Effects of antibiotics on caecal electrolyte transport and morphology in rats. Contribution to the pathogenesis of antibiotic-associated diarrhoea

Effect of Whole Grain Qingke (Tibetan Hordeum vulgare L. Zangqing 320) on the Serum Lipid Levels and Intestinal Microbiota of Rats under High-Fat Diet

This study investigated the hypolipidemic effect of whole grain Qingke (WGQ) and its influence on intestinal microbiota. Changes in the serum lipid, intestinal environment, and microbiota of Sprague-Dawley rats fed high-fat diets supplemented with different doses of WGQ were determined. Results showed that high doses of WGQ significantly decreased (P < 0.05) the Lee's index, serum total cholesterol, low-density lipoprotein cholesterol, and non-high-density lipoprotein cholesterol levels whereas they increased the body weight of the rats. Cecal weight and short-chain fatty acid (SCFA) concentration increased with increasing WGQ dose. An Illumina-based sequencing approach showed that the relative abundance of putative SCFA-producing bacteria Prevotella and Anaerovibrio increased in the rats fed the WGQ diet. Principal component analysis revealed a significant difference in intestinal microbiota composition after the administration of the WGQ diet. These findings provide insights into the contribution of the intestinal microbiota to the hypolipidemic effect of WGQ.

Absorption and bioavailability of glucosamine in the rat

The objective of this study was to determine reasons behind the low oral (p.o.) bioavailability of glucosamine. By using male Sprague-Dawley rats, the movement of glucosamine through everted gut, the effect of dose and glucose, and inhibition of a glucose transporter (GLUT2) by quercetin were studied. Glucosamine pharmacokinetics and the effect of dosing, route of administration, food and antibiotic to eradicate gut microflora was also studied. Both in vitro and in vivo studies demonstrated linear absorption kinetics for glucosamine. Absorption from duodenum was the greatest. Glucose had no effect on the transport, whereas quercetin significantly reduced the extent of glucosamine transport. Intraperitoneal doses were completely absorbed, whereas p.o. doses demonstrated low bioavailability, indicating the gut as the site of presystemic loss. Food had no significant effect on glucosamine pharmacokinetics. Antibiotic treatment resulted in strong trends towards increased bioavailability with significant increase in fecal recovery. Incubation of glucosamine with faeces resulted in a significant loss. Glucosamine's low bioavailability is, at least in part, due to its dependence on a transport-facilitated absorption and presystemic loss brought about by the gut microflora.

Antibiotic-induced mesenteric adenopathy in an intussusception mouse model: a randomized, controlled trial

BACKGROUND

Idiopathic intussusception is a leading cause of intestinal obstruction in young children. Although the etiology remains obscure, lymphoid hyperplasia is found in a majority of cases. Antibiotics, the most frequently prescribed medication class in the pediatric population, have been recently associated with intussusception. The authors sought to determine whether enteral antibiotic exposure influences the development of mesenteric adenopathy, bowel dilation or intussusception in an animal model.

MATERIALS AND METHODS

The authors conducted a randomized, controlled animal trial using a previously described intussusception model. Mice were gavaged with normal saline, amoxicillin-clavulanate or azithromycin twice daily for 5 days to assess the influence of enteral antibiotic exposure on intussusception, mesenteric adenopathy and bowel dilation. One pediatric surgeon performed all laparotomies and was blinded to group designation. Chi2 and Fisher exact tests were used to evaluate differences between antibiotic exposed and control groups.

RESULTS

Mesenteric adenopathy was identified in 4.1% of the normal saline controls compared with 54.1% (P < 0.01) and 38.9% (P < 0.01) of the amoxicillin-clavulanate and azithromycin exposed animals, respectively. A total of four intussusceptions were observed in the antibiotic-exposed groups combined whereas no intussusception cases were identified in the control group (P = 0.30).

CONCLUSIONS

This is the first study to describe a significant association between antibiotic use and mesenteric adenopathy in any animal species.

A comparative study of the repeat dose toxicity of grepafloxacin and a number of other fluoroquinolones in rats

Grepafloxacin is a new oral fluoroquinolone with potent activity against community acquired respiratory pathogens, including Streptococcuspneumoniae, and pharmacokinetic properties which allow once daily dosing. As part of its safety evaluation a study of 4 weeks duration was performed to compare the toxicity of grepafloxacin with that of a number of commercially available quinolones in the rat. Groups of eight male Sprague-Dawley rats received either control material or grepafloxacin, enoxacin, lomefloxacin, ofloxacin or ciprofloxacin at an oral dosage of 300 mg/kg/day for 4 consecutive weeks. Effects related to the antibacterial activity of the drugs were seen as increased caecal weight, decreased urinary excretion of sodium, increased water consumption, decreased urine volume, increased urine osmolality, soft stools and suppressed body weight gain. It is well documented that fluoroquinolones can cause lesions in the cartilage of the major diarthrodial joints, and blister formation or erosion on the joint surface was observed in all quinolone-treated groups other than the grepafloxacin group. Some quinolones, have been found to cause crystalluria, which is often associated with secondary nephropathy in laboratory animals due to the poor solubility of quinolones under the alkaline conditions of the urine. In the present study, needle-like crystals in the urinary sediment were observed in enoxacin and ciprofloxacin treated groups only. In conclusion, grepafloxacin was well tolerated and showed a low potential for joint toxicity and crystalluria compared to other quinolones.

Clostridium difficile toxin-induced colitis after use of clindamycin phosphate vaginal cream

OBJECTIVE

To report a case of toxin-positive Clostridium difficile-induced colitis (CDIC) after use of clindamycin phosphate vaginal cream.

CASE SUMMARY

A 25-year-old postpartum white woman developed multiple watery stools and abdominal cramping on day 6 of therapy with clindamycin vaginal cream for bacterial vaginosis. She received no other concomitant medications. The patient's stool sample was found to be positive for the C. difficile toxin. Due to the costs and risks of standard therapy, we decided to manage the patient supportively. Complete resolution of the diarrhea occurred shortly thereafter.

DISCUSSION

No published clinical studies in patients receiving clindamycin vaginal cream for bacterial vaginosis have documented C. difficile toxin in stool samples of patients with diarrhea. Approximately 5-6% of intravaginal clindamycin is absorbed in the bloodstream, making systemic effects possible.

CONCLUSIONS

This report indicates clindamycin phosphate vaginal cream as the most probable cause of CDIC due to the temporal relationship between the occurrence of diarrhea and clindamycin administration, lack of concomitant medications, and documentation of C. difficile toxin.

Adaptation of electrolyte transport in rat large intestine after proximal resection. I. Cecum and colon after 60% jejunoilectomy

Electrolyte transport was studied in rat cecum and colon adapting to 60% resection of the small intestine. Four weeks after surgery, the absorbing gross surface area, dry and wet weight, net absorption in vivo of sodium, chloride and volume, net potassium secretion, transmural electrical potential difference and mucosal Na-K-ATPase specific activity were determined. In the cecum, all tissue mass parameters were increased compared to sham-operated controls. Net transport was stimulated per organ but not per unit mass, and potential difference and Na-K-ATPase remained unaffected. In the colon, surface area and wet weight increased slightly while dry weight and electrolyte transport were not influenced. Thus, by enlargement without a change in cell function, the cecum but not the colon contributes to electrolyte homoeostasis after 60% jejunoilectomy in the rat. Na-K-ATPase specific activity and electrical potential difference were higher in the colon than the cecum, suggesting segmental heterogeneity of the larger bowel with respect to Na-K-ATPase-linked active sodium absorption.

[Clostridium difficile and antibiotic-associated colitis in risk patients: 2-month epidemiologic study in an intensive care unit]

A toxin produced by Clostridium difficile has been implicated in the pathogenesis of antibiotic-associated colitis. It is not known how often the microorganism is encountered in Germany particularly in high risk patients. Therefore, following a lethal case of colitis, stool samples of 90 patients and 30 staff members of an intensive care unit were screened routinely for C. difficile over 2 months. The organism was found in 6 of 41 patients treated with antibiotics (14.6%); four of them apparently acquired C. difficile while in hospital whereas in 2 a pre-existing carrier state could not be excluded. Colitis developed in 3 of the 6 patients as judged from endoscopy or a positive cytotoxin assay; in 2 patients (not subjected to endoscopy) colitis was suspected on clinical grounds, and 1 patient became an asymptomatic carrier. C. difficile was not found in 49 patients without antibiotic medication, in the health personal and in 12 patients of a general ward. Patients harbouring C. difficile were clustered in certain bed sites of the unit. Environmental studies recovered the microorganism from bed pan washing machines of bedridden and from toilets of ambulant patients but not from other sites like the hands of the personal. These results suggest that chronic carriers of C. difficile, as far as they are identified by current bacteriological methods, are rare in Germany (not more than 2 out of 132 persons investigated, i.e. 1.5%). The frequent finding of C. difficile in patients treated in certain bed sites supports the view that the infection may be acquired from exogenous sources. Antibiotic-associated colitis should be considered more often when intensive care patients are treated with antibiotics.

[Antibiotic-associated diarrhoea and enterocolitis (author's transl)]

Many antibiotics, particularly the lincomycins, may cause diarrhoea with or without enterocolitis. The pathogenesis of antibiotic-associated diarrhoea without colitis is uncertain; colloidosmotic water binding in the colon by endogenous glycoproteins undegraded by colonic bacteria is considered. Antibiotic-associated enterocolitis is now known to be due to toxin-producing clostridia, proven for Cl. difficile. Improved methods for the detection of toxin and clostridia are presently being studied. Endoscopically, pseudomembranes are characteristic but not antibiotic-specific, they may be absent or missed diagnostically. A possible role of asymptomatic clostridia-carriers in enterocolitis clustering remains to be determined. The potentially lethal course of the disease requires rapid diagnosis and therapy, with discontinuation of the antibiotic, intensive supportive measures and, at least in severe disease, oral vancomycin.