UMEM Educational Pearls - Infectious Disease

Title: Avian Influenza A or “bird flu”

Category: Infectious Disease

Keywords: avian, influenza, infectious (PubMed Search)

Posted: 10/31/2024 by Visiting Speaker (Updated: 12/12/2024)
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By Bobbi-Jo Lowie, MD

Assistant Professor 

Emergency Medicine

University of Maryland School of Medicine

Since April of 2024 there have been 36 confirmed cases of avian influenza A across the United States. Avian influenza, primarily caused by influenza viruses that infect birds, can pose significant health risks to both animals and humans. The most notable strains include H5N1 and H7N9, with H5N1 being particularly alarming due to its high mortality rate among infected humans. The virus primarily spreads from birds to humans through direct contact with infected birds, their droppings, or contaminated environments. Although there have been recorded cases of human-to-human transmission, this usually occurs only in close-contact situations.

In humans, avian influenza can present with symptoms ranging from mild respiratory illness to severe pneumonia. Patients may experience fever, cough, sore throat, muscle aches, and in severe cases, gastrointestinal symptoms. Those that have more moderate or severe illness may develop shortness of breath, altered mental status, or seizures. Complications include acute respiratory failure, pulmonary hemorrhage among others, with respiratory failure being the most common cause of death in this patient population.

Diagnosing avian influenza involves a combination of clinical presentation, travel history, and exposure to birds and confirmation through PCR testing of upper respiratory tract samples like a nasopharyngeal swab.

 Treatment for avian influenza focuses on antiviral medications such as oseltamivir which is most effective when administered early in the course of the illness but still administered after 48 hours of illness. Supportive care is essential for managing severe cases, especially those that progress to acute respiratory distress syndrome.



Title: What do I need to know about the recent MPox Outbreak?

Category: Infectious Disease

Keywords: Mpox, monkeypox, outbreak, democratic republic of congo (PubMed Search)

Posted: 8/25/2024 by Mercedes Torres, MD
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Background:

  • Monkeypox virus (MPXV) has two distinct genetic clades (subtypes of MPXV), I and II, which are endemic to central and west Africa, respectively. 
  • The global mpox outbreak that began in 2022 is caused by MPXV II
  • The recent outbreak in Democratic Republic of Congo (DRC) is caused by MPXV I

What’s new?

  • Democratic Republic of Congo (DRC) has reported more than 22,000 suspect cases of MPXV I since January 1, 2023 (annual median of 3,767 suspect MPXV I cases in prior 6 years)
  • Largest number of yearly suspected MPXV I cases ever recorded 
  • More widespread than any previous outbreak, resulting in transmission to neighboring countries [Republic of the Congo (ROC), the Central African Republic (CAR), Burundi, Rwanda, and Uganda].

Who is at risk?

Patients with epidemiologic characteristics and lesions or other signs and symptoms consistent with mpox. This includes anyone with travel to DRC or any of its neighboring countries (ROC, CAR, Rwanda, Burundi, Uganda, Zambia, Angola, Tanzania, and South Sudan) in the previous 21 days.

What to look for? 

  • Rash that may be located on the hands, feet, chest, face, mouth, anus or near the genitals
  • Lesions are firm or rubbery, well-circumscribed, deep-seated, and often develop umbilication (see below).

(Above photos from https://www.cdc.gov/poxvirus/mpox/clinicians/clinical-recognition.html)

  • Lesions progress through four stages—macular, papular, vesicular, to pustular—before scabbing over and desquamation. They are often described as painful until the healing phase when they become itchy (crusts).
  • Fever, chills, swollen lymph nodes 
  • Fatigue, myalgia (muscle aches and backache), headache
  • Respiratory symptoms like sore throat, nasal congestion, and cough
  • Illness lasts 2-4 weeks
  • Once all scabs have fallen off and a fresh layer of skin has formed, a person is no longer contagious.

What to do?

If mpox is suspected in a patient:

  • Isolate the patient in a single patient room (no special air filtration is required).
  • Use PPE (Gown, gloves, eye protection, and NIOSH-approved particulate respirator equipped with N95 filters or higher).
  • Intubation and any procedures likely to spread oral secretions should be performed in an airborne infection isolation room.
  • Notify your local health department immediately.
  • Evaluate all suspected cases related to DRC or its neighboring countries with laboratory testing (rather than clinical diagnosis alone). 
  • Counsel patients about staying away from other people and not sharing things they have touched with others; and cleaning and disinfecting the spaces they occupy regularly to limit household contamination.
  • Recommend mpox vaccine to asymptomatic close contacts of cases of MPXV.
  • Offer treatment with oral tecovirimat (TPOXX), available through the STOMP Trial. To enroll in STOMP, in the US call 1-855-876-9997.

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Title: Single dose aminoglycosides in complicated cystitis

Category: Infectious Disease

Keywords: Idea, cystitis, aminoglycosides, single dose (PubMed Search)

Posted: 7/27/2024 by Robert Flint, MD (Updated: 7/28/2024)
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The Infectious Disease Society of America in 2023 recommended a single dose of an aminoglycoside for uncomplicated cystitis treatment in those with resistance or other contraindications to first line oral agents who were otherwise well enough to be discharged. This very small study (13 participants) suggest this strategy works for complicated (“male sex, urinary flow obstruction, renal failure or transplantation, urinary retention, or indwelling catheters”) cystitis patients who could otherwise be discharged home.

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Title: HIV/AIDS medications and their common side effects

Category: Infectious Disease

Keywords: HIV, Medications (PubMed Search)

Posted: 6/20/2020 by Michael Bond, MD (Updated: 6/21/2020)
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HIV/AIDS medications and their common side effects
  • Didanosine: pancreatitis
  • Indinavir: nephrolithiasis
  • Isoniazid: hepatitis
  • Trimethoprim-sulfamethoxazole: hyperkalemia, Stevens-Johnson Syndrome
  • Ritonavir: paresthesias, metabolic syndrome
  • Pentamidine: hyperglycemia or hypoglycemia
  • Efavirenz: psychosis
  • Dapsone: hepatitis
  • Nevirapine: hepatic failure
  • AZT: bone marrow suppression and macrocytic anemia
Thing you need to know for your certifying exam


Title: Update to C. Difficile Treatment

Category: Infectious Disease

Keywords: clostridium difficile, antibiotics, vancomycin (PubMed Search)

Posted: 8/4/2018 by Ashley Martinelli (Updated: 12/12/2024)
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  • IDSA/SHEA recently released a guideline update for the management of Clostridium difficle infections
  • Discontinue inciting antibiotic therapy as soon as possible
  • Metronidazole is no longer considered first line therapy for C. difficle infection
  • Treatment course for 10 days unless initial fulminant or recurrence requiring vancomycin taper
  • Remember: Vancomycin IV does not cross into the GI tract and cannot be used to treat C. difficile

Clinical Definition

Treatment

Initial episode, non-severe

WBC ≤ 15,000 AND  SCr <1.5

  • Vancomycin PO 125mg 4x daily, OR
  • Fidaxomicin PO 200mg 2x daily

If above agents unavailable, metronidazole PO 500mg 3x daily

 

Initial episode, severe

WBC ≥ 15,000 OR  SCr >1.5

  • Vancomycin PO 125mg 4x daily, OR
  • Fidaxomicin PO 200mg 2x daily

 

Initial episode, fulminant

Hypotension, shock, ileus, megacolon

  • Vancomycin PO 500mg 4x daily
  • Ileus? Give vancomycin enema 500mg q8h

 

First Recurrence

 

  • Prolonged vancomycin PO taper 125mg 4x daily, OR
  • Vancomycin PO 125mg 4x daily x 10 days if metronidazole was used initially
  • Consider fidaxomicin PO 200mg 2x daily if vancomycin used for initial treatment


 

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Debating between cefepime or piperacillin/tazobactam for your septic patient? Use this table to help you decide.

 

 

Cefepime

Piperacillin/Tazobactam

Gram Negative Spectrum

Pseudomonas aeruginosa 

Yes

Yes

Aerobic gram negative organisms 

E. coli 

Klebsiella sp. 

Proteus mirabilis 

M catarrhalis  

H. influenza 

E. coli 

Klebsiella sp. 

Proteus mirabilis 

M. catarrhalis 

H. influenza 

Anerobic gram negative organisms 

No

B. fragilis 

 

Gram Positive Spectrum

MRSA 

No

No

Aerobic gram positive organisms 

MSSA 

CoNS 

Group A Strep 

S. pneumoniae 

 

MSSA 

CoNS 

Group A Strep 

S. pneumoniae 

E. faecalis 

Anaerobic gram positive organisms 

P. acnes 

Peptostreptococci 

P. acnes 

Peptostreptococci 

Clostridium sp. 

Infection Site Concerns

CNS Penetration 

Yes

No1

Urine Penetration 

Yes

Yes

Lung Penetration 

Yes

Low2

Dosing Frequency (Normal Renal Function)

Q8h 

Q6h 

1Tazobactam CNS penetration is limited, thus limiting antipseudomonal activity in the CNS 

2. Low pulmonary penetration, may not achieve therapeutic levels in patients with critical illness 

 

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Title: Risk Factors for Community Associated C. difficile Infection

Category: Infectious Disease

Keywords: c. difficile, antibiotic (PubMed Search)

Posted: 12/2/2017 by Ashley Martinelli (Updated: 12/6/2017)
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Community-associated Clostridium difficile infection (CA-CDI) represents 41% of all CDI cases annually.  The association of specific outpatient exposures was assessed in a case control study by Guh, et al. They reviewed the CDC’s active surveillance reporting from 10 states through the Emerging Infections Program (Maryland participates).

Cases: ≥18, + C. difficile stool specimen collected as an outpatient or within 3 days of hospitalization, with no overnight stay in a health care facility in the prior 12 weeks, and no prior CDI diagnosis

Controls: matched 1:1 for age and sex within the same surveillance catchment area as the case patient on the date of the collection specimen. Exclusion criteria: prior diagnosis of CDI, diarrheal illness, overnight stay in health care facility in the prior 12 weeks

Data Collection: telephone interview, standardized questionnaire or comorbidities, medication use, outpatient health care visits, household and dietary exposures in the prior 12 weeks

Results: 452 participants (226 pairs), over 50% were ≥ 60 years of age, 70.4% female, and 29% were hospitalized within 7 days of diagnosis, no patients developed toxic megacolon or required colectomy.

Cases had more health care exposures, including the emergency department (11.2% vs 1.4% p <0.0001), urgent care (9.9% vs 1.8%, p=0.0003). In addition, cases also reported higher antibiotic exposures (62.2% vs 10.3%, p<0.0001) with statistically significant higher exposure to cephalosporins, clindamycin, fluoroquinolones, metronidazole, and beta-lactam and/or beta-lactamase inhibitor combination. The most common antibiotic indications were ear or sinus infections, URI, SSTI, dental procedure, and UTI. No differences were found in household or dietary exposures.

Take-home point: This study highlighted the risk for CA-CDI infection for patients presenting to an ED and reiterates that exposures to fluoroquinolones, cephalosporins, beta-lactam and/or beta-lactamase inhibitor combinations, and clindamycin significantly increases the risk of CA-CDI infection. Reducing unnecessary outpatient antibiotic prescribing may prevent further CA-CDI. 36% of case patients did not have any antibiotic or outpatient health care exposure; therefore, additional risk factors may exist.

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Title: Cellulitis--Does your patient really have it?

Category: Infectious Disease

Keywords: cellulitis (PubMed Search)

Posted: 12/15/2016 by Michael Bond, MD (Updated: 12/17/2016)
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Take home points:

  1. Cellulitis is overdiagnosed
  2. 1/3 of patients diagnosed with cellulitis in the ED are ultimately given a different diagnosis
  3. The most common final diagnoses are vascular or inflammatory conditions.
  4. The over treatment of cellulitis increases healthcare costs, increases risk of adverse reactions, and can contribute to the development of drug resistant organisms.

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Title: Zika Update: Signs and Symptoms

Category: Infectious Disease

Keywords: Zika, arbovirus, infectious disease, mosquitos (PubMed Search)

Posted: 8/31/2016 by Jon Mark Hirshon, PhD, MPH, MD
Click here to contact Jon Mark Hirshon, PhD, MPH, MD

Zika virus and its transmission is currently an important infectious disease topic in the United States and the Western Hemisphere.  With domestic spread in the Continental United States, and the likely further spread to other parts of the southern United States, continued vigilance by healthcare providers remains important.

 

What are the signs and symptoms of Zika?

 

Most common signs and symptoms are:

  • Fever
  • Rash
  • Arthralgias
  • Conjunctivitis (generally nonpurulent)

 

Other symptoms can include

  • Myalgias
  • Headaches
  • Retro-orbital pain
  • Gastrointestinal upset

 

Symptoms can generally last 2 to 7 days.  Most individuals will have minimal or no significant symptoms and may not seek medical care. These symptoms are similar to other arboviruses, such as dengue or chikungunya. Potential serious complications include Guillian Barre syndrome.

 

Of course, the main concern remains infection of pregnant women and the impact that Zika has on the developing fetus, especially for the brain.

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Title: Cutaneous Larva Migrans- What is it?

Category: Infectious Disease

Keywords: Rash, Cutaneous larva migrans, nematode, tropics (PubMed Search)

Posted: 3/16/2016 by Jon Mark Hirshon, PhD, MPH, MD
Click here to contact Jon Mark Hirshon, PhD, MPH, MD

Cutaneous larva migrans (CLM) is an acquired dermatosis

  • Seen in patients returning from the tropics
    • Often seen in patient with a history of sunbathing or in barefoot beachgoers
  • Caused by the larvae of various nematode parasites of the hookworm family (Ancylostomatidae), with Ancylostoma braziliense the most frequently found in humans.

 

Clinical manifestations:

  • Linear, serpentine erythematous lesions
  • Intense pruritus
  • Will often heal spontaneously over weeks or months without treatment

 

Treatment:

  • Thiabendazole (applied topically)
    • Oral alternatives include other anti-parasitic medications such as albendazole, ivermectin
    • Oral thiabendazole as a single dose can be used, but is less effective than albendazole or ivermectin
  • Consider antibiotics if there is secondary bacterial infections
  • Freezing the leading edge has been previously used, but is considered ineffective and painful.

 

Bottom Line:

  • Consider CLM the next time a patient complains of a linear, erythematous itchy rash after returning from their all-inclusive stay in a Caribbean resort

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Attachments



Borrella mayonii a new species

There is a new bacteria that is causing Lyme disease. Borrella burgdorferi is the typical bacteria associated with lyme disease, but now several cases of Borrelia mayonii have been isolated from patients and ticks that live in Minnesota, Wisconsin and North Dakota. What is unique about this new species is that it is associated with nausea, vomiting, diffuse macular rashes, and neuro symptoms [e.g.: confusion, visual disturbance, and somnolence) along with the typical lyme disease symptoms of arthralgias and headaches.


Current lyme tests should detect this new species and treatment is the same as Borrella burgdorferi. The take home pearl is that we may see patients with "atypical" lyme disease symptoms so this should be on our differential for patients presenting with rashes, nausea, vomiting and neurologic complaints.



Title: New C. Diff Colitis Medication

Category: Infectious Disease

Keywords: C. Diff Colitis (PubMed Search)

Posted: 7/16/2011 by Michael Bond, MD (Updated: 12/12/2024)
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C. Diff Colitis

The general treatment recommendations for C. Diff Colitis are to place the patient on PO metronidazole and if they fail this treatment PO vancomycin (125 mg 4x day).  Vancomycin is generally reserved for resistant cases due to the fear that it could induce Vancomycin resistant enterococcus.

For severally ill patients it is recommended that you prescribe IV metronidazole and PO vancomycin when they are not actively vomiting.  Remember there is no role for IV vancomycin as it does not get into the bowel lumen to eradicate the infection.

There is some great news though, the FDA recently approved a new drug, a macrolide antibiotic fidaxomicin (Dificid), for the treatment of C. Diff Colitis. Fidaxomicin was found to be as effective as vancomycin in preventing recurrence 3 weeks after treatment.  Currently it is recommended that fidaxomicin be reserved for cases where patients are having recurrences after 3 weeks of vancomycin treatment.

The FDA news release can be found at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm257024.htm
 



Title: Soft Tissue Infection in Cirrhotic Patients

Category: Infectious Disease

Keywords: infection, cirrhosis (PubMed Search)

Posted: 4/4/2011 by Rob Rogers, MD (Updated: 12/12/2024)
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Hemorrhagic bullae in an ill-appearing patient with underlying cirrhosis should prompt consideration for an invasive infection due to Vibrio vulnificus.

V. Vulnificus is a gram negative rod and causes a highly lethal infection in patients with cirrhosis.

Antibiotics for these patients should include coverage for this organism. This should include doxycycline and a third genaration cephalosporin.

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Title: Rabies Update: News from the CDC

Category: Infectious Disease

Keywords: rabies, vaccination, animal bite, racoon, bat (PubMed Search)

Posted: 8/5/2010 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD

The number of rabies vaccines recommended by the ACIP (Advisory Committee on Immunization Practices) has been reduced from 5 to 4 doses for unvaccinated patients.

This was based on evidence from multiple source, including pathogenesis data, animal trials, clinical studies, and epidemiological surveillance. The first dose of the 4-dose regimen should be administered as soon as possible after exposure (day 0). Additional doses are then given on day 3, 7, and 14. The first dose of rabies vaccine should be administered with HRIG, infiltrating as much as possible into the wound, with the remainder given IM at a distant site from the vaccine.

This recommendation is not applicable to immunocompromised patients, who should continue to receive the full five doses.

http://www.cdc.gov/vaccines/pubs/vis/downloads/vis-rabies.pdf

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Spinal Epidural Abscess Pitfalls

  • The classic triad of back pain, fever, and neurologic deficits are found in < 15% of patients at the time of presentation
  • Up to 75% will be afebrile
  • Up to 67% will have a normal initial neurologic exam
  • < 40% have a WBC greater than 12,000 cells/mm3
  • < 33% will have an abnormality on plain film in the first 7-10 days

Take Home Point: In the patient with risk factors for spinal epidural abscess (IVDU, DM, indwelling catheters, etc) do not exclude the diagnosis based upon the absence of a fever, a normal WBC count, and a normal neurologic exam.



Title: Herpes Encephalitis

Category: Infectious Disease

Keywords: Encephalitis, Herpes (PubMed Search)

Posted: 9/22/2009 by Rob Rogers, MD (Updated: 12/12/2024)
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Herpes Encephalitis-When to Consider

Herpes encephalitis is a potential lethal condition with high morbidity. Obviously our job in the ED is to rule-out bacterial meningits. So, when should we consider the diagnosis of herpes encephalitis?

  • High wbc in the CSF with a negative gram stain
  • Lymphcytic predominance in the CSF
  • Altered patient and abnormal CSF
  • And, just about any of the softer "rule-out aseptic meningitis" patients

Although no great guidelines exist, consider ordering a herpes PCR when sending studies on the "rule-out meningitis" patient. What about emperically treating a patient with Acyclovir? Again, no great data. Consider treating with 10 mg/kg IV q 8 hours for patients with abnormal CSF (in addition to the Ceftriaxone/Vanc, etc.) if you are worried about them, if they are altered (or encephalopathic), and if the CSF is abnormal (elevated wbc) with a negative gram stain. Acyclovir can always be discontinued when the PCR returns negative.



 

Daptomycin and MRSA

  • Several new antibiotics are approved for the treatment of infections due to MRSA: linezolid, daptomycin, and tigecycline.
  • Although most are familiar with linezolid, it seems that both daptomycin and tigecycline are being used more frequently.
  • A few pearls on daptomycin:
    • administered IV once daily
    • dose needs to be adjusted in patients with renal failure
    • exerts its effect through a calcium-dependent binding to the bacterial membrane resulting in cell death
  • Importantly, daptomycin is inactivated by pulmonary surfactant and therefore should not be given in patients with suspected MRSA pneumonia.

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Title: Infections That Cause Temperature-Pulse Dissociation

Category: Infectious Disease

Keywords: Infections, Temperature (PubMed Search)

Posted: 12/29/2008 by Rob Rogers, MD (Updated: 12/12/2024)
Click here to contact Rob Rogers, MD

This pearl is dedicated to Dr. Michael Rolnick....

 

Infections That Cause Temperature-PulseDissociation

Certain infections may cause temperature-pulse dissociation (relative bradycardia in association with fever).

Remember that normally there will be an increase in pulse rate by 10 bpm for every 1 degree increase in temperature. So, if a patient has a temperature of 103 F, expect them to be tachycardic.

Any intracellular organism has the potential to cause a relative bradycardia (Faget's sign)

Infections that cause dissociation:

  • Salmonella typhi
  • C burnetii (agent of Q fever)
  • Chlamydia infections
  • Dengue fever


Title: CA-MRSA, treatment

Category: Infectious Disease

Keywords: CA-MRSA, Treatment (PubMed Search)

Posted: 12/27/2008 by Michael Bond, MD (Updated: 12/12/2024)
Click here to contact Michael Bond, MD

It is almost impossible to get through a shift these days with out seeing an abscess that is caused by CA-MRSA.  As of the 2007 Antibiotic nomogram (2008 data not yet available) at University of Maryland CA-MRSA was only 70% sensitive to clindamycin, and >98% sensitive to bactrim and > 96% sensitive to doxcycline.  A local community hospital in Baltimore is showing only 55% sensitivity to clindamycin.

As a New Year's resolution to yourself I recommend that you check with your local hospital's Micrology department to see what the sensitivities are to bactrim, clindamycin, doxycycline.  If sensitivities are less than 80% it would generally be recommended that these medications not be used as initial empiric treatment.

For Baltimore bactrim and doxycycline should probably be the preferred treatment options.

Have a Great New Year.



Title: Healthcare Associated Pneumonia

Category: Infectious Disease

Keywords: Pneumonia (PubMed Search)

Posted: 11/18/2008 by Rob Rogers, MD (Updated: 12/12/2024)
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Healthcare Associated Pneumonia (HCAP)....why is this important for the emergency physician?

Most of us are very familiar with the types of pneumonias commonly seen in clinical practice: community-acquired pneumonia (CAP), hospital-acquired pneumonia(HAP), and ventilator-associated pneumonia (VAP). But, some may not be that aware of a relatively newer type of pneumonia that has been well-defined, healthcare-associated pnemonia (HCAP). Experts in infectious disease and critical care now say that we (the ED) should be assessing ALL pneumonia patients for HCAP risk factors.

Why care, you ask?

  • Higher mortality than CAP
  • May look like CAP
  • Treated much differently than CAP

Risk factors: (most are common sense)

  • Nursing home or extended care facility resident
  • Recently admiited to a hospital for 2 or more days in the preceeding 90 days
  • Home wound care or attending a clinic for wound care
  • Dialysis patient
  • Home infusion therapy (antibiotics)
  • Immunosuppresive therapy or disease

Treatment:

  • 3 drugs....not like treatment of CAP!
  • Usually a combination of a big gun anti-pseudomonal (e.g. Pip/Tazo) combined with a broad spectrum respiratory fluoroquinolone (e.g. Moxi), combined with Vancomycin
  • Key difference between treatment of CAP and HCAP is consideration for multi-drug resistant pathogens, pseudomonas, and MRSA.