Pathogen Of Low Virulence Research Articles

Chronic Bacterial Endophthalmitis

We studied a specific syndrome of uveitis secondary to intraocular bacterial pathogens of low virulence after extracapsular cataract extraction and intraocular lens implantation in three eyes. The onset of photophobia, visual impairment, conjunctival redness, and uveitis was delayed for four days to 12 weeks after surgery. Chronic inflammation persisted for five weeks to 16 months before a definitive diagnosis was made. Signs and symptoms were suppressed by administration of topical and systemic corticosteroids. Intraocular biopsy and antibiotic injection both established the cause as bacterial endophthalmitis and resulted in resolution of signs and symptoms. Staphylococcus epidermidis was cultured in two eyes and Achromobacter was cultured in one.

Vertical transmission of diseases and population dynamics of insects with discrete generations: A model

Regulation of insect populations with discrete generations by vertically transmitted diseases with short-lived propagules is discussed through the development of a mathematical model. It is concluded that regulation of host populations by such diseases can be achieved over a wide range of conditions and that this type of disease-host interaction can lead to stable damped oscillations or limit cycles of host density. Characteristics of such pathogens leading to stability of host populations include low virulence, imperfect vertical transmission, horizontal transmission late in the host's life cycle and low dispersion of propagules in the environment. Major features of the population dynamics of insects interacting with such diseases are (1) long, high amplitude cycles especially in marginal habitats where rates of increase are low; (2) regulation, even by low-virulence pathogens; (3) prolonged low host density between peaks; and (4) low average disease prevalence in cases of high virulence. Vertically transmitted diseases, though often of low virulence, may be essential elements of the population dynamics of many insect pests.

The mouse mastitis model: observations relevant to the treatment and control of coliform mastitis.

The response to intramammary inoculation ofEscherichia coli in mice is described and the contribution of endotoxin to the clinical signs is considered. The implications of these responses for therapy are examined. The role of the neutrophil is assessed and it is considered that the rate of arrival of neutrophils in the gland is of more importance in limiting infection than the number of existing neutrophils at the time of challenge. The effect of inducing a neutrophil response by colonization of the gland by a pathogen of low virulence is described and the dangers of inducing chronic infections are emphasised. Using a modification of the mouse model in which organisms are placed on the tip of damaged or undamaged teats of suckling or non-suckling mice it is demonstrated by the pattern of response that staphylococci actively colonize the teat and subsequently invade the gland whereasE. coli infections result from the chance entrance of contaminating organisms.

Aeromonas hydrophila Infection of the Skin

<i>A eromonas hydrophila</i>, a motile Gram-negative bacterium, has been only rarely reported as the cause of human disease. The organism was previously thought to be an opportunistic pathogen of low virulence often associated with polymicrobic infections and infections in debilitated patients, particularly those with neoplasms.¹More recent reports describe an increasing incidence of serious diseases resulting from primary infection with<i>A hydrophila</i>. These include septicemia, osteomyelitis, necrotizing myositis, endocarditis, meningitis, and wound infections.^2,3 Although skin and soft-tissue infections caused by<i>Aeromonas</i>sp rank second in frequency only to gastrointestinal tract infections, they are not well recognized and reported in the dermatology literature. Cutaneous manifestations may be accompanied by fever, malaise, and leukocytosis and include cellulitis, pustular eruptions, furunculosis, wound abscesses,³gas gangrene, and extensive ecthyma gangrenosum-like lesions, the latter occurring in patients with underlying malignant neoplasms. A few reports of primary wound infections describe intense local muscle

Aeromonas hydrophila infection of a puncture wound

Aeromonas hydrophila is a gram-negative organism generally considered a pathogen of low virulence, rarely reported as causing infection in man. Recently it has been recognized as causing infection in wounds. This article reports the case of a patient who suffered a puncture wound while standing in a fresh water lake. He subsequently developed a rapidly progressing cellulitis requiring hospitalization. This organism was cultured from the wound and responded dramatically to appropriate antimicrobial therapy.

Puerperal Fever With Haemophilus vaginalis Septicemia

A small gram-negative pleomorphic rod identified as Haemophilus vaginalis was isolated simultaneously from the blood and the endometrium of an 18-year-old woman with puerperal fever 72 hours after rupture of the membranes and 30 hours after an uncomplicated cesarean section. This organism is fastidious in its growth requirements and slow growing; it can easily be missed in the laboratory. Haemophilus vaginalis is a controversial pathogen of low virulence and has been found mainly in vaginitis. It may be a causative organism of puerperal fever.

Improved sampling method for demonstration of local antibodies in the vagina.

IN infections with pathogens of low virulence strictly localized to a few or single organs, it is often difficult, if not impossible, to obtain reliable diagnostic findings by means of tests for antibodies circulating in the blood stream. This holds true in particular if only some parts of a mucous membrane are involved. In such cases, however, it may prove practicable to utilize the local antibody production for diagnostic purposes.