Approach to nosocomial infections: Clinical sciences

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Introduction0:00–1:18

Nosocomial infections, also called healthcare-associated infections, or HAIs for short, are infections that patients acquire while receiving medical care for another condition.
Anyone who is hospitalized, lives in long-term care, or receives care at an outpatient facility, such as a dialysis unit or rehabilitation center, can develop a nosocomial infection.
Nosocomial infections are most commonly caused by multidrug-resistant bacteria, such as Methicillin-Resistant Staphylococcus Aureus or MRSA, Vancomycin-Resistant Enterococcus or VRE, and Carbapenem-Resistant Enterobacteriaceae or CRE.
Less common causes include viruses and fungi. The most common nosocomial infections include catheter-associated urinary tract infections or CAUTI; central line-associated bloodstream infections or CLABSI; surgical site infections or SSI; hospital-acquired pneumonia or HAP; ventilator-associated pneumonia or VAP; and Clostridioides Difficile infection or CDI.

Unstable patient1:18–1:41

If your patient presents with signs and symptoms suggestive of nosocomial infection, you should first perform an ABCDE assessment to determine if the patient is unstable or stable.
If the patient is unstable, first stabilize the airway, breathing, and circulation, and start broad-spectrum antibiotics, before continuing with further workup.
Now, let’s go back to the ABCDE assessment and take a look at stable patients. In this case, obtain a focused history and physical examination, and order labs including a complete blood count with a differential.

Stable patient1:41–2:52

History typically reveals current or recent treatment at an inpatient or outpatient healthcare facility, as well as systemic symptoms of infection, such as fever, chills, and fatigue.
On exam, the patient might present with altered mental status, like confusion or lethargy, but also localized findings depending on the type of infection.
Additionally, labs typically show leukocytosis. Alright, now if these features are present, you should suspect nosocomial infection and assess the source of infection.
Now, here's a clinical pearl! Keep in mind that some populations, such as elderly or immunosuppressed patients, may not develop fever and leukocytosis in response to infection.
These patients may only present with vague symptoms, like fatigue or changes in mental status.You can start by assessing indwelling devices like urinary catheters and central lines.

CAUTI2:52–3:54

First, let’s start with catheter-associated urinary tract infection, or CAUTI. These patients typically have a urinary catheter in place, or one was removed within the past two days.
Symptoms usually include suprapubic discomfort, dysuria, as well as urinary frequency and urgency; while physical exam often reveals suprapubic or costovertebral angle tenderness.
In this case, consider catheter-associated urinary tract infection, or CAUTI, so don’t forget to change the urinary catheter and then order a urinalysis and urine culture to avoid getting a contaminated or colonized sample.
If the urinalysis reveals pyuria and bacteriuria, and the urine culture is positive, then the patient has CAUTI. Next up is central line-associated bloodstream infection or CLABSI.

CLABSI3:54–5:19

This is associated with either a central line that’s been in place for more than 2 days, or symptoms of infection that developed on the day of central line removal or the next day.
In addition to systemic signs, there are also localized signs of infection at the central line insertion site, like erythema, tenderness, and purulence.
In this case, you should consider CLABSI, so don’t forget to send two or more samples for blood cultures taken from different sites, like a peripheral vein and the central line.
One positive blood culture for bacteria that is a true pathogen, meaning for bacteria that are not a part of human microflora; or two positive blood cultures for bacteria that are commensal organisms from the normal microflora, are highly suggestive of CLABSI.Here’s a high yield fact!
Staphylococcus epidermidis is a coagulase-negative baterium that’s part of the normal skin flora, but it’s among the most common causes of nosocomial blood infections, especially in patients with prosthetic valves, cardiac devices, central lines, catheters, and IV drug use.
That’s because coagulase-negative species are able to produce an adherent biofilm that allows them to survive and colonize these devices.

SSI5:19–6:25

Now, let’s take a step back. If the patient doesn’t have findings consistent with CAUTI or CLABSI, you should assess for surgical site infection or SSI.
A patient with SSI usually reports a recent surgical intervention, pain at the surgical site, and a possible presence of implanted material, like mesh for a hernia repair, or a prosthetic joint.
On physical exam, you will usually find peri-incisional signs of infection, such as swelling, warmth, and erythema. In some cases you might notice purulent drainage from the surgical site, while in others the incision might split open at the skin, which is called wound dehiscence.
There might also be induration, in which the skin becomes harder and thicker due to inflammation. Finally, you might detect fluctuance, which is associated with a collection of fluid or pus under the skin, giving it a “boggy” feel on palpation.
All these findings suggest that there’s a surgical site infection!Going back, if there are no signs of SSI, you should next assess for a respiratory infection, such as hospital-acquired pneumonia or HAP and ventilator-associated pneumonia or VAP for short.

HAP6:25–7:28

Suspect HAP in a patient who develops respiratory symptoms of infection 48 hours or more after admission to a hospital. On admission, the patient shouldn’t have presented with fever or respiratory symptoms.
The most common respiratory symptoms include productive cough, pleuritic chest pain, and shortness of breath. The physical examination will usually reveal rales, decreased breath sounds in the affected lung, and decreased oxygen saturation.
If so, you should consider HAP and order a chest x-ray. If the chest X-ray reveals a new lung infiltrate, consolidation, or effusion, you can diagnose hospital-acquired pneumonia.On the other hand, you should suspect VAP in a patient on mechanical ventilation that develops signs of infection after more than 48 hours after intubation.

VAP7:28–8:25

Physical exam findings, such as purulent secretions in the endotracheal tube, tachycardia, rales, and decreased breath sounds in the affected lung fields, should make you consider VAP.
So, the next step is to get imaging, like a chest X-ray and point of care ultrasound, or POCUS. Chest X-ray might reveal a new lung infiltrate, consolidation, or effusion.
However, unlike in HAP, the imaging of choice for VAP is a POCUS, because it’s ideal for patients who can’t be easily transported.
Common findings on POCUS include subpleural consolidation, liver-like echogenicity of the lung, and dynamic air bronchograms.
If a patient has these findings, you can diagnose VAP. Finally, if there are no signs of respiratory infection, you should assess for gastrointestinal infections, which in hospitalized patients, can be a Clostridioides Difficile infection or CDI, more commonly referred to as C.

CDI8:25–9:59

diff. These patients typically report large volumes of watery diarrhea, with more than 3 loose stools in 24 hours; and lower or diffuse abdominal pain.
Additionally, history may reveal recent hospitalization, as well as recent or current use of antibiotics or proton pump inhibitors.
On the flip side, physical exam findings usually include abdominal distension and tenderness, as well as decreased bowel sounds.
If so, consider CDI and obtain a stool sample for CDI testing. You should try to obtain a liquid stool sample, but if there’s minimal stool present, you can also do a rectal swab.
Send the sample for a glutamate dehydrogenase antigen test, and C. difficile toxins A and B.
If both tests come back positive, it confirms CDI. However, some individuals can have one positive and one negative test, meaning that the results are inconclusive.
In this case, order a nucleic acid amplification test, or NAAT for short. A positive NAAT testing confirms the diagnosis of CDI, while negative rules out the infection.Alright, as a quick recap… Nosocomial infections, also called healthcare-associated infections, or HAIs for short, are infections that patients acquire while receiving medical care for another condition.

Review9:59–11:13

If your patient presents with signs and symptoms suggestive of nosocomial infection, you should first perform an ABCDE assessment to determine if the patient is unstable or stable.
If the patient is unstable, first stabilize the airway, breathing, and circulation, and start broad-spectrum antibiotics, before continuing with further workup.
Once you stabilize the patient, or if your patient was initially stable, you should try to identify the source of infection.
Start by assessing indwelling devices like urinary catheters and central lines, to rule out or confirm the diagnoses like catheter-associated urinary tract infection and central line-associated bloodstream infection.
Next, assess for a possible surgical site infection. If you rule out those as well, your next step is to assess for respiratory infections, primarily hospital-acquired pneumonia and ventilator-associated pneumonia.
Finally, don’t forget to rule out gastrointestinal infections,