Mycoplasma: Symptoms, Types, Causes and Treatment

Mycoplasmas are among the smallest and most unique bacteria known, notorious for causing a range of infections in humans and animals. Unlike most bacteria, mycoplasmas lack a cell wall, which gives them both resilience against certain antibiotics and the ability to trigger atypical disease presentations. This article provides a comprehensive overview of mycoplasma infections—exploring their symptoms, various types, underlying causes, and the latest in treatment strategies.

Symptoms of Mycoplasma

Mycoplasma infections can manifest in diverse ways, often mimicking other common illnesses. Especially in children and young adults, Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia, but symptoms can extend far beyond the lungs. Recognizing these signs is crucial for timely diagnosis and management.

Symptom	Frequency/Details	System(s) Affected	Source(s)
Cough	Persistent, sometimes dry	Respiratory	1 3 12
Low-grade Fever	Common, may be prolonged	Systemic	3 5 12
Chest Pain	May double likelihood of infection	Respiratory	1
Headache	Often present	Neurological	1 4 3
Skin Rash	Up to 25% in children	Dermatological	2 3 12
Nausea/Vomiting	Seen in ~33% of pediatric cases	Gastrointestinal	3
Fatigue/Myalgia	General malaise	Musculoskeletal	1 3
Neurological Signs	Encephalitis, ataxia, seizures	CNS	2 4

Table 1: Key Symptoms Associated with Mycoplasma Infections

Respiratory Symptoms

The most common manifestation of mycoplasma infection is in the respiratory tract. Patients frequently present with a persistent, sometimes dry cough, low-grade fever, and chest discomfort. These symptoms can be subtle, earning Mycoplasma pneumoniae the nickname "walking pneumonia" due to the relatively mild nature compared to typical bacterial pneumonia. Chest pain, in particular, is a noteworthy finding that can significantly raise suspicion for mycoplasma, especially in hospitalized children 1 3 12.

Extrapulmonary and Systemic Symptoms

Mycoplasma infections are not confined to the lungs. Many patients, especially children, develop symptoms outside the respiratory system. Skin rashes and mucocutaneous lesions can occur in up to a quarter of pediatric cases, and gastrointestinal symptoms like nausea and vomiting are also surprisingly common 2 3. Neurological involvement, though less frequent, can be severe—ranging from headaches to encephalitis, ataxia, and even seizures 2 4.

Diagnostic Challenges

One of the challenges in diagnosing mycoplasma infections is the non-specific nature of symptoms, which can resemble viral infections or other atypical bacterial pathogens. The absence of certain signs, such as wheezing, might slightly increase suspicion, but no single symptom is definitive 1. Radiological imaging often shows positive findings in suspected pneumonia, but laboratory confirmation remains essential 3.

Types of Mycoplasma

The Mycoplasma genus is diverse, containing several species that affect humans and animals. Each species has distinct clinical relevance, ranging from respiratory illnesses to urogenital infections and even chronic inflammatory conditions.

Species	Main Disease/Location	Host(s)	Source(s)
M. pneumoniae	Atypical pneumonia, respiratory	Humans	6 9 12
M. genitalium	Urethritis, cervicitis	Humans	9 15
M. hominis	Urogenital infections	Humans	6 9
Ureaplasma spp.	Urogenital infections	Humans	6 9
M. bovis	Mastitis, pneumonia	Cattle	8 14
M. mycoides cluster	Pleuropneumonia, agalactia	Ruminants	7 8

Table 2: Common Mycoplasma Species and Associated Diseases

Human Pathogenic Mycoplasma

• Mycoplasma pneumoniae: The most well-known, causing up to 20% of community-acquired pneumonias, particularly in children and young adults. It is also associated with a range of extrapulmonary manifestations 6 9 12.
• Mycoplasma genitalium: Recognized as an emerging cause of nongonococcal urethritis in men and cervicitis in women, with rising antibiotic resistance 9 15.
• Mycoplasma hominis and Ureaplasma species: Mostly linked to urogenital tract infections and implicated in complications such as pelvic inflammatory disease and neonatal morbidity 6 9.

Animal Mycoplasmas

• Mycoplasma bovis: An important veterinary pathogen, causing mastitis, bronchopneumonia, and chronic inflammatory diseases in cattle 8 14.
• Mycoplasma mycoides cluster: Includes several pathogens responsible for contagious pleuropneumonia in ruminants, leading to significant agricultural losses 7 8.

Emerging and Less Common Types

A growing list of Mycoplasma species is recognized as potential human pathogens, with more than 16 species identified in humans. Some species, like M. fermentans, are occasionally recovered from respiratory infections but their pathogenic role remains less clear 6 9.

Causes of Mycoplasma

Understanding what causes mycoplasma infections involves exploring both how people (or animals) get exposed and the biological mechanisms that enable these bacteria to cause disease. Mycoplasmas’ unique biology makes them adept at evading host defenses and persisting in various environments.

Cause/Factor	Description/Mechanism	Implication	Source(s)
Human-to-human	Respiratory droplets, close contact	Epidemics/endemic spread	12 19
Lack of cell wall	Not susceptible to beta-lactams	Atypical presentation, resistance	10 19
Adhesion factors	Attach to host cells, evade clearance	Persistent infection	11 13
Immune evasion	Suppress or avoid immune responses	Chronic/relapsing disease	13 14
Exotoxins	CARDS toxin, hydrogen peroxide	Tissue damage, inflammation	10 13

Table 3: Causes and Pathogenic Mechanisms of Mycoplasma Infection

Transmission and Epidemiology

• Respiratory Mycoplasmas: M. pneumoniae is primarily spread via respiratory droplets, requiring close person-to-person contact. Outbreaks can occur in closed communities, schools, and families, with cycles of epidemics every few years 12 19.
• Urogenital Mycoplasmas: M. genitalium, M. hominis, and Ureaplasma spp. are sexually transmitted or acquired perinatally 9.

Pathogenic Mechanisms

• Absence of Cell Wall: Mycoplasmas' lack of a cell wall renders them inherently resistant to many antibiotics (like penicillins) and allows them to assume flexible shapes, aiding tissue invasion. This also leads to atypical clinical presentations 10 19.
• Adhesion and Toxins: Specialized adhesion proteins allow mycoplasmas to attach firmly to host cells. They secrete toxins such as the CARDS toxin and produce metabolic byproducts (e.g., hydrogen peroxide) that damage host tissues and trigger inflammation 10 11 13.
• Immune Evasion: Mycoplasmas utilize numerous strategies to evade the host immune system, including antigenic variation, biofilm formation, and suppression of immune cell responses. These mechanisms contribute to chronic or relapsing infections in both humans and animals 13 14.

Host and Environmental Factors

• Age and Immunity: Children, young adults, and immunocompromised individuals are at increased risk. Epidemics are influenced by herd immunity dynamics, with reinfections possible when immunity wanes 12.
• Environmental Persistence: Some mycoplasmas can persist in the environment or within hosts for extended periods, aiding their transmission and survival 13.

Treatment of Mycoplasma

Treating mycoplasma infections requires an understanding of their unique resistance profiles and the emerging challenge of antibiotic resistance. The absence of a cell wall makes many standard antibiotics ineffective, necessitating tailored therapeutic approaches.

Drug/Class	Target Mycoplasma	Efficacy/Notes	Source(s)
Macrolides	M. pneumoniae, M. genitalium	First-line; resistance rising	15 19
Tetracyclines	Respiratory/urogenital	Effective; not for young children	18 19
Fluoroquinolones	Resistant strains	Alternative; avoid in children	18 19
Immunomodulators	Severe extrapulmonary cases	Used with antibiotics	2
Doxycycline + targeted therapy	M. genitalium	Sequential approach for resistance	16

Table 4: Treatments and Approaches for Mycoplasma Infections

First-Line Antibiotics

• Macrolides (Azithromycin, Clarithromycin): The preferred therapy for M. pneumoniae, especially in children, due to safety and efficacy. Typical regimens involve a 5-day course of azithromycin or 7–14 days of clarithromycin 19.
• Tetracyclines (Doxycycline, Minocycline): Effective against many mycoplasmas but contraindicated in children under 8 years due to effects on bone and teeth 18 19.
• Fluoroquinolones (Levofloxacin): Reserved for adults or cases with macrolide resistance, as these drugs are not recommended for children 18 19.

Rising Antibiotic Resistance

• Macrolide Resistance: A significant and growing problem, especially in Asia where resistance rates can exceed 90%. Resistance leads to longer illness duration, necessitating alternative therapies 5 19.
• Sequential and Resistance-Guided Therapy: For M. genitalium, starting with doxycycline to reduce bacterial load, followed by resistance testing and targeted therapy (high-dose azithromycin or sitafloxacin), has shown high cure rates (>92%) 16.
• Declining Efficacy: A single dose of azithromycin for M. genitalium has dropped below 70% efficacy in recent years, underscoring the need for new treatments 15.

Adjunct and Special Treatments

• Immunomodulators: Severe extrapulmonary manifestations (e.g., encephalitis) may require corticosteroids or immunoglobulins alongside antibiotics 2.
• Anticoagulants: Considered in cases with vascular complications due to mycoplasma-induced thrombi 2.
• Supportive Care: Many cases, especially mild respiratory infections, are self-limiting and may only require symptomatic management 17.

Challenges and Future Directions

• Treatment Evidence Gaps: Despite widespread use, robust evidence for the benefit of antibiotics in all cases (especially mild pediatric pneumonia) is limited, highlighting the need for better clinical trials 17.
• Prevention of Resistance: Judicious use of antibiotics, resistance surveillance, and development of new drugs are critical to address rising resistance 19.

Conclusion

Mycoplasma infections are complex and varied, affecting people of all ages with symptoms that often overlap with other illnesses. Their unique biology—marked by the absence of a cell wall and a diverse set of virulence factors—makes both diagnosis and treatment challenging. The rise of antibiotic resistance, particularly to macrolides, underscores the importance of appropriate antibiotic stewardship and ongoing research.

Key Takeaways:

• Symptoms are broad, including respiratory, dermatological, neurological, and gastrointestinal manifestations. Extrapulmonary symptoms can be prominent, especially in children 1 2 3 4.
• Types of mycoplasma include several human and animal pathogens, with M. pneumoniae and M. genitalium most significant for humans 6 7 8 9 15.
• Causes involve direct transmission, unique pathogenic mechanisms, and sophisticated immune evasion strategies 10 11 12 13 14.
• Treatment relies on macrolides, tetracyclines, and fluoroquinolones, but rising resistance necessitates new approaches and careful antibiotic use 15 16 18 19.

By staying alert to the multifaceted nature of mycoplasma infections and tailoring treatment to emerging resistance patterns, clinicians and researchers can better manage and prevent these persistent pathogens.