Bacteria belonging to the genus Klebsiella frequently cause human nosocomial infections. In particular, the medically most important Klebsiella species, Klebsiella pneumoniae, accounts for a significant proportion of hospital-acquired urinary tract infections, pneumonia, septicemias, and soft tissue infections. The principal pathogenic reservoirs for transmission of Klebsiella are the gastrointestinal tract and the hands of hospital personnel. Because of their ability to spread rapidly in the hospital environment, these bacteria tend to cause nosocomial outbreaks. Hospital outbreaks of multidrug-resistant Klebsiella spp., especially those in neonatal wards, are often caused by new types of strains, the so-called extended-spectrum-β-lactamase (ESBL) producers. The incidence of ESBL-producing strains among clinical Klebsiella isolates has been steadily increasing over the past years. The resulting limitations on the therapeutic options demand new measures for the management of Klebsiella hospital infections. While the different typing methods are useful epidemiological tools for infection control, recent findings about Klebsiella virulence factors have provided new insights into the pathogenic strategies of these bacteria. Klebsiella pathogenicity factors such as capsules or lipopolysaccharides are presently considered to be promising candidates for vaccination efforts that may serve as immunological infection control measures.

/pdf/klebsiella-spp-as-nosocomial-pathogens-epidemiology-taxonomy-1qbzenizx4.pdf

Klebsiella spp. as Nosocomial Pathogens: Epidemiology, Taxonomy, Typing Methods, and Pathogenicity Factors

Toll-like receptor 2 functions as a pattern recognition receptor for diverse bacterial products

Protectants used in the cryopreservation of microorganisms

Background: This study was undertaken to characterize the vaginal microbiota throughout normal human pregnancy using sequence-based techniques. We compared the vaginal microbial composition of non-pregnant patients with a group of pregnant women who delivered at term. Results: A retrospective case–control longitudinal study was designed and included non-pregnant women (n = 32) and pregnant women who delivered at term (38 to 42 weeks) without complications (n = 22). Serial samples of vaginal fluid were collected from both non-pregnant and pregnant patients. A 16S rRNA gene sequence-based survey was conducted using pyrosequencing to characterize the structure and stability of the vaginal microbiota. Linear mixed effects models and generalized estimating equations were used to identify the phylotypes whose relative abundance was different between the two study groups. The vaginal microbiota of normal pregnant women was different from that of non-pregnant women (higher abundance of Lactobacillus vaginalis, L. crispatus, L. gasseri and L. jensenii and lower abundance of 22 other phylotypes in pregnant women). Bacterial community state type (CST) IV-B or CST IV-A characterized by high relative abundance of species of genus Atopobium as well as the presence of Prevotella, Sneathia, Gardnerella, Ruminococcaceae, Parvimonas, Mobiluncus and other taxa previously shown to be associated with bacterial vaginosis were less frequent in normal pregnancy. The stability of the vaginal microbiota of pregnant women was higher than that of non-pregnant women; however, during normal pregnancy, bacterial communities shift almost exclusively from one CST dominated by Lactobacillus spp. to another CST dominated by Lactobacillus spp. Conclusion: We report the first longitudinal study of the vaginal microbiota in normal pregnancy. Differences in the composition and stability of the microbial community between pregnant and non-pregnant women were observed. Lactobacillus spp. were the predominant members of the microbial community in normal pregnancy. These results can serve as the basis to study the relationship between the vaginal microbiome and adverse pregnancy outcomes.

/pdf/the-composition-and-stability-of-the-vaginal-microbiota-of-2ovue5t683.pdf

The composition and stability of the vaginal microbiota of normal pregnant women is different from that of non-pregnant women

Biology of Borrelia species.

Factors influencing colonisation and antibiotic-resistance patterns of gram-negative bacteria in hospital patients.

Borrelia hispanica from infected guinea pigs and Treponema pallidum from testicular syphilomas of rabbits were assayed for the presence of endotoxin with the Limulus lysate test. A suspension of Borrelia, containing 1.3 × 108 spirochetes/ml, was nonreactive both when it was tested as intact organisms, and when tested after disruption of the spirochetes by sonication. Eight different suspensions of treponemes, ranging from 0.6 × 109 to 3 × 109 treponemes/ml, were negative at a 1:10 dilution and were no more active than control suspensions of normal rabbit testes. Therefore, it was concluded that T. pallidum, as well as the Borrelia, possessed no endotoxin.

Lack of endotoxin in Borrelia hispanica and Treponema pallidum.

A newborn had congenital syphilis, which was characterized by wide-spread infection of meninges, liver, pancreas, peritoneum, and long bones. In spite of treatment given to the mother ten days prior to delivery, and massive doses of penicillin G potassium given to the infant for 17 days after birth, viable and virulent Treponema pallidum were recovered from both the aqueous fluid and ground eye tissue removed at the autopsy, which was performed when the child died at age 22 days.

Failure of penicillin in a newborn with congenital syphilis.

Influence of lysozyme upon the treponeme immobilization reaction.

Hardy, Paul H., Jr. (Johns Hopkins University, Baltimore, Md.) and E. Ellen Nell. Influence of osmotic pressure on the morphology of the Reiter treponeme. J. Bacteriol. 82: 967–978. 1961.—Spherical bodies similar to those that develop spontaneously in cultures of treponemes, and which have been considered by many investigators to represent one stage in a complex life cycle of these organisms, can be produced rapidly with the Reiter treponeme by merely altering the medium in which the organisms are suspended. Osmotic pressure appears to be the major factor responsible for this effect, as shown by the observation that treponemes suspended in NaCl solutions of 0.15 to 0.10 m retain their spirochetal morphology, whereas organisms suspended in more dilute salt solutions rapidly become spherical. Moreover, the concentration of salt appears to influence both the rate and extent of sphere formation. Further evidence that osmotic pressure is primarily involved is demonstrated by the selectivity of the conditions under which spheres form. Treponemes suspended in various 0.3 osmolal solutions either retain their spiral shape or form spheres, depending upon the nature of the solute. Viability studies of suspensions containing predominantly spherical forms, which have developed spontaneously or have been artificially induced, have failed to produce evidence that the resulting growth of treponemes came from the spheres. It is concluded, therefore, that the naturally occurring spheres probably arise as the result of an osmotic imbalance which develops between the cells and their environment, and that the spheres represent degenerative forms rather than an intermediate stage in a life cycle.

Paul H. Hardy

Papers

Factors influencing colonisation and antibiotic-resistance patterns of gram-negative bacteria in hospital patients.

Lack of endotoxin in Borrelia hispanica and Treponema pallidum.

Failure of penicillin in a newborn with congenital syphilis.

Influence of lysozyme upon the treponeme immobilization reaction.

Influence of osmotic pressure on the morphology of the reiter treponeme