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31

T or F. Nosocomial pneumonia (aka HAI pneumonia) is the leading cause of death among hospital- acquired infections.

T. The greatest risk for infection occurs when the patient is placed on a ventilator. Infection occurs through micro-aspiration of oropharyngeal tract or GI tract bacteria, or from the introduction of bacteria from the hospital setting.

32

What are the most common pathogens that cause Nosocomial pneumonia (aka HAI pneumonia)?

The most common pathogens are Gram-negative rods (E. coli, Klebsiella, Enterobacter, Ps. aeruginosa, or Acinetobacter) and Gram-positive cocci (Staph aureus and Streptococci).

Two MOST common are: Staph. aureus and Ps. aeruginosa

Multidrug resistance is common among isolates, which is typical of HAI infections.

33

What are some common symptoms of Nosocomial pneumonia (aka HAI pneumonia)?

May be characterized by a patient that comes in and is placed on a ventilator, gets better, and then gets worse and develops more symptoms such as fever.

Symptoms include fever, purulent sputum, and decline in oxygenation, cough if not on ventilator. Infiltrates will be seen on lung x-ray.

34

What is the appropriate treatment for Nosocomial pneumonia (aka HAI pneumonia)??

Treatment starts with empiric therapy (like Vanco?) to cover most possible organisms but should be narrowed when a definitive diagnosis is made.

However, nosocomial pneumonias can be polymicrobial requiring broad spectrum coverage.

35

What are some characteristics of Psuedomonas aeruginosa?

1. aerobic, gram-negative rod

2. releases a fruity odor

3. Produces pyocyanin (blue) and fluorescin (yellow) to produce blue-green color

4. Some strains produce a slime layer commonly seen in CF patients

36

Is Pe. aeruginosa ever found normally in the body? If so, where?

Yes, in 10% of the population it is found in the GI tract.

Most it is mostly found in the environment- e.g. soil, water, vegetation

37

T or F. Pse. aeruginosa is a frank pathogen

F. it is opportunistic

38

Where do Pse. aeruginosa infections usually occur in the body?

They can infect a wide range of places including pulmonary, urinary, and soft tissue sites

39

The vast majority of Pse. aeruginosa infections impact what types of patients?

burn victims, HAI infections, and CF patients

40

What kinds of antibiotic are currently used in treating Pse. aeruginosa infections?

3rd and 4th generation cephalosporins, carbapenems, some beta- lactams with beta lactamase inhibitors, and newer aminoglycosides are used in treatment

41

What is an antibiogram?

A machine at hospitals that log the effectiveness of certain antibiotics to certain bacteria over a time period (say in the past year)

42

Case 3
• A 49 y/o male presents to the ED with cough and shortness of breath x 1 week’s duration and a one-day history of severe headache and vomiting. His spouse reports that he has been acting funny over the last 24 hours, and what actually brought them in was she witnessed him having what she thinks was a seizure earlier that day. He has been having fevers up to 102°F, rigors, and night sweats for the past 5 days as well.

• PMH: splenectomy after splenic injury from car accident 10 years ago. Has not seen a primary care provider ever.
Has never received any vaccinations.

• Social history: smokes 1 ppd, drinks a 6 pack of beer every 1- 2 days.

Vital signs: T 101.6oF, BP 90/60, HR 125, RR 28, O2 saturation 88% on RA. Patient appears toxic. Eye exam is abnormal.
• Antibiotics (Vancomycin and Ceftriaxone) plus dexamethasone (steroid) are administered for suspected bacterial meningitis.
• Head CT is done immediately. No acute abnormalities are found.
• Lumbar puncture is then done. Sample Gram stains of the CSF and diagnosis is made as Streptococcus pneumoniae meningitis
• The doctor discontinues the Vancomycin but continues the Ceftriaxone and Dexamethasone.
• However, the patient’s condition deteriorates even further over the next 48 hours and he dies.

Case 3
• A 49 y/o male presents to the ED with cough and shortness of breath x 1 week’s duration and a one-day history of severe headache and vomiting. His spouse reports that he has been acting funny over the last 24 hours, and what actually brought them in was she witnessed him having what she thinks was a seizure earlier that day. He has been having fevers up to 102°F, rigors, and night sweats for the past 5 days as well.

• PMH: splenectomy after splenic injury from car accident 10 years ago. Has not seen a primary care provider ever.
Has never received any vaccinations.

• Social history: smokes 1 ppd, drinks a 6 pack of beer every 1- 2 days.

Vital signs: T 101.6oF, BP 90/60, HR 125, RR 28, O2 saturation 88% on RA. Patient appears toxic. Eye exam is abnormal.
• Antibiotics (Vancomycin and Ceftriaxone) plus dexamethasone (steroid) are administered for suspected bacterial meningitis.
• Head CT is done immediately. No acute abnormalities are found.
• Lumbar puncture is then done. Sample Gram stains of the CSF and diagnosis is made as Streptococcus pneumoniae meningitis

• The doctor discontinues the Vancomycin but continues the Ceftriaxone and Dexamethasone.
• However, the patient’s condition deteriorates even further over the next 48 hours and he dies.

43

What feature of the Gram stain distinguishes S. pneumoniae from other streptococci?

diplococci (all other streps are chains) and they have a characteristic 'lancid' shape where their ends are pointed

44

Why was the vancomycin dropped? Did that likely cause the patient’s death?

The doctor assumed that the Strep. peumn was susceptible to ceftriaxone, as to has been for years in practice. ONLY RECENTLY, has resistance been developed

You can no longer assume that Strep. pen meningitis are susceptible to third generation cephalosporins

The recommendation is to continue the Vanco and Ceftrixaone until susceptibility testing returns

45

If not, what is a possible reason the patient died?

the lack of a spleen makes a patient more susceptible to infection from bacteria with CAPSULES such as Strep. pneumo

46

Was there anything significant in his history that could have contributed to this severe infection?
– If so, which virulence factor was responsible?

the lack of a spleen makes a patient more susceptible to infection from bacteria with CAPSULES such as Strep. pneumo

47

Can you think of a way this infection might have been prevented?

Vaccination is needed with a splenectomy

48

How does the presence of a capsule in bacteria such as Strep. peumo. cause increased virulence?

it is antiphagocytic and that property allows it an increased chance to reach the CSF.

49

How does the lack of a spleen cause increased susceptibility to bacteria with capsules?

the spleen is the major site in the body for removal on ENCAPSULATED bacteria from systemic circulation

50

What is Pneumococcal meningitis?

Meningitis is an infection of the meninges, most commonly by hematogenous spead of a nasopharyngeal infection

51

What are the classic symptoms of Pneumoccoal meningitis?

Early symptoms include fever, headache, and stiff neck. This can be followed by irrational behavior and seizures, eventually resulting in coma

52

What is the most common cause of Pneumococcal meningitis?

S. pneumoniae is the most common cause overall, but other bacteria can affect select age groups. Viral (or aseptic) meningitis is also possible, but less severe and generally self-limiting.

53

How can the dissemination of Strep. pneumo be diagnosed?

S. pneumoniae meningitis can be diagnosed by Gram stain (gram-positive) and culture of CSF

54

T or F. S. pneumoniae remains largely sensitive to penicillin

T. however it is gaining resistance and vancomycin should always be continued until susceptibilities are back. Empiric therapy should be initiated as soon as bacterial meningitis is suspected.

Capsular polysaccharide vaccine is available for prevention.

55

What should you do if you suspect meningitis in the ER?

give vancomycin, ceftriaxone, plus dexamethasome (dexamethasone is only shown to improve outcomes in ADULTS with Strep. Pneumo meningitis)

56

What happens if you find out it is not Strep. pneumo causing the meningitis?

you stop the dexamethasome in ADULTS (children are different)

57

What are the most common pathogens that cause meningitis in neonates?

GBS (group B strep), E. Coli, Listeria monocytogenes

58

What are the most common pathogens that cause meningitis in young children?

S. pneumo., N. meningitidis, and Haemophilus infleunzae (significant reduction with vaccine)

59

What are the most common pathogens that cause meningitis in young adults?

S. pneumo., N. meningitidis

60

What are the most common pathogens that cause meningitis in elderly patients?

S. pneumo., N. meningitidis, L. monocytogenes