour are linear and that there is no pan-industry standard for this measurement, in terms of calibration of judges.
• VSCs are important components of oral odour and GC is the most accurate method of measuring VSCs in breath. Therefore the GC is the ‘gold standard’ for measuring VSCs.
• Portable VSC measures include the Halimeter and portable GC (requires validation). Other measures include enzymatic tests and microbiological measures. Performing all these measures in combination should give better correlations with odour judge scores.
• Research should be performed in the following areas: Detecting the component gases in oral odour. Defining ‘bad breath in a bottle’ and olfactory thresholds. Measuring oral odour substrates/substrate availability.


Suggestion for next ISBOR meeting  Gather odour judges from research and industry and have them assess a cross-section of oral odour patients, in parallel with the instrumental measurement of odour.

Workshop 2 Odor measurements using instruments and other laboratory tests (GC, GCMS, Halimeter, Sensors, HPLC, OK2KISS, BANA etc)

The quadloop: a novel device for plating and streaking microbial samples

During the 20th century, bad breath and analysis of breath for medical diagnosis evolved as two separate fields. Papers on bad breath were published almost exclusively in dental journals, whereas papers on exhaled breath analysis were more commonly found in medical and chemical analysis journals. When Daniel van Steenberghe and Mel Rosenberg first discussed setting up an international society for breath odor research, it was Daniel's vision that the association reach out across the borders of dental research to various medical disciplines. Indeed, following the establishment of ISBOR (International Society for Breath Odor Research in 1995), experts were invited in a wide range of medical areas to participate in the ISBOR conferences. However, there were still no links between bad breath researchers and medical breath analysis investigators. All that changed in May 2005 when Mel Rosenberg was invited to participate in the international meeting on Breath Analysis held in Innsbruck, organized by Anton Amann. During the conference, it became apparent that a large, excellent cadre of researchers worldwide were studying problems of exhaled breath analysis which were similar to those of bad breath research. We would like to elaborate. In a sense, bad breath is simply breath analysis using the nose (until now, human) as the detector. Although researchers in the field of oral malodor routinely use GC and other instrumental techniques for gas analysis, it is acknowledged by most researchers in the field that the gold standard of bad breath detection and measurement is based on the nose of odor judges. It has been known for centuries that the odor or smell of an individual's breath is in some cases an indicator or a symptom of disease, even though the nature of the disease was not always understood. The classic case of this is the sweet smell of a person suffering from diabetes resulting from the excessive amount of acetone emitted in the breath and through the skin. In the time of the Babylonian Talmud (over 1500 years ago), bad breath was considered a major medical affliction, akin to suffering from leprosy. Volatile gases emanating from the breath, which the nose can detect, have been linked to various other rare medical disorders. Current instrumental techniques allow researchers to identify and measure hundreds of gases that might be involved in clinical states. Some of these (e.g., nitric oxide, carbon dioxide) are not smelled and thus are 'invisible' to the nose. Such gases may not contribute to bad breath as such, yet are important for clinical diagnosis. Nevertheless, we see much room for cooperation and collaboration. First and foremost, modern bad breath research requires state-of-the-art instrumental analysis to detect which molecules are involved in different kinds of bad breath (tongue odor smells quite different as compared with interdental odor, for example). A large variety of odorous molecules can be detected in breath and in putrefied saliva samples. Yet we do not know their individual contributions to the overall odor or 'bouquet'. Most comparisons of odor judge scores and GC (or similar) instrumental analysis yield correlation coefficients of the order of R2 = 0.6. Are there other odorous gases that we should be measuring, yet are not? Are there non-odorous gases that can nevertheless be used to strengthen the correlations? Conversely, are there gases that the nose can pick up that are poorly identified by routine GC analyses? Can trained judges (human or animal) pick up gases of importance that our instruments might have missed? Thirdly, bad breath relates to oral disease, which is, in turn, related to general health. We still do not understand the relationship between periodontal disease and breath. Are there specific gases (whether odorous or not) that we should be on the lookout for? We should keep in mind that periodontal disease is a major health concern worldwide. The possibility that oral and pharyngeal microbiota contribute dozens of gases to the breath must be considered in general breath analysis for systemic diagnosis. These gases can obscure and interfere with measurement of endogenous systemic gases. Should subjects rinse and gargle with mouthrinse before undergoing medical breath analysis procedures? Finally, we share the same concerns regarding how we collect the breath samples, trap and isolate the volatiles we are looking for. The next international conference on these topics will be jointly organized by the International Society for Breath Odor Research (ISBOR) and the International Association for Breath Research (IABR) in Dortmund on 26–30 April 2009. This conference will be the first occasion where people from both fields—breath odor research and exhaled breath analysis—will come together to present and discuss their research and ideas, thus offering an excellent occasion to bridge between the fields. The topics presented and discussed will range from 'in vitro models of tongue odor', 'toxicities of oral malodorous compounds to general and oral health', 'exhaled breath testing in intensive care' to 'lung cancer screening by exhaled breath analysis'. We look very much forward to this joint conference by ISBOR and IABR and see much room for cooperation and unanticipated discovery in the coming years. Hopefully, our new joint journal will catalyse this process.

https://iopscience.iop.org/article/10.1088/1752-7163/2/4/040201/pdf

Bad breath and exhaled breath analysis—common fields with common denominators

In some 15–30% of patients complaining of a serious breath odor problem, little or no ­malodor can be detected by the examiner either organoleptically by smelling the patient’s breath or using laboratory techniques (Quirynen et al. 2009; Seemann et al. 2006). These patients vary in their level of conviction regarding their perceived odor problem. Some are uncertain and just wish to confirm or rule out a breath odor problem, whereas others firmly believe that the problem exists. In extreme cases, patients may appear psychotic and/or contemplate suicide (Yaegaki and Coil 1999). Some researchers have dichotomously subclassified these patients into “Pseudohalitosis” and “Halitophobia” based on their treatment response and need of psychiatric consultation (Yaegaki and Coil 2000). Alternatively, other researchers regard “Halitophobia” as a “mild to severe” spectrum of conditions that includes any level of exaggerated concern of having a breath odor problem (Rosenberg and Leib 1997).

Psychological Aspects of Breath Odors

Bad breath is no laughing matter for the child or adolescent who has it. Most cases can be alleviated by relatively simple measures, but not before the cause is pinpointed by a targeted history and physical exam.

Mel Rosenberg

Papers

Workshop 2 Odor measurements using instruments and other laboratory tests (GC, GCMS, Halimeter, Sensors, HPLC, OK2KISS, BANA etc)

The quadloop: a novel device for plating and streaking microbial samples

Bad breath and exhaled breath analysis—common fields with common denominators

Psychological Aspects of Breath Odors

Beating bad breath