Microbial Overgrowth Research Articles

Cleavage of human complement component C5 by cysteine proteinases from Porphyromonas (Bacteroides) gingivalis. Prior oxidation of C5 augments proteinase digestion of C5.

Since severe periodontitis is characterized by an acute inflammatory response with cellular infiltration and microbial overgrowth, plasma proteins could be exposed to both proteinases and oxidants released from the granulocytes, as well as to proteinases from the microorganisms. When human complement component C5 was digested by cysteine proteinases (i.e. gingipain-R and gingipain-K) from Porphyromonas gingivalis, limited cleavage of the C5 molecule was observed. If C5 was first oxidized by hydroxyl radicals, these gingipains converted modified C5 to fragments that exhibited significantly greater pro-inflammatory activity than did digests of unmodified C5. After cleavage of oxidized C5 by gingipain-R, the digest exhibited measurably greater neutrophil enzyme release and chemotaxis of human polymorphonuclear leukocytes (PMNs) compared with the activities of unoxidized C5 digests. Gingipain-K generates virtually no polarization or chemotactic activity of human PMNs from C5, nor is enzyme release stimulated by these C5 digests. However, when oxidized C5 was digested by gingipain-K, human PMNs were stimulated for polarization, chemotaxis and enzyme release indicating that an active fragment had been generated. Proteolysis of oxidized C5 evokes greater neutrophil activation than does proteolysis of unoxidized protein, a fact which supports the hypothesis that oxidation and proteolysis may be coupled to enhance the destructive effects of the inflammatory process. These results, in which digests of both oxidized and unmodified complement component C5 were evaluated, support the general concept that oxidation and proteolysis may participate cooperatively in amplifying both the severity and duration of the inflammatory reaction.

Microbial colonization of the Groningen speaking valve and its relationship to valve failure.

Speaking valve failure may be related to biofilm development. An inter-observer validated method of assessing microbial overgrowth in defective prostheses was developed. Two independent observers recorded colonisation of the valves on a 100 mm linear analogue scale in several defined areas. Inter-observer agreement was high in all areas. In vitro opening pressure and derived forward resistances were measured. The relationship between colonization of the valves and the in vitro measurements was investigated. Significant correlations for a two-tailed Spearman's test were recorded between the resistance and microbial colonization of the hinge and oesophageal areas (rs 0.22: P < 0.05, rs 0.25: P < 0.05, n = 80). There was no significant association for resistance and colonization of the tracheal surface, and no significant association between the opening pressure and the colonization. This work suggests that microbial colonization of the prosthesis in the oesophageal and hinge areas is associated with valve failure.

Gastroduodenal motility in mechanically ventilated critically ill patients

To determine the main characteristics of gastroduodenal motility in mechanically ventilated, critically ill patients. Case series; comparison with a parallel control group. Intensive care unit in a university teaching hospital. Twelve adult critically ill patients who required > 2 days of mechanical ventilation as a consequence of neurologic or respiratory disease. Control sample of 12 overnight, fasting, healthy volunteers. Pressure changes in the gastric antrum, proximal duodenum, and distal duodenum were simultaneously recorded during a 4-hr period by a multilumen tube (perfused catheter technique). The migrating motor complex and its three successive phases were identified according to usual definitions (phase 1, period of quiescence; phase 2, period of irregular contractile activity; phase 3 or activity front, period of high-frequency, regular contractions). Contractions and activity fronts at each site were quantified. The mean duration of the migrating motor complex was determined in the duodenum, as well as the contribution of each phase (phases 1, 2, 3) to the length of the complete cycle. The propagation characteristics of each activity front were assessed visually. In the patients, the number of contractions was markedly decreased in the antrum, where activity fronts were totally absent. In the duodenum (proximal and distal), the number of contractions and the occurrence of activity fronts were comparable in both groups. Although the duration of the duodenal migrating motor complex was similar in the two groups, the relative contribution of the quiescence period (phase 1) to the total cycle length increased and the contribution of phase 2 decreased in the patients. Three patients exhibited abnormally propagated (retrograde or stationary) activity fronts in the duodenum. Gastroduodenal motility is severely impaired in this group of mechanically ventilated patients. Activity fronts of the migrating motor complex never originated in the stomach, which was hypokinetic; qualitative disorders of the migrating motor complex were present in the duodenum. The loss of peristaltic activity in the stomach and, to a lesser degree, in the duodenum is consistent with an important role for motility disorders in the occurrence of digestive microbial overgrowth in such patients.

Untreated diabetes mellitus promotes intestinal microbial overgrowth

Gastrointestinal dysfunction is a common secondary complication of insulin-dependent diabetes mellitus, yet its etiology is unclear. Enteric microbial overgrowth may play a role. To quantitate the changes in mucosal-adherent enteric microbial populations in untreated diabetes mellitus and to assess the impact of two forms of insulin replacement therapy upon enteric microbial populations, age-matched male Lewis rats were rendered diabetic by the administration of intravenous streptozotocin (55 mg/kg). After diabetes was confirmed (blood glucose level greater than 250 mg/dL), rats were divided into three groups: no treatment (no insulin), treatment with daily insulin to maintain normoglycemia (3 to 7 units of protamine zinc insulin subcutaneously), or transplantation with a vascularized heterotopic duct-ligated pancreatic isograft. After 1 month, rats were killed, and segments of the proximal, middle, and distal small bowel were obtained. Mucosal samples were rinsed in phosphate-buffered saline to remove nonadherent bacteria prior to aerobic and anaerobic culturing. Microbial recovery was expressed as the log 10 colony-forming unit/mg tissue wet weight. Untreated diabetes resulted in an overgrowth of mucosal-associated small bowel aerobic and anaerobic microbial populations compared with populations in normal nondiabetic age-matched control rats. Insulin treatment and pancreatic transplantation prevented microbial overgrowth in the diabetic small intestine. Pancreatic transplantation resulted in strict normoglycemia equivalent to that in nondiabetic control rats, whereas insulin treatment resulted in slightly higher blood glucose levels at sacrifice and wide fluctuations in blood glucose levels compared with nondiabetic control rats. These data suggest that sustained normalization of glucose levels is not required to prevent microbial overgrowth in diabetic rats.

Clinical significance of changes of flora in the upper digestive tract

Dysbiosis does not necessarily mean disease. Typical clinical picture of disease caused by metabolic activity of dysbiotic microflora is the microbial over-growth syndrome. We studied case histories of 434 patients without consideration of their basic illnesses and correlated them with types of dysbioses of duodenal juice. 55% of 314 patients with gastrointestinal disorders revealed a dysbiosis. A dysbiosis could also be found in up to 64% of pancreatic diseases, whereas intestinal dysfunctions and chronic inflammatory diseases usually show normal colonization. These cases express alteration of milieu conditions and disturbed interorganic connections. We only treated cases with objective pathological findings, obtaining best results with chemotherapeutic treatment of dysbioses with only one species.

Recent studies on the microbial ecology of the upper gastrointestinal tract

Microecological problems have escalated recently in clinical medicine. We studied the microecology of the upper small bowel. Duodenal flora was examined, displaying microbial growth in 90.8% of the 400 patients examined. The microflora was classified according to germ quality into definite types of colonization. Frequency of microbial colonization is normally 36.7% and 63.3% by overgrowth, indicating differing dysbioses. Simulation of microbial overgrowth in the duodenum is possible with a continuous-flow culture, demonstrating a biocenosis of several groups of micro-organisms with great metabolic activity. Continuous culture technique suggests possibilities for future studies of human gastrointestinal microecology.

IMPACT OF PARENTAL ANTIBIOTICS (AB) IN THE FECAL FLORA OF NEWBORN AND INFANTS

Digestive tract troubles and selection of resistant are the known effects of (AB). We demonstrated that they can also give a disturbance of the intestinal microbial ecosystem (IME), causing overgrowth and/or decrease or disappearance of certain bacterial species. The bacterial overgrowth in (IME) can be the starting point of secondary systemic infections in newborn. MATERIAL AND METHODS : The effects of 10 (AB) were analyzed using the differential qualitative and quantitative technic which numerates all the bacteria present in the fecal flora. In 20 neonates having a secondary systemic infection, we studied the modifications of the (IME) sequentially, before, during and after AB. RESULTS : 1 - (AB) given by parenteral route, if they are secreted in the intestinal tract, can cause a microbial overgrowth depending of the (AB) administered : Penicillin G (6) : E. coli + Klebsiella ; Ampicillin (11) : Klebsiella + Enterobacter ; Cefotaxime (25) : Pseudomonas aeruginosa ; Cefoperazone (9) : yeasts ; Cefotiam (10) : Enterobacter ; Fosfomycin (7) : Enterobacteriacae ; Mezlocillin (9), Colistin (11), Aminoglycosides (25) : no overgrowth. 2 - In 20 neonates with a septicemia accuring during (AB), we demonstrated the sequence : normal (IME) before (AB) ; overgrowth of a bacterial species during AB and septicemia due to the same bacterial species, in a variable delay. (AB) in cause were Ampicillin (10), Penicillin G (6) and Cefotaxim (4). CONCLUSIONS : The (AB) effects in the equilibrium of the (IME) must be kept in mind to explain most of the acquired infection in newborn.

Virus adsorption to mineral surfaces is reduced by microbial overgrowth and organic coatings

In experiments with strains of poliovirus, reovirus, echovirus, and Coxsackievirus, overgrowth with exopolymer-forming bacteria reduced virus adsorption to mineral surfaces. Adsorption was improved when organic materials adsorbed to minerals were removed by low-temperature ashing. In a soil series, virus adsorption increased with soil depth. This paralleled a decrease in organic content, but differences in charge development of the soil particles may also be involved. Prolonged (40-year) irrigation with treated sewage effluents, leading to a buildup of organic coatings, also decreased adsorption. However, saturation of the virus-binding capacity of the soil as a result of continuous exposure to virus-containing effluents was not apparent.

VI. Poultry

Milk’s combination of water, fats, proteins, and vitamins allows for the growth of a variety of bacteria, especially psychrotrophic bacteria that are able to grow under cold conditions. Raw milk, pasteurized milk, cheese, and other dairy products support different and diverse groups of microorganisms which can cause product spoilage. Light can also contribute to the spoiling of dairy products. There are many techniques, however, such as pasteurization and special packaging, which are used to protect these dairy products from the adverse effects of microbial overgrowth and light. Farmers, dairy processors, and consumers use many methods to measure the degree of spoilage and gage milk quality. Preventing microbial growth and extending shelf life not only can alleviate costs for producers, retailers, and consumers, but also can limit the environmental impact of dairy product production and consumption.

STOMACH AS SOURCE OF BACTERIA COLONISING RESPIRATORY TRACT DURING ARTIFICIAL VENTILATION

10 adults had intermittent positive-pressure ventilation for 3-34 days. All 10 had paralytic ileus. Microbial overgrowth in the stomach was found in 9 patients (bacterial in 7 and fungal in 2); gram-negative bacteria predominated. The trachea invariably became colonised by bacteria, mainly gram-negative organisms. In 3 instances the gram-negative bacteria were found in the stomach before they appeared in the tracheal aspirate, and in 1 case the pathogen originated in the fæces.

A new substrate for the rapid evaluation of enteric microbial overgrowth.

The possibility of a new approach to diagnosis of intestinal bacterial overgrowth has been evaluated in laboratory animals. The diagnostic test involves oral administration of an enzyme-labile substrate consisting of para-aminobenzoic acid (PABA) conjugated to a bile acid. In the presence of enteric bacteria, PABA is split from the bile acid and is rapidly absorbed and excreted in the urine. The amount of PABA recovered during the 6 hr following the administered dose of the conjugate may be used as an index of bacterial overgrowth in the upper-gastrointestinal tract. The procedure has been shown to be a reliable index of this condition in laboratory animal models.

RNA and DNA of gastric and duodenal mucosa in antrectomized and gastrin-treated rats.

RNA and DNA of gastric and duodenal mucosa in antrectomized and gastrin-treated rats.

Amyloidosis associated with primary agammaglobulinemia, severe diarrhea and familial hypogammaglobulinemia

A twenty-five year old man, who had had recurrent respiratory tract infections from the age of eight, was found to have primary agammaglobulinemia. Its congenital character was ascertained by the discovery in the proband's family of a twelve year old niece who since the age of five had had superinfected bronchiectases and was found to have a deficiency in serum immunoglobulins. Gastrointestinal disturbances in the proband were associated with widespread amyloid involvement of the digestive tract, liver and kidneys. Mild malabsorption was present, with giardiasis and moderate microbial overgrowth in the intestinal aspirate. The intestinal submucosa showed an absolute lack of IgA-containing plasma cells. The coexistence of primary agammaglobulinemia and amyloidosis has been reported in detail in five of more than 300 published cases of primary agammaglobulinemia. The cases in question, including our own, illustrate the development of amyloidosis in the absence of immunoglobulin synthesis, and raise pertinent questions regarding the pathogenesis of amyloid.