Bacterial Pneumonia Blood Test

What is Bacterial Pneumonia?

Bacterial pneumonia is a serious lung infection that inflames the air sacs in one or both lungs. It is caused by bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus that invade lung tissue. The Complement Component C4 Pleural Fluid test is the most important test for assessing immune system activation and inflammatory response severity in bacterial pneumonia.

RECOMMENDED TEST Complement Component C4, Pleural Fluid
Google reviews 505 reviews
$435 $339
What's included
Fast & easy, results by email & SMS
No extra fees paid at the lab
No need to visit a doctor
Private & confidential
No insurance needed
Results explained
Why Private MD Labs?
90-day money-back guarantee Lab order in minutes Save a trip to the doctor Low prices since 2005 Labs within 2 miles

What causes bacterial pneumonia?

Bacterial pneumonia is caused by bacterial pathogens that invade and infect the lung tissue, with Streptococcus pneumoniae being the most common culprit, followed by Haemophilus influenzae, Staphylococcus aureus, and Mycoplasma pneumoniae. These bacteria enter the lungs through inhalation or aspiration, overwhelming the respiratory defenses and causing inflammation of the air sacs (alveoli). When bacteria multiply in the lungs, they trigger an intense immune response that fills the alveoli with fluid and pus, making breathing difficult and causing the characteristic symptoms of pneumonia.

What is the best test for bacterial pneumonia?

The Complement Component C4 Pleural Fluid test is the most important blood test for bacterial pneumonia because it measures the activation of your immune system's complement pathway in response to bacterial infection. This test detects elevated C4 complement levels in the fluid surrounding your lungs, providing crucial information about the severity of the inflammatory response and how aggressively your body is fighting the infection. While chest X-rays remain the primary diagnostic tool for visualizing lung infection, this specialized blood test helps doctors assess immune system function, distinguish bacterial from viral causes, and monitor how well treatment is working by tracking changes in complement activation over time.

When should I get tested for bacterial pneumonia?

You should get tested if you experience persistent cough with thick yellow, green, or bloody mucus, high fever above 102°F with chills and sweating, sharp chest pain that worsens with breathing or coughing, or severe shortness of breath and rapid breathing. Testing is especially urgent if you have difficulty breathing, confusion or changes in mental awareness, bluish lips or fingernails, or if you are over 65 years old or have a weakened immune system. Early testing helps confirm bacterial infection, assess severity, and guide appropriate antibiotic treatment before complications develop.

What are the symptoms of bacterial pneumonia?
Bacterial pneumonia symptoms typically develop suddenly and include high fever (often 102-105°F), severe cough producing thick greenish or yellow phlegm, sharp stabbing chest pain that worsens with deep breathing or coughing, and shortness of breath even at rest. You might also experience rapid breathing, chills with shaking, sweating, fatigue, confusion (especially in older adults), nausea, vomiting, and muscle aches. Unlike viral pneumonia which develops gradually, bacterial pneumonia often strikes quickly and makes you feel extremely ill within 24-48 hours.
Who is at risk for bacterial pneumonia?
People at highest risk for bacterial pneumonia include adults over 65, infants and young children under 2, and anyone with weakened immune systems from conditions like HIV, cancer treatment, or organ transplants. Chronic health conditions such as COPD, asthma, heart disease, diabetes, and liver or kidney disease significantly increase susceptibility. Smokers, people who abuse alcohol, those recently hospitalized or on ventilators, and individuals with swallowing difficulties that cause aspiration are also at elevated risk for developing bacterial lung infections.
What happens if bacterial pneumonia is left untreated?
Untreated bacterial pneumonia can lead to life-threatening complications including bacteremia (bacteria spreading into the bloodstream), sepsis and septic shock, lung abscesses (pus-filled cavities in lung tissue), and pleural effusion or empyema (infected fluid accumulation around the lungs). The infection can cause acute respiratory distress syndrome (ARDS) requiring mechanical ventilation, permanent lung damage with scarring, and respiratory failure. Without prompt antibiotic treatment, bacterial pneumonia has a mortality rate of up to 30% in severe cases, particularly in elderly patients or those with compromised immune systems.
Can bacterial pneumonia be diagnosed with a blood test?
Blood tests cannot definitively diagnose bacterial pneumonia on their own, but they play a crucial supporting role in confirming bacterial infection and assessing severity. The Complement Component C4 test measures immune system activation in pleural fluid, while a complete blood count (CBC) typically shows elevated white blood cells indicating bacterial infection. Blood cultures can identify the specific bacteria causing the infection in about 20-25% of cases. Chest X-rays remain the primary diagnostic tool for visualizing lung infiltrates, but blood tests help distinguish bacterial from viral pneumonia, guide antibiotic selection, and monitor treatment response.
How is bacterial pneumonia treated?
Bacterial pneumonia is treated primarily with antibiotics tailored to the suspected or identified bacterial pathogen, with common choices including azithromycin, amoxicillin, ceftriaxone, or fluoroquinolones like levofloxacin. Mild cases can be treated at home with oral antibiotics, plenty of rest, increased fluid intake, and fever reducers like acetaminophen or ibuprofen. Severe cases require hospitalization for intravenous antibiotics, oxygen therapy, breathing treatments, and close monitoring. Most people start feeling better within 2-3 days of starting antibiotics, though complete recovery typically takes 1-3 weeks depending on age, overall health, and severity of infection.
How can I prevent bacterial pneumonia?
You can prevent bacterial pneumonia by getting vaccinated with the pneumococcal vaccine (PPSV23 and PCV13), which protects against the most common bacterial cause, Streptococcus pneumoniae, as well as the annual flu vaccine since influenza often leads to secondary bacterial pneumonia. Practice good hygiene by washing hands frequently, avoiding touching your face, not sharing drinks or utensils, and staying away from people who are sick. Strengthen your immune system by quitting smoking, limiting alcohol consumption, eating a nutritious diet, getting adequate sleep, managing chronic health conditions, and staying physically active to maintain healthy lung function.
What can I do at home for bacterial pneumonia?
While taking prescribed antibiotics, you can support recovery at home by getting plenty of rest to help your immune system fight the infection, drinking 8-10 glasses of water daily to thin mucus and make coughing more productive, and using a humidifier or breathing steam to ease breathing and loosen congestion. Take fever reducers like acetaminophen or ibuprofen as directed to manage pain and reduce fever, avoid smoking and secondhand smoke exposure, and prop yourself up with pillows when sleeping to make breathing easier. Warm saltwater gargles can soothe throat irritation from coughing, and consuming warm liquids like herbal tea with honey or chicken soup provides comfort and hydration while supporting recovery.
How’s this work?
Getting your blood test with us is easy, private & backed by the power of science.

Long story short:
  1. In the test options, use the filters or search box to narrow your choices and find the test you want.
  2. If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test.
  3. Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout.
  4. If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want.
  5. When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system.
  6. Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way.
  7. You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy!
  8. If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.
How do I know which test to get?
In the test options, find the test you want. If you’re not sure which test to get, we can lend a hand in finding the right option.

Just text or call us at 754-799-7833, email us at support@privatemdlabs.com, and we'll gladly help you. We've got your back and reply quickly.
Is it possible to make changes to my lab order if I made a mistake with the name, date of birth, or any other details?
Absolutely! We totally understand that errors can happen. No worries, we're here to help you.

Just reach out to us via text at 754-799-7833 or shoot us an email at support@privatemdlabs.com. Remember to include your order number and let us know the correct information you’d like to update. Our awesome team will jump right in and make sure everything is sorted out and accurate for you.

There are no changes necessary if your address is wrong on the requisition though. We don’t mail anything out.

Our lab requires an address to be listed to generate an order.
Do you accept health insurance?
Only HSA & FSA is accepted.

Our services are strictly self-pay and cannot be submitted to your health insurance provider except for Health Savings Accounts or Flexible Savings Accounts.

This policy applies to all insurance companies, including federal health insurance programs like Medicare.

If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com.
Can I cancel my order?
Yes.

We get it – sometimes your needs change.

As long as your samples haven’t been collected yet, we’re happy to help you cancel your order.

If you have any further questions, please text us at 754-799-7833 or email support@privatemdlabs.com.

You can read more about our cancellation policy here.
How can I find a lab location near me?
During the ordering process, you’ll be able to select a specific lab near you, with no strings attached! You can switch it up later easily and visit any of our authorized locations as long as it’s the same lab company you selected your test for (Quest Diagnostics or Labcorp).

Before you proceed with your order, feel free to browse through all our lab locations here. This will give you the peace of mind of knowing that there's a lab nearby your home, office or your favorite gym.

If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.
Here’s how easy it is to get blood work done on your terms
Choose a checkup
Order your test Save a trip to the doctor. Your results will come with clear, friendly explanations. Takes 2 minutes
Book a lab
Book an appointment Visit any of our 4,000 nearby lab locations to have your samples collected. Book or walk-in
Choose a checkup
Get results Receive a clear, easy-to-digest health report by email & SMS within a few business days. Get answers, fast

Here’s why 1,000,000+ customers chose us for affordable hassle-free private blood testing.

You get clinical lab reports & simplified health insights.
Save time & gas, go straight to the lab. Our doctors cover the rest.
Results start landing the next day after your lab visit.*
We don’t sell or share your data. Your time & privacy matter.
US-licensed doctors have your back if things get unclear.
No hidden fees, nice discounts for regular checkups.
Save a trip to the doctor, go directly to the lab
Instant orders, results often overnight*
Results explained in simple language
Reviewed by US licensed doctors
Fast & confidential, we never sell or share your data
No insurance needed, transparent pricing
Demo results
Testosterone 375 ng/dL
Demo results
Normal Optimal 400 - 1000 High
375 ng/dL

What this means

Your testosterone levels are slightly below the optimal range. While this is not necessarily cause for concern, it may contribute to occasional fatigue, reduced motivation, or lower muscle mass over time.

* Regular blood test results (e.g., CBC) typically start arriving the next business day after sample collection. More complex tests, such as hormone panels, may take up to 10–15 business days due to their complexity.

Us vs. Them

Not overhyped or overpriced. Just comprehensive blood testing made simple and for everyone.

* Regular blood test results (e.g., CBC) typically start arriving the next business day after sample collection. More complex tests, such as hormone panels, may take up to 10–15 business days due to their complexity.

1,000,000+ blood tests later, here's what our customers say

Google reviews 505 reviews Next
Complement Component C4, Pleural Fluid
Google reviews 505 reviews
$435 $339
What's included
Fast & easy, results by email & SMS
No need to visit a doctor
Private & confidential
No insurance needed
Results explained
No extra fees paid at the lab

Sample results

Sample image
For you & your coach Health insights Written in human language, backed by science.
Sample image
For you & your doc Classic lab report A familiar and comprehensive lab report.

Ask AI

Your 24/7 Lab Guide

Quick questions:

Which test is right for my symptoms?
What could be causing this?
When should I get tested?
A
Hi, I'm AI. I can help you find the right test, explain results, or prepare for your visit. What can I help with?
Just now
A
AI provides insights, not medical diagnoses.