MANITOBA AMR

Learning Cases

Case 1: Influenza

Case 2: Community-Acquired Pneumonia

Case 1: Influenza

Stacey, a 60-year-old woman, comes into your clinic with muscle aches, fever, and general fatigue, which came on suddenly three days ago. Previously, she had felt well. She is not in distress and her vital signs are normal.

Based on her history and a physical examination, you feel there is a high likelihood she has influenza or another viral, flu-like illness. A rapid test for influenza A is positive, in the clinic. Stacey states that she would like antibiotics in order to feel better. 

How would you approach your discussion with the patient?

Find out

Your response to Stacey can explain that antibiotics will not help her feel better. Antibiotics are not indicated, nor expected to be of benefit for influenza. Influenza is caused by a virus and antibiotics cannot cure a virus. It would be appropriate to discuss with her that the natural history of influenza infection, or what we normally expect in the case of flu, would suggest that her symptoms are likely to improve within 5-7 days. You can also give her clear information about when antibiotics would be beneficial. You can advise that she should return if she develops symptoms that point towards a secondary bacterial infection, such as persistent fever, increasing difficulty breathing, or if her symptoms do not improve over the next 3-4 days.

A key component in this case is effectively communicating with the patient to ensure they understand the reasoning behind not prescribing antibiotics. Often, providing a written handout can ensure that your patient retains the key messages you have discussed and may help them feel they have ‘gotten something’ out of the appointment. One such resource is the Viral Prescription Pad (see References). This resource helps patients understand their diagnosis, gives recommended over-the-counter analgesics they can use, and instructions to return if certain symptoms arise.

This would also be an ideal time to discuss the benefits of the annual influenza vaccination and health promotion strategies for the future. You can remind Stacey that building good hand washing habits is a simple and effective way to prevent the flu.  

Sometimes good antimicrobial stewardship practice involves knowing when medications other than antibacterial agents are likely to be of benefit. It is important to note, although not applicable in this case, that there are certain factors that put patients with influenza virus infection at a higher risk for progressive disease. These include severe disease (requiring hospitalization); however, some patients with milder disease are at risk for severe disease (see Risk Factors). In these patients with suspected or proven influenza, antiviral medication (oseltamivir) would be indicated if they presented to clinic within 48 hours of symptom onset to reduce the risk of severe outcomes such as hospitalization or death. 

Risk Factors:

Major risk factors that predispose individuals to severe influenza (Adapted from Aoki et al, 2019)

  • Severe chronic illness, including asthma and other chronic pulmonary diseases, cardiovascular disease, chronic renal insufficiency, diabetes mellitus, and chronic neurological or neudevelopmental disorders
  • Obesity with BMI ≥40
  • Age younger than 5, or older than 64
  • Immunosuppression due to disease (eg. HIV infection with CD4 is < 200 × 106/L) or medication
  • Pregnant women and women up to 4 weeks postpartum

References: 

Case 2: Community-Acquired Pneumonia

Jesse, a 5-year-old boy, presents to your office with fever, cough, and tachypnea. These symptoms started 3 days ago. He has been eating well throughout this time and has stable vital signs when the pediatrician examines him. 

A rapid test, performed by the clinic nurse, is negative for SARS-CoV2 virus. The chest X-ray results are shown below: 

X-ray image of lungs with an infection.
Image Credit: https://www.intechopen.com/chapters/42153 (Accessed Sept 17, 2022).

Based on the clinical symptoms and chest X-ray findings, you determine that Jesse is well enough to be treated as an outpatient, but will still require antibiotics to help clear the infection. 

Given the circumstances of this case, which antibiotic would you prescribe for Jesse? 

  1. Clindamycin 
  2. Amoxicillin-Clavulanic acid (Amox-Clav)
  3. Amoxicillin
  4. Azithromycin
Find out

The best choice in this case is (c) amoxicillin. The findings on chest X-ray indicate a bacterial etiology of the community-acquired pneumonia (CAP), therefore, it is appropriate to treat with antibiotics. Streptococcus pneumonia is the most common bacterial cause of CAP and knowing this will help with the choice of antibiotic.Amoxicillin is a very effective antibiotic against S. pneumoniae and is recommended to treat community acquired bacterial pneumonia by the Canadian Paediatric Society.

An important part of preventing antimicrobial resistance is choosing the most effective and narrow spectrum antibiotic for the situation. Antibiotics should be chosen to be the narrowest spectrum possible while still targeting the causative bacteria, which in this case would be amoxicillin. The other antibiotic options in this case are broader spectrum antibiotics, but would not be appropriate for this situation. Broad spectrum antibiotics can have a greater effect on the normal flora, or microbiome, of the patient. This can contribute to antimicrobial resistance by allowing overgrowth of drug-resistant bacteria within the microbiome of the patient. 

In this case, CAP was caused by bacteria, but bacteria are actually the second most common cause of CAP. The most common pathogens responsible for CAP in healthy children are respiratory viruses, especially during the winter. Some common viral causes include respiratory syncytial virus, influenza virus, parainfluenza virus and human metapneumovirus. 

The duration of treatment for children with uncomplicated community acquired pneumonia who are well enough to be treated as outpatients is also an important question. In adults, 5-7 days has been shown to be as effective as longer courses; in children, the typical antibiotic course has been somewhat longer (7 to 10 days) by historical practice. However, a recent RCT demonstrated that, similar to adults, in children aged 6 months to 5 years old with non-severe CAP, 5 days of antibiotic therapy is as effective as 10 days (see References). Practice guidelines are increasingly adopting the shorter, equally effective duration of 5 days.

References: 

  • Le Saux N, Robinson JL. Uncomplicated pneumonia in healthy Canadian children and youth: Practice points for management. Paediatr Child Health. 2015 Nov-Dec;20(8):441-50. doi: 10.1093/pch/20.8.441.
  • Canadian Pediatric Society 2018 “Uncomplicated pneumonia in healthy Canadian children and youth: Practice points for management”. See:  https://cps.ca/en/documents/position/pneumonia-management-children-youth
  • Greenberg D, Givon-Lavi N, et al. Short-course antibiotic treatment for community-acquired alveolar pneumonia in ambulatory children: a double-blind, randomized, placebo-controlled trial. Pediatr Infect Dis J 2014. Feb;33(2):136-42. doi: 10.1097/INF.0000000000000023.