UMEM Educational Pearls - Infectious Disease

Category: Infectious Disease

Title: Diabetes and Osteomyelitis

Keywords: diabetes, osteomyelitis, temperature, white blood cell count (PubMed Search)

Posted: 7/1/2008 by Mike Winters, MBA, MD (Updated: 5/29/2024)
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Does this Patient with Diabetes have Osteomyelitis?

  • Diagnosis of lower extremity osteomyelitis in the diabetic patient remains challenging
  • Bone biopsy with culture remains the gold standard for diagnosis but is not always obtainable
  • What clinical features, therefore, raise the likelihood of osteomyelitis?
  • In this review, an ulcer size > 2 cm2 (LR 7.2), ability to probe to bone using a sterile stainless steel probe (LR 6.4), and an ESR > 70 mm/h were found to be useful in predicting the presence of osteomyelitis
  • Clinical features NOT found to be useful included fever (sensitivity 19%), presence of erythema, swelling, or purulence (LR 1), elevated white blood cell count (sensitvity 14%-54%), and superficial swab culture
  • A note about radiographic studies:
    • bony changes on plain films may take up to 2 weeks to develop
    • plain films alone are only marginally useful if positive (LR 2.3)
    • MRI is more accurate than bone scan or plain films
    • If you are going to order a radiographic study, your best bet is the MRI

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Category: Infectious Disease

Title: Food Poisoning

Keywords: Food Poisoning, Diarrhea (PubMed Search)

Posted: 6/14/2008 by Michael Bond, MD (Updated: 5/29/2024)
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Now that we have entered the session of cookouts, picnics, and family get togethers I thought I would review some of the more common causes of food poisoning and the typical foods that they are found in.


Foods Typically Found In

Onset of Symptoms

Staphylococcus aureus

Meat and seafood salads, sandwich spreads and high salt foods.

4-6 hours


Meat; poultry, fish and eggs and now tomatoes

12 to 24 hours. Assoociated with fever

Clostridium perfringens

Meat and poultry dishes, sauces and gravies.

12 to 24 hours.

Vibrio parahaemolyticus

Raw and cooked seafood.

12 to 24 hours.  Associated with fever

Bacillus cereus

Starchy food. Typically Chinese Fried Rice in test questions

12 to 24 hours.

Campylobacter jejuni

Meat, poulty, milk, and mushrooms.

 24 hours


Category: Infectious Disease

Title: Meningitis Prophalaxis

Keywords: meningitis, fluoroquinolone (PubMed Search)

Posted: 2/25/2008 by Michael Bond, MD (Emailed: 3/1/2008) (Updated: 5/29/2024)
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It has become standard that close contacts of individuals being treated for bacterial meningitis be treated prophalacticly with antibiotics to prevent additional cases.  Fluoroquinolones, in particular ciprofloxicin, have been the drug of choice as a single dose provided adequate protection.

Now the CDC is reporting the first cluster of fluoroquinolone-resistant meningococcal disease in North America have been documented along the Minnesota-North Dakota border.  As of now, the CDC still recommends ciprofloxacin for all parts of the country except for a 34-county area in the Minnesota-North Dakota area.  In that area the CDC is recommending rifampin, ceftriaxone or azithromycin be used.

This needs to be followed closely as the resistant organism is extremely likely to spread across the country and it will probably this time next year when nobody can use ciprofloxacin anymore.

Category: Infectious Disease

Title: The Numbered Skin Rashes

Keywords: Dermatology, Rash, (PubMed Search)

Posted: 2/17/2008 by Michael Bond, MD (Updated: 5/29/2024)
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Most of use remember that Fifth disease is a viral infection presenting with a distinctive rash (slapped check) caused by Parvovirus B19.  But do you know the numbering of the other six Contagious Illnesses that are associated with rashes:

  1. First Disease – Measles caused by the rubeola virus
  2. Second Disease – Scarlet Fever caused by Streptococcus pyogenes Group A
  3. Third Disease – German Measles caused by rubella virus
  4. Fourth Disease – Dukes Disease – In the late 1880-1900’s it was widely published about but in the 1960’s it was not proven to exist by either epidemiologic criteria or isolation of an etiologic agent.  Now felt to be a mild form of scarlet fever.  Some reports of it being caused by a Coxsackvirus or Echovirus
  5. Fifth Disease - Erythema infectiosum caused by Parvovirus B19. Slapped Check
  6. Sixth Disease - Exanthem subitum (meaning sudden rash), also referred to as roseola infantum (or rose rash of infants), sixth disease. Presents as rapid onset high fever, followed by a fine red rash when the fever subsides. Caused by Herpes Virus 6.


Category: Infectious Disease

Title: Ludwig's Angina

Keywords: Ludwig, Angina (PubMed Search)

Posted: 1/13/2008 by Michael Bond, MD (Updated: 5/29/2024)
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 Ludwig’s Angina:

Ludwig’s angina is most commonly a polymicrobial disease of mixed aerobic / anaerobic bacterial origin. Dental disease is the most common cause of Ludwig’s angina.

Diagnosis is usually made after obtaining a CT scan of the Neck and upper chest. 

Once the diagnosis is made, treatment should consist of broad spectrum antibiotics and surgical evaluation by ENT or Oral Surgery for possible I&D. Aggressive management of the patient’s airway is a must, and the patient should be intubated early in the course of the illness if there is any sign of airway compromise. Nasal intubation may be preferred by ENT/Oral Surgery.

Typical Antibiotics include a Penicillin with clindamycin or metronidazole.

Ludwig’s Angina Trivia:

  • Initially described in 1836 by the German physician Wilhelm Frederick von Ludwig.
  • It was called angina, which finds its origin from the Greek word, anchone, which means strangulation.  The term, angina was used to connote throat pain and infection as angina originates from the Greek word, anchone, that means strangulation.
  • It is believed that Elizabeth I of England died of Ludwig's angina in 1603.

Category: Infectious Disease

Title: MRSA in Baltimore City

Keywords: MRSA, resistant bacteria, sepsis, antiobiotics, baltimore (PubMed Search)

Posted: 10/17/2007 by Daniel Lemkin, MS, MD (Updated: 5/29/2024)
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A recent study came out which confirms what we already knew... that MRSA infections are no longer confined to ICUs but are spreading to the community. What the new study does show, is that it affects particular populations disproportionately and Baltimore City, more than any other study population. The full article is attached below, or can be obtained for free from the JAMA website.

"Unadjusted incidence rates of all types of invasive MRSA ranged between approximately 20 to 50 per 100 000 in most ABCs sites but were noticeably higher in 1 site (site 7, Baltimore City) (TABLE 2)."

"... we calculated interval estimates excluding site 7 (Baltimore City) to allow the reader to interpret a range of estimates reflecting different metropolitan areas. Regarding the high observed incidence rates reported by site 7, we conducted an evaluation to determine whether these results were valid, including a review of casefinding methods, elimination of cases to include only those with zip codes represented in the denominator, contamination in any laboratory, and other potential causes for increased rates; however, none were in error."


0710170948_jama_mrsa.pdf (129 Kb)

Category: Infectious Disease

Title: CAP 2007

Keywords: community acquired pneumonia, CURB-65, empiric antibiotics (PubMed Search)

Posted: 9/18/2007 by Mike Winters, MBA, MD (Updated: 5/29/2024)
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Important EM pearls from the recent 2007 IDSA/ATS guidelines for treatment of community-acquired pneumonia (CAP) Patients should be treated for a minimum of 5 days CURB-65 a new pneumonic; any patient with ? 2 warrants admission Confusion Uremia elevated Respiratory rate low Blood pressure age > 65 Outpatient CAP treatment Healthy + no abx in past 3 months ? macrolide Comorbidities OR use of abx within last 3 months ? a respiratory fluoroquinolone OR ?-lactam + macrolide Inpatient CAP treatment ICU patients ? ?-lactam + either azithromycin or a respiratory fluoroquinolone Non-ICU patients ? respiratory fluoroquinolone OR ?-lactam + macrolide Mandell LA, et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults Clinical Infectious Diseases 2007;44:S27-S72

Category: Infectious Disease

Title: Tuberculosis Screening

Keywords: TB, PPD, Conversion (PubMed Search)

Posted: 7/12/2007 by Michael Bond, MD (Emailed: 7/8/2007) (Updated: 5/29/2024)
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PPD is considered positive: >= 15 mm Induration: Anybody >= 10 mm induration: Born in a high-revalence country, are in a medically underserved population ( e.g.:Blacks, Hispanics, and Native Americans), individuals with a medical condition that increases risk of TB (e.g.; silicosis, gastrectomy, chronic renal failure, immunosuppressant therapy, malignancy, IV drug abusers, and those that work in the medical field. >=5mm induration: HIV or suspected HIV-positive, close contacts of newly diagnosed TB Cases (everybody on the plane), and abnormal CXR with fibrotic changes suggesting old TB MMWR September 08, 1995/ 44(RR-11);18-34

Category: Infectious Disease

Title: Avian Influenza H7N9

Posted: 4/12/2013 by Andrea Tenner, MD (Emailed: 5/29/2024) (Updated: 5/29/2024)
Click here to contact Andrea Tenner, MD

General Information:

-As of April 5th, 14 confirmed cases of a new influenza A virus (H7N9) have occurred in China.  Six of those have died. 

-Presumed transmission via infected poultry in bird markets, and thus far no person-to-person transmission has occurred.

-Likely susceptible to oseltamavir or inhaled zanamivir


Area of the world affected:


Relevance to the US physician:

- Suspect in patients with a respiratory illness and appropriate travel history.

- Refer to CDC within 24 hours if test positive for flu A but cannot be subtyped

- If H7N9 is suspected, patients should be under droplet and airborne precautions


Bottom Line:

No human-to-human transmission from H7N9 thus far, but the possibility exists.  Any unsubtypeable influenza A patient should be placed on droplet and airborne precautions and oseltamavir or zanamivir started immediately.


University of Maryland Section of Global Emergency Health
Author: Andi Tenner, MD, MPH


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