An enemy in shadows-Mycoplasma hominis septic arthritis and iliopsoas abscess: Case report and review of the literature

Accurate etiological diagnosis of Mycoplasma hominis mediastinitis in immunocompetent patients using metagenomic next-generation sequencing: a case series and literature review

Background

As a culture-independent method, metagenomic next-generation sequencing (mNGS) is widely used in microbiological diagnosis with advantages in identifying potential pathogens, guiding antibiotic therapy, and improving clinical prognosis, especially in culture-negative cases. Mycoplasma hominis (M. hominis) mediastinitis is a rare and severe disease for which etiological diagnosis is important but challenging. The application of mNGS in the etiological diagnosis of mediastinitis has seldom been studied.

Methods

By searching the electronic medical history retrieval system with "Mycoplasma hominis" and "mediastinitis", seven patients diagnosed with M. hominis mediastinitis were reviewed in Zhongshan Hospital, Fudan University, Shanghai from 9 December 2020 to 14 February 2023. Microbiological cultures and mNGS were conducted for blood, abscess, and/or mediastinal fluid. Adjustment of the antibiotic therapy due to mNGS was assessed. A literature review was conducted in the PubMed database beginning in 1970 for M. hominis infection and mediastinitis.

Results

For the seven patients, cultures of blood, abscess, and mediastinal fluid were negative whereas mNGS identified M. hominis in serum, abscess, and/or mediastinal fluid and was used to guide specific antibiotic therapy. The stringent mapped reads number of genera (SMRNG), stringent mapped reads number of species (SMRN), and coverage rate of M. hominis detection by mNGS were significantly higher in body fluid (abscess or mediastinal fluid) than in serum. All seven patients had underlying heart diseases and underwent previous cardiac surgery. The most common symptoms were fever and sternal pain. After detection of M. hominis, antibiotics were adjusted to quinolones or doxycycline except for one patient, whose diagnosis was clarified after death. Two patients died. Literature review since 1970 identified 30 cases of extra-genital infection caused by M. hominis. Including our seven new cases, 2 (5.4%) were neonates and 35 (94.6%) were adults. Thirty (81.1%) cases were postoperative infection and 15 (40.5%) had implanted devices. Five patients (13.5%) died.

Conclusions

mNGS might be a promising technology in the detection of fastidious pathogens such as M. hominis. Accurate etiological diagnosis by mNGS could guide antibiotic therapy and facilitate clinical management.

Mycoplasma hominis peritonitis after oocyte donation

We report the case of a young, immunocompetent, non-pregnant woman diagnosed with acute abdomen 3 weeks after an ultrasound-guided transvaginal oocyte retrieval (TVOR). Peritoneal fluid, obtained during exploratory laparoscopy, yielded Mycoplasma hominis as the sole pathogen. The patient's symptoms and signs improved after 24-hour treatment with intravenous clindamycin, ampicillin and gentamycin. Complete resolution was achieved with oral doxycycline for 14 days.

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

Mycoplasmas as economically important and pantropic pathogens can cause similar clinical diseases in different hosts by eluding host defense and establishing their niches despite their limited metabolic capacities. Besides, enormous undiscovered virulence has a fundamental role in the pathogenesis of pathogenic mycoplasmas. On the other hand, they are host-specific pathogens with some highly pathogenic members that can colonize a vast number of habitats. Reshuffling mycoplasmas genetic information and evolving rapidly is a way to avoid their host's immune system. However, currently, only a few control measures exist against some mycoplasmosis which are far from satisfaction. This review aimed to provide an updated insight into the state of mycoplasmas as pathogens by summarizing and analyzing the comprehensive progress, current challenge, and future perspectives of mycoplasmas. It covers clinical implications of mycoplasmas in humans and domestic and wild animals, virulence-related factors, the process of gene transfer and its crucial prospects, the current application and future perspectives of nanotechnology for diagnosing and curing mycoplasmosis, Mycoplasma vaccination, and protective immunity. Several questions remain unanswered and are recommended to pay close attention to. The findings would be helpful to develop new strategies for basic and applied research on mycoplasmas and facilitate the control of mycoplasmosis for humans and various species of animals.