Revista Argentina de microbiologia最新文献

Despite conducting studies to investigate food contamination in hospitals in different parts of Iran in recent years, there have been no reliable studies to identify Salmonella enteritidis, Salmonella typhimurium, Bacillus cereus, Bacillus subtilis, and Clostridium perfringens in hospital food in Mashhad. Therefore, this study was conducted with the aim of investigating some major foodborne pathogens in hospital food. In this study, 360 food samples were randomly selected from 12 different menus from 13 hospitals affiliated with Mashhad University of Medical Sciences, Mashhad, Iran. Microbial culture methods for the recovery/isolation or enumeration of Salmonella spp., Bacillus spp. and C. perfringens as well as toxinotyping of C. perfringens using the PCR method were performed. B. cereus and C. perfringens were detected in 4 out of 360 food samples, 2 (0.55%) of which were B. cereus and, the remaining 2 (0.55%) were C. perfringens; B. subtilis was not detected in any of the food samples. Furthermore, Salmonella was found in 21 (5.82%) food samples, 12 (3.33%) of which were S. typhimurium, 4 (1.11%) were S. enteritidis, and 5 (1.38%) belonged to other Salmonella species. The most contaminated foods were salad, kebab, and rice samples, which accounted for 36%, 16%, and 12% of the contaminated foods, respectively. In our study, two strains of S. typhimurium and S. enteritidis, were the primary causative agents of food contamination among the investigated pathogens. More stringent control measures should be implemented in hospital catering, particularly for unprocessed foods such as salads.

Staphylococcus aureus is an important pathogen in healthcare facilities, with its resistance to a number of antibiotics currently being a global concern. In this report the presence of S.aureus, resistance gene virulence and antibiotic susceptibility profiles were determined in the mobile phones of senior nursing students. S.aureus was isolated in 11.84% (9/76) of the samples. Furthermore, 44.44% of the mobile phones carried the mecA (MRSA) gene, while none carried the vanA gene. Virulence genes identified were 100% hla, 88.89% hlb, 22.22% tst and sec, and 11.11% sea. The antibiogram revealed that 33.33% of the strains were resistant to cefoxitin and 44.44% showed inducible resistance to clindamycin (ICRSA). The mobile phones of senior nursing students represent an important reservoir of drug-resistant and virulent strains of S.aureus, which could act as infectious foci for the transmission of this pathogen.

Bovine viral diarrhea virus (BVDV) causes significant economic losses in the international livestock industry and in Argentina, where it circulates at high prevalence. Under high prevalence conditions, BVDV infections are controlled through vaccination once persistently infected animals are identified and segregated. This study evaluated the feasibility of controlling BVDV circulation under field conditions by combining diagnosis, management measures, and vaccination in 2 dairy farms in the province of Santa Fe. Commercial ELISAs were used for the detection of the NS3 (P80) protein or antibodies against this protein as well as an RT-nested PCR for the detection of the viral genome, and viral seroneutralization to assess vaccine efficacy. The average seroprevalence of the farms was 58.4%, with a persistently infected animal rate of 2.4%. After segregating the persistently infected animals and vaccinating them with a commercial combined vaccine containing inactivated BVDV, abortion rates significantly decreased (p<0.05) in farm 1 (from 20.5 to 11.6%) and in farm 2 (from 34 to 23.4%) during the second year of the control strategy. Conception rates increased from 29 to 33% in farm 1 during the first year, while in farm 2, the increase was 7 points during the second year. This methodology achieved conditions in which BVDV ceased to circulate, constituting the first controlled report on BVDV management in dairy farms using tools available to producers in Argentina.

DNA extraction is crucial for conducting procedures, such as whole-genome sequencing, which demand methods that are reproducible and cost-effective. Lysing Staphylococcus aureus cells is particularly challenging due to their peptidoglycan layer that is resistant to common treatments. Traditional methods involve costly enzymatic lysis using lysostaphin. Here, we developed a novel approach for lysis utilizing liquid nitrogen and mechanical disruption in a mortar. DNA from S. aureus USA300 and related clinical isolates were purified using phenol-chloroform extraction followed by precipitation. The integrity and purity of DNA were confirmed, obtaining suitable concentration and purity for various molecular biology techniques. The quality of the employed DNA was validated by amplifying fragments of different genes using PCR. This method circumvents lysostaphin, yielding DNA that is suitable for use in other techniques.

Carbapenemase-producing Enterobacterales (CPE) have increased in the last decade. In low-income countries, colistin is considered a last resort antimicrobial to treat CPE infections, whose most worrisome mechanism of resistance is MCR-1 production. This study aims to understand the epidemiology of colistin resistance in CPE in the region, through the surveillance of the mcr-1 gene in CPE isolates in Ecuador. A total of 361 CPE isolates were collected across three periods, from 2016 to 2022. Colistin resistance was assessed using the broth microdilution method and the most frequent carbapenemase-encoding genes and the mcr-1 gene were studied. Colistin resistance rate increased from 3.76% to 23.74% during the study period. The mcr-1 gene was not identified in any of the isolates studied and Klebsiella pneumoniaebla_KPC was the most prevalent microorganism (n=322; 89.20%). In conclusion, colistin resistance increased in CPE in Ecuador and was not mediated by the mcr-1 gene. Our results highlight the need to closely monitor national politics on antimicrobial resistance under the One Health Approach.

Klebsiella pneumoniae sequence type 258 (ST258) is the main cause of the global spread of KPC and a significant public health problem. In 2015, ceftazidime/avibactam (CZA) was introduced as a therapeutic alternative and since it has contributed to the development of new KPC variants. Here we present the identification of two consecutive isolations of K. pneumoniae ST258 (KP1 and KP2), from a patient with urinary tract infection. KP1 and KP2 harbored bla_KPC-2 and bla_KPC-35, respectively. KP2 exhibited a modified susceptibility profile to carbapenems and resistance to CZA. To the best of our knowledge, this is the first report of K. pneumoniae ST258 in Peru, which highlights the increasing problem of CZA resistance.

Acute respiratory infection (ARI) is one of the principal causes of morbidity worldwide, with respiratory viruses being common etiological agents. Among them, endemic human coronaviruses (hCoVs) including CoV-229E, CoV-OC43, CoV-NL63, and CoV-HKU1 can cause mild ARI but are usually not evaluated in the clinical setting. The aim of this work was to determine the prevalence of all respiratory pathogens, with the focus placed on endemic hCoVs in the pre-pandemic period. Circulating species, clinical associations and coinfections with other respiratory pathogens were evaluated in 510 immunocompetent patients (children and adults) with ARI using the FilmArray® Respiratory Panel (BioFire/bioMérieux). A total of 399 children (252 outpatients and 147 hospitalized) and 111 adult outpatients were enrolled in the pre-pandemic period (2008-2010 and 2016). Endemic hCoVs were the third and fifth more frequently detected viruses among adults and outpatient children, respectively, with an overall frequency close to 10%. The most prevalent species were CoV-OC43 (42.8%) and CoV-HKU1 (40.5%), followed by CoV-NL63 (19.0%) and CoV-229E (4.8%). Tachypnea, wheezing and chest indrawing were more frequent in hospitalized children compared to outpatients. All adult patients presented with symptoms of a common cold. Endemic hCoVs were detected year-round, primarily between June and November. Our results highlight their clinical relevance, and the need to include endemic hCoVs in routine screening. In the post-pandemic period, further long-term surveillance is needed for understanding the epidemiology of endemic hCoVs and their evolution, as a tool to anticipate the possible emergence of new species.

Methicillin-resistant Staphylococcus aureus (MRSA) causes a wide range of infections and contributes to elevated morbidity, mortality, and healthcare costs. Herbal compounds combined with drug delivery systems could be an effective alternative option for treating resistant bacteria. This study evaluates the antimicrobial prowess of carvacrol-loaded niosomes against MRSA strains. In this study, six carvacrol-niosome formulations with different ratios of Span and Tween were prepared. The physicochemical attributes of the optimized synthesized niosomes were assessed using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) as well as DLS Zetasizer. Encapsulation efficiency (EE) and in vitro drug release were studied. The antibacterial activity of the synthesized carvacrol-niosomes, in concentrations varying between 7.8 and 1000μg/ml, was evaluated using microdilution broth methods. The optimized niosomes, with a size of 207.3nm and an impressive EE of 91%, exhibited a spherical structure as confirmed by the electron microscopy analysis. Impressively, these carvacrol-niosomes demonstrated superior antimicrobial effectiveness against S. aureus, reducing MIC levels 4-fold to 62.5±0.0μg/ml and MBC to 125±0.0μg/ml, a significant improvement over the 250±0.0μg/ml MIC and 500±0.0μg/ml MBC of free carvacrol. Additionally, while empty niosomes showed minimal cytotoxicity with 88.32±1.32% cell viability at 100μg/ml, free carvacrol led to a marked reduction in viability to 39.46±1.26%. However, niosomes encapsulating carvacrol notably increased cell survival to 59.67±1.62% at this concentration. These findings underscore the enhanced antimicrobial potency of carvacrol when enclosed within niosomes, suggesting its potential as a potent herbal remedy for combating methicillin-resistant S. aureus.

The WHO aims to reduce the number of deaths from TB by 95% and decrease its incidence rate by 90% between 2015 and 2035. The recommended rapid diagnostic tests are accurate and cost-effective, allow for a prompt start to treatment, and influence other outcomes that are important to the patient. To detect latent infection, the tuberculin skin test and interferon γ release (IGRA) tests are used. Although IGRA is an expensive test, it has greater specificity and is not affected by previous exposure to the BCG vaccine, among other advantages. For the diagnosis of active TB, smear microscopy is commonly employed. Culture is a more sensitive, but also more complex method. It constitutes the definitive diagnosis and allows phenotypic sensitivity tests to be performed. TB-LAM has limited sensitivity; however, unlike other methodologies, it has shown promising results in individuals living with HIV and CD4 T-cell counts below 200/mm³. Finally, among the molecular biology-based tests, commercial methods using real-time PCR allow mass diagnosis and sensitivity testing to first- and second-line drugs to be conducted within a few hours of receiving the sample. These are highly sensitive and specific tests, and their use is recommended as the initial diagnostic test in both pulmonary and extrapulmonary TB cases.

Aeromonas spp. are opportunistic pathogens that cause both intra- and extraintestinal infections. The objective of this work was the phenotypic and genotypic characterization of a collection of Aeromonas strains, in addition to determining their sensitivity to different antimicrobials. Thirty seven isolates were analyzed. 54% were of intra-abdominal origin, 22% from skin and soft tissues, 19% from the bloodstream, among other less frequent sites. By amplification and sequencing of the gyrB gene, which was considered the reference method, the following were identified: 37,8% as species of the Aeromonas hydrophila complex, 32,4% as species of the Aeromonas veronii complex, and 29,7% as species of the complex Aeromonas caviae. Identification by traditional biochemical tests presented a better correlation with molecular identification than mass spectrometry (MALDI TOF MS). Regarding antibiotic sensitivity, cefotaxime, ceftazidime, cefepime, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, ciprofloxacin, amikacin, gentamicin and nitrofurantoin showed activity on more than 80.0% of the isolates tested. The sensitivity and specificity of the phenotypic methods to determine the presence of carbapenemases in relation to the detection of the cphAgene, the reference method, was 60,9% and 100%, respectively, for the colorimetric assay (Blue Carba), and of 91,3% and 50,0% respectively, for the modified Hodge test. The overall resistance to colistin was 32,4%. The automated method showed a very higher error (VME) of 16,2%, while the rapid colorimetric screening method (CRTc) showed an excellent correlation (VME 0%) with the reference method, broth microdilution.