Mycoplasma pneumoniae is a major cause of respiratory infections and a possible etiology of acute hepatitis. Acute hepatitis due to M. pneumoniae infection is often combined with presentation of pneumonia, even without lung involvement. The presentations and etiologies of M. pneumoniae-associated hepatitis with simultaneous, delayed, or without, lung involvement are different, and should be discussed separately. The most widely available and effective drug of treatment is macrolides, and its clinical outcome is extremely good.

Keywords: hepatitis, Mycoplasma pneumoniae

Mycoplasma pneumoniae, one of the smallest organisms that can survive alone in nature, is a common cause of upper respiratory tract infections. The first mycoplasmas were discovered in 1898 by Nocard and Roux in animals with contagious bovine pleuropneumonia. In 1944, Eaton isolated a pathogenic Mycoplasma from a patient with atypical pneumonia. It was named M. pneumoniae by Chanock in 1962.¹ M. pneumoniae is a short rod that is invisible on Gram staining due to lack of a cell wall,² and it can grow under both aerobic and anaerobic conditions. It is a major cause of respiratory infections in school-aged children and young adults.³ Although the incidence of the disease does not vary greatly by season, outbreaks of M. pneumoniae infections tend to occur in the summer or early fall.⁴

M. pneumoniaeinfection is transmitted through aerosols from person to person, and persons with active mycoplasmal infection will carry the organism in the nose, throat, trachea and sputum. Most M. pneumoniaeinfections in adults involve the respiratory tract, and symptoms range from nonproductive cough to severe pneumonia.⁵ The severity of disease appears to be related to the degree to which the host immune response reacts to the infection.⁴

Extrapulmonary manifestations of M. pneumoniae infection may be found in the dermatologic, cardiovascular, neurologic, hematologic, musculoskeletal and gastrointestinal systems.⁶ Approximately 25% of patients hospitalized for treatment of M. pneumoniae can present extrapulmonary complications at some time during the disease course.⁷ Skin lesions include maculopapular rashes, erythema multiforme minor, and Stevens-Johnson syndrome. Cardiovascular involvement includes myocarditis, pericarditis and rheumatic fever-like syndrome. Neurologic complications include meningoencephalitis, aseptic meningitis, cerebellar ataxia and Guillain-Barre syndrome. Hematologic involvement includes hemolysis with positive Coombs’ test and reticulocytosis. Musculoskeletal presentations include nonspecific myalgia, arthralgias and polyarthropathies. Gastrointestinal manifestations include vomiting, abdominal pain, and albeit rare, pancreatitis and hepatitis.^7,8 The immune-mediated damage by cross-reactive anti-M. pneumoniae antibodies is thought to be responsible for most of the extrapulmonary manifestations.⁹

Simultaneous M. pneumoniae-associated pneumonia and acute hepatitis

Elevated liver enzyme assays are frequently observed during M. pneumoniae infection. Squadrini et al.,¹⁰ reported that 50% of patients presenting with serologically-confirmed M. pneumoniae disease showed evidence of hepatic disorder.¹⁰ The most widely recognized manifestation of M. pneumoniae-related hepatitis is elevated alanine aminotransferase (ALT) level. The hepatic dysfunction was found to be transitory and recovery of normal liver function correlated directly with the resolution of the mycoplasma respiratory disease. Although rare, chronic active hepatitis has also been reported.¹¹

The pathogenesis of self-limiting hepatitis may be attributed to several factors, including a direct cytolytic effect mediated by the infecting mycoplasma resulting in perinecrotic edema; immunological, autoimmune disorder resulting from the production of heterophil antibiotics; or the mitogenic properties of M. pneumoniae acting on lymphocytes, which plays a role in the development of complications involving target organs.⁶ Suzuyama et al.⁸ decumented that inflammatory signs such as higher body temperature, greater number of leukocytes, and elevated C-reactive protein (CRP) levels were more likely to appear in patients with abnormal liver function than those with normal liver function.⁸ Doxboeck et al.,¹² noted that patients with M. pneumoniae-associated pneumonia and abnormal liver function had higher leukocyte and CRP levels than those with normal liver function.¹² Shin et al.,¹³ found male gender, younger age, and higher CRP were associated with M. pneumoniae-related hepatitis.¹³ In summary, patients with simultaneous pneumonia and hepatitis due to M. pneumoniae infection have greater disease severity and more acute inflammatory reactions.

M. pneumoniae-associated acute hepatitis without pneumonia

Viral hepatitis accounts for most cases of acute hepatitis. Some bacterial infections are often associated with acute hepatitis, such as Salmonella, Rickettsia, Brucella or M. pneumonia.¹⁴ Hepatitis due to M. pneumoniae was first described in 1975.¹⁵ Selected cases of M. pneumoniae-associated acute hepatitis were retrieved from MEDLINE and are summarized in Table 1.^9,14,16,17

In general, acute hepatitis due to M. pneumoniae without lung infection has been largely documented in children with a cholesteric pattern.^9,10 Hyperbilirubinemia usually occurs as the indirect type, mostly because of hemolysis in mycoplasma infections. In contrast, adults with M. pneumoniae infection have demonstrated a hepatocellular pattern of liver enzymes without jaundice.^14-17 According to these reports, the fever of individuals with M. pneumoniae subsided rapidly, on average in 1 to 2 weeks after treatment, but ALT did not normalize till about one month later. The persistent ALT elevation may be mediated by immunological mechanisms, such as cross-reactive antibodies induced by M. pneumoniae interacting with sialyloligosaccharides on hepatic cells.¹⁹ The outcomes of these cases were extremely good, and no mortality was reported. In children, M. pneumoniae has been reported to be implicated in infectious mononucleosis or Kawasaki disease with hepatic manifestations.^16,20

Delayed acute hepatitis after acute M. pneumoniae infection

On the basis of previous reports, the delayed onset of liver injury after M. pneumoniae infection was largely due to the use of treatment drugs.²¹ The time course of liver injury has been reported to be 5 to 10 days. The association of macrolide antibiotics with cholestatic hepatitis is well-known,²² and azithromycin-induced hepatotoxicity has also been reported in adults.²³

Because M. pneumoniae is an intracellular pathogen, cultures are not always available and those that are usually exhibit slow growth with low sensitivity, making them unreliable for routine diagnosis. There is little evidence to indicate direct invasion of M. pneumonia.¹⁴ Few previous liver pathology reports demonstrated non-specific findings, either hepatocellular destruction with inflammatory infiltration or lobular hepatitis.^24,25 Since liver biopsy in patients with M. pneumoniae infection is usually nonspecific, it might not be necessary to confirm diagnosis.

The characteristic findings of patients with M. pneumoniae-associated acute hepatitis with or without pneumonia are fever, elevated liver function test, positive IgM serology against M. pneumoniae followed by IgG seroconversion, with resolution by antibiotics and exclusion of other possible etiologies. It is advisable to test simultaneously for both IgM and IgG in paired specimens collected 2 to 3 weeks apart, and a fourfold or greater rise in antibody titers indicates a current or recent infection.²⁶ In some adults with previous M. pneumoniae infection, long-term high seroprevalence of IgG antibodies and lack of an IgM response were observed, and that imposes serious limitations on the use of serology as the sole means for diagnosis of M. pneumoniae infection.^1,27 Thus, a feasible approach would be to incorporate polymerase chain reaction (PCR) and the serological studies for IgG and IgM for optimum diagnosis of M. pneumoniae infections.

M. pneumoniaehas no cell wall and therefore is naturally resistant to penicillin, cephalosporins, all beta-lactams and vancomycin, sulfonamides, trimethoprin, and rifampin. M. pneumoniaeis susceptible to macrolides, cyclines, and quinolones. Interestingly, macrolides were more frequently used in patients with M. pneumoniae-associated hepatitis than quinolones. The reason might be that macrolides metabolize in the liver and are excreted primarily in the bile in contrast to quinolones which metabolize via renal excretion.²⁸ Up to now, no consensus on the duration of therapy with macrolides has been reached, and treatment schemes spanning from one to three weeks have been described. Clinical outcomes have been favorable in published cases, and no associated fatalities have been reported to date. However, eradication of M. pneumoniae from immunocompromised individuals can be extremely difficult, and requires prolonged therapy.

M. pneumoniae is a major cause of respiratory infections and a possible etiology of acute hepatitis. Acute hepatitis due to M. pneumoniae infection is often combined with presentation of pneumonia, even without lung involvement. The most widely available and effective drug of treatment is macrolides, and its clinical outcome is extremely good.

None.

Authors declare that there is no conflict of interest.

1. Vervloet LA, Marguet C, Camargos PA. Infection by Mycoplasma pneumoniae and its importance as an etiological agent in childhood community-acquired pneumonias. Braz J Infect Dis. 2007;11(5):507‒514.
2. Baum SG. Mycoplasma pneumoniae and atypical pneumonia. In: Mandell GL, Bennett JE, Dolin R (Eds.), Principles and Practice of Infectious Disease. Churchill Livingstone Philadelphia. USA; 2010. 2481 p.
3. Feigin ED, Cherry JD. Textbook of Pediatric Infectious Disease. 3rd ed. WB Saunders: Philadelphia, USA; 1992. 1866‒1876 p.
4. Waites KB, Talkington DF. Mycoplasma pneumoniae and its role as a human pathogen. Clin Microbiol Rev. 2004;17(4):697‒728.
5. Grullich C, Baumert TF, Blum H. Acute Mycoplasma pneumoniae infection presenting as cholestatic hepatitis. J Clin Microbiol. 2003;41(1):514‒515.
6. Chen CJ, Juan CJ, Hsu ML, et al. Mycoplasma pneumoniae infection presenting as neutropenia, thrombocytopenia, and acute hepatitis in a child. J Microbiol Immunol Infect. 2004;37(2):128‒130.
7. Vervloet LA, Marguet C, Camargos PA. Infection by Mycoplasma pneumoniae and its importance as an etiological agent in childhood community-acquired pneumonias. Braz J Infect Dis. 2007;11(5):507‒514.
8. Suzuyamam Y, Iwasaki H, Izumikawa K, et al. Clinical complications of Mycoplasma penumoniae disease-other organs. Yale J Biol Med. 1983;56(5-6):487‒491.
9. Arav-Boger R, Assia A, Spirer Z, et al. Cholestatic hepatitis as a main manifestation of Mycoplasma pneumoniae infection. J Pediatr Gastroenterol Nutr. 1995;21:459‒460.
10. Squadrini F, Lami G, Pellegrino F, et al. Acute hepatitis complicating Mycoplasma pneumoniae infection. J Infect. 1988;16(2):201‒202.
11. Jansson E, Wegelius R, Visakorpi JK. Chronic active hepatitis and concomitant mycoplasma infection. Lancet. 1972;1(7765):1395.
12. Daxboeck F, Gattringer R, Mustafa S, et al. Elevated serum alanine aminotransferase levels in patients with serologically verified Mycoplasma pneumoniae pneumoniae. Clin Microbiol Infect. 2005;11(6):507‒510.
13. Shin SR, Park SH, Kim JH, et al. Mycoplasma pneumoniae-related acute hepatitis. Digestion. 2012;86(4): 302‒308.
14. Romero-Gomez M, Otero MA, Sanchez-Munoz D, et al. Acute hepatitis due to Mycoplasma pneumoniae infection without lung involvement in adult patients. J Hepatol. 2006;44(4):827‒828.
15. Murray HW, Masur H, Senterfit LB, et al. The protean manifestations of Mycoplasma pneumoniae infection in adults. Am J Med. 1975;58(2):229‒242.
16. Narita M, Yamada S, Nakayama T, et al. Two cases of lymphadenopathy with liver dysfunction due to Mycoplasma pneumoniae infection with mycoplasmal bacteraemia without pneumonia. J Infect. 2001;42(2):154-156.
17. Lee SW, Yang SS, Chang CS, et al. Mycoplasma pneumonia-associated acute hepatitis in an adult patient without lung infection. J Chin Med Assoc. 2009;72(4):204-206.
18. Quioc JJ, Trabut JB, Drouhin F, et al. Acute cholestatic hepatitis revealing Mycoplasma pneumoniae infection without lung involvement in an adult patient. Eur J Gastroenterol Hepatol. 2009;21(2):220‒221.
19. Roelcke D, Kreft H, Northoff H, et al. Sia-b1 and I antigens recognized by Mycoplasma pneumoniae-induced human cold agglutinins. Transfusion. 1991;31(7):627‒630.
20. Leen C, Ling S. Mycoplasma infection and Kawasaki disease. Arch Dis Child. 1996;75(3):266‒267.
21. Carrascosa MF, Lucena MI, Andrade RJ, et al. Fatal acute hepatitis after sequential treatment with levofloxacin, doxycycline, and naproxen in a patient presenting with acute Mycoplasma pneumoniae infection. Clin Ther. 2009;31(5):1014‒1019.
22. Fox JC, Szyjkowski RS, Sanderson SO, et al. Progressive cholestatic liver disease associated with clarithromycin treatment. J Clin Pharmacol. 2002;42(6): 676‒680.
23. Baciewicz AM, Al-Nimr A, Whelan P. Azithromycin-induced hepatotoxicity. Am J Med. 2005;118:1438‒1439.
24. Kountouras D, Deutsch M, Emmanuel T, et al. Fulminant Mycoplasma pneumoniae infection with multi-organ involvement: a case report. Eur J Intern Med. 2003;14(5):329‒331.
25. Jansson E, Wegelius R, Visakorpi JK. Chronic active hepatitis and concomitant mycoplasma infection. Lancet. 1972;1(7765):1395.
26. Thacker WL, Talkington DF. Analysis of complement fixation and commercial enzyme immunoassays for detection of antibioties to Mycoplasma pneumoniae in human serum. Clin Diag Lab Immunol. 2000;7(5):778‒780.
27. Razin S. Diagnosis of mycoplasma infections. In S Razin, R Hermann (Eds.), Molecular biology and pathogenicity of mycoplasma; 2002. 531‒544 p.
28. Mansel JK, Rosenow EC, Smith TF, et al. Mycoplasma pneumonia. Chest. 1989;95:639‒646.