Revista Argentina de microbiologia最新文献

The main current diagnostic challenge in Clostridioides difficile infection (CDI) is to detect patients with the poorest prognoses. We have studied the association between the presence of toxin in the feces, the amplification of the toxin B gene at low cycles in PCR (Ct), and the detection of the binary toxin or ribotype with severity, recurrence, and poor prognosis. Toxigenic C. difficile has been investigated in adult diarrheal feces, regardless of the clinical request. Glutamate dehydrogenase (GDH), toxin A (TcdA) and toxin B (TcdB) have been assessed by immunoassay and the gene encoding toxin B (tcdB) and the binary toxin (cdtA) by PCR. The toxigenic strains recovered by toxigenic culture were typed by PCR-Ribotyping and subtyped by MLVA (multilocus-variable number tandem DNA repeat analysis). Eighty-two (82) cases of CDI were detected from 677 samples (12.1%). Patients with Ct ≤ 27.5 often presented criteria for severity, recurrence, and poor prognosis (59.3% versus 40.7%, P=.15; 80% versus 20%, P=.10; and 60.3% versus 39.7%, P=.055, respectively). The mean Ct was lower when recurrence was observed (25.48; SD=2.41; P=.058). By logistic regression, the variable most likely to indicate a poor prognosis was Ct ≤ 27.5 (OR=2.663; 95% CI=.983-7.636; P=.059). In summary, the cycle threshold of the PCR for toxin B is a possible marker of severity, recurrence, and poor prognosis in CDI. The diversity of ribotypes observed is remarkable, with no clonal relationship between isolates of the same ribotype.

The confirmation of two cases of hantavirus pulmonary syndrome (HPS) in the city of San Miguel de Tucuman, province of Tucuman, is described in the present study. In 2021, the diagnosis of two patients with HPS with no history of travel outside the province was confirmed. The infection was determined by serology in both cases. Case 1 had an unfavorable outcome, was confirmed by the detection of specific IgM antibodies for orthohantavirus and the identification in a serum sample from three days of evolution of a viral genotype, which was previously unreported to be in circulation in Argentina. In Case 2, specific IgM and IgG type antibodies were detected in two serum samples, with no amplification of the viral genome. Due to the recreational habits of the patients, it is possible to infer exposure to infected rodent fluids during outdoor activities in their areas of residence. In conclusion, the circulation of a new viral genotype of orthohantavirus in Argentina is confirmed.

We conducted a prolective cohort study with the aim of estimating the incidence of healthcare-associated infections and identifying associated factors in an intensive care unit in Mexico. Diagnosis of central venous catheter-associated bacteremia, ventilator-associated pneumonia and urinary catheter-associated urinary tract infection was established according to the Centers for Disease Control and Prevention definitions; risk factors were analyzed by logistic regression. Four hundred twenty-six patients who had 486 admissions were studied, 55.9% were male and the median age was 4 years. The healthcare-associated infections incidence rate was 14.8 events/1000 patient-days. The prevalent microorganisms were gram negative bacilli. The factors associated with healthcare-associated infections were chronic conditions (p=0,01), the number of central venous catheters inserted and the days duration of central venous catheter, mechanical ventilation and the urinary catheter (the 4 variables with p≤0.001).

The aim of this study was to identify the clinical and demographic characteristics of patients with a confirmed diagnosis of spondylodiscitis through microbiological cultures. A descriptive, observational, and retrospective study was conducted. Patients were included based on clinical and radiological evidence of vertebral infection, unspecified discitis, and/or positive microbiological cultures consistent with spondylodiscitis. For the comparison between men and women, the Student's t-test and odds ratio were employed. The Chi-square test was used to examine correlations between affected spinal levels, isolated microorganisms, and associated comorbidities. A total of 86 cases of discitis were identified, 65% of which involved male patients. The mean age was 59.0±11.5 years (range: 38-83), and the average body mass index (BMI) was 28±4.05kg/m². Primary discitis predominated in 68% of cases, mainly at the thoracic level. Seventeen patients presented with spondylodiscitis not associated with chronic degenerative diseases. The most frequently isolated microorganisms were Staphylococcus aureus (28 cases) and Escherichia coli (21 cases). In 16 cases, intracellular pathogens such as Mycobacterium tuberculosis and Brucella spp. were identified, leading to an average hospital stay of 30 days. Spondylodiscitis is a serious complication, and this study highlights differences from previously published data, particularly in terms of the microorganisms involved and the demographic profile of the population.

The emergence and spread of multidrug-resistant Escherichia coli carrying mcr-1 is recognized as a threat to public health. The aim of this study was to determine the prevalence of the mcr-1 gene in colistin-resistant E. coli isolates from commercial pig farms in Chaco, Argentina from 2020 to 2021. A total of 140 rectal swab samples were collected from pigs in six different pig production farms. Antimicrobial susceptibility was determined by broth microdilution. mcr-1 to mcr-5 genes were identified by multiplex PCR and clonality was assessed by ERIC and REP-PCR. The prevalence of mcr-1 was 16.4% and mcr-2, mcr-3, mcr-4 and mcr-5 genes were not detected. Colistin MIC values showed a bimodal distribution with a MIC50, MIC90 and a range of 4, 8 and 4-8μg/ml, respectively. The resistance profile to other antimicrobials was: ampicillin, 87% (20); ampicillin-sulbactam, 47.8% (11); amoxicillin-clavulanic, 13% (3); chloramphenicol, 82.6% (19); ciprofloxacin, 60.9% (14); minocycline, 26.1% (5) and trimethoprim/sulfamethoxazole, 43.5% (10). Eighty-seven percent (87%) of the strains were categorized as MDR and 12 phenotypic resistance patterns with different clonality profiles were observed. A high prevalence of mcr-1 is demonstrated in colistin-free pig farms from Chaco, Argentina. The mcr-1 positive E. coli isolates showed an alarming level of multidrug resistance and high clonal diversity. It is necessary to continuously monitor the presence of the mcr-1 gene not only in pig production, but also in humans and the environment.

Protothecosis is an infectious disease caused by microalgae of the genus Prototheca. Prototheca can be found in soil and water and transiently colonize animals. Cutaneous protothecosis can involve not only the skin but also the underlying subcutaneous tissue and lymph nodes. This can lead to clinical signs and a microscopic tissue image that closely resembles a fungal infection. Treatment typically involves antifungal medications. We report the first case of fatal disseminated protothecosis caused by Prototheca wickerhamii in the city of Rosario, Argentina in a 5-year-old female poodle dog. The dog exhibited ocular signs of uveitis and lymphadenitis. To reach a clinical and etiological diagnosis, imaging studies, routine laboratory tests and serological tests were performed. A mycological analysis was conducted on the material obtained by puncturing three lymph nodes. Additionally, morphological, metabolic, and molecular analyses were performed. Antifungal susceptibility testing was also conducted using broth microdilution and diffusion methods. Phenotypic, metabolic, and sequencing techniques identified the isolated organism as P. wickerhamii. This isolate displayed susceptibility to amphotericin, variable susceptibility to itraconazole and voriconazole, and resistance to fluconazole and caspofungin. The frequent presence of pets in our homes highlights the need for a more comprehensive diagnostic approach. This is important because, from a public health perspective, dogs could serve as indicators of algal presence in the environments they frequently share with humans.

Postharvest diseases of carrots are one of the most important concerns in carrot storage, as they affect the shelf life of carrots and cause significant financial losses. In this study, ten commercial carrot samples from supermarkets and local markets in Texcoco, State of Mexico, Mexico, were analyzed for bacterial spoilage after incubation at 28°C in a humidity chamber. Carrots from seven samples developed bacterial spoilage after five days of incubation, of which baby carrots (industrially processed) showed the most severe rot. Twenty-three bacterial strains were isolated from the tissues of spoiled carrots. To identify and characterize the spoilage pathogens, the isolated strains were inoculated into healthy carrots in laboratory tests. Of the 23 strains analyzed, eight caused carrot tissue spoilage. Biochemical and molecular characterization by 16S ribosomal RNA gene sequencing identified Gluconobacter cerinus (1032.2, 1059 and 1070.1), G.kondonii (1027.1), G.wancherniae (1033.1) and Paenibacillus polymyxa (1074.2, 1076 and 1077) as the causal agents of the carrot rot evaluated in this study. In addition, these bacteria showed virulence in other plant pathogenicity tests; Gluconobacter strains induced a hypersensitivity reaction in tobacco leaves and Paenibacillus strains showed pectolytic activity in potato tubers. This study is the first to report G.cerinus, G.kondonii, G.wancherniae and P.polymyxa as causal agents of commercial carrot rot.

Plant growth promoting microorganisms play a substantial role in current plant production practices. Yeasts have shown a promising role in enhancing plant production. We studied the production of indole 3-acetic acid (IAA)-like compounds in three psychrotolerant Patagonian native yeast strains. The yeast Tausonia pullulans CRUB 1772, Candida saitoana CRUB 1770 and Saccharomyces eubayanus CRUB 2014 were evaluated using the Salkowski's colorimetric technique and high-performance liquid chromatography (HPLC). T. pullulans CRUB 1772 was the highest producer of IAA-like compounds using the colorimetric technique. Nevertheless, none of the tested yeasts reached the production level of the bacterial strain A. argentinense Az39 used as positive control. The HPLC analysis revealed that only C. saitoana CRUB 1770 and S. eubayanus CRUB 2014 were able to truly produce IAA. Other peaks were also observed, which might correspond to intermediate compounds within the IAA biosynthetic pathway.

Cryptogenic liver abscesses (CLA) caused by hypervirulent Klebsiella pneumoniae (hvKP) strains are emerging in Western countries. The aim of the study was to describe the clinical characteristics of patients from Argentina with hvKP-related CLA as well as the molecular analysis of isolated strains. A retrospective chart review of 15 patients hospitalized in 8 hospitals of Argentina between October 2015 and November 2018 was performed. PCR assays for genes associated with capsular and multilocus sequence typing (MLST) determination and virulence factors were conducted in 8 hvKP isolates from these patients. We found that the mean age of patients was 60 years, 73% of them were men and 40% suffered from diabetes. Bacteremia was detected in 60% of them and 73% had ≥1 metastatic foci of infection. There were no in-hospital deaths, but two patients with endophthalmitis required eye enucleation. Of the 8 studied isolates, 4 belonged to K1 and 4 to K2 serotypes, with the rpmA and iroB genes being present in all of them, and isolates 7 and 5 also harboring the iucA and the rmpA2 genes, respectively. MSLT analysis showed that most of the K1 serotypes belonged to ST23 while a diverse MLST pattern was observed among the K2 strains. In addition, the four hvKP strains associated with metastatic complications and belonging to three distinct sequence types, exhibited the rpmA, iroB and iuc virulence genes. We were able to demonstrate important morbidity associated with this syndrome, a significant diversity in the hvKP clones causing CLA in Argentina, and the potential utility of the rpmA and iroB genes as predictors of virulence.