Detection of Legionella bozemanae, a new cause of septic arthritis, by PCR followed by specific culture

Legionella longbeachae wound infection: case report and review of reported Legionella wound infections

Extrapulmonary manifestations of infection with Legionella species, of which 24 may cause disease in humans, are very rare. Here, we describe a case of a 61-year-old woman with no history of immunosuppression presenting with pain and swelling of her index finger after a prick by rose thorns during gardening. Clinical examination showed fusiform swelling of the finger with mild redness, warmth, and fever. The blood sample revealed a normal white blood cell count and a slight increase in C-reactive protein. Intraoperative observation showed extensive infectious destruction of the tendon sheath, while the flexor tendons were spared. Conventional cultures were negative, while 16S rRNA PCR analysis identified Legionella longbeachae that also could be isolated on buffered charcoal yeast extract media. The patient was treated with oral levofloxacin for 13 days, and the infection healed quickly. The present case report, with a review of the literature, indicates that Legionella species wound infections may be underdiagnosed due to the requirement for specific media and diagnostic methods. It emphasizes the need for heightened awareness of these infections during history taking and clinical examination of patients presenting with cutaneous infections.

Case report: A prosthetic valve endocarditis caused by Legionella bozemanae in an immunocompetent patient

Extrapulmonary infections with Legionella species are rare, but important to acknowledge. We report a case of infective endocarditis (IE) with Legionella bozemanae in a 66-year-old immunocompetent man with an aortic homograft. The diagnosis was made by direct 16S rRNA gene amplification from valve material, confirmed by a targeted Legionella-PCR in serum and the detection of L. bozemanae specific antibodies. To our knowledge, this is the first confirmed case of IE with L. bozemanae as causative pathogen. The infected aortic prosthesis was replaced by a homograft, and the patient was successfully treated with levofloxacin and azithromycin for 6 weeks.

Case report of arthritis caused by Legionella anisa and review of the literature

BACKGROUND

Legionella spp. is recognized as a common cause of community acquired pneumonia, with Legionella pneumophila serogroup 1 being the most prevalent. At least 70 species are described so far but few are identified in pathogenic conditions. Data on extrapulmonary infections are scarce.

CASE PRESENTATION

A 73-yar-old male with chronic lymphoid leukemia was hospitalized for an insidious wrist arthritis. Ultrasound of the wrist showed a carpal and radiocarpal fluid effusion with positive Doppler signal. While routine bacterial cultures remained sterile, 16S rRNA PCR identified Legionella anisa. Ciprofloxacin 500 mg twice a day for a period of six weeks improved arthritis with full recovery at the end of the treatment.

CONCLUSION

Legionella non pneumophila are a rare cause of septic arthritis especially found in immunosuppressed patients and identification of species could help clinician to adapt antibiotherapy.

Presence of Viable, Clinically Relevant Legionella Bacteria in Environmental Water and Soil Sources of China

The distribution of pathogenic Legionella in the environmental soil and water of China has not been documented yet. In this study, Legionella was detected in 129 of 575 water (22.43%) and 41 of 442 soil samples (9.28%) by culture. Twelve Legionella species were identified, of which 11 were disease-associated. Of the Legionella-positive samples, 109 of 129 (84.50%) water and 29 of 41 (70.73%) soil were positive for L. pneumophila, which accounted for about 75% of Legionella isolates in both water and soil, suggesting L. pneumophila was the most frequent species. Soil showed a higher diversity of Legionella spp. as compared with water (0.6279 versus 0.4493). In contrast, serogroup (sg) 1 was more prevalent among L. pneumophila isolates from water than from soil (26.66% versus 12.21%). Moreover, many disease-associated sequence types (STs) of L. pneumophila were found in China. Intragenic recombination was acting on L. pneumophila from both water and soil. Phylogeny, population structure, and molecular evolution analyses revealed a probable existence of L. pneumophila isolates with a special genetic background that is more adaptable to soil or water sources and a small proportion of genetic difference between water and soil isolates. The detection of viable, clinically relevant Legionella demonstrates soil as another source for harboring and dissemination of pathogenic Legionella bacteria in China. Future research should assess the implication in public health with the presence of Legionella in the soil and illustrate the genetic and pathogenicity difference of Legionella between water and soil, particularly the most prevalent L. pneumophila. IMPORTANCE Pathogenic Legionella spp. is the causative agent of Legionnaires' disease (LD), and L. pneumophila is the most common one. Most studies have focused on L. pneumophila from water and clinical samples. However, the soil is another important reservoir for this bacterium, and the distribution of Legionella spp. in water and soil sources has not been compared and documented in China yet. Discovering the distribution of Legionella spp. and L. pneumophila in the two environments may help a deep understanding of the pathogenesis and molecular evolution of the bacterium. Our research systematically uncovered the distributions of Legionella spp. in different regions and sources (e.g., water and soil) of China. Moreover, phylogeny, population structure, and molecular evolution study revealed the possible existence of L. pneumophila with a special genetic background that is more adaptable to soil or water sources, and genetic difference may exist.

Development of a Fluorescent Tool for Studying Legionella bozemanae Intracellular Infection

Legionnaires' disease incidence is on the rise, with the majority of cases attributed to the intracellular pathogen, Legionella pneumophila. Nominally a parasite of protozoa, L. pneumophila can also infect alveolar macrophages when bacteria-laden aerosols enter the lungs of immunocompromised individuals. L. pneumophila pathogenesis has been well characterized; however, little is known about the >25 different Legionella spp. that can cause disease in humans. Here, we report for the first time a study demonstrating the intracellular infection of an L. bozemanae clinical isolate using approaches previously established for L. pneumophila investigations. Specifically, we report on the modification and use of a green fluorescent protein (GFP)-expressing plasmid as a tool to monitor the L. bozemanae presence in the Acanthamoeba castellanii protozoan infection model. As comparative controls, L. pneumophila strains were also transformed with the GFP-expressing plasmid. In vitro and in vivo growth kinetics of the Legionella parental and GFP-expressing strains were conducted followed by confocal microscopy. Results suggest that the metabolic burden imposed by GFP expression did not impact cell viability, as growth kinetics were similar between the GFP-expressing Legionella spp. and their parental strains. This study demonstrates that the use of a GFP-expressing plasmid can serve as a viable approach for investigating Legionella non-pneumophila spp. in real time.

Legionellosis Caused by Non-Legionella pneumophila Species, with a Focus on Legionella longbeachae

Although known as causes of community-acquired pneumonia and Pontiac fever, the global burden of infection caused by Legionella species other than Legionella pneumophila is under-recognised. Non-L. pneumophila legionellae have a worldwide distribution, although common testing strategies for legionellosis favour detection of L. pneumophila over other Legionella species, leading to an inherent diagnostic bias and under-detection of cases. When systematically tested for in Australia and New Zealand, L. longbeachae was shown to be a leading cause of community-acquired pneumonia. Exposure to potting soils and compost is a particular risk for infection from L. longbeachae, and L. longbeachae may be better adapted to soil and composting plant material than other Legionella species. It is possible that the high rate of L. longbeachae reported in Australia and New Zealand is related to the composition of commercial potting soils which, unlike European products, contain pine bark and sawdust. Genetic studies have demonstrated that the Legionella genomes are highly plastic, with areas of the chromosome showing high levels of recombination as well as horizontal gene transfer both within and between species via plasmids. This, combined with various secretion systems and extensive effector repertoires that enable the bacterium to hijack host cell functions and resources, is instrumental in shaping its pathogenesis, survival and growth. Prevention of legionellosis is hampered by surveillance systems that are compromised by ascertainment bias, which limits commitment to an effective public health response. Current prevention strategies in Australia and New Zealand are directed at individual gardeners who use potting soils and compost. This consists of advice to avoid aerosols generated by the use of potting soils and use masks and gloves, but there is little evidence that this is effective. There is a need to better understand the epidemiology of L. longbeachae and other Legionella species in order to develop effective treatment and preventative strategies globally.

The clinical presentation of Legionella arthritis reveals the mode of infection and the bacterial species: case report and literature review

BACKGROUND

While Legionella is a common cause of pneumonia, extrapulmonary infections like arthritis are scarce. Here, we describe a case of monoarthritis due to Legionella bozemanii, with no history of pneumonia. We provide a literature review of the 9 previously published Legionella arthritis and highlight a dichotomous epidemiology suggesting different physiopathological pathways leading to joint infection.

CASE PRESENTATION

A 56-year old woman under immunosuppressive treatment by oral and intra-articular corticosteroids, methotrexate, and tocilizumab for an anti-synthetase syndrome was hospitalized for worsening pain and swelling of the left wrist for 3 days. Clinical examination showed left wrist synovitis and no fever. The arthritis occurred a few days after an accidental fall on wet asphalt responsible for a cutaneous wound followed by a corticosteroid intra-articular injection. Due to both the negativity of conventional culture of articular fluid and suspicion of infection, 16S rRNA and specific PCRs were performed leading to the identification of L. bozemanii. Legionella-specific culture of the articular fluid was performed retrospectively and isolated L. bozemanii. The empiric antibiotic therapy was switched for oral levofloxacin and rifampin and the patient recovered after a 12-week treatment.

CONCLUSION

We report a case of L. bozemanii monoarthritis in an immunosuppressed woman, following a fall on wet asphalt and intra-articular corticosteroid injection. The review of the literature found that the clinical presentation reveals the mode of infection and the bacterial species. Monoarthritis more likely occurred after inoculation in patients under immunosuppressive therapy and were associated with non-Legionella pneumophila serogroup 1 (Lp1) strains that predominate in the environment. Polyarthritis were more likely secondary legionellosis localizations after blood spread of Lp1, the most frequently found in pneumonia. In both settings, 16S rRNA and Legionella-specific PCR were key factors for the diagnosis.

Arthritis caused by Legionella micdadei and Staphylococcus aureus: metagenomic next-generation sequencing provides a rapid and accurate access to diagnosis and surveillance

Legionella spp. is an important pulmonary pathogen but rarely causes extra-pulmonary infections. We report a case of joint infection caused by Legionella micdadei and Staphylococcus aureus in a 54-year-old male with medication history of oral steroid for systemic lupus erythematosus (SLE). He developed arthritis in his right metacarpophalangeal (MCP) joints without precursor pneumonia. In the joint aspirate, S. aureus was detected through culture. The existence of L. micdadei and S. aureus were indicated by metagenomic next-generation sequencing (mNGS) and confirmed by 16S rRNA sequence analysis. After oral levofloxacin treatment for 54 days, the patient's symptoms ameliorated and blood test results improved, which were consistent with the dynamic trend of reads numbers in mNGS data. Our case included, arthritis caused by Legionella spp. have been reported in 11 patients. However, our case is the first to report septic arthritis caused by L. micdadei in native joints and monitored by mNGS. This case demonstrated an application of mNGS for etiological diagnosis and semi-quantification in joint aspirate. mNGS may serve as a promising tool for rapid and accurate etiological diagnosis and surveillance, contributing to appropriate antimicrobial drug applications and timely medication adjustments when necessary.

Septic arthritis due to Legionella cincinnatiensis: case report and review of the literature

Legionella spp. are an important cause of pulmonary and rarely extrapulmonary infections. L. cincinnatiensis has only been implicated in five cases to date. We herein report the first case of L. cincinnatiensis septic arthritis in a 90-year old lady with a past medical history of chronic kidney disease. She developed septic arthritis of her left wrist after having received intraarticular corticosteroid injections and oral corticosteroids administered for presumed chondrocalcinosis. Appropriate antimicrobial treatment of L. cincinnatiensis septic arthritis was delayed until identification of this organism in joint biopsies by broad-range bacterial PCR targeting the 16S rRNA gene with subsequent rDNA sequence analysis and by culture on special media. Reviewing all reported cases of septic arthritis caused by Legionella spp. other than L. cincinnatiensis it is notable that diagnosis was established by PCR in the majority of cases and only subsequently confirmed by special culture. Although most patients were immunosuppressed, outcome was favourable. Treatment consisted of a fluoroquinolone alone or in combination with rifampicin or a macrolide. Our case highlights the need for a high index of suspicion for infections with unusual/fastidious organisms when symptoms are suggestive of septic arthritis but conventional methods fail to identify a causative organism.

Septic arthritis in immunocompetent and immunosuppressed hosts

Septic arthritis has long been considered an orthopedic emergency. Historically, Neisseria gonorrhoeae and Staphylococcus aureus have been the most common causes of septic arthritis worldwide but in the modern era of biological therapy and extensive use of prosthetic joint replacements, the spectrum of microbiological causes of septic arthritis has widened considerably. There are also new approaches to diagnosis but therapy remains a challenge, with a need for careful consideration of a combined medical and surgical approach in most cases.