Antimicrobial susceptibility among clinical Nocardia species identified by multilocus sequence analysis

Pulmonary Nocardiosis: A Clinical Analysis of 30 Cases

Objective Pulmonary nocardiosis frequently develops as an opportunistic infection in patients with malignant tumor and is treated with steroids. This study was performed to clarify the clinical features of pulmonary nocardiosis in Japan. Methods The patients definitively diagnosed with pulmonary nocardiosis at our hospital between January 1995 and December 2015 were retrospectively investigated. Results Nineteen men and 11 women (30 in total) were diagnosed with pulmonary nocardiosis. Almost all patients were complicated by a non-pulmonary underlying disease, such as malignant tumor or collagen vascular disease, or pulmonary disease, such as chronic obstructive pulmonary disease or interstitial pneumonia, and 13 patients (43.3%) were treated with steroids or immunosuppressors. Gram staining was performed in 29 patients, and a characteristic Gram-positive rod was detected in 28 patients (96.6%). Thirty-one strains of Nocardia were isolated and identified. Seven strains of Nocardia farcinica were isolated as the most frequent species, followed by Nocardia nova isolated from 6 patients. Seventeen patients died, giving a crude morality rate of 56.7% and a 1-year survival rate of 55.4%. The 1-year survival rates in the groups with and without immunosuppressant agents were 41.7% and 59.7%, respectively, showing that the outcome of those receiving immunosuppressants tended to be poorer than those not receiving them. Conclusion Pulmonary nocardiosis developed as an opportunistic infection in most cases. The outcome was relatively poor, with a 1-year survival rate of 55.4%, and it was particularly poor in patients treated with immunosuppressant agents. Pulmonary nocardiosis should always be considered in patients presenting with an opportunistic respiratory infection, and an early diagnosis requires sample collection and Gram staining.

Central nervous system nocardiosis in Queensland: A report of 20 cases and review of the literature

Nocardia infection of the central nervous system (CNS) is an uncommon but clinically important disease, often occurring in immunocompromised individuals and carrying a high mortality rate. We present 20 cases of microbiologically proven CNS nocardiosis diagnosed in Queensland from 1997 to 2015 and review the literature from 1997 to 2016.Over 50% of cases occurred in immunocompromised individuals, with corticosteroid use posing a particularly significant risk factor. Nine (45%) patients were immunocompetent and 3 had no comorbidities at time of diagnosis. Nocardia farcinica was the most frequently isolated species (8/20) and resistance to trimethoprim-sulfamethoxazole (TMP-SMX) was found in 2 isolates. Overall, 35% of our patients died within 1 year, with the majority of deaths occurring in the first month following diagnosis. Interestingly, of the 7 deaths occurring at 1 year, 6 were attributed to N farcinica with the seventh isolate being unspeciated, suggesting the virulence of the N farcinica strain.

Disseminated Nocardia farcinica in an immunocompetent patient

Nocardia farcinica is a gram-positive, partially acid-fast, methenamine silver-positive aerobic actinomycete that is infrequently associated with nocardiosis. The relative frequency of Nocardia farcinica isolates in nocardiosis is unknown but thought to be under diagnosis. It is increasingly been recognized in immunocompetent patients.

We report a case of disseminated Nocardia farcinica causing brain abscess in 55 year old immunocompetent man who was successfully treated with long term antibiotics.

The present report illustrates that early detection and treatment of disseminated Nocardia farcinica can lead to a good outcome.

Unusual presentation of disseminated Nocardia abscessus infection in a patient with AIDS

A 40-year-old man with AIDS presented with symptoms of a chronic cough, subacute headache, generalised weakness with falls, urinary and faecal incontinence, and acute onset subcutaneous nodules. A chest CT scan showed multiple cavitary and nodular pulmonary infiltrates. MRI of his brain and spinal cord revealed innumerable ring-enhancing lesions. Pathological examination of the purulent material obtained from his subcutaneous lesions, as well as transbronchial tissue specimens obtained by biopsy, revealed beaded and branching Gram-positive rods, subsequently identified by 16S RNA sequencing to be Nocardia abscessus species. We observed an excellent therapeutic response to a combination antimicrobial therapy with resolution of the subcutaneous, pulmonary and central nervous system (CNS) lesions. Infections caused by N. abscessus are rare and typically occur in immunocompromised patients. In this article, we will review the presentation, diagnosis and treatment of N. abscessus infection.

Trends in antibiotic resistance in bacterial keratitis isolates from South India

AIMS

To report trends in antibiotic resistance in cases of bacterial keratitis from a large eye hospital in South India.

METHODS

In this retrospective cross-sectional study, the microbiology laboratory records of patients with infectious keratitis diagnosed at an eye hospital in South India from 2002 to 2013 were reviewed to determine the proportion with antibiotic non-susceptibility.

RESULTS

3685 bacterial isolates had susceptibility testing performed over the 12-year period. The two most common organisms with resistance were Streptococcus pneumoniae (n=1204) and Pseudomonas aeruginosa (n=894). Antibiotic non-susceptibility was generally uncommon for these two organisms and no significant trends were detected over the course of the study. In contrast, Staphylococcus aureus (N=211) isolates demonstrated a significant increase in fluoroquinolone non-susceptibility over the 12-year study period. This coincided with a significant increase in methicillin-resistant S. aureus (MRSA) during the study period, though the increase in fluoroquinolone resistance was likewise seen in methicillin-sensitive S. aureus (MSSA). For example, ofloxacin resistance in MSSA increased from 11.1% in 2002 to 66.7% in 2013 (p=0.002). No trends were apparent for the aminoglycosides, cefazolin or vancomycin, for which in vitro non-susceptibility generally appeared to be low.

CONCLUSION

Resistance to antibiotics was generally stable for infectious keratitis isolates from a large eye hospital in South India, except for S. aureus, which experienced a significant increase in fluoroquinolone resistance from 2002 to 2013. Fluoroquinolone antibiotics currently have poor in vitro activity against both MRSA and MSSA in South India and are therefore not the ideal therapy for Staphylococcal corneal ulcers.

Multicenter Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Study for Identification of Clinically Relevant Nocardia spp

This multicenter study analyzed Nocardia spp., including extraction, spectral acquisition, Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification, and score interpretation, using three Nocardia libraries, the Bruker, National Institutes of Health (NIH), and The Ohio State University (OSU) libraries, and compared the results obtained by each center. A standardized study protocol, 150 Nocardia isolates, and NIH and OSU Nocardia MALDI-TOF MS libraries were distributed to three centers. Following standardized culture, extraction, and MALDI-TOF MS analysis, isolates were identified using score cutoffs of ≥2.0 for species/species complex-level identification and ≥1.8 for genus-level identification. Isolates yielding a score of <2.0 underwent a single repeat extraction and analysis. The overall score range for all centers was 1.3 to 2.7 (average, 2.2 ± 0.3), with common species generally producing higher average scores than less common ones. Score categorization and isolate identification demonstrated 86% agreement between centers; 118 of 150 isolates were correctly identified to the species/species complex level by all centers. Nine strains (6.0%) were not identified by any center, and six (4.0%) of these were uncommon species with limited library representation. A categorical score discrepancy among centers occurred for 21 isolates (14.0%). There was an overall benefit of 21.2% from repeat extraction of low-scoring isolates and a center-dependent benefit for duplicate spotting (range, 2 to 8.7%). Finally, supplementation of the Bruker Nocardia MALDI-TOF MS library with both the OSU and NIH libraries increased the genus-level and species-level identification by 18.2% and 36.9%, respectively. Overall, this study demonstrates the ability of diverse clinical microbiology laboratories to utilize MALDI-TOF MS for the rapid identification of clinically relevant Nocardia spp. and to implement MALDI-TOF MS libraries developed by single laboratories across institutions.

Pulmonary Nocardiosis Caused by Nocardia concava with a Literature Review

A 68-year-old man was admitted to our hospital with anorexia and leg pain. He was diagnosed with ANCA-associated vasculitis through a renal biopsy. Immunosuppression with two courses of steroid pulse therapies and intravenous cyclophosphamide followed by oral prednisolone at 40 mg/day were administered. About one month after starting the immunosuppression therapy, he complained of hemosputum. Chest computed tomography showed a cavitary lesion in the lung. Cultures from his sputum showed Nocardia species, and we were able to identify the species as N. concava using a 16S rRNA gene sequence analysis. Only three detailed reports of N. concava infection have so far been published worldwide.

Nocardia Arthritis: 3 Cases and Literature Review

Nocardia are Gram-positive filamentous bacteria responsible for infections ranging from opportunistic life-threatening disseminated diseases to chronic skin and soft-tissue infections.Even if virtually all organs can be infected, articular involvement is rare. Therefore, we report 3 recent cases and performed a literature review of cases of Nocardia arthritis in order to describe clinical features, therapeutic challenges, and outcome of these patients.Among 34 patients (31 in the literature plus our 3 cases), 21 (62%) were due to hematogenous dissemination, 9 (26%) were due to direct bacterial inoculation through the skin, and in 4 cases, the mechanism of infection was unknown. Four out of these 34 cases occurred on prosthetic joints.Whereas hematogenous infections mostly occurred in immunocompromised hosts (17 of 21, 81%), direct inoculation was mostly seen in immunocompetent patients.Eighty-two percent of patients (28 out of 34) received trimethoprim-sulfamethoxazole-containing regimens and median antibiotic treatment duration was 24 weeks (range, 12-120) for hematogenous infections and 12 weeks (range, 6-24) for direct inoculations. Outcome was favorable in 27 cases despite unsystematic surgical management (17 cases) without sequelae in 70% of the cases.Nocardia arthritis is rare but its management is complex and should rely on a combined approach with rheumatologist, infectious diseases expert, and surgeon.

Nocardia Septic Arthritis Complicating an Anterior Cruciate Ligament Repair

Nocardia infection following anterior cruciate ligament (ACL) allograft reconstruction is a rare occurrence. We report a case of Nocardia infection of an allograft ACL reconstruction and septic arthritis of the knee joint due to an organism most similar to the novel Nocardia species Nocardia aobensis.