The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.

Wound microbiology and associated approaches to wound management.

Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Evidence-based guidelines for managing patients with intra-abdominal infection were prepared by an Expert Panel of the Surgical Infection Society and the Infectious Diseases Society of America. These updated guidelines replace those previously published in 2002 and 2003. The guidelines are intended for treating patients who either have these infections or may be at risk for them. New information, based on publications from the period 2003-2008, is incorporated into this guideline document. The panel has also added recommendations for managing intra-abdominal infection in children, particularly where such management differs from that of adults; for appendicitis in patients of all ages; and for necrotizing enterocolitis in neonates.

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Diagnosis and Management of Complicated Intra-abdominal Infection in Adults and Children: Guidelines by the Surgical Infection Society and the Infectious Diseases Society of America

Quantitative and qualitative examination of the fecal flora of 20 clinically healthy Japanese-Hawaiian males was carried out by using anaerobic tube culture techniques Cultural counts were 93% of the microscopic clump counts Isolated colonies were selected in a randomized manner to give an unbiased sampling of the viable bacterial types Each isolate was characterized for species identification From a total of 1,147 isolates, 113 distinct types of organisms were observed Statistical estimates indicate that these types account for 94% of the viable cells in the feces The quantitative composition of the flora of this group of people, together with differential characteristics of previously unreported species, is presented for those kinds of bacteria which each represented at least 005% of the flora

Human fecal flora: the normal flora of 20 Japanese-Hawaiians.

The microbiota of an animal's intestinal tract plays important roles in the animal's overall health, productivity and well-being. There is still a scarcity of information on the microbial diversity in the gut of livestock species such as cattle. The primary reason for this lack of data relates to the expense of methods needed to generate such data. Here we have utilized a bacterial tag-encoded FLX 16s rDNA amplicon pyrosequencing (bTEFAP) approach that is able to perform diversity analyses of gastrointestinal populations. bTEFAP is relatively inexpensive in terms of both time and labor due to the implementation of a novel tag priming method and an efficient bioinformatics pipeline. We have evaluated the microbiome from the feces of 20 commercial, lactating dairy cows. Ubiquitous bacteria detected from the cattle feces included Clostridium, Bacteroides, Porpyhyromonas, Ruminococcus, Alistipes, Lachnospiraceae, Prevotella, Lachnospira, Enterococcus, Oscillospira, Cytophage, Anaerotruncus, and Acidaminococcus spp. Foodborne pathogenic bacteria were detected in several of the cattle, a total of 4 cows were found to be positive for Salmonella spp (tentative enterica) and 6 cows were positive for Campylobacter spp. (tentative lanienae). Using bTEFAP we have examined the microbiota in the feces of cattle. As these methods continue to mature we will better understand the ecology of the major populations of bacteria the lower intestinal tract. This in turn will allow for a better understanding of ways in which the intestinal microbiome contributes to animal health, productivity and wellbeing.

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Evaluation of the bacterial diversity in the feces of cattle using 16S rDNA bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP)

Anearobic bacteria in human disease , Anearobic bacteria in human disease , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Anaerobic bacteria in human disease

Anaerobic Infections in Humans

The susceptibility trends for the species of the Bacteroides fragilis group against various antibiotics from 1997 to 2004 were determined by using data for 5,225 isolates referred by 10 medical centers. The antibiotic test panel included ertapenem, imipenem, meropenem, ampicillin-sulbactam, piperacillin-tazobactam, cefoxitin, clindamycin, moxifloxacin, tigecycline, chloramphenicol, and metronidazole. From 1997 to 2004 there were decreases in the geometric mean (GM) MICs of imipenem, meropenem, piperacillin-tazobactam, and cefoxitin for many of the species within the group. B. distasonis showed the highest rates of resistance to most of the β-lactams. B. fragilis, B. ovatus, and B. thetaiotaomicron showed significantly higher GM MICs and rates of resistance to clindamycin over time. The rate of resistance to moxifloxacin of B. vulgatus was very high (MIC range for the 8-year study period, 38% to 66%). B. fragilis, B. ovatus, and B. distasonis and other Bacteroides spp. exhibited significant increases in the rates of resistance to moxifloxacin over the 8 years. Resistance rates and GM MICs for tigecycline were low and stable during the 5-year period over which this agent was studied. All isolates were susceptible to chloramphenicol (MICs < 16 μg/ml). In 2002, one isolate resistant to metronidazole (MIC = 64 μg/ml) was noted. These data indicate changes in susceptibility over time; surprisingly, some antimicrobial agents are more active now than they were 5 years ago.

National Survey on the Susceptibility of Bacteroides fragilis Group: Report and Analysis of Trends in the United States from 1997 to 2004

Rifampin, 7-chlorolincomycin, vancomycin, and metronidazole (Flagyl@) were evaluated for bactericidal activity against Bacteroides fragilis. Tetracycline, a bacteriostatic agent, was included for comparative purposes. Standard tube-dilution determinations of MICs were done with brucella broth (Pfizer) plus 5% laked blood, followed by subculture onto blood-agar plates for determination of minimal bactericidal concentration (MBC). Metronidazole and 7-chlorolincomycin inhibited all 19 strains tested at concentrations readily achieved in serum; however, only metronidazole was consistently bactericidal (MBC, 0.78-6.25 ntg/ml). All strains were resistant to vancomycin and eight were resistant to tetracycline. Rifampin, although generally very active, demonstrated the "skip-tube phenomenon," suggesting that resistance to this agent may be a problem with anaerobes as with other organisms. In conclusion, metronidazole and 7-chlorolincomycin were effective in vitro against 19 strains of B. fragilis. Only metronidazole was consistently bactericidal. This agent, therefore, might be of benefit in the therapy of infections due to B. fragilis, particularly endocarditis.

Bactericidal Activity of Five Antimicrobial Agents against Bacteroides fragilis

Background. The rationale and lessons learned through the evolution of the National Survey for the Susceptibility of Bacteroides fragilis Group from its initiation in 1981 through 2007 are reviewed here. The survey was conceived in 1980 to track emerging antimicrobial resistance in Bacteroides species. Methods. Data from the last 11 years of the survey (1997-2007), including 6574 isolates from 13 medical centers, were analyzed for in vitro antimicrobial resistance to both frequently used and newly developed anti-anaerobic agents. The minimum inhibitory concentrations of the antibiotics were determined using agar dilution in accordance with Clinical and Laboratory Standards Institute recommendations. Results. The analyses revealed that the carbapenems (imipenem, meropenem, ertapenem, and doripenem) and piperacillin-tazobactam were the most active agents against these pathogens, with resistance rates of 0.9%-2.3%. In the most recent 3 years of the survey (2005-2007), resistance to some agents was shown to depend on the species, such as ampicillin-sulbactam against Bacteroides distasonis (20.6%) and tigecycline against Bacteroides uniformis and Bacteroides eggerthii (∼7%). Very high resistance rates (>50%) were noted for moxifloxacin and trovafloxacin, particularly against Bacteroides vulgatus. During that period of study, non-B. fragilis Bacteroides species had >40% resistance to clindamycin. Metronidazole-resistant Bacteroides strains were also first reported during that period. Conclusions. In summary, resistance to antibiotics was greater among non-B. fragilis Bacteroides species than among B. fragilis and was especially greater among species with a low frequency of isolation, such as Bacteroides caccae and B. uniformis. The emergence of resistance among the non-B. fragilis Bacteroides species underscores the need for speciation of B. fragilis group isolates and for clinicians to be aware of associations between species and drug resistance.

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Sydney M. Finegold

Papers

Anaerobic bacteria in human disease

Anaerobic Infections in Humans

National Survey on the Susceptibility of Bacteroides fragilis Group: Report and Analysis of Trends in the United States from 1997 to 2004

Bactericidal Activity of Five Antimicrobial Agents against Bacteroides fragilis

Lessons Learned from the Anaerobe Survey: Historical Perspective and Review of the Most Recent Data (2005-2007)