Microbe mystery pt 1

​The Microbial Mystery Game!

By Eric Perry and Ericka Hayes

Multiple Choice

A one month old infant who was prematurely born on November 1st at 30 weeks gestation, develops a fever of 104, rhinitis and a cough.

The infant goes on to develop acute respiratory distress requiring ventilator support.

A nasal pharyngeal swab is collected and tested for respiratory viral pathogens.

The test is positive for a virus who’s infection might have been prevented by the prophylactic administration of Beyfortus (nirsevimab). What is this virus?

• Influenza A

• Influenza B

• RSV

• Adenovirus

• Parainfluenza or Human metapneumovirus

​FDA Approves New Drugs to Prevent RSV in Babies and Toddlers

​July 17, 2023

Therapeutic indication

• Beyfortus is indicated for the prevention of RSV lower respiratory tract disease in:

  • Neonates and infants during their first RSV season

  • Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season

Multiple Choice

A patient presents to his primary care physician after returning from a two week ecotourism trip in the Amazon. The patient reports staying in thatched roof homes and inconsistently using insecticide treated bed nets during his travels, but was careful to take his malaria prophylaxis as directed.

Upon presentation, the patient has a swollen eyelid and reports experiencing body aches, headache and diarrhea.

Given this patient's history and presentation, what laboratory diagnostic test would you suggest?

• Stool ova and parasite examination with iodine wet mount and trichrome stain

• Stool culture

• Blood culture

• Thick and thin blood smears with Giemsa stain

• Plasmodium immunoassay

Multiple Choice

This image of thin blood smear with Giemsa stain shows what organism.

• Plasmodium vivax

• Leishmania donovani

• Trypanosoma cruzi

• Plasmodium falciparum

• Trypanosoma brucei

​This patient was infected with Trypanosoma cruzi while on his trip to the Amazon. Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted by the feces of an infected triatomine bug ("kissing bug").

Generally, transmission occurs after a triatomine bug bite is scratched, and the bite is infected with the bug's feces.

An indication that a person may be acutely ill withTrypanosoma cruzi is known as Romaña's sign - swelling of the eyelid caused by introduction of triatomine bug feces into the eye.

It is likely that this patient was exposed to triatomine bugs due to his accommodations while traveling (thatched roof homes) and his inconsistent bed net usage.

If untreated, acute Chagas disease can progress into a "chronic indeterminate" form marked by the absence of blood parasitemia. Individuals progressing to this chronic stage can remain asymptomatic for decades. However, 20-30% of asymptomatic individuals will experience a reactivation of disease and may develop life threatening medical issues, including heart rhythm abnormalities, a dilated heart, a dilated esophagus or a dilated colon. Additionally, immunosuppression can result in a reactivation of disease and parasitemia.

Infection with T. cruzi is diagnosed through preparation of thin and thick blood smears stained with Giemsa stain. Trypomastigotes can be seen on both smear types. On thin smears, the trypomastigotes are "C" shaped with a central nucleus and prominent, subterminal kinetoplast, as in the image above.

Treatment of T. cruzi infection is recommended for all infected individuals. Treatment options include Benznidazole or Nifurtimox.