Cause or Therapy?
When it comes to diarrhea, antibiotics can be both the cause and the cure. These drugs are used successfully in the treatment of severe diarrheal episodes (dysentery) caused by parasitic infestations or bacterial infections: traveller's diarrhea, salmonellosis, shigellosis, leishmaniasis, giardiasis, campylobacteriosis, klebsiella, cholera, amoebiasis.
However, antibiotics can also be the primary cause of the problem in the diaries that are caused by viruses (viral gastroenteritis, better known as intestinal, rotavirus or Norwalk virus influences).
Risk factors
The information regarding the antibiotics most implicated in the onset of diarrheal manifestations is rather inhomogeneous; greater homogeneity is noted instead in defining common risk factors, such as immunosuppression, the age above 60 years, prolonged hospitalization, the use of broad-spectrum drugs, the long duration of antibiotic therapy and the combined treatment with more antibiotics.
Symptoms
The clinical presentation of diarrhea caused by antibiotics is variable, also in relation to the aforementioned risk factors, and may range from mild or transient episodes to pseudomembranous colitis, characterized by necrosis of the colorectal mucosa and profuse diarrhea with mucorrhea, blood in the stool and - in the most serious cases - from fearful complications, with toxic megacolon, intestinal perforation, hypokalaemia, intestinal haemorrhage, and sepsis.
Causes
Diarrhea associated with antibiotics is mainly caused by the destruction of the normal microbial flora of the large intestine, consequent to the use of the drug. With a concentration of several billion bacteria per gram of intestinal content, the bacterial flora of the colon forms an ecosystem that prevents the overgrowth of opportunistic pathogenic species, subtracting nourishment from them, secreting substances with antibiotic activity and competing for the sites of adhesion to the enteric mucosa. This protective action of the intestinal microflora is lost when the "friendly" bacterial population is decimated by the bactericidal effect of antibiotic therapy; consequently there is a risk that pathogenic species colonize the large intestine causing inflammation (colitis) accompanied by diarrhea. The overgrowth of the Clostridium difficile bacterium, for example, accounts for 10-25% of episodes of diarrhea associated with antibiotics and is the causative agent - in the most serious infectious episodes - of the aforementioned pseudomembranous colitis. The same applies to other bacterial, fungal and parasitic species, such as C. perfringens, Staphylococcus aureus, Candida spp, Klebsiella oxytoca, and Salmonella spp. The bacterial alteration is also associated with a state of suffering of the intestinal mucosa, with alteration of its absorption capacity; the lack of assimilation of fatty acids, for example, favors the appearance of diarrhea.
Treatment
In the case of diarrhea associated with antibiotics it is advisable, when possible, to suspend the antibiotic therapy considered responsible for the disorder, or in any case replace it. At the same time it may be necessary to opt for antibiotics directed against the causative agent responsible for diarrhea, such as metronidazole, vancomycin or fidaxomicin in case of Clostridium difficile infections. As in all cases of diarrhea, rehydration therapy for the treatment or prevention of dehydration and electrolyte disorders, to be carried out by replenishing liquids and salts orally or, in the most serious cases, intravenously, is of fundamental importance.
| Composition of the Oral Rehydration Solution of WHO / UNICEF | ||
Sodium chloride (NaCl) | g | 3.5 |
Glucose | g | 20.0 |
(or cooking sugar) | g | 40.0 |
Sodium bicarbonate | g | 2.5 |
Potassium chloride (KCl) | g | 1.5 |
Water (boiled or disinfected) | ml | 1000 |
However, classical antidiarrheal drugs are contraindicated, unless otherwise prescribed by a doctor, since - by slowing down the peristaltic movements - they tend to increase the time the toxins remain in the large intestine.
Probiotics
Since diarrhea associated with antibiotics is caused primarily by the alteration of the intestinal microbial flora, the therapeutic and preventive efficacy of a supplementation of specific probiotic strains ( Lactobacillus acidophilus, L casei GG, L bulgaricus, Bifidobacterium bifidum, B longum, Enterococcus faecium, Streptococcus thermophilus, or Saccharomyces boulardii ) has been investigated in numerous studies, obtaining promising but sometimes discordant results. To learn more, read: Probotics and Diarrhea.
