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Morning Report: Thursday, January 12th

Shigella Infection

Epidemiology

Common cause of bacterial diarrhea worldwide (especially in developing countries)

In the US:Third in frequency (after Salmonella and

Campylobacter)Primarily affects children

○ Peak incidence ages 1-4

The Details…

Gram-negative bacilli Four species:

S. dysenteriaeS. boydiiS. flexneriS. sonnei

Most common subtypes in the US

Only Shiga toxin-producing species!

Transmission

*Person-to-person via the fecal-oral routeTransmission in institutions

○ *Child care centersGrouping of susceptible childrenLack of adherence to hand-washing proceduresSmall inoculum required for disease production

Food borne transmission○ Cold salads○ Raw veggies

Sexual transmission

Clinical Presentation

Incubation period 1-7 days, average 3 days

Range of GI illnessMild diarrhea life-threatening dysentary

Clinical Presentation Course

Presentation: abrupt onset of high fever, generalized toxicity, crampy abdominal pain*, high-volume, watery stools

24-48h later: Small-volume, bloody, mucoid stools* with tenesmus

Neurologic manifestations (40%)Severe HASeizuresMeningeal signsLethargyDelirium/ hallucinations

Physical Exam

VS: high fever (>102F) Gen: toxic-appearing Abd: lower quadrant abdominal pain,

distension GU: tenderness on rectal exam

+/- signs of dehydration

Laboratory Findings

Bandemia Stool microscopy

Large number of PMNs+/- RBCs

Stool cultureSend stool specimen promptly to labCan be grown on MacConkey or Hektoen-

Enteric agarsAlways want speciation and sensitivities

*Treatment

Mainstay= SUPPORTIVE CARE!Correction of fluid and electrolyte losses

○ Substantial volume depletion uncommon○ Hyponatremia

NO intestinal antimotility drugsEarly restoration of oral intake

*Treatment

AntibioticsLead to improvement in symptoms and

decreased spread of infection to contactsThe problem…increasing antimicrobial

resistance!!○ Ampicillin○ TMP-SMX

So, who do I treat and what do I use to treat them?

*Treatment

Who to treat?Red Book

○ Severe disease○ Underlying immunosuppressive conditions○ Dysentery○ In mild cases Rx to prevent spread of the

organism

*Treatment

What to use?Parenteral

○ Ceftriaxone○ Cipro

Oral○ Azithromycin

First-line oral Rx for children <18yo when Abx susceptibility is unknown

○ FluoroquinolonesFirst-line oral Rx for children >17yo and adults

*Treatment

What to use?Oral

○ CefiximeAlternative to azithromycin in children <18yo

○ Ampicillin or TMP-SMXOnly if sensitivities are known

Control Measures

Most importantly….METICULOUS HAND HYGIENE!!!

Control Measures

HospitalContact precautions

*Day careNotify local health departmentStool cultures should be performed on all

symptomatic attendees and staffAffected persons should be excluded until:

○ Initiation of appropriate ABx○ ≥24 hours after diarrhea has resolved○ Stool cultures are negative for Shigella

Complications

IntestinalProctitis or rectal prolapseToxic megacolonIntestinal obstructionColonic perforation

Complications

SystemicBacteremiaMetabolic disturbancesLeukemoid reactionNeurologic diseaseReactive arthritis

○ Alone or in association with conjunctivitis and urethritis (Reiter syndrome)

Hemolytic-uremic syndrome○ Caused by EHEC (O157:H7), S. dysenteriae

A Question… A previously healthy 3 ½ yo girl presents following 2 days of

diarrhea, vomiting, and low-grade fever. Her symptoms began shortly after the family dined at a local fast-food restaurant. She has had 4-6 watery, mucoid stools per day. Her parents are very concerned because the have started to see some blood in her stool. On PE, the alert, somewhat irritable child has a T 38.6C, HR 100, RR 16. Her oral MM are dry. CRT~2 secs. Her abdomen is diffusely tender without distension. Labs show HgB 11.5, WBC 14.5, Na 136, K 4.5, Bicarb 18. Of the following, which is the most appropriate treatment? A. A glucose-electrolyte solution B. Cholestyramine C. Loperamide D. Metronidazole E. TMP-SMX

A Question… A 5yo girl presents after having a brief generalized

seizure. Her mother reports that the child has had a 3 day h/o fever, tenesmus, and bloody diarrhea. On PE, you find a mildly toxic-appearing child who has a T104F and diffuse abdominal tenderness. The rectal exam produces significant pain. Stool from her rectum is guaiac-positive. You tell the mother that you believe the diarrhea has an infectious cause. Of the following, the MOST likely pathogen is: A. Cryptosporidium sp B. Rotavirus C. Salmonella sp D. Shigella sp E. Yersinia sp

A Question… You are evaluating a 2 yo boy with a 10h history of a temperature

of 40.0C and progressively worsening diarrhea. Yesterday he attended a birthday party at the petting zoo, but he had no other history of ill contacts or unusual exposures. His mother states that he has had 8 watery bowel movements with mucus and streaks of blood in the last 10h. On PE, the boy is irritable and has a temp of 39.5C. His MM are slightly tacky, and his abdomen is diffusely TTP. The rest of the PE is normal. Labs show WBC 16.0 with 65% neutrophils and 9% bands. Microscopic exam of the stool shows fecal leukocytes, blood and mucus. Of the following, the MOST likely etiologic agent for this patient’s condition is A. Campylobacter B. E. Coli C. Salmonella D. Shigella E. Yersinia enterocolitica

Infectious DiarrheaTransmission Symptoms Labs Treatment

Salmonella Chicken, milk, eggs; exotic pets (reptiles)

Fever, diarrhea with blood/ mucous

High WBC with left shift, +stool WBC, RBC (?+ BCx)

None with uncomplicated GE; at risk* Amoxil, Bactrim

Shigella Person-to person; daycare! Fresh fruits and veges

Fever, abd. pain, watery diarrhea that becomes bloody, szs

High WBC and band ct, +stool WBC, RBC

Azithromycin, quinolones

Campylobacterjejuni

Undercooked poultry or meat

Fever, abd pain, diarrhea with blood, vomiting

+stool WBC, RBC; Cx with chocolate agar

Erythromycin

E.Coli O157:H7

Undercooked beef, unpasturized milk

Fever, diarrhea with blood/ mucous

+stool WBC, RBC; look for signs of HUS

Abx not indicated! (increases risk for HUS)

Yersiniaenterocolitica

Pork (chitterlings) Dysenteric syndrome, can mimic appy/ Crohns

+stool WBC, RBC Bactrim, aminoglycosides, cephalosporins (3rd), quinolones

Clostridiumdifficile

ABx exposure Mild diarrhea dysentric syndrome

Dx with toxin assay

PO Flagyl (Vanc)

Thanks for your attention!!

Noon Conference: JIA, Dr. Brown