Antimicrobial Resistance and Antimicrobial Activity of Staphylococcus lugdunensis Obtained from Two Spanish Hospitals.

Staphylococcus lugdunensis is a coagulase-negative-staphylococci (CoNS) that lately has gained special attention in public health as a human pathogen and also as a bacteriocin-producer bacteria. In this study, we characterized 56 S. lugdunensis isolates recovered from human samples in two Spanish hospitals. Antimicrobial susceptibility testing was performed and antimicrobial resistance and virulence genotypes were determined. Antimicrobial activity (AA) production was evaluated by the spot-on-lawn method against 37 indicator bacteria, including multidrug-resistant (MDR) isolates, and the presence of the lugD gene coding for lugdunin bacteriocin was analyzed by PCR. The antibiotic resistance detected was as follows (% resistance/genes detected): penicillin (44.6%/blaZ), oxacillin (1.8%/mecA on SCCmec-V), erythromycin-clindamycin inducible (7.1%/erm(C), msrA), tetracycline (5.3%/tetK), gentamicin and/or tobramycin (3.6%/ant(4')-Ia, acc(6')-aph(2″)), and fosfomycin (21.4%). A MDR phenotype was detected in 5% of isolates. Twenty-one of the S. lugdunensis isolates showed susceptibility to all 20 antibiotics tested (37.5%). The screening for AA revealed 23 antimicrobial producer (AP) isolates with relevant inhibition against coagulase-positive-staphylococci (CoPS), including both methicillin-susceptible and -resistant S. aureus. The lugD gene was detected in 84% of the 56 S. lugdunensis isolates. All of the AP S. lugdunensis isolates (n = 23) carried the lugD gene and it was also detected in 24 of the non-AP isolates, suggesting different gene expression levels. One of the AP isolates stood out due to its high antimicrobial activity against more than 70% of the indicator bacteria tested, so it will be further characterized at genomic and proteomic level.

Combination of Photodynamic Therapy and Oral Antifungals for the Treatment of Onychomycosis.

Onychomycosis accounts for 50% of nail disorders, making it one of the most prevalent fungal diseases and a therapeutic challenge. Photodynamic therapy (PDT) could constitute a therapeutic alternative, owing to its good adherence, the low probability of resistance, the lack of interaction with antimicrobials, and its favorable adverse effect profile. This retrospective observational study included all patients with a microbiological diagnosis of onychomycosis treated with PDT at Miguel Servet University Hospital, Zaragoza (Spain), between January 2013 and June 2021. The protocol consisted of pre-treatment with 40% urea for 7 days, followed by 16% methyl-aminolevulinate (MAL) for 3 h and subsequent irradiation with a red-light LED lamp (37 J/cm2), every 1 or 2 weeks. Combined treatment with oral and/or topical antifungals was recorded. Of the 20 patients included (mean age, 59 ± 17 years), 55% were men. The most frequently detected microorganism was Trichophyton rubrum (55%). The most commonly affected location was the feet (90%): 50% of these cases were associated with tinea pedis. The median (standard deviation) number of PDT sessions was 6 (2.8). PDT was combined with systemic terbinafine (250 mg/day) in 10 cases (in 8 cases, this was administered for only 1 month), and with topical terbinafine in 3 cases. A complete clinical response was achieved in 80% (16) of cases and microbiological cure in 60% (12). PDT is a therapeutic alternative for onychomycosis, and can be administered either in monotherapy or combined with antifungals, allowing for a reduction in the duration and possible adverse effects of antifungal treatment and achieving higher cure rates than those obtained with either treatment alone.

Beyond CC398: Characterisation of Other Tetracycline and Methicillin-Resistant Staphylococcus aureus Genetic Lineages Circulating in Spanish Hospitals.

Tetracycline resistance (TetR) has been evidenced as a good phenotypic marker for detection of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of the clonal complex CC398. The aim of this study was to characterise a collection of 95 TetR-MRSA isolates, not belonging to the lineage CC398, that were obtained in a previous multicentre study, to detect other MRSA clonal complexes that could be associated with this phenotypic TetR marker. The TetR-MRSA isolates were recovered from 20 Spanish hospitals during 2016 and they were characterised to determine their antimicrobial resistance and virulence phenotypes/genotypes as well as the presence of the immune evasion cluster (IEC). A high proportion of isolates belonging to the CC1 lineage (46%) were observed, as well as to the CC5, CC8 and CC45 lineages (11% each one). Thirty-two different spa-types were identified, being predominantly CC1-t127 (40%) and CC45-t1081 (11%). The IEC system (with the gene scn as marker) was present in 73% of isolates and 16% produced the Panton Valentine leucocidin (PVL). A high proportion of MRSA-CC1 isolates were scn-negative (38.6%) and 52.9% of them were blaZ-negative. A multidrug resistance (MDR) phenotype was identified in 86% of MRSA isolates. The knowledge of other TetR-MRSA genetic lineages, in addition to CC398, is highly relevant, since most of them were MDR and some of them presented important virulence factors. Strains potentially associated with livestock (as the subpopulation CC1-t127-scn-negative) or with humans (as the CC45 lineage or the subpopulation CC1-scn-positive) have been found in this study. The use of tetracycline-resistance for detection, not only of CC398 but also of other LA-MRSA lineages should be tracked in the future.

Penicillin susceptibility among invasive MSSA infections: a multicentre study in 16 Spanish hospitals.

OBJECTIVES: To determine the prevalence of penicillin susceptibility among MSSA causing bloodstream infections (BSIs) in 16 Spanish hospitals and to characterize the penicillin-susceptible MSSA (MSSA-PENS) isolates. METHODS: A total of 1011 Staphylococcus aureus isolates were collected from blood cultures in 16 Spanish hospitals during 2018-19 (6-12 months) and their susceptibility to 18 antimicrobials was determined. The MSSA-PENS isolates were selected and examined by PCR to determine the presence of the blaZ gene, other resistance genes and the genes lukF/lukS-PV, eta, etb and tst. The immune evasion cluster (IEC) type was also analysed. All the MSSA-PENS isolates were submitted to S. aureus protein A (spa) typing and the clonal complexes (CCs) were assigned according to their spa type. RESULTS: The prevalence of MSSA was 74.6% (754/1011) and 14.9% (151/1011) were MSSA-PENS-blaZnegative. MSSA-PENS-blaZnegative isolates (n = 151) were ascribed to 88 spa types and 11 CCs. The most frequent CCs were CC5 (35/151) and CC398 (25/151), with t002-CC5 and t571-CC398 being the most common lineages. Pan-susceptibility was identified in 117 of the 151 MSSA-PENS-blaZnegative isolates (77.5%). In the remaining isolates, erythromycin and clindamycin resistance was the most frequent resistance found, although tobramycin, ciprofloxacin, fusidic acid, mupirocin and/or tetracycline resistance was also detected. Thirty-eight MSSA-PENS-blaZnegative isolates were IEC negative and four isolates were Panton-Valentine leucocidin ('PVL') positive. CONCLUSIONS: A high penicillin susceptibility rate was detected among MSSA, opening therapeutic opportunities for BSIs. The emergence of new successful MSSA-PENS clones could be responsible for these data. The detection among MSSA-PENS-blaZnegative isolates of the clonal lineage CC398 or the absence of an IEC raises questions about their possible animal origin, requiring further analysis.

Comparison of Antibacterial Activity and Wound Healing in a Superficial Abrasion Mouse Model of Staphylococcus aureus Skin Infection Using Photodynamic Therapy Based on Methylene Blue or Mupirocin or Both.

Background: Antibiotic resistance and impaired wound healing are major concerns in S. aureus superficial skin infections, and new therapies are needed. Antimicrobial photodynamic therapy (aPDT) is a new therapeutic approach for infections, but it also improves healing in many wound models. Objective: To compare the antimicrobial activity and the effects on wound healing of aPDT based on Methylene Blue (MB-aPDT) with mupirocin treatment, either alone or in combination, in superficial skin wounds of S. aureus-infected mice. Additionally, to evaluate the clinical, microbiological, and cosmetic effects on wound healing. Materials and Methods: A superficial skin infection model of S. aureus was established in SKH-1 mice. Infected wounds were treated with MB-aPDT, MB-aPDT with a daily topical mupirocin or only with mupirocin. No treatment was carried out in control animals. Daily clinical and microbiological examinations were performed until complete clinical wound healing. Histopathological studies and statistical analysis were performed at the end of the study. Results: MB-aPDT treatment induced the best wound healing compared to mupirocin alone or to mupirocin plus MB-aPDT. Superficial contraction at 24 h and a greater reduction in size at 48 h, quicker detachment of the crust, less scaling, and absence of scars were observed. Histopathological studies correlated with clinical and gross findings. By contrast, mupirocin showed the highest logaritmic reduction of S. aureus. Conclusions: MB-aPDT and mupirocin treatments are effective in a murine superficial skin infection model of S. aureus. One session of MB-aPDT was the best option for clinical wound healing and cosmetic results. The addition of mupirocin to MB-aPDT treatment improved antimicrobial activity; however, it did not enhance wound healing. No synergistic antibacterial effects were detected.

Prevalence and Genetic Characteristics of Staphylococcus aureus CC398 Isolates From Invasive Infections in Spanish Hospitals, Focusing on the Livestock-Independent CC398-MSSA Clade.

BACKGROUND: Livestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported. OBJECTIVES: To determine the prevalence of Staphylococcus aureus (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates. METHODS: One thousand twenty-two SA isolates (761 MSSA, 261 MRSA) recovered from blood cultures during 6-12 months in 17 Spanish hospitals (2018-2019) were studied. CC398 lineage identification, detection of spa-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing. RESULTS: Forty-four CC398-MSSA isolates (4.3% of SA; 5.8% of MSSA) and 10 CC398-MRSA isolates (1% of SA; 3.8% of MRSA) were detected. Eleven spa-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent spa-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin-inducible-resistant/erm(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km2) (p = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately spa-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (p < 0.005). CONCLUSION: CC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers.

Mechanisms of Linezolid Resistance Among Clinical Staphylococcus spp. in Spain: Spread of Methicillin- and Linezolid-Resistant S. epidermidis ST2.

This study aimed at determining the mechanisms of linezolid resistance and the molecular characteristics of clinical Staphylococcus aureus (n = 2) and coagulase-negative staphylococci (n = 15) isolates obtained from four Spanish hospitals. The detection of linezolid resistance mechanisms (mutations and acquisition of resistance genes) was performed by PCR/sequencing. The antimicrobial resistance and virulence profile was determined, and the isolates were typed by different molecular techniques. Moreover, the genetic environment of the cfr gene was determined by whole-genome sequencing. The cfr gene was detected in one methicillin-resistant S. aureus (MRSA) that also displayed the amino acid change Val118Ala in the ribosomal protein L4. The second S. aureus isolate was methicillin susceptible and showed different alterations in the ribosomal protein L4. All remaining linezolid-resistant Staphylococcus epidermidis (n = 14) and Staphylococcus hominis isolates (n = 1) showed the mutation G2576T (n = 14) or C2534T (n = 1) in the 23S rRNA. Moreover, different amino acid changes were detected in the ribosomal proteins L3 and L4 in S. epidermidis isolates. All S. epidermidis isolates belonged to the multilocus sequence type ST2. Linezolid-resistant staphylococci (LRS) showed a multiresistance phenotype, including methicillin resistance that was detected in all isolates but one, and was mediated by the mecA gene. The cfr gene in the MRSA isolate was located together with the fexA gene on a conjugative 38,864 bp plasmid. Linezolid- and methicillin-resistant S. epidermidis ST2 showing mutations in the 23S rRNA and in the ribosomal proteins L3 and L4 are spread among Spanish hospitals, whereas LRS carrying acquired linezolid resistance genes are rarely detected.

Bacteriemia por Staphylococcus aureus sensible a penicilina. Importancia epidemiológica, clínica y posibles implicaciones terapéuticas / Penicillin-susceptible Staphylococcus aureus bacteremia: Epidemiological and clinical relevance. Possible therapeutic implications

INTRODUCCIÓN: El aumento de la sensibilidad a penicilina en Staphylococcus aureus (SA-PenS) podría tener relevancia terapéutica. Pretendemos conocer esta situación en nuestro medio. MATERIAL Y MÉTODOS: Se analizaron bacteriemias por SA en un hospital durante 2,5 años (2015-2017). Estudiamos la sensibilidad a antimicrobianos, genes de resistencia a beta-lactámicos (blaZ, mecA) y presencia de leucocidina de Panton-Valentine. En aislados SA-PenS-blaZnegativo se determinó el tipo de spa, MLST y genes de resistencia a antimicrobianos no-beta-lactámicos. RESULTADOS: Hubo 84 pacientes con bacteriemia por SA (35,7% SARM y 64,3% SASM), se analizaron 77. El 22% de los SASM estudiados (n = 11) fueron PenS-blaZnegativo (CMI-Pen ≤ 0,3 μg/ml), correspondiendo al 14,3% del total de SA. En SASM-PenS-blaZnegativo se detectaron 8 tipos-spa y 7 complejos clonales. CONCLUSIÓN: Detectamos alta prevalencia de SARM/SA y de SASM-PenS-blaZnegativo/SASM en hemocultivos. Una CMI-Pen ≤ 0,3 μg/ml se correspondió con SASM-PenS-blaZnegativo. Esta situación plantea opciones terapéuticas que deberán reevaluarse con estudios más amplios y ensayos clínicos

INTRODUCTION: The increase in penicillin susceptibility among Staphylococcus aureus (SA-PenS) might have therapeutic relevance. We aimed to study the current situation in our environment. MATERIAL AND METHODS: Over a 2.5 years period, all SA isolates from bacteraemia in one hospital were analysed. For all isolates, antimicrobial susceptibility profile, beta-lactam resistance genes (blaZ, mecA) and Panton-Valentine leucocidine encoding-genes were studied. For SA-PenS-blaZnegative isolates, spa-type, MLST and the presence of other resistance genes were studied. RESULTS: Among 84 patients with SA bacteraemia (35.7% MRSA and 64.3% MSSA), 77 were analysed; 22.2% of MSSA isolates were PenS and blaZnegative (Pen-MIC ≤ 0.03 μg/ml) corresponding to 14.3% of the total SA. In MSSA-PenS-blaZnegative isolates, eight spa-types and 7 clonal-complexes were detected. CONCLUSION: A high prevalence of MRSA/SA and MSSA-PenS-blaZnegative/MSSA was detected in blood cultures. Pen-MIC ≤ 0,3 μg/ml corresponded to MSSA-PenS-blaZnegative. This situation raises therapeutic options which should be further evaluated in larger studies and clinical trials

Importancia del complejo clonal CC398 en las bacteriemias por Staphylococcus aureus en un hospital secundario de Aragón / Relevance of clonal complex CC398 in bacteremia caused by Staphylococcus aureus in a secondary hospital of Aragon, Spain

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Mechanisms of Linezolid Resistance Among Enterococci of Clinical Origin in Spain-Detection of optrA- and cfr(D)-Carrying E. faecalis.

The mechanisms of linezolid resistance among 13 E. faecalis and 6 E. faecium isolates, recovered from six Spanish hospitals during 2017-2018, were investigated. The presence of acquired linezolid resistance genes and mutations in 23S rDNA and in genes encoding for ribosomal proteins was analyzed by PCR and amplicon sequencing. Moreover, the susceptibility to 18 antimicrobial agents was investigated, and the respective molecular background was elucidated by PCR-amplicon sequencing and whole genome sequencing. The transferability of the linezolid resistance genes was evaluated by filter-mating experiments. The optrA gene was detected in all 13 E. faecalis isolates; and one optrA-positive isolate also carried the recently described cfr(D) gene. Moreover, one E. faecalis isolate displayed the nucleotide mutation G2576T in the 23S rDNA. This mutation was also present in all six E. faecium isolates. All linezolid-resistant enterococci showed a multiresistance phenotype and harbored several antimicrobial resistance genes, as well as many virulence determinants. The fexA gene was located upstream of the optrA gene in 12 of the E. faecalis isolates. Moreover, an erm(A)-like gene was located downstream of optrA in two isolates recovered from the same hospital. The optrA gene was transferable in all but one E. faecalis isolates, in all cases along with the fexA gene. The cfr(D) gene was not transferable. The presence of optrA and mutations in the 23S rDNA are the main mechanisms of linezolid resistance among E. faecalis and E. faecium, respectively. We report the first description of the cfr(D) gene in E. faecalis. The presence of the optrA and cfr(D) genes in Spanish hospitals is a public health concern.

Simultaneous Nasal Carriage by Methicillin-Resistant and Methicillin Susceptible Staphylococcus aureus of Lineage ST398 in a Live Pig Transporter.

Methicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST)398 is a livestock associated (LA) lineage with zoonotic potential, especially in humans with live pig contact. The objective of this study was to characterize two S. aureus strains of lineage ST398 (one methicillin-resistant (MRSA), one methicillin-susceptible (MSSA)) isolated from the same nasal sample of a patient admitted in the Intensive-Care Unit of a Spanish Hospital, and with previous occupational exposure to live pigs, by whole-genome-sequencing (WGS). The sample was obtained during routine surveillance for MRSA colonization. Purified genomic DNA was sequenced using Illumina HiSeq 2000 and processed using conventional bioinformatics software. The two isolates recovered were both S. aureus t011/ST398 and showed similar resistance-phenotypes, other than methicillin susceptibility. The possession of antibiotic resistance genes was the same, except for the mecA-gene located in SCCmecV in the MRSA isolate. The MSSA isolate harbored remnants of a SCCmec following the deletion of 17342bp from a recombination between two putative primases. Both isolates belonged to the livestock-associated clade as defined by three canonical single-nucleotide-polymorphisms, and neither possessed the human immune evasion cluster genes, chp, scn, or sak. The core genome alignment showed a similarity of 99.6%, and both isolates harbored the same mobile genetic elements. The two nasal ST398 isolates recovered from the patient with previous occupational exposure to pigs appeared to have a livestock origin and could represent different evolutionary steps of animal-human interface lineage. The MSSA strain was formed as a result of the loss of the mecA gene from the livestock-associated-MRSA lineage.

Penicillin-susceptible Staphylococcus aureus bacteremia: Epidemiological and clinical relevance. Possible therapeutic implications. / Bacteriemia por Staphylococcus aureus sensible a penicilina. Importancia epidemiológica, clínica y posibles implicaciones terapéuticas.

INTRODUCTION: The increase in penicillin susceptibility among Staphylococcus aureus (SA-PenS) might have therapeutic relevance. We aimed to study the current situation in our environment. MATERIAL AND METHODS: Over a 2.5 years period, all SA isolates from bacteraemia in one hospital were analysed. For all isolates, antimicrobial susceptibility profile, beta-lactam resistance genes (blaZ, mecA) and Panton-Valentine leucocidine encoding-genes were studied. For SA-PenS-blaZnegative isolates, spa-type, MLST and the presence of other resistance genes were studied. RESULTS: Among 84 patients with SA bacteraemia (35.7% MRSA and 64.3% MSSA), 77 were analysed; 22.2% of MSSA isolates were PenS and blaZnegative (Pen-MIC≤0.03µg/ml) corresponding to 14.3% of the total SA. In MSSA-PenS-blaZnegative isolates, eight spa-types and 7 clonal-complexes were detected. CONCLUSION: A high prevalence of MRSA/SA and MSSA-PenS-blaZnegative/MSSA was detected in blood cultures. Pen-MIC≤0,3µg/ml corresponded to MSSA-PenS-blaZnegative. This situation raises therapeutic options which should be further evaluated in larger studies and clinical trials.

Antimicrobial resistance phenotypes and genotypes of methicillin-resistant Staphylococcus aureus CC398 isolates from Spanish hospitals.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of lineage CC398 is an emerging clone causing human infections but is mostly found in pigs. The aim of this study was to characterize the antimicrobial resistance phenotypes/genotypes of a collection of 137 MRSA CC398 isolates obtained in a previous study from 17 Spanish hospitals, using tetracycline resistance as marker for selection. A multidrug-resistant (MDR) phenotype was present in 79% of analysed isolates, with 17% of them resistant to at least six different antimicrobial families. All tetracycline-resistant isolates (n=137) carried the tetM gene and 75% also carried the tetK gene. Almost 50% of MRSA CC398 isolates showed macrolide and/or lincosamide resistance: a) 39% of isolates were ERYR-CLIR (all with constitutive phenotype), with 87% of them carrying the ermC gene, followed by msrA (25%), ermB (21%), vgaA (17%), ermA (6%), lsaB (4%), linA (2%), linB (2%), and ermT (2%, this isolate with the new spa-type t18071); and b) 9% of MRSA CC398 isolates showed the dissociated ERYS-CLIR phenotype carrying the linA, linB, lsaB and vgaA genes. Other antimicrobial resistance phenotypes in these MRSA CC398 isolates included resistance to ciprofloxacin (67%), aminoglycosides (21%), mupirocin (6%), chloramphenicol (4%) or fusidic acid (2%). The more common resistance genes detected for some of these antimicrobials were: aac(6')-Ie-aph(2'')-Ia (16%) and ant(4')-Ia (12%) for aminoglycosides, and fexA (3%) for chloramphenicol. The high rate of MDR phenotypes with a wide range of antimicrobial resistance genes shown in this study reduce the potential therapeutic options in case of infections.

Estacionalidad de las bacteriemias en urgencias / Seasonality of bacteremia cases in an emergency department

Objetivo. Valorar la variabilidad de la estacionalidad en los episodios de bacteriemia. Método. Estudio de cohortes retrospectivo de las bacteriemias significativas de los hemocultivos extraídos en un servicio de urgencias. Se analizó la incidencia, etiología, rentabilidad y pronóstico, así como las variaciones en función de las estaciones del año. Resultados. Se realizaron 4.384 solicitudes de hemocultivos, que representó una tasa de solicitud del 4,1%. La rentabilidad diagnóstica fue del 12,2%. La incidencia de bacteriemia fue de 490 episodios por cada 100.000 atenciones. En invierno, respecto a la media del resto de estaciones, resultaron significativos el incremento en la solicitud de hemocultivos (4,6% frente a 3,8%, p < 0,001), el descenso de la rentabilidad diagnóstica (10,2% frente a 13%, p = 0,01), el incremento en la tasa de contaminación (4,9 % frente a 3,8%, p = 0,02), una menor frecuencia de aislamientos de Escherichia coli (36,4% frente a 46,9%, p = 0,03) y mayor de Streptococcus pneumoniae (14,5% frente a 5,9%, p = 0,001). Conclusiones. Se identifica una variabilidad significativa en cuanto al perfil microbiológico, rentabilidad y contaminantes en los hemocultivos obtenidos durante la estación invernal

Objective. To assess seasonal variation in episodes of bacteremia. Methods. Retrospective cohort study of cases of significant bacteremia found in blood cultures ordered in a hospital emergency department. The incidence, etiology, diagnostic and prognostic yield were analyzed for each season of the year. Results. A total of 4384 blood cultures were ordered in 4.1% of the emergency patients attended. The diagnostic yield was 12.2% (incidence, 490 cases per 100 000 cases attended). Cultures were ordered more often in winter (in 4.6% of the patients vs in 3.8% in the other seasons on average, P<.001). The diagnostic yield was lower in winter than in the other seasons (10.2% vs 13%, P=.01), and the contamination rate was higher (4.9% vs 3.8%, P=.02). Escherichia coli was isolated in fewer cultures in winter than in other seasons (36.4% vs 46.9%, P=.03), and Streptococcus pneumoniae was isolated in more (14.5% vs 5.9%, P=.001). Conclusions. The microbiological profile of blood cultures, their diagnostic yield, and rate of contamination differ greatly in winter

Seasonality of bacteremia cases in an emergency department. / Estacionalidad de las bacteriemias en urgencias.

OBJECTIVES: To assess seasonal variation in episodes of bacteremia. MATERIAL AND METHODS: Retrospective cohort study of cases of significant bacteremia found in blood cultures ordered in a hospital emergency department. The incidence, etiology, diagnostic and prognostic yield were analyzed for each season of the year. RESULTS: A total of 4384 blood cultures were ordered in 4.1% of the emergency patients attended. The diagnostic yield was 12.2% (incidence, 490 cases per 100 000 cases attended). Cultures were ordered more often in winter (in 4.6% of the patients vs in 3.8% in the other seasons on average, P<.001). The diagnostic yield was lower in winter than in the other seasons (10.2% vs 13%, P=.01), and the contamination rate was higher (4.9% vs 3.8%, P=.02). Escherichia coli was isolated in fewer cultures in winter than in other seasons (36.4% vs 46.9%, P=.03), and Streptococcus pneumoniae was isolated in more (14.5% vs 5.9%, P=.001). CONCLUSION: The microbiological profile of blood cultures, their diagnostic yield, and rate of contamination differ greatly in winter.

OBJETIVO: Valorar la variabilidad de la estacionalidad en los episodios de bacteriemia. METODO: Estudio de cohortes retrospectivo de las bacteriemias significativas de los hemocultivos extraídos en un servicio de urgencias. Se analizó la incidencia, etiología, rentabilidad y pronóstico, así como las variaciones en función de las estaciones del año. RESULTADOS: Se realizaron 4.384 solicitudes de hemocultivos, que representó una tasa de solicitud del 4,1%. La rentabilidad diagnóstica fue del 12,2%. La incidencia de bacteriemia fue de 490 episodios por cada 100.000 atenciones. En invierno, respecto a la media del resto de estaciones, resultaron significativos el incremento en la solicitud de hemocultivos (4,6% frente a 3,8%, p < 0,001), el descenso de la rentabilidad diagnóstica (10,2% frente a 13%, p = 0,01), el incremento en la tasa de contaminación (4,9 % frente a 3,8%, p = 0,02), una menor frecuencia de aislamientos de Escherichia coli (36,4% frente a 46,9%, p = 0,03) y mayor de Streptococcus pneumoniae (14,5% frente a 5,9%, p = 0,001). CONCLUSIONES: Se identifica una variabilidad significativa en cuanto al perfil microbiológico, rentabilidad y contaminantes en los hemocultivos obtenidos durante la estación invernal.

Multicenter study of clinical non-Beta-lactam-antibiotic susceptible MRSA strains: Genetic lineages and Panton-Valentine leukocidin (PVL) production / Estudio multicéntrico de cepas clínicas de SARM sensibles a antibióticos no-Beta-lactámicos: líneas genéticas y producción de la leucocidina de Panton-Valentine

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is considered a major cause of healthcare-associated (HA) and community-acquired (CA) infections. Considering non-β-lactam susceptibility as a potential marker for mecC-MRSA and CA-MRSA, the aim of this study was to determine the frequency and the associated genetic lineages of non-beta-lactam-antibiotic susceptible MRSA (NBLS-MRSA) strains in a multicenter study in Spain. METHODS: A collection of 45 NBLS-MRSA strains recovered in the period from January to June 2016 from 12 Spanish hospitals was analyzed. Molecular typing through spa-type characterization, agr group and multi-locus-sequence typing was performed. Methicillin-resistant genes (mecA and mecC) as well as immune evasion cluster (scn-chp-sak-sea-sep, considering scn gene as the marker of IEC system) and Panton-Valentine leukocidin (PVL) genes were determined with PCR/sequencing. RESULTS: The NBLS-MRSA phenotype was uncommon in the 12 hospitals analyzed (NBLS-MRSA/MRSA frequency: 0.3%-7.7%). All strains contained the mecA gene (and none contained mecC). Twenty-two different spa-types were detected among NBLS-MRSA strains, with spa-t008/agr-I the most prevalent (27%). The main clonal complexes were (CC/%): CC8/42.2%, CC5/33.3% and CC30/4.4%, with ST8 and ST5 as the main sequence types. The PVL toxin was present in 38% of strains (with spa-types t008, t024, t019, t044, t068, t318 and t3060). The IEC genes were detected in 78% of strains: IEC type-B (n = 17), type-F (n = 16), type-A (n = 1) and type-E (n = 1); 10 MRSA isolates were scn-negative. CONCLUSION: The NBLS-MRSA phenotype is uncommon in the analyzed hospitals; although no mecC-positive strains were detected, it could be a good marker for MRSA PVL-positive isolates (38%), frequently associated with CA-MRSA infections

INTRODUCCIÓN: Staphylococcus aureus resistente a meticilina (SARM) es una de las principales causas de infecciones tanto relacionadas con la asistencia sanitaria como asociadas a la comunidad (AC). Considerando la sensibilidad a antibióticos no-β-lactámicos como marcador potencial de SARM-mecC y SARM-AC, el objetivo de este estudio fue determinar la frecuencia y líneas genéticas de cepas SARM sensibles a antibióticos no-β-lactámicos (SARM-SNBL) en un estudio multicéntrico en España. MÉTODOS: Se analizaron 45 cepas SARM-SNBL procedentes de 12 hospitales obtenidas durante enero-junio de 2016. El tipado molecular se realizó mediante caracterización del spa-tipo, grupo agr y multi-locus-sequence typing. Mediante PCR/secuenciación se determinaron los genes: de resistencia a meticilina (mecA y mecC), del sistema de evasión inmune humano (scn-chp-sak-sea-sep, usando scn como marcador del sistema IEC) y de la leucocidina de Panton-Valentine (LPV). RESULTADOS: El fenotipo SARM-SNBL fue infrecuente en los 12 hospitales analizados (frecuencia SARM-SNBL/SARM: 0,3-7,7%). Todas las cepas fueron mecA-positivas (ninguna mecC). Se detectaron 22 spa-tipos diferentes, siendo el spa-t008/agr-I el prevalente (27%). Los principales complejos clonales fueron (CC/%): CC8/42,2%, CC5/33,3% y CC30/4,4%, destacando las secuencias tipo ST8 y ST5 como mayoritarias. El 38% de las cepas fue LPV-positiva (spa-tipos t008, t024, t019, t044, t068, t318 y t3060). El 78% de las cepas fue IEC-positivo: tipo-B (n = 17), tipo-F (n = 16), tipo-A (n = 1) y tipo-E (n = 1); 10 aislados fueron scn-negativos. CONCLUSIÓN: El fenotipo SARM-SNBL es poco frecuente en los hospitales analizados; aunque no se detectaron cepas mecC-positivas, este fenotipo puede ser un buen marcador de aislados SARM LPV-positivos, frecuentemente asociados a infecciones por SARM-AC

Epidemiology of MRSA CC398 in hospitals located in Spanish regions with different pig-farming densities: a multicentre study.

BACKGROUND: Tetracycline resistance (TetR) is a marker of livestock-associated MRSA of lineage CC398. OBJECTIVES: To determine the MRSA CC398 prevalence among TetR-MRSA recovered in Spanish hospitals located in regions with different pig-farming densities, and the influence of pig density as a key risk factor for its acquisition. METHODS: TetR-MRSA isolates (n = 232) recovered from clinical and epidemiological samples during January-June 2016 in 20 hospitals in 13 regions with different pig-farming densities were analysed. MRSA CC398 identification, detection of spa types, methicillin resistance genes and immune evasion cluster (IEC) genes were performed by PCR/sequencing. Statistical analyses were performed to establish the relationships between MRSA CC398 prevalence and pig density. RESULTS: The global MRSA prevalence was 29.7% (6.9% TetR-MRSA/MRSA), with 137 CC398 isolates recovered, representing 4.1% of total MRSA and 59.1% of TetR-MRSA. Among MRSA CC398, 16 different spa types were recorded (t011: 72.3%), and all but two strains were IEC negative. Higher pig-density regions were associated with significant MRSA CC398 increases in hospitals located in adjacent regions (P < 0.001). Linear regression models explained the relationships between MRSA CC398 and pig density (P < 0.001), with an increase of 6.6 MRSA CC398 cases per 100 MRSA per increase of 100 pigs/km2 in a region. CONCLUSIONS: High pig density leads to a significant increase in MRSA CC398 in hospitals in Spain, and its combination with a high human population could help its dissemination. In Spain, the prevalence of the zoonotic CC398 lineage is closely related to pig-farming density; therefore, specific tools could be implemented in order to detect its dissemination.