Diagnostic Approach to Infective Diarrhoea in the Community and Rational Antibiotic Therapy

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Diagnostic Approach to Infective Diarrhoea in the
Community and Rational Antibiotic Therapy

• Dr. A. Ayyagari
• Prof. Head
• Department of Microbiology
• SGPGIMS, Lucknow (U.P.) India

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Introduction

• Major public health problem in India under 5
  years. 1/3 of admission and 17 of death)
• Definition passage of loose, liquid or watery
  stool.
• Acute diarrhoea (GE)- sudden onset which usually
  last 3-7 days, may 10-14 days.
• Non inflammatory e.g. V. cholerae (no abnormal
  histology)
• Inflammatory- with blood and mucus e.g. Shigella

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Chronic Diarrhoea (gt14 days)

• Inflammatory- ulcerative colitis, Crohns
  disease, radiation colitis
• Osmotic- Whipples disease, Celiac sprue,
  Pancreatic insufficiency
• Secretory- Carcinoid syndrome, ZE syndrome, VIP
  adenomas etc.
• Altered motility- IBS, neurologic disease, fecal
  impaction
• Factitious- laxative abuse

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Cause of Acute diarrhoea (lt14 days)

• Infectious diarrhoea
• Medications
• Ischemic colitis
• Sup. Mesenteric arterial or venous thrombosis
• Acute diverticulitis

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Infectious diarrhoea- Mechanisms causes
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Infectious diarrhoea- Mechanisms causes
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Diarrhoea in HIV/AIDS patient

• Bacteria Virus Parasite
• C. jejunii CMV Cryptosporidium
• Shigella sp Enteric adeno Isospora belli
• Salmonella Calici virus Cyclospora
• C. difficle HIV Microsporidia
• EAEC
• Mycobacterium avium complex

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Diagnostic approach to Infective Diarrhoea

• History
• Dietary details, travel history, source of
  drinking water, sexual preferences
• Physical examination
• BP, pulse rate, pulse volume, Abd. Exam,
  hepatosplenomegaly, lymphadenopathy

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Lab Diagnosis- Sample collection

• -collected in acute stage
• -before the start of the treatment
• -before the radiological examination
• -no contamination with urine water or any other
  infective material
• -In wide mouthed leak proof screw capped
  container (25 ml) with a spoon (do not soil the
  rim of the container)
• -amount 5 ml of liquid stool/pea size of
  formed stool
• -Number max. 3 samples (2 after normal movement
  and 1 after cathartic)

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Lab Diagnosis- Sample Transport

• Cary blair transport media (pH 8.4)- Campy.,
  Vibrio
• Buffered glycerol transport media (pH 7.0)-
  Shigella
• V.R media (pH 8.6)- V. cholerae
• Hanks balanced salt solution- Virus
• Stuart and Amies- general purpose transport media

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Microscopy

• Wet mount- Ova and trophozoites of parasites
• WBCs indicate invasive pathogens
• Phase contrast microsciopy- Campylobacter
• Immune electron microscopy- Viruses
• Staining methods -
• Oocyst
• Acis-fast stains- Cold/hot Kinyoun modified
  stain,
• Giemsa stain, PAS stain, Direct fluorescence
  stain,
• E. histolytica- Trichrome stain
• Microsporidium- ModifiedTrichrome
• Gram stain

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Lab Diagnosis- Enrichment medium
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• Formed/semiformed stool
• (110 dilution in 2-3 ml PBS or 0.1 peptone
  water)
• ?
• Liquid stool
• (Cholera suspected by characteristic Motility
  and immobilisation by specific sera)
• ? ? ?
• Grams stain if required MacConkey
  Selenite F broth
• ? XLD/DCA GN broth
• Typical morphology DSRA ?
• Further processing Subculture on
  of DCA/MAC
• Pure LF cononies within 6 hour
• All NLF col(oxidase negative) on MacConkey,
  should be S/c on DCA
• All black centered colony on DCA
• All non sorbitol fermenter colony (EHEC)

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Classification of Enteropathogenic E. coli
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Antibiotic Associated Diarrhea

• Most common cause of diarrhea among hospitalized
  patients (Range-1 in 10 to 1 in 10000)
• 3-5 billion annual infection annually, 3 million
  deaths/ year.
• 1.5 episodes per person/ year gt 50 death
  elderly
• Self limiting, 50 within 3 days.

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Antibiotics implicated in AAD

• Frequently Ampicillin, Amoxicillin-clavulenate,
  2nd 3rd generation Cephalosporin, Clindamycin
• Uncommon Tetracycline, sulfonamides, Quinalone,
  Erythromycin, Chloramphenicol, TMP,
• Antineoplastic agents gt Methotrexate, Other
  agents (Anon, 1993)- Dexorubin, cyclophosphamide
• Tube feeding-? Nosocomial CD collitis.

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Lab Diagnosis of AAD

• Specimen- Stool (fresh sample), colonic biopsy
• Non specific- ?? leucocytes in stool in AAD PMC
• Colonoscopy/ sigmoidoscopy (erythema, edema,
  friability, adhered yellow plaques) in PMC.
  Endoscopy ? Normal in mild cases
• Radiographic imaging
• Surveillance of nosocomial infection-
• Swab from inanimate surroundings hospital
  personnel

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Stool Tests for C. difficile Infection
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Viruses causing Acute Gastroenteritis
Other viruses- Torovirus ss()RNA, Picovirna
virus dsRNA, Enterovirus 22 ss()RNA, Aichi
virus ss()RNA
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Diagnosis of Viral diarrhoea

• Non Rota-
• Direct and immune Em
• Antigen detection- EIA with hyper immune sera ,
  EIA with monoclonal antibody
• Antibody detection
• Culture
• Hybridization probes- for adeno viruses
• RT-PCR for HuCV
• Rota-
• EIA, membrane EIA, LA, EM, culture, RT-PCR

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Rational Antibiotic Therapy

• Most cases are self limiting and subside with
  supportive therapy
• Indication of antibiotic therapy
• Cholera
• Febrile bloody diarrhoea
• Travelers diarrhoea
• extremes of age
• Food handlers
• Immunocompromised
• Day care attendee
• Residents of institutional facility
• Epidemic outbreaks

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Rational Antibiotic Therapy

• Problems of empiric therapy-
• Not effective in EHEC, salmonella enterocolitis
• In children- most cases are viral
• Emerging drug resistance
• Side effects
• Alteration of gut flora
• Induction of disease producing phage e.g
  Shigatoxin phage induced by quinolones

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Therapeutic recomendations

• Shigella- TMP-SMZ, Cipro, Norflox
• Salmonella-Quinolones, Ceftrixone
• V.cholerae - Doxycycline, Tetracycline,
  Erythromycin
• E. coli-Cipro, norflox
• C. difficile-Metronidazole, Vanco
• Cryptosporidium- Paromomycin
• Isospora- TMP-SMZ,
• Cyclospora-TMP-SMZ

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Control measures

• WHO, UNICEF- oral rehydration therapy.
• Short-term
• (a) ORT 1978 started in 85-86 (National
  program), 92-93 (included in maternal and child
  health program)
• (b) normal food intake, breast fed
• (c)Chemotherapy- Infective Cholera
• Toxins Shigella,
  E. coli, Campylobacter
• Invasive
  Salmonella

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Control measures

• Long-term
• Nutrition
• Sanitation- to stop the transmission
• Oro-Faecal
• Water supply
• Food
• Health education- environment, clean drinking
  water
• Immunization
• Fly control

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Vibrio cholerae on TCBS
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Salmonella on XLD
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Cryptosporidium parvum in stool(Modified acid
fast)
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Isospora belli-Direct smear(Kinyoun stain)
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Cyclospora cayetanensis-oocyst (modified acid
fast)
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Microsporidian spores(Modified Trichrome blue
stain)
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Clostridium difficile growth under UV light