Evaluación del parámetro BACT-info del citómetro de flujo UF-5000 (Sysmex) para la clasificación gram en infección del tracto urinario / Evaluation of Sysmex UF-5000 flow cytometer flag BACT-info for Gram discrimination in urinary tract infection

Introducción: El urocultivo como gold standard para diagnóstico de infección del tracto urinario (ITU) supone una carga de trabajo considerable en los Servicios de Microbiología Clínica, debido al elevado número de muestras recibidas que finalmente serán negativas. Por ello, utilizar sistemas de cribado que además reduzcan el tiempo de respuesta del diagnóstico de ITU es necesario. El nuevo citómetro de flujo UF-5000 (Sysmex Corporation) es capaz de diferenciar entre bacterias gramnegativas y grampositivas mediante el parámetro BACT-info según el fabricante. El objetivo de nuestro estudio fue evaluar la capacidad de discriminación gram del citómetro UF-5000. Métodos: Estudio prospectivo de 449 orinas recogidas de forma consecutiva, en el período 7/3/2022-27/5/2022, en las que se comparó el flag BACT-info con el urocultivo como método de referencia. Resultados: La sensibilidad obtenida tanto para bacterias gramnegativas como positivas fue superior al 95%. Sin embargo, en el caso de bacterias grampositivas, el índice Kappa moderado (0,49) y el valor predictivo positivo bajo (37,1%) indicó que la correlación entre el flag BACT-info y el urocultivo no era aceptable, por lo que no sería recomendable informarlo al clínico peticionario. Conclusión: El uso del citómetro UF-5000 supone un adelanto en la orientación etiológica de las ITUs causadas por bacterias gramnegativas. Informar la morfología gram en la muestra de orina reduce el tiempo de respuesta en el diagnóstico microbiológico de ITU, lo que tendría un impacto en la disminución y optimización del tratamiento empírico, y, por ende, en la generación de resistencias antimicrobianas. (AU)

Introduction. Urine culture as a gold standard for the diagnosis of urinary tract infection (UTI) involves a considerable workload in Clinical Microbiology Departments, due to the high number of samples received that will ultimately be negative. Therefore, it is necessary to use screening systems that also reduce the turnaround time for UTI diagnosis. The new flow cytometer UF-5000 (Sysmex Corporation) is able to differentiate between Gram-negative and Gram-positive bacteria using the BACT-info parameter according to manufacturer. The aim of our study was to evaluate the gram discrimination ability of the UF-5000 cytometer. Methods. A prospective study with 449 urine samples collected consecutively was conducted, in the period 7/3/2022- 27/5/2022, in which the BACT-info flag was compared with urine culture as the reference method. Results. The sensitivity obtained for both Gram-negative and Gram-positive bacteria was above 95%. However, for Gram-positive bacteria, the moderate Kappa index (0.49) and the low positive predictive value (37.1%) indicated that the correlation between BACT-info flag and urine culture was not acceptable and should not be reported to the requesting clinician. Conclusion. Implementation of the third generation UF5000 cytometer represents a significant advance in the aetiological orientation of UTIs caused by Gram-negative bacteria. Reporting the Gram morphology in the urine samples reduces the response time in the microbiological diagnosis of UTI, which would have an impact on the reduction and optimisation of empirical treatment, and thus on the generation of antimicrobial resistance. (AU)

Two episodes of bacteremia of zoonotic origin caused by different Streptococcus canis isolates in the same patient within a time span of 1 year.

Two episodes of bacteremia of cutaneous origin in a female patient were caused by two unrelated Streptococcus canis isolates within 1-year interval between the two infection episodes. The most likelihood transmission route in both episodes was a dog pet that habitually licked patient´s legs. Isolates were characterised by antimicrobial susceptibility test and whole genome sequencing. They belonged to sequence type (ST) 40 and 43, respectively. The ST40 isolate harboured antimicrobial resistance genes aadE, ermB and tetO, displaying resistance to erythromycin, clindamycin and tetracyclines, while ST43 isolate did not presented any known antimicrobial resistance determinant and was susceptible to all antibiotics tested. S. canis infections are rare in human; however, attention is needed for patients at risk with companion animals.

Brain abscess caused by Porphyromonas gingivalis and Eubacterium nodatum mimicking acute stroke.

We described a case of a 65-year-old man with a brain abscess caused by Porphyromonas gingivalis and Eubacterium nodatum. The patient presented right central facial nerve palsy, mutism and right hemiparesis at the examination. The patient underwent a left frontal craniotomy with evacuation of the brain abscess. Specimens were collected for microbiological analysis and intravenous treatment was started with levetiracetam, dexamethasone, meropenem (1 g/8 h) and linezolid (600 mg/12 h). After identification of anaerobic bacteria the antibiotic treatment was changed to piperacillin/tazobactam (4 g/0,5 g/8 h), fulfilling 8 weeks of antibiotic with good clinical and radiological evolution.

Description of eight human infections caused by Bacteroides pyogenes in a tertiary hospital of northern Spain.

Bacteroides pyogenes is a Gram-negative obligate anaerobe, saccharolytic, non-motile, non-pigment-producing and non-spore-forming rod. Reports of human infections caused by B. pyogenes are scarce, with approximately 30 cases documented in scientific literature. The aim of this study was to describe the clinical characteristics of 8 different patients and to study the in vitro antibiotic susceptibility of the strains, as well as to evaluate the in vivo activity of the prescribed treatments. We conducted a descriptive retrospective study by searching all B. pyogenes isolates from January 2010 to March 2023 at the Basurto University Hospital. This included all cases, both in monomicrobial or polymicrobial cultures. Among the eight patients, three experienced severe infections such as bacteremia and osteomyelitis. All the strains were susceptible to amoxicillin/clavulanic acid, piperacillin/tazobactam, imipenem, meropenem, clindamycin, metronidazole and moxifloxacin.

Disseminated Nocardia farcinica infection associated with bacteraemia and osteomyelitis pubis in an elderly patient.

OBJECTIVE: We describe a rare case of a disseminated Nocardia farcinica infection associated with hip osteomyelitis. METHODS: A 91-year-old female patient was admitted with oedema of her right leg, fever of 38 °C and data consistent with ruptured Baker's cyst. A disseminated Nocardia farcinica infection including bloodstream infection, pneumonia and multiple abscesses along both lower limbs was observed. RESULTS: After a four-week course of 320 mg/1600 mg/12 h of intravenous trimethoprim/sulfamethoxazole and multiple chirurgic drainages the patient was discharged with oral trimethoprim/sulfamethoxazole. Nevertheless, the patient expired done month after being discharged from the hospital. CONCLUSIONS: The implementation of a combination of intravenous antibiotics and drainages resulted in an initial improvement in the patient's condition. However, despite these interventions, the patient ultimately passed away probably due to natural causes.

Fusobacterium ulcerans: from gut to commensal and bacterial translocation?

The genus Fusobacterium contains currently 13 species presenting as non-sporing, obligate anaerobic, Gram-negative fusiform rods. Fusobacterium ulcerans was discovered in 1988 causing tropical ulcers. We present the case of a patient with diverticulitis complicated with bacteremia. Both aerobic bottles were positive at 20 and 24 h, while one anaerobic bottle was positive at 36 h. Escherichia coli and Fusobacterium ulcerans were identified from subcultures by MALDI-TOF MS with a score of 2.02 and 2.35, respectively. The 16S rRNA gene was sequenced in order to confirm the identification of F. ulcerans with a 100% homology to the reference strain. The patient was treated with 4 g/0,5 g of IV piperacillin/tazobactam and later with 1 g/0,2 g of amoxicillin/clavulanic during 7 days with good clinical evolution.