A predominance of Lactobacillus species in the vaginal flora is considered normal. In women with bacterial vaginosis, the prevalence and concentrations of intravaginal Gardnerella vaginalis and anaerobes are increased, whereas the prevalence of intravaginal Lactobacillus species is decreased. Because some lactobacilli are known to produce hydrogen peroxide (H2O2), which can be toxic to organisms that produce little or no H2O2-scavenging enzymes (e.g., catalase), we postulated that an absence of H2O2-producing Lactobacillus species could allow an overgrowth of catalase-negative organisms, such as those found among women with bacterial vaginosis. In this study, H2O2-producing facultative Lactobacillus species were found in the vaginas of 27 (96%) of 28 normal women and 4 (6%) of 67 women with bacterial vaginosis (P less than 0.001). Anaerobic Lactobacillus species (which do not produce hydrogen peroxide) were isolated from 24 (36%) of 67 women with bacterial vaginosis and 1 (4%) of 28 normal women (P less than 0.001). The production of H2O2 by Lactobacillus species may represent a nonspecific antimicrobial defense mechanism of the normal vaginal ecosystem.

Prevalence of hydrogen peroxide-producing Lactobacillus species in normal women and women with bacterial vaginosis.

The vaginal microflora of healthy asymptomatic women consists of a wide variety (two to five isolates at any one time) of anaerobic and aerobic bacterial genera and species dominated by the facultative, microaerophilic, anaerobic genus Lactobacillus. That the vaginal flora forms part of a dynamically changing ecosystem is evident from the variable prevalence and population levels of each bacterial species detected with repetitive longitudinal sampling, with pregnancy, and with stage in the menstrual cycle. This review emphasizes the role that vaginal lactobacilli may play in control of the vaginal microflora and maintenance of the normal state. Lactobacilli possess many antagonistic properties and produce many metabolites that may be important in maintaining dominance in the vagina. Contradictory data from previous studies regarding the impact of factors such as contraception, catamenial products, and physiologic elements on the vaginal microflora are due in part to poor study design and differences in methodology. Well-designed and controlled investigations with large numbers of individuals in each group are needed, and the limitations of the methodology for such investigations must be considered. Studies of the normal flora, exploring the interaction of lactobacilli and other bacterial species, must be performed before the pathologic processes resulting in vaginitis or systemic sequelae are investigated. The healthy human body harbors an extensive number of microorganisms that inhabit surfaces and cavi

Emerging role of lactobacilli in the control and maintenance of the vaginal bacterial microflora.

An inverse correlation between colonization of the human nasopharynx by Streptococcus pneumoniae and Haemophilus influenzae, both common upper respiratory pathogens, has been reported. Studies were undertaken to determine if either of these organisms produces substances which inhibit growth of the other. Culture supernatants from S. pneumoniae inhibited growth of H. influenzae, whereas culture supernatants from H. influenzae had no effect on the growth of S. pneumoniae. Moreover, coculture of S. pneumoniae and H. influenzae led to a rapid decrease in viable counts of H. influenzae. The addition of purified catalase prevented killing of H. influenzae in coculture experiments, suggesting that hydrogen peroxide may be responsible for this bactericidal activity. H. influenzae was killed by concentrations of hydrogen peroxide similar to that produced by S. pneumoniae. Hydrogen peroxide is produced by the pneumococcus through the action of pyruvate oxidase (SpxB) under conditions of aerobic growth. Both an spxB mutant and a naturally occurring variant of S. pneumoniae, which is downregulated in SpxB expression, were unable to kill H. influenzae. A catalase-reversible inhibitory effect of S. pneumoniae on the growth of the respiratory tract pathogens Moraxella catarrhalis and Neisseria meningitidis was also observed. Elevated hydrogen peroxide production, therefore, may be a means by which S. pneumoniae is able to inhibit a variety of competing organisms in the aerobic environment of the upper respiratory tract.

Inhibitory and Bactericidal Effects of Hydrogen Peroxide Production by Streptococcus pneumoniae on Other Inhabitants of the Upper Respiratory Tract

Large discrepancies in the available data on skin microbiology stimulated investigations of the number, interactions, and location of commensals and the true efficiency of disinfection by using skin biopsy, culture of frozen sections, and other methods.Most current procedures were less than 0.5% as sensitive as the biopsy method described. This gave mean bacterial counts ranging from 4,400/cm(2) on the breast to 400,000/cm(2) in the axillae. An iodine preparation removed 95% of accessible organisms, but about 20% of bacteria were protected by follicles, crevices, and lipids. Commensals in over 20% of people produced antibiotics against a wide range of pathogens. Conversely, "satellitism" was demonstrable in 12% of people.

https://www.bmj.com/content/bmj/1/5793/136.full.pdf

Skin Bacteria and Skin Disinfection Reconsidered

Further observations on an inhibitory substance (nisin) from lactic streptococci.

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The Inhibitory Action of Saliva on the Diphtheria Bacillus: The Antibiotic Effect of Salivary Streptococci.

Except where otherwise noted, all tests for inhibition were made by placing standard drops of he materials to be tested on the surfaces of agar pour plates containing various concentrations of diphtheria bacilli. The zones of growth inhibition around the drops were measured after suitable incubation. Details of the method, description of the medium and of the diphtheria bacillus strain used in the tests were given in the previous

The inhibitory action of saliva on the diphtheria bacillus: hydrogen peroxide, the inhibitory agent produced by salivary streptococci.

SummaryA spontaneous epizootic of encephalomyelitis which killed 62%percnt; of 240 uninoculated mice is described. A virus was isolated which resembles GD VII virus in its properties, and which is ...

Richard Thompson

Papers

The Inhibitory Action of Saliva on the Diphtheria Bacillus: The Antibiotic Effect of Salivary Streptococci.

The inhibitory action of saliva on the diphtheria bacillus: hydrogen peroxide, the inhibitory agent produced by salivary streptococci.

A spontaneous epizootic of mouse encephalomyelitis.