Clinical manifestations and antimicrobial susceptibility of Nocardia species at a tertiary hospital in Taiwan, 2011-2020

Multiple brain abscesses caused by Nocardia farcinica infection after hand injury: A case report and literature review

RATIONALE

Nocardia infection is commonly regarded as an opportunistic pulmonary pathogen affecting debilitated or immunocompromised individuals. Brain abscesses caused by Nocardia farcinica are rare and pose a diagnostic challenge. Traditional diagnostic techniques for identifying Nocardia species, such as blood culture, microscopy, and pathology, have shown inadequate performance. In the reported case, we applied metagenomic next-generation sequencing (mNGS) to diagnose a case of brain abscess due to N. farcinica.

PATIENT CONCERNS

A 66-year-old female developed a brain abscess after sustaining a hand injury. The patient exhibited a gradual change in personality and experienced tremors in her right upper limb for a duration of 1 month.

DIAGNOSES

The pathogen responsible for the multiple brain abscesses was identified in the cerebrospinal fluid as N. farcinica through mNGS.

INTERVENTIONS

Antibiotic treatment included trimethoprim-sulfamethoxazole, linezolid, amikacin, meropenem, and moxifloxacin.

OUTCOMES

The patient's symptoms and signs improved significantly after administration of antibiotics to which the pathogen is known to be sensitive. After 5 months of follow-up, magnetic resonance imaging of the head showed that the abscess was basically cured. The patient lived a normal life with no adverse drug reactions.

LESSONS

Nocardia brain infection is characterized by an insidious onset and lacks distinctive clinical and imaging features. mNGS was advantageous for the timely identification and management of Nocardia-associated brain abscess in the present case and obviated the need for invasive brain surgery. Expeditious and precise diagnosis coupled with prompt antibiotic therapy can significantly reduce the mortality rate associated with this condition.

Successful treatment with amoxicillin-clavulanic acid: cutaneous nocardiosis caused by Nocardia brasiliensis

AIM

To emphasize the role of non-sulfonamides in the treatment of Nocardia infection and reduce the adverse reactions caused by sulfonamides.

METHODS

We retrospectively analyzed a case of cutaneous nocardiosis in an immunocompetent individual. The colonies obtained by staining the pus in the lesion with antacid and culturing the agar plates were identified by flight mass spectrometry. The pathogenic identification showed Nocardia brasiliensis infection and the patient was treated with amoxicillin-clavulanic acid.

RESULTS

After treatment with amoxicillin and clavulanic acid, the ulcer gradually peeled and crusted, leaving dark pigmentation. The patient has finally recovered.

CONCLUSION

Sulfonamides are the first-line antibacterial agents for years in treatment of nocardiosis but are of great toxicity and side effects. This patient was successfully treated with amoxicillin-clavulanic acid and it provided a reference protocol for patients with sulfonamide-resistant Nocardia or sulfonamides intolerance.

Phenotypic and genotypic analysis of antimicrobial resistance in Nocardia species

BACKGROUND

Antimicrobial resistance is common in Nocardia species but data regarding the molecular mechanisms beyond their resistance traits are limited. Our study aimed to determine the species distribution, the antimicrobial susceptibility profiles, and investigate the associations between the resistance traits and their genotypic determinants.

METHODS

The study included 138 clinical strains of Nocardia from nine Israeli microbiology laboratories. MIC values of 12 antimicrobial agents were determined using broth microdilution. WGS was performed on 129 isolates of the eight predominant species. Bioinformatic analysis included phylogeny and determination of antimicrobial resistance genes and mutations.

RESULTS

Among the isolates, Nocardia cyriacigeorgica was the most common species (36%), followed by Nocardia farcinica (16%), Nocardia wallacei (13%), Nocardia abscessus (9%) and Nocardia brasiliensis (8%). Linezolid was active against all isolates, followed by trimethoprim/sulfamethoxazole (93%) and amikacin (91%). Resistance to other antibiotics was species-specific, often associated with the presence of resistance genes or mutations: (1) aph(2″) in N. farcinica and N. wallacei (resistance to tobramycin); (ii) blaAST-1 in N. cyriacigeorgica and Nocardia neocaledoniensis (resistance to amoxicillin/clavulanate); (iii) blaFAR-1 in N. farcinica (resistance to ceftriaxone); (iv) Ser83Ala substitution in the gyrA gene in four species (resistance to ciprofloxacin); and (v) the 16S rRNA m1A1408 methyltransferase in N. wallacei isolates (correlating with amikacin resistance).

CONCLUSIONS

Our study provides a comprehensive understanding of Nocardia species diversity, antibiotic resistance patterns, and the molecular basis of antimicrobial resistance. Resistance appears to follow species-related patterns, suggesting a lesser role for de novo evolution or transmission of antimicrobial resistance.

The species distribution and antimicrobial resistance profiles of Nocardia species in China: A systematic review and meta-analysis

BACKGROUND

Nocardia species can cause local or disseminated infection. Prompt diagnosis and appropriate treatment of nocardiosis are required, because it can cause significant morbidity and mortality. Knowledge of local species distribution and susceptibility patterns is important to appropriate empiric therapy. However, knowledge on the epidemiology and antimicrobial susceptibility profiles of clinical Nocardia species remains limited in China.

METHODS

The data of isolation of Nocardia species were collected from databases such as Pubmed, Web of Science, Embase as well as Chinese databases (CNKI, Wanfang and VIP). Meta-analysis was performed using RevMan 5.3 software. Random effect models were used and tested with Cochran's Q and I2 statistics taking into account the possibility of heterogeneity between studies.

RESULTS

In total, 791 Nocardia isolates were identified to 19 species levels among all the recruited studies. The most common species were N. farcinica (29.1%, 230/791), followed by N. cyriacigeorgica (25.3%, 200/791), N. brasiliensis (11.8%, 93/791) and N. otitidiscaviarum (7.8%, 62/791). N. farcinica and N. cyriacigeorgica are widely distributed, N. brasiliensis mainly prevalent in the Southern, N. otitidiscaviarum mainly distributed in the east coastal provinces of China. Totally, 70.4% (223/317) Nocardia were cultured from respiratory tract specimens, 16.4% (52/317) from extra-pulmonary specimens, and 13.3% (42/317) from disseminated infection. The proportion of susceptible isolates as follows: linezolid 99.5% (197/198), amikacin 96.0% (190/198), trimethoprim-sulfamethoxazole 92.9% (184/198), imipenem 64.7% (128/198). Susceptibility varied by species of Nocardia.

CONCLUSIONS

N. farcinica and N. cyriacigeorgica are the most frequently isolated species, which are widely distributed in China. Pulmonary nocardiosis is the most common type of infection. Trimethoprim-sulfamethoxazole can still be the preferred agent for initial Nocardia infection therapy due to the low resistance rate, linezolid and amikacin could be an alternative to treat nocardiosis or a choice in a combination regimen.

Clinical manifestations and outcome of nocardiosis and antimicrobial susceptibility of Nocardia species in southern Taiwan, 2011-2021

BACKGROUND/PURPOSE

Nocardiosis is an uncommon infectious disease. This study aimed to assess the clinical outcome of patients with nocardiosis and examine the antimicrobial susceptibility profiles of Nocardia spp. isolated.

METHODS

We retrospectively reviewed the medical records of all inpatients diagnosed with nocardiosis between 2011 and 2021. The identification of Nocardia spp. at the species level was performed with the use of MALDI-TOF and 16S rRNA assays. The antimicrobial susceptibility of Nocardia spp. was performed using the microbroth dilution method. Factors associated with 90-day all-cause mortality were identified in multivariate logistic regression analysis.

RESULTS

Of 60 patients with nocardiosis in the 11-year study period, the lungs (55.0%) were the most common site of involvement, followed by the skin and soft tissue (45.0%). Twenty-two patients (36.7%) died within 90 days following the diagnosis. All of the Nocardia isolates were susceptible to trimethoprim-sulfamethoxazole, linezolid, and amikacin, whereas more than 70% of the isolates were not susceptible to ciprofloxacin, imipenem-cilastatin, moxifloxacin, cefepime, and clarithromycin. Nocardiosis involving the lungs (relative risk [RR], 9.99; 95% confidence interval [CI], 1.52-65.50; p = 0.02), nocardiosis involving the skin and soft tissue (RR, 0.15; 95% CI, 0.02-0.92; p = 0.04), and treatment with trimethoprim-sulfamethoxazole (RR, 0.14; 95% CI, 0.03-0.67; p = 0.01) were independently associated with 90-day all-cause mortality.

CONCLUSIONS

Nocardia spp. identified between 2011 and 2021 remained fully susceptible to trimethoprim-sulfamethoxazole, linezolid, and amikacin. Nocardiosis of the lungs, skin and soft tissue infection, and treatment with trimethoprim-sulfamethoxazole were independently associated with 90-day all-cause mortality.