Bacteriology Review. Patient case: SP. Sputum Acceptability. Additional information: 1/29/2008. Acceptable. Unacceptable!

Transcription

1 Patient case: SP Bacteriology Review 2008 January 24, 2008 Presented by Mary A. Ullman, PharmD. SP is a 40 year old female who presents to the clinic with worsening cough and chest pain over the past few days. Patient s cough is described as deep and coarse. She reports coughing up thick, greenish gunk. A chest x-ray and sputum culture are taken and reveal the following Sputum Acceptability Acceptable Unacceptable! (>10 epithelial cells and <25 PMNs per LPF) Gram stain of sputum shows Gram + cocci; lancet-shaped pairs Catalase = negative Alpha hemolytic Optochin test = sensitive OPT 1

2 What is causing SP s pneumonia????? a) Haemophilus influenzae b) Streptococcus pneumoniae c) Staphylococcus aureus d) Streptococcus viridans Patient case: KC KC is a two year old male who presents with high fever, persistent irritability, and listlessness. KC is found to have numerous gaps in his vaccination schedule. His parents avoid vaccines because they cause autism. CSF cultures are drawn for suspected meningitis and reveal the following Gram stain of CSF shows tiny Gram coccobacilli A sheep blood agar plate is inoculated with the CSF. There is no growth after incubation with CO 2. 2 A chocolate agar plate inoculated with the CSF grows many colonies following incubation with CO 2. What bacteria is most likely responsible for KC s meningitis? a) Moraxella catarrhalis b) Neisseria meningitidis c) Streptococcus pneumoniae d) Haemophilus influenzae Why is KC at an increased risk for this infection? Patient case: NM NM is a 19 year old college student studying Art History. She was brought to the ED by paramedics after a panicked call to 911 by her roommate. Her roommate reported that at 9 o clock this morning, NM had complained of not feeling well and had a throbbing headache. When the roommate returned to the dorm at 2 o clock she found NM to be non-responsive with a forehead that was hot to the touch. IV fluids are started and CSF cultures are drawn. 2

3 Gram stain of CSF shows Gram - diplococci adjacent sides flattened The highest incidence of infection with this organism is in the school age group (5-25 y) particularly in populations residing in close quarters such as dormitories or military barracks. Cells have a characteristic coffee bean shape Oxidase test = positive The infection caused by this organism progresses rapidly and can result in death a few hours after the onset of symptoms if not treated. What organism is most likely responsible for this infection? a) Neisseria meningitidis b) Listeria monocytogenes c) Pseudomonas aeruginosa d) Streptococcus pneumoniae Why was NM at risk for this infection? Lived in a dorm Is there anything else you should do in this case? Treat the toommate Patient case: DT DT is a 38 year old male who presents with redness and swelling of a wound on his right forearm. DT states that two days ago he was working in his shed when he cut his arm on the edge of the hedge trimmer. He states he did not clean the wound right away because he was busy. A Gram stain and culture from the wound aspirate reveal the following Gram stain of wound aspirate shows Gram + cocci in groups 3

4 Catalase = positive Coagulase = positive What bacteria is causing DT s infection? a) Clostridium tetani b) Staphylococcus epidermidis c) Staphylococcus aureus d) Streptococcus pyogenes Why is this a likely organism in this situation? Part of normal flora on skin Before prescribing antibiotics, what other test may be useful? Methicillin/oxacillin to rule out of CA-MRSA Patient case: HB HB is a 24 year old male who was admitted to the burn unit 8 days ago. HB was admitted after a suicide attempt using self immolation. He now has 2 nd -3 rd degree burns over 50% of his body. His fever worsens and his wounds appear greenish and mucous-like. Blood cultures are drawn and broad spectrum antibiotics are begun. Gram stain of an isolate from the blood cultures show Gram - bacilli Glucose fermentation = negative (far left tube) Oxidase test = positive 4

5 What is the likely pathogen? a) Staphylococcus aureus b) Escherichia coli c) Acinetobacter baumannii d) Pseudomonas aeruginosa Why was HB at risk for this organism? In a burn unit/ immunocompromised Patient case: YD YD is a 56 year old female who presents to the ED with an infected puncture wound. YD reports that a few days ago she was gardening at home when she tripped and stepped on one of her weeding tools which punctured the heel of her left foot. The wound did not bleed much but appeared to be deep. A wound culture is collected and sent to the microbiology lab. Gram stain of wound aspirate shows boxy Gram + bacilli The organism is anaerobic. The organism is a sporeformer. Colonies on blood agar have irregular edges with a characteristic double zone of hemolysis To what genus does this organism belong? Clostridium Which Clostridium species is most likely to cause the following: Diarrhea associated with antibiotic use? Difficile Infection due to deep puncture wound? Tetani Gas gangrene? Perfringens Illness due to ingestion of home-canned foods? Botulinum Patient case: QT QT is a 3 day old neonate admitted to the NICU. QT is febrile and listless. CSF is collected. Gram stain and culture results are as follows. 5

6 Gram stain of CSF shows Gram + bacilli QT s mom was particularly fond of Schwans Butter Brickle ice cream and consumed several half-gallons during the past several weeks. This bacteria will grow at refrigerator temperatures. There is a narrow zone of beta hemolysis around colonies growing on blood agar. Catalase = positive What is the likely cause of QT s meningitis? a) Listeria moncytogenes b) Escherichia coli c) Group B streptococus d) Staphylococcus aureus Patient case: MC MC is a 22 year old male who presents to the clinic with complaints of pain on urination and cloudy discharge. MC would not give a specific patient history, stating only that he and his friends had a wild time in Cancun during spring break. Gram stain of urethral discharge revealed the following Gram stain of male urethral discharge shows Gram intracellular diplococci What organism is most likely causing MC s discomfort? a) Chlamydia trachomatis b) Treponema pallidum c) Neisseria gonorrhea d) Escherichia coli 6

7 Patient case: EV What other disease(s) should MC be tested for? Chlamydia, HIV, hepatitis, syphilis Why might a gram stain be ineffective in identifying all of MC s likely pathogens? Can t gram stain them EV is a 72 year old woman who presents with confusion and mild fever. A psychiatric evaluation and CSF cultures reveal nothing. Because of the woman s age and her presenting symptoms, a urinalysis and urine culture are ordered. The culture reveals the following Gram stain of urine shows Gram + cocci in pairs and chains Catalase = negative Hemolysis = none (gamma) Bile esculin = positive Growth in 6.5% NaCl = present PYR test = positive To which genus does the bacteria belong? a) Enterococcus b) Escherichia c) Streptococcus d) Pseudomonas Which species is most likely? Faecalis (80 90% of entercocci species isolated) Why is this infection potentially difficult to treat? Often drug resistant (VRE) Patient case: TR TR is a 38 year old female who presents with a 3 day history of nausea, vomiting, and diarrhea. She reports that a couple of days ago she ate at Taco Bell and has not been feeling well since. A stool culture is collected and a Gram stain of the likely pathogen (after isolation on selective agar) reveals. 7

8 Gram stain of colonies from a stool culture shows Gram - bacilli What additional tests would help to identify the organism? Glucose fermentation reaction Oxidase test If the organism is able to ferment glucose and is oxidase negative, what is the likely pathogen? a) Listeria monocytogenes b) Clostridium difficile c) Vibrio cholera d) Escherichia coli What additional information should you have before you empirically treat this patient with antibiotics? is the diarrhea bloody? Treating 0157:H7 with abx can result in HUS Conclusions Organism ID and site of infection are key bits of information when making treatment decisions. A solid understanding of common laboratory tests used for organism ID is important. As soon as possible ID and susceptibility testing results should be used to tailor treatment. Remember: you can reach your desired destination much faster if you are pointed in the right direction!!! 8