What is Proteus mirabilis Infections?
Proteus mirabilis is a kind of bacteria that belongs to the Enterobacteriaceae family, a group of bacteria often found in the gut. This particular type of bacteria does not need oxygen to survive (facultative anaerobe), and it can process a sugar called maltose but not lactose. Proteus mirabilis has some unusual features. For example, it can move around surfaces like a swarm, and it can grow longer and produce a sticky substance (polysaccharide) when it comes into contact with solid surfaces, such as medical equipment. This allows the bacteria to attach and move easily along these surfaces.
Its ‘propeller-like’ appendages, or flagella, give it the ability to move, which not only supports its settling down and thriving in certain areas (colonization), but also has been linked with its ability to build up sticky communities of bacteria (biofilms). This is suggested to help it resist the body’s immune responses and certain antibiotics.
You can find Proteus in lots of settings like soil and water, and while it’s also a normal part of the bacteria in the human intestine (along with similar types of bacteria like Klebsiella species and E. coli), it can sometimes cause serious infections in people.
What Causes Proteus mirabilis Infections?
Ninety percent of infections caused by a bacteria called Proteus come from a species known as P. mirabilis. These infections are usually gotten outside a hospital setting, often within the community.
While it’s rare, Proteus bacteria can also cause infections in hospitals or long-term care facilities. The bacteria can infect patients from contaminated skin or the mouth lining of patients and staff.
People are at a higher risk of getting a Proteus infection in hospitals if they have a history of repeated infections, physical issues in their urinary tract, or have had medical procedures performed on their urinary tract. These factors also increase the risk of getting other infections from bacteria such as Klebsiella, Enterobacter, Pseudomonas, Staphylococci, and Enterococci.
Urinary tract infections, also known as UTIs, can happen when bacteria travel up the urinary tract. This can occur along the lining of a catheter, which is a tube used for medical procedures, or can result from contact with infected urine.
Risk Factors and Frequency for Proteus mirabilis Infections
Proteus, a type of bacteria, often causes urinary tract infections (UTIs), especially among individuals aged 20 to 50 years old. Women in this age group are the most likely to get UTIs. In healthy women, Proteus is behind 1% to 2% of all UTIs, while for UTIs acquired in a hospital setting, Proteus causes about 5% of cases. For UTIs related to the use of urinary catheters, the association with Proteus is even stronger, accounting for 20% to 45% of cases.
There are various factors that contribute to the likelihood of getting a UTI. These include:
- Sexual activity in men and women
- Unprotected anal intercourse in men
- Having an uncircumcised penis
- Immune system deficiencies, such as having a low CD4 count (less than 200 per microliter of blood)
In addition, certain conditions can increase the risk of getting a Proteus infection including:
- Being female
- Having a urinary catheter for a long period
- Not cleaning or caring for a urinary catheter properly
- Suffering from other health conditions
- Not having access to antibiotics for general use
In the US, 35% of patients with blood infections caused by gram-negative bacteria (like Proteus) get the infection from UTIs.
Signs and Symptoms of Proteus mirabilis Infections
People with a Proteus infection may suffer from inflammation in parts of the urinary tract, such as the urethra (urethritis), bladder (cystitis), prostate (prostatitis) or the kidneys (pyelonephritis). If people are frequently experiencing kidney stones, it could hint at an ongoing chronic Proteus infection.
- Those with urethritis usually have symptoms like painful urination, cloudy urine (sometimes with discharge), and needing to pee more often. These symptoms tend to be mild and are often overlooked by individuals.
- Cystitis, however, usually comes on quickly and can include symptoms such as painful urination, feeling the need to urinate a lot, lower abdominal or lower back pain, urinating in small amounts, dark urine, or blood in urine. Those with cystitis might also develop a fever which could mean they have a more severe condition, like pyelonephritis, a blood infection, or even sepsis.
- Prostatitis comes on more quickly in men and has the same symptoms as cystitis, but can also include fever and chills. Prostatitis is more common as men get older. If the prostate is blocked, people may also feel pain around the anus. A swollen and tender prostate might be noticed during a physical exam.
- Lastly, pyelonephritis usually happens due to other conditions like urethritis or cystitis, so those can have overlapping symptoms. There are more specific symptoms of pyelonephritis, such as pain in the side of the body where your kidneys are, nausea and vomiting, fever, blood in the urine, and sometimes, an enlarged kidney could be felt during a physical exam.
Testing for Proteus mirabilis Infections
If your doctor suspects you have an infection caused by Proteus mirabilis, a type of bacteria, the best way to confirm this is through a laboratory test known as a culture. Proteus bacteria are typically found in a rod-shaped form and can survive with or without oxygen. They have a unique way of moving that becomes apparent when grown in a lab. However, identifying Proteus in a culture is not enough. Your doctor will also take into account your symptoms to make sure the diagnosis is correct.
Apart from the culture test, other tests your doctor may use include analyzing a urine sample to check for pyuria (a condition where there are too many white blood cells in the urine, usually a sign of a urinary tract infection) and leukocyte esterase (a substance produced by white blood cells and is also a sign of infection). If these are absent in your urine, it may mean that something else is causing your symptoms, not an infection. Your doctor might also use a test called a Gram stain to check for bacteria in your urine.
If your urine has consistently been too alkaline (the opposite of acidic) and your culture test comes back positive for Proteus, your doctor may suspect you have kidney stones. This is because Proteus bacteria can contribute to the formation of a specific type of kidney stone known as a struvite stone.
If your symptoms do not improve after antibiotic treatment, your doctor may suggest getting an ultrasound or CT scan of your kidneys and abdomen. This is to check for potential complications such as kidney stones or a pocket of pus near the kidneys, known as a perinephric abscess.
Treatment Options for Proteus mirabilis Infections
If you have a simple urinary tract infection (UTI) caused by P. mirabilis, a type of bacteria, it is usually treated outside the hospital. The usual treatment involves taking antibiotics like trimethoprim/sulfamethoxazole (TMP/SMZ) or an oral fluoroquinolone (for example, ciprofloxacin) for three days.
When you have a simple, acute inflammation of the kidney called pyelonephritis, it can also be treated outside the hospital. The treatment usually involves a fluoroquinolone antibiotic, which you need to take for 7 to 14 days. If fluoroquinolones aren’t suitable for you, another option is a one-time dose of either ceftriaxone or gentamycin (these are other types of antibiotics). After this, you will need to take either TMP/SMZ, an oral fluoroquinolone, or cephalosporin (yet another type of antibiotic) for 7 to 14 days.
However, if your condition is more severe, or if you are already in a hospital, your doctor may start your antibiotic treatment with an injection (also known as intravenous administration). The antibiotics used might be ceftriaxone, gentamycin, fluoroquinolone, gentamycin combined with ampicillin, or aztreonam. Once your fever is gone, your doctor might switch your treatment to oral antibiotics such as cephalosporin, an oral fluoroquinolone, or TMP/SMZ. You will need to continue these for up to 14 more days.
If your UTI is complicated, which means you have other health conditions that could make the treatment fail, you can still be treated outside the hospital. If this is the case, your doctor will give you oral antibiotics for 10 to 21 days. It’s important that you have regular follow-up appointments in this case.
You can avoid getting infected by Proteus (the family of bacteria that P. mirabilis belongs to) if you practice good hygiene. This includes thorough cleaning of medical equipment and surfaces. And if a procedure called catheterization (where a tube is inserted into your body to drain urine from your bladder) is suggested, it should only be used if there’s no other option.
What else can Proteus mirabilis Infections be?
Other bacteria similar to E. Coli or Klebsiella can cause symptoms that might make you think you have a urinary tract infection (UTI) or bacteremia, which is when bacteria enter your bloodstream. A bacterial culture test helps doctors figure out what’s causing the infection and the best way to treat it.
What to expect with Proteus mirabilis Infections
Proteus infections mostly affect the urinary tract. Fortunately, most of these infections are treatable with the antibiotics that are currently available. The results of treatment are usually good for patients who have a strong immune system.
Possible Complications When Diagnosed with Proteus mirabilis Infections
Generally, in individuals with a healthy immune system, symptoms typically improve without any issues. However, if a person’s immune system is weakened, they face a greater possibility of severe and prolonged infections, or even a blood infection, known as sepsis.
Common Risk Profiles:
- People with a healthy immune system – Symptoms typically improve easily
- People with a weakened immune system – Greater risk for severe and prolonged infections or sepsis
Preventing Proteus mirabilis Infections
Lowering risk factors like long-term use of a urinary catheter can reduce the chances of getting an infection. A urinary catheter is a flexible tube used to empty the bladder and collect urine in a drainage bag. It’s important to limit the time a catheter is in place to protect against possible infections.
