Antibiotics prescribing for infectious diarrhea

DEFINITION OF ACUTE DIAEEHEA ㅡ 3 or more episodes a day, < 14 day and sample takes shape of pot. Empirical treatment for patients well enough to be managed in primary care is not usually recommended because the majority of illnesses seen in the community do not have an identifiable bacterial cause. If Campylobacter is strongly suspected as the cause of diarrhea (e.g., undercooked meat and abdominal pain), consider empirical treatment with clarithromycin if treating early (within 3 days). Urgently refer all previously healthy children with acute painful, bloody diarrhea or confirmed E. coli O157.

WHEN TO INVESTIGATE

Send a stool specimen for culture and sensitivity if systemically unwell, blood or pus in the stool. It is necessary to exclude other pathologies; immunocompromised. Diarrhea occurs after high risk foreign travel (also request tests for ova, cysts, and parasites). Recent antibiotics or hospitalization (also request C. difficile) or diarrhea is persistent (e.g., > 1 week). Consider Bristol stool chart types 5-7, that is not clearly attributable to an underlying cause (e.g., laxatives). If the diarrhea has stopped, culture is rarely indicated, as recovery of the pathogen is unlikely.

          Consider blood tests if infection and other causes of acute diarrhea excluded and a chronic cause is suspected. Blood cultures should be considered in the following patients: infants < 3 months of age, immunocompromised patients, suspected enteric fever (by Salmonella Typhi or Salmonella Paratyphi), high-risk conditions (e.g., hemolytic anemia, travel to areas with known enteric fever with fever of unknown etiology), and cute diarrhea accompanied by signs of sepsis.

MANAGEMENT

GENERAL TREATMENT ㅡ Fluid replacement is essential and oral route is preferred. Avoid hyperosmolar foods such as canned fruit juices. If there is severe dehydration or oral route is not possible, consider IV rehydration (such as with Ringer lactate). Antibiotic use not recommended in most patients. Consider antibiotic therapy if symptoms severe (such as passage ≥ 6 stools daily or duration without improvement > 72 hours) or do not improve after rehydration therapy or antidiarrheal medication AND bacterial or parasitic pathogen strongly suspected such as with fever or bloody stool, especially if history and symptoms raise suspicion of systemic infection, suspected hospital-associated or antibiotic therapy-associated diarrhea and suspected traveler's diarrhea (characterized by ≥ 3 loose stools over 24-hour period shortly after or during travel), consider quinolone.

SPECIAL SITUATIONS ㅡ For gastroenteritis caused by Entamoeba histolytica, antibiotic treatment is usually recommended for all people with amoebiasis. The antibiotic of choice is metronidazole, followed by a 10-day course of diloxanide. The recommended doses for adults are:

• For mild-to-moderate intestinal amoebiasis, Metronidazole 500 mg three times a day for 5–10 days, followed by diloxanide 500 mg three times a day for 10 days.
  For amoebic dysentery, Metronidazole 500 mg three times a day for 5 days, followed by diloxanide 500 mg three times a day for 10 days. Tinidazole is an alternative to metronidazole.

          Gastroenteritis due to Salmonella infection. Consider antibiotic treatment for people who are older than 50 years of age, immunocompromised or have cardiac valve disease or endovascular abnormalities, including prosthetic vascular grafts. If antibiotic treatment is indicated, prescribe ciprofloxacin 500 to 750 mg twice a day for 7 days, or Ceftriaxone 1g q12hr or 2 gm q24hr for 10-14 day. Alternatives may be trimethoprim/sulfamethoxazole 800/160 mg 1 tab q12hr for 14 day, or azithromycin 500 mg 1-2 tab q24hr for 7 days.

Gastroenteritis caused by Shigella. Antibiotic treatment is not recommended for healthy people with mild shigellosis. Consider antibiotic treatment for people with severe disease, immunocompromised oe with bloody diarrhea. The antibiotics of choice are ciprofloxacin 500 mg twice a day for 3 day only, or 2 g single dose or azithromycin 500 mg once a day for 3 days.

Gastroenteritis caused by Giardia intestinalis. Prescribe antibiotic treatment for all people with confirmed giardiasis. Metronidazole is the drug of choice for treating giardiasis. Prescribe 400 mg three times a day for 5 days, or 500 mg twice a day for 7–10 days, or 2 grams once a day for 3 days. Tinidazole is an alternative to metronidazole.

Gastroenteritis caused by Campylobacter. If systemically unwell and campylobacter suspected consider azithromycin (Zithromax), 500 mg once per day for 3 to 5 days or clarithromycin 500 mg twice daily for 5-7 days if treated early within 3 days. Ciprofloxacin 500 mg twice a day for 5–7 days is an alternative to macrolides. Consider prolonged treatment if the patient is immunocompromised

Enteropathogenic/enteroinvasive - Escherichia coli. Ciprofloxacin, 500 mg twice per day for 3 days. or TMP/SMX DS, 160/800 mg twice per day for 3 days.

Gastroenteritis caused by Escherichia coli 0157 (VTEC). Management is entirely supportive; there is no specific treatment for gastroenteritis due to Vero cytotoxin-producing Escherichia coli 0157 (VTEC). Discuss the individual's management, including the use and frequency of baseline blood tests (for example full blood count, blood film for fragmented blood cells, urea and electrolytes, lactate dehydrogenase, and C-reactive protein) with a specialist clinician. Do not prescribe antibiotics. Avoid antibiotics due their potential association with the development of hemolytic-uremic syndrome (HUS). Avoid antimotility drugs, such as loperamide, and opioids. Advise against the use of nonsteroidal anti-inflammatory drugs, such as ibuprofen. Most adults can go back to work 48 hours after the first normal stool. There are no routine methods for detecting enterotoxigenic E. coli, the commonest cause of traveller’s diarrhea.

GUIDANCE OF CLOSTRIDIUM DIFFICILE ㅡ Patients with C. difficile infection can be asymptomatic (carrier) or present with diarrhea and toxic megacolon at the extreme. Caused by two necrolytic toxins (A and B) produced by C. difficile. It is the most common cause of hospital- acquired diarrhea. Infection typically follows antibiotic therapy. Diarrhea may occur during or up to 4 weeks following cessation of treatment. Diarrhea is usually profuse and watery, and may be bloody in 75% of patients. It is commonly associated with abdominal cramps and tenderness, fever (> 38.5°C when severe), and an elevated WBC (> 30 × 109/L).

          Diagnosis is based on the detection of C. difficile toxin or toxin gene in stool. Culture of the organism itself is unhelpful; 75% of healthy adults carry the organism. Sigmoidoscopy is not diagnostic but may show mucosal inflammation, together with multiple yellow plaques (pseudomembranous colitis), which is highly suggestive and should prompt laboratory investigation. Laboratory testing consists of checking for the antigen and toxin. If the antigen is negative, diarrhea is highly unlikely to be due to C. difficile infection. 

          Management is based on rehydration and correct electrolyte abnormalities. Complications include toxic megacolon and colonic perforation. Faecal transplantation from healthy individuals has shown promising results in clinical trials (80% cure rate on first transplant, with further 80% cure rate if the first transplant is unsuccessful). Antigen positive and toxin positive: isolate and barrier- nurse. Mild disease responds to oral metronidazole 500 mg three times a day. Oral vancomycin 250 mg four times a day for 7– 14 days is an alternative. Severe disease requires oral vancomycin as first line, and addition of IV metronidazole if not improving. Antigen positive, toxin negative: isolate if symptomatic; review (and stop, if possible) antibiotics; stop PPIs and laxatives, if possible. If high risk (age > 65, on antibiotics/ PPI, antibiotics within last 30 days, recurrent hospital admissions), consider oral metronidazole and/ or vancomycin.

REFERENCES

• Shane, A.L., Mody, R.K., Crump, J.A., Tarr, P.I., Steiner, T.S., Kotloff, K., Langley, J.M., Wanke, C., Warren, C.A., Cheng, A.C., Cantey, J. and Pickering, L.K. (2017). 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clinical Infectious Diseases, [online] 65(12), pp.e45–e80. Available at: https://academic.oup.com/cid/article/65/12/e45/4557073.

  Barr, W. and Smith, A. (2014). Acute Diarrhea in Adults. American Family Physician, [online] 89(3), pp.180–189. Available at: https://www.aafp.org/afp/2014/0201/p180.html.

  Oxford acute medicine Handbook 4th edition. Page.247