Background

• Moraxella catarrhalis, a Gram-negative bacterium, is commonly found in the upper respiratory tract of humans. Although it typically exists as a commensal organism, it can also induce various infections, especially among individuals with compromised immune systems or pre-existing respiratory conditions. Moraxella catarrhalis is a notable pathogen primarily associated with respiratory tract infections such as otitis media, sinusitis, and chronic obstructive pulmonary disease (COPD) exacerbations.
• Originally discovered in the late 19th century, Moraxella catarrhalis has since been acknowledged as a significant contributor to respiratory infections, particularly impacting children and the elderly. Over the years, extensive research has been conducted to comprehend the pathogenesis, epidemiology, and clinical manifestations of Moraxella catarrhalis infections. Consequently, this has led to advancements in diagnostic techniques and treatment strategies.

Epidemiology

• Prevalence: Moraxella catarrhalis is a prevalent bacterium worldwide and is commonly found in the respiratory tracts of healthy individuals. It is estimated that approximately 20-40% of healthy adults and up to 100% of healthy children can carry the bacterium in their upper respiratory tract.
• Age Distribution: Infections caused by M. catarrhalis can manifest at any stage of life. While children are more prone to colonization, the clinical relevance of positive culture results is relatively low among pediatric patients. According to a particular study, only 9% of M. catarrhalis cultures were deemed clinically significant in children under the age of 5, whereas 33% of isolates from children aged 6-10 were found to be of clinical importance. However, it is noteworthy that all positive cultures for M. catarrhalis held clinical significance in adults.
• Transmission: The exact mode of transmission of Moraxella catarrhalis is not fully understood, but it is believed to spread through respiratory droplets. Close contact with an infected individual, such as through coughing, sneezing, or direct contact with respiratory secretions, is thought to be the primary route of transmission.

Anatomy

Pathophysiology

• M catarrhalis has been demonstrated to exhibit enhanced cell adhesion and proinflammatory responses following exposure to cold shock conditions (26°C for 3 hours). This physiological reaction can be observed with prolonged exposure to cold temperatures, leading to symptoms resembling a common cold.
• The humoral responses against M catarrhalis show an age-dependent pattern, as the levels of immunoglobulin G (IgG) gradually increase in children. Antibody responses primarily target outer-membrane proteins, with a predominant presence of IgG3 subclass.
• While M catarrhalis is generally considered a commensal in the nasopharynx, it commonly causes otitis media and sinusitis and occasionally leads to laryngitis. In individuals with underlying chronic lung disease, both children and adults, M catarrhalis can cause bronchitis and pneumonia, and it can also lead to bacteremia and meningitis, particularly in those with weakened immune systems. Bacteremia can further give rise to localized infections like osteomyelitis or septic arthritis. Additionally, M catarrhalis is associated with nosocomial infections.

Etiology

• Transmission: Moraxella catarrhalis is primarily transmitted through respiratory droplets. It can be spread from person to person through close contact, such as coughing, sneezing, or sharing contaminated items like utensils or towels.
• Colonization: Moraxella catarrhalis typically colonizes the upper respiratory tract, particularly in children and elderly individuals. It can persist asymptomatically in the nasopharynx for extended periods, and under certain circumstances, it can overgrow and cause an infection.
• Virulence factors: Moraxella catarrhalis possesses various virulence factors that contribute to its ability to cause infection. These include adhesins, which allow the bacterium to attach to the respiratory epithelial cells, and various enzymes and toxins that facilitate tissue damage and evasion of the immune system.
• Co-infection: Moraxella catarrhalis can also cause opportunistic infections in conjunction with other pathogens, such as respiratory viruses or other bacteria. These co-infections can lead to more severe disease manifestations.

Genetics

Prognostic Factors

• In patients with pre-existing conditions who require hospitalization, the prognosis for M catarrhalis infection is generally unfavorable.
• Patients receiving care in pulmonary units or pediatric intensive care units
• advanced age group patients
• Patients admitted to the hospital for extended durations
• The primary infections associated with M catarrhalis involve the upper respiratory tract, specifically causing otitis media and sinusitis in children and lower respiratory tract infections in adults. In the case of adults, the likelihood of contracting M catarrhalis infections is higher when underlying conditions are present, particularly in elderly patients.
• A study examining 42 instances of pneumonia where M catarrhalis was the sole agent identified in sputum cultures revealed a mortality rate of 45% within three months of pneumonia onset, directly linked to underlying health issues.

Clinical History

• Age Group:
• Children, especially those under the age of 2, are particularly prone to Moraxella catarrhalis infections. This bacterium is a common cause of ear infections (otitis media) in young children.
• In older adults, particularly those with weakened immune systems or underlying health conditions, Moraxella catarrhalis infections can also occur. These infections can manifest as respiratory tract infections, including bronchitis and pneumonia.
• Associated Comorbidity or Activity:
• Chronic Obstructive Pulmonary Disease (COPD): Moraxella catarrhalis is recognized as a prevalent pathogen associated with exacerbations of COPD. Moraxella catarrhalis in the respiratory tract of individuals with COPD can exacerbate symptoms and induce heightened inflammation.
• Sinusitis: Moraxella catarrhalis is one of the frequently encountered bacteria in cases of acute sinusitis. It can contribute to the inflammation and infection of the sinus cavities, leading to symptoms such as facial pain, nasal congestion, and sinus pressure.
• Otitis media: Moraxella catarrhalis is a common culprit behind middle ear infections, particularly in children. It can infect the middle ear, resulting in symptoms like ear pain, fluid accumulation, and occasionally fever.
• Bronchitis: Moraxella catarrhalis can induce acute bronchitis, which is characterized by inflammation in the bronchial tubes of the lungs. This condition is commonly seen as a secondary infection that follows a viral respiratory illness.
• Pneumonia: While less prevalent than other pathogens such as Streptococcus pneumoniae or Haemophilus influenzae, Moraxella catarrhalis can cause community-acquired pneumonia, particularly in older adults with pre-existing lung conditions.
• Acuity of Presentation:
• The acuity or severity of the presentation of Moraxella catarrhalis infection can vary depending on the specific type of infection and the affected individual’s overall health.
• Acute Otitis Media: Moraxella catarrhalis is a common cause of ear infections, especially in children. The infection typically presents with sudden onset ear pain, fever, irritability, and sometimes, fluid drainage from the ear.
• Sinusitis: Moraxella catarrhalis can also cause sinus infections. Symptoms include facial pain, pressure, nasal congestion, headache, and thick nasal discharge that may be greenish or yellowish.
• Lower Respiratory Tract Infections: Moraxella catarrhalis can lead to infections such as bronchitis and pneumonia, particularly in individuals with chronic lung diseases.

Physical Examination

• Vital Signs: Measure the patient’s vital signs, including temperature, heart rate, respiratory rate, and blood pressure.
• General Appearance: Assess the patient’s overall appearance, looking for signs of distress or systemic illness.
• Respiratory Examination: Auscultate the lungs to identify any abnormal breath sounds (e.g., crackles, wheezes) or decreased breath sounds, which may indicate a lower respiratory tract infection.
• Ear Examination: Inspect the ears for signs of inflammation, such as redness, swelling, or discharge, which could suggest otitis media.
• Throat Examination: Evaluate the throat for redness, tonsillar enlargement, or exudate, which may indicate pharyngitis or tonsillitis.
• Nose Examination: Check for nasal congestion, discharge, or sinus tenderness, which could indicate sinusitis.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

• Viral respiratory infections: Many respiratory infections are caused by viruses, such as the common cold viruses (rhinovirus, coronavirus), influenza viruses, or respiratory syncytial virus (RSV). These infections often share similar symptoms with bacterial infections, but they are typically self-limiting and do not require antibiotic treatment.
• Chronic sinusitis: Chronic sinusitis is characterized by persistent inflammation of the sinuses.It can be caused by various factors, including bacterial or fungal infections, allergies, or structural abnormalities.
• Chronic obstructive pulmonary disease (COPD): In patients with a history of smoking or long-term exposure to irritants, chronic bronchitis or emphysema (types of COPD) should be considered. These conditions can lead to recurrent respiratory infections and persistent symptoms such as cough, shortness of breath, and sputum production.

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

Moraxella catarrhalis is a specific strain of bacteria capable of triggering respiratory tract infections, particularly among individuals with compromised immune systems or preexisting respiratory conditions. The standard approach to treating Moraxella catarrhalis infections often includes the administration of antibiotics. The following treatment options are frequently prescribed

Antibiotics Therapy:

• The most common antibiotics used to treat Moraxella catarrhalis infections include:
• Beta-lactamase inhibitors: Combination antibiotics such as amoxicillin-clavulanate or ampicillin-sulbactam often treat Moraxella catarrhalis infections. These drugs combine a beta-lactam antibiotic with a beta-lactamase inhibitor, which helps overcome the bacteria’s resistance mechanisms.
• Macrolides: Antibiotics like azithromycin or clarithromycin may be prescribed for individuals allergic to beta-lactam antibiotics or in cases where beta-lactamase inhibitors are ineffective.
• Fluoroquinolones: In more severe cases or when other antibiotics fail, fluoroquinolones such as levofloxacin or moxifloxacin may be considered.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

use-of-the-non-pharmacological-therapy-for-modifying-the-environment-good-hand-washing-technique

• Handwashing is still important as a general preventive measure, especially to reduce the risk of transmitting other pathogens.

Handwashing should be done:

• Before and after preparing food
• Before eating
• After using the restroom
• After blowing your nose, coughing, or sneezing
• After touching potentially contaminated surfaces or objects
• After caring for someone who is sick

sterilization-of-instruments-and-tubes

• Sterilization of instruments and tubes is crucial in preventing the spread of infections, including Moraxella catarrhalis infections.
• several methods commonly used for sterilizing instruments and tubes, including:
• Autoclaving: Autoclaving is a highly effective method of sterilization that uses steam under high pressure and temperature.
• Chemical sterilization: Chemical sterilization involves the use of disinfectants or sterilizing agents to kill microorganisms on instruments and tubes. One commonly used chemical agent is glutaraldehyde, which is effective against Moraxella catarrhalis.
• Ethylene oxide sterilization:This method requires specialized equipment and expertise, as the gas is highly flammable and toxic. Ethylene oxide effectively kills a wide range of microorganisms, including Moraxella catarrhalis.

cessation-of-smoking

• Reduced susceptibility to infection: By quitting smoking, the respiratory tract can start recovering, improving its defense mechanisms and reducing susceptibility to Moraxella catarrhalis and other respiratory infections.
• Improved lung function: Smoking cessation allows the lungs to heal, leading to improved lung function and a reduced risk of infections.
• Prevention of complications: By quitting smoking, individuals can reduce the risk of complications such as pneumonia, exacerbations of COPD, and worsening of sinusitis or otitis media.

good-general-health-habits

• Practice good hygiene: To ensure proper hygiene, it is important to regularly cleanse your hands with soap and water for a minimum duration of 20 seconds. This practice should be particularly emphasized before meals, after using the restroom, and following exposure to public spaces. In instances where soap and water are not accessible, employing an alcohol-based hand sanitizer is recommended.
• Avoid close contact with infected individuals: The transmission of Moraxella catarrhalis infections can occur via respiratory droplets. Maintaining a safe distance from individuals coughing or sneezing is advisable to minimize the risk of transmission.
• Practice respiratory etiquette: To prevent the transmission of respiratory droplets, it is important to ensure that you cover your mouth and nose either with a tissue or your elbow when you cough or sneeze. It is crucial to dispose of used tissues appropriately and follow up by washing your hands.
• Strengthen your immune system: Having a strong immune system is crucial for warding off infections. To promote a healthy lifestyle, it is advisable to engage in regular physical activity, consume a well-rounded diet that includes ample servings of fruits, vegetables, whole grains, and lean proteins, and ensure adequate sleep.
• vaccinations: Vaccinations play a crucial role in safeguarding individuals against specific bacterial and viral infections. It is essential to adhere to the suggested immunization timetable for yourself and your family.

Use of beta lactamase Inhibitor in Moraxella catarrhalis Infection

The most commonly recommended agents for treatment include amoxicillin-clavulanate.The medication consists of combination substances amoxicillin and clavulanic acid. Amoxicillin, derived from penicillin, exhibits comparable effectiveness against gram-positive and gram-negative bacteria. It targets various bacterial strains such as Enterococcus species, Listeria monocytogenes, Streptococcus species, Haemophilus influenzae, Moraxella catarrhalis, Corynebacterium diphtheria, It has been observed that over 90% of M catarrhalis strains exhibit resistance to amoxicillin, and the prevalence of resistance can vary across different regions.

Use of combination antibiotics in Moraxella catarrhalis infection

Moraxella catarrhalis is a bacterium that can cause respiratory tract infections, such as sinusitis, otitis media (middle ear infection), and bronchitis. trimethoprim and sulfamethoxazole are effective against Moraxella catarrhalis because they target specific enzymes involved in synthesizing bacterial DNA and folic acid, which are essential for bacterial growth and reproduction.

The combination of trimethoprim and sulfamethoxazole works synergistically, enhancing their antibacterial activity. trimethoprim inhibits the enzyme dihydrofolate reductase, while sulfamethoxazole inhibits the enzyme dihydropteroate synthase. By blocking these enzymes, trimethoprim and sulfamethoxazole interferes with the synthesis of DNA and folic acid, respectively, ultimately leading to the inhibition of bacterial growth.

Use of Macrolide Antibiotics in Moraxella catarrhalis infection

In addition to its efficacy against Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis, azithromycin is officially recommended and approved by the FDA for the management of community-acquired pneumonia (CAP). Furthermore, azithromycin has obtained regulatory approval for the treatment of various other upper respiratory infections such as acute otitis media and acute exacerbation of chronic obstructive pulmonary disease (COPD).

In a separate research investigation, it was discovered that the effectiveness of oral azithromycin 500 mg, taken once daily for a duration of three days, was like that of a 10-day treatment involving oral clarithromycin 500 mg administered twice daily, in managing acute exacerbation of chronic bronchitis.

Use of ketolide Antibiotics in Moraxella catarrhalis Infection

Telithromycin, an erythromycin A derivative known as a ketolide, exhibited promising in vitro efficacy against Moraxella catarrhalis in research conducted on individuals suffering from acute exacerbations of chronic bronchitis. Nevertheless, the utilization of telithromycin has been linked to instances of severe liver disease. It is important to highlight that telithromycin is contraindicated for patients with myasthenia gravis.

In a study, it was determined that a daily dose of 400 mg of Moxifloxacin, a type of quinolone, proved to be an efficient remedy for community-acquired pneumonia caused by M catarrhalis.

Second-generation cephalosporins effectively combat Haemophilus influenzae (H. influenzae), Moraxella catarrhalis, and Bacteroides spp. These antibiotics are commonly prescribed for treating respiratory infections like pneumonia and bronchitis. The range of applications for second-generation cephalosporins is similar to that of first-generation cephalosporins, encompassing conditions related to bloodstream infections, otitis media, genitourinary tract, respiratory tract ,and surgical prophylaxis. Second-generation cephalosporins offer broad-spectrum coverage against various bacteria, including H. influenzae, Enterobacter aerogenes, Neisseria species, and Serratia marcescens, in addition to the gram-negative bacteria addressed by first-generation cephalosporins.

Medication

Future Trends

Media Gallary

References

Molecular Aspects of Moraxella catarrhalis Pathogenesis – PMC (nih.gov)

Prevalence and resistance pattern of Moraxella catarrhalis in community-acquired lower respiratory tract infections – PMC (nih.gov)