CHALLENGE SET EXERCISE FALL 2008

Transcription

1 CHALLENGE SET EXERCISE FALL 2008

2 Scenario 1 Fifteen year old female presents to clinic with cat bite to hand. Aerobic wound culture ordered No Gram Stain

3 Organism 1 Characteristics Growth on Blood and Chocolate Agar No Growth on MacConkey Gram Stain: Gram Negative Coccobacillus Oxidase Positive Weak Catalase Positive Urease Negative Not Yersinia No Growth on MacConkey Gram stain Not Brucella, Why? Urease positive

4 What is the Best Answer for Organism 1? Gram negative coccobacillus, suspicious for Fransicella tularensis, unable to further ID Actual mimic organism sent: Fransicella philomiragia

5 Background F. tularensis is the etiologic agent of the disease tularemia Communicable from animals to humans under natural conditions Infections can be acquired many ways: In Nebraska we have seen a greater incidence from cat bite Tick bites Contact with dead infected animal carcasses Ingestion of contaminated food and water Inhalation of infectious aerosols

6 Clinical Background Ulceroglandular Most Common Form (45 to 80% of cases) Papule, ulcer at portal of entry, lymphadenopathy Glandular 10 to 25 % of cases No sign of cutaneous lesion Oculoglandular Eyelids and conjuctivae inflamed Oropharyngeal Sore throat out of proportion to physical signs Typhoid Acute septicemia Pneumonic Most severe and lethal form May present as unresponsive community acquired pneumonia

7 Responses to Organism 1 5% 33% 62% Organsim 1 Appropriate Answers Organism 1 Inappropriate Answers Organism 1 Unable to Identify

8 E. coli F. tularensis

9 F.Philomiragia versus F. tularensis Biochemical Characteristics Test F.philomiragia F. tularensis Gram Stain Gram negative coccobacillus Gram negative coccobacillus Oxidase + Catalase +(weak) + (weak) Urease Β lactamase + Satellite XV requirement Growth on MacConkey May show delayed growth Hemolysis non non

10 Group Biochemical Results: F.Philomiragia B lactamase Catalase 42 deg. C Indole Motility Oxidase Nitrate Satellite Urease Positive 43% 65% 0% 4% 4% 21% 4% 0% 0% Negative 4% 0% 4% 52% 26% 75% 26% 9% 65% Not Performed 43% 30% 78% 35% 57% 4% 57% 78% 30% No Answer 9% 4% 17% 9% 13% 0% 13% 13% 4%

11 Overall 87% would refer isolate 57% to NPHL 30% to Reference Laboratory If any doubt don t hesitate to call NPHL.

12 Scenario 2 A third shift lab worker presents to Emergency Room with fever, malaise, night sweats, and muscle aches. Blood culture ordered No Gram stain

13 Organism 2 Characteristics Growth on Blood and Chocolate Gram Stain: Gram negative coccobacillus Oxidase positive Satellite negative Urease positive Not Yersinia No Growth on MacConkey Gram stain Not Fransicella, Why? Oxidase negative Urease negative

14 What is the best answer for Organism 2? GN cocccobacillus, suspicious for Brucella sp., unable to identify further Actual mimic organism sent: Psychrobacter phenylpyruvicus

15 Response to Organism 2 19% Organism 2 Appropriate Answers Organism 2 Inappropriate Answers 81%

16 Background A zoonotic disease caused by 4 Brucella sp. including: Brucella abortus (cows) Brucella melitensis (goats) Brucella suis (pigs) Brucella canis (dogs) Infective dose is organisms

17 Clinical Significance Incubation period of 5 days to greater than 6 months Duration of illness is weeks to months Signs: Fever Profuse sweating Malaise Hepatospelnomegaly Headache and muscle/back pain Undulant Fever

18 Brucella is the most commonly reported laboratory associated infection Cases occurred by the following: sniffing plates Direct skin contact Aerosol generating procedures

19 Psychrobacter phenylpyruvicus versus Brucella Biochemical Characteristics Tests Brucella sp Psychrobacter phenylpyruvicus Source Blood Various Gram Stain Tiny CCB Broad CCB Oxidase Positive Positive Urease Strong Positive (within 24 hours) Positive XV factors None None Note: B.suis and B. canis are urease positive usually within 5 minutes.

20 Group Biochemical Results: Psychrobacter phenylpyruvicus B lactamase Catalase 42 deg. C Indole Motility Oxidase Nitrate Satellite Urease Positive 0% 78% 0% 0% 4% 91% 0% 0% 70% Negative 13% 0% 0% 22% 48% 4% 9% 13% 0% Not Performed 74% 13% 83% 57% 30% 4% 65% 70% 17% No Answer 13% 9% 17% 22% 17% 0% 26% 17% 3%

21 Gram Stain Brucella sp.

22 Overall 83% would refer isolate 58% to NPHL 25% to Reference Laboratory 8% continue to work up If any doubt don t hesitate to call NPHL.

23 Sentinel Protocol Important reactions Gram Stain Catalase Motility India Ink Oxidase Urease Indole B lactamase Staph streak B.anthracis Large GPR Pos Non Capsule Prod. Y. pestis GNR Pos Neg Neg Neg F.tularensis GNCB Wk pos Neg Neg Pos Neg Brucella sp. GNCB Pos Pos Neg

24 Beware commercial identification systems are unreliable with inert organisms (i.e. Yersinia) Interpret your results with caution

25 Reminders: Sentinel Laboratory procedures are posted on the NPHL website. ( If you have a STATPack, the procedures can be found on the Electronic Textbook. Ever a question, do not hesitate to call NPHL or page at (402) Someone is always able to assist.

26 Questions????