Late-onset prosthetic valve endocarditis caused by Mycoplasma hominis, diagnosed using broad-range bacterial PCR

A subacute presentation of Mycoplasma hominis prosthetic valve endocarditis

Mycoplasma hominis is a rare but important cause of prosthetic valve endocarditis. It is usually associated with acute progression of symptoms and can be difficult to diagnose as it does not grow in standard culture media. We report a case of an immunocompetent man in his 70s who presented with 14-month subacute decline with shortness of breath and evidence of a splenic infarct. Following a redo aortic valve replacement and diagnosis of M. hominis through 16S ribosomal ribonucleic acid PCR, he improved clinically with oral doxycycline therapy. He remained well at follow-up 2 years post-cessation of antibiotics. We present a literature review highlighting the role of PCR testing in the microbiological identification of M. hominis.

Blood Culture-Negative Infective Endocarditis by Mycoplasma hominis: Case Report and Literature Review

Mycoplasma hominis is a habitual colonizing microorganism of the lower genital tract but can exceptionally be the causal agent of blood culture-negative infective endocarditis (IE). Only 11 cases of this entity have been published to date. The study objectives were to describe the first case diagnosed in our center of IE by M. hominis on pacemaker lead and to carry out a narrative review. Among published cases of IE by this microorganism, 72.7% were male, with a mean age of 45 years and a history of valve surgery; the diagnosis was by culture (54.5%) or molecular technique (45.5%), and the prognosis was favorable in 72.7% of cases. The most frequently prescribed antibiotics were doxycycline, quinolones, and clindamycin.

Tetracycline Resistance Mediated by tet(M) Has Variable Integrative Conjugative Element Composition in Mycoplasma hominis Strains Isolated in the United Kingdom from 2005 to 2015

A minimal genome and absent bacterial cell wall render Mycoplasma hominis inherently resistant to most antimicrobials except lincosamides, tetracyclines, and fluoroquinolones. Often dismissed as a commensal (except where linked to preterm birth), it causes septic arthritis in immunodeficient patients and is increasingly associated with transplant failure (particularly lung) accompanying immunosuppression. We examined antimicrobial susceptibility (AST) on strains archived from 2005 to 2015 submitted to the Public Health England reference laboratory and determined the underlying mechanism of resistance by whole-genome sequencing (WGS). Archived M. hominis strains included 32/115 from invasive infection (sepsis, cerebrospinal [CSF], peritoneal, and pleural fluid) over the 10-year period (6.4% of all samples submitted from 2010 to 2015 were positive). No clindamycin resistance was detected, while two strains were resistant to moxifloxacin and levofloxacin (resistance mutations S83L or E87G in gyrA and S81I or E84V in parC). One of these strains and 11 additional strains were tetracycline resistant, mediated by tet(M) carried within an integrative conjugative element (ICE) consistently integrated at the somatic rumA gene; however, the ICEs varied widely in 5 to 19 associated accessory genes. WGS analysis showed that tet(M)-carrying strains were not clonal, refuting previous speculation that the ICE was broken and immobile. We found tet(M)-positive and -negative strains (including the multiresistant 2015 strain) to be equally susceptible to tigecycline and josamycin; however, the British National Formulary does not include guidance for these. Continued M. hominis investigation and AST surveillance (especially immunocompromised patients) is warranted, and the limited number of therapeutics needs to be expanded in the United Kingdom.

CONSERVATION CHALLENGES: THE LIMITATIONS OF ANTEMORTEM TUBERCULOSIS TESTING IN CAPTIVE ASIATIC LIONS (PANTHERA LEO PERSICA)

Genetic diversity of captive wild animals can be enhanced by moving those individuals with valuable genes between collections and through introduction of a new pair from a range country. This requires movement of animals, which is inherent with disease risks, such as the introduction of pathogenic Mycobacterium sp. (MTBC) into a zoological collection. Decisions need to be made based on the outcome of perimovement disease screening using an array of tests, the majority of which are unvalidated in the species. A pair of endangered Asiatic lions (Panthera leo persica) imported from India to the United Kingdom were screened for MTBC using the comparative intradermal tuberculosis (TB) test, the feline interferon-γ blood test, and the experimental bacteriophage assay. Reactions on all three tests prompted screening of the three resident Asiatic lions using the same tests, all of which were negative for MTBC. Based on these test results, the decision had to be made to exclude the genetically valuable pair from the current collection. MTBC could not be identified using further tests, including culture and PCR on a bronchoalveolar lavage, on feces, or on postmortem tissues. This case series highlights the usefulness of a control group when interpreting unvalidated test results for detection of MTBC, the value of training big cats for conscious blood sampling, and the practical implications of placing the comparative intradermal TB test in the eyelids, when dealing with a species that requires a general anesthetic for most hands-on interventions.

Salvage heart transplantation for Mycoplasma hominis prosthetic valve endocarditis: A case report and review of the literature

Heart transplantation (HT) has been rarely performed in patients with infective endocarditis (IE) and is considered a "last resort" procedure. Orthotropic HT with bicaval technique was performed in a man with culture-negative endocarditis. Mycoplasma hominis was later detected using 16S ribosomal DNA PCR from surgically removed valve tissue. Literature review and previous results are summarized. HT may be considered as salvage treatment in selected patients with intractable IE. In cases when there is no growth in culture, 16S ribosomal DNA PCR sequencing can be used to identify the pathogen in excised valvular tissue. Mycoplasma spp. is extremely uncommon and difficult to diagnose cause of infective endocarditis (IE). There are no proposed or defined criteria for heart transplantation (HT) in patients with refractory IE, and HT has been rarely performed in this setting. We report a case of M hominis prosthetic valve endocarditis diagnosed by 16S ribosomal DNA PCR in a patient who underwent a salvage HT. We reviewed in the literature other cases of IE caused by Mycoplasma spp.

Ureaplasma parvum causing life-threatening disease in a susceptible patient

A 56-year-old man with lymphoma developed orchitis followed by septic arthritis of his right glenohumeral joint. Synovial fluid cultures were negative but PCR amplification test was positive forUreaplasmaparvum. The patient was treated with doxycycline. Two and a half years later, the patient presented with shortness of breath and grade III/IV diastolic murmur on auscultation. Echocardiography revealed severely dilated left heart chambers, severe aortic regurgitation and several mobile masses on the aortic valve cusps suspected to be vegetations. He underwent valve replacement; valve tissue culture was negative but the 16S rRNA gene amplification test was positive for U. parvumHe was treated again with doxycycline. In an outpatient follow-up 1 year and 3 months later, the patient was doing well. Repeated echocardiography showed normal aortic prosthesis function.

First report of Sneathia sanguinegens together with Mycoplasma hominis in postpartum prosthetic valve infective endocarditis: a case report

BACKGROUND

The presence of more than one bacterial agent is relatively rare in infective endocarditis, although more common in prosthetic cases. Molecular diagnosis from a removed heart tissue is considered a quick and effective way to diagnose fastidious or intracellular agents.

CASE PRESENTATION

Here we describe the case of postpartum polymicrobial prosthetic valve endocarditis in a young woman. Sneathia sanguinegens and Mycoplasma hominis were simultaneously detected from the heart valve sample using broad range 16S rRNA polymerase chain reaction (PCR) followed by sequencing while culture remained negative. Results were confirmed by independent PCR combined with denaturing gradient gel electrophoresis. Before the final agent identification, the highly non-compliant patient left from the hospital against medical advice on empirical intravenous treatment with aminopenicillins, clavulanate and gentamicin switched to oral amoxycillin and clavulanate. Four months after surgery, no signs of inflammation were present despite new regurgitation and valve leaflet flail was detected. However, after another 5 months the patient died from sepsis and recurrent infective endocarditis of unclarified etiology.

CONCLUSIONS

Mycoplasma hominis is a rare causative agent of infective endocarditis. To the best of our knowledge, presented case is the first report of Sneathia sanguinegens detected in this condition. Molecular techniques were shown to be useful even in polymicrobial infective endocarditis samples.

Laboratory Approach to the Diagnosis of Culture-Negative Infective Endocarditis

Blood-culture negative endocarditis (BCNE) accounts for up to 35% of all cases of infective endocarditis (IE) and is a serious life-threatening condition with considerable morbidity and mortality. Rapid detection and identification of the causative pathogen is essential for timely, directed therapy. Blood-culture negative endocarditis presents a diagnostic and therapeutic challenge. Causes of BCNE are varied including: treatment with antibiotic agents prior to blood culture collection; sub-optimal specimen collection; and/or infection due to fastidious (eg. nutritionally variant streptococci), intracellular (eg. Coxiella burnetii, Bartonella species) or non-culturable or difficult to culture organisms (eg. Mycobacteria, Tropheryma whipplei and fungi); as well as non-infective aetiologies. Here, we review aetiological and diagnostic approaches to BCNE including newer molecular based techniques, with a brief summary of imaging investigation and treatment principles.

Mycoplasma hominis, a Rare but True Cause of Infective Endocarditis

Mycoplasma spp. are rarely recognized agents of infective endocarditis. We report a case of Mycoplasma hominis prosthetic valve endocarditis diagnosed by 16S ribosomal DNA (rDNA) PCR and culture of valves in a 74-year-old man. We reviewed the literature and found only 8 other cases reported.