High frequency of gram-negative bacilli harboring blaKPC-2 in the different stages of wastewater treatment plant: A successful mechanism of resistance to carbapenems outside the hospital settings.

Wastewater treatment plants (WWTPs) are considered to be a reservoir and a source of bacterial resistance. Worryingly, the presence of carbapenem-resistant Gram-negative bacilli (CRGNB) in WWTPs has recently been reported, but there are still many research gaps regarding its emergence and impact. The distribution of CRGNB in the different stages of a WWTP in Colombia and the relationship between the physicochemical factors involved with their presence are described in this paper. Additionally, given the impact on public health, the CRGNB detected were compared with isolates previously found in hospital patients. Residual water samples were taken from five different stages of a WWTP between January and July 2017. A total of 390 GNB were isolated, and a significant frequency of CRGNB harboring blaKPC-2 (38.2%, n = 149/390) was detected, of which 57% were Enterobacteriaceae, 41.6% Aeromonadaceae, and 1.3% Pseudomonadaceae. The Enterobacteriaceae were more frequent in the raw effluent compared to the Aeromonadaceae, which in turn were more prevalent in the recycled activated sludge and final effluent. Environmental variables such as pH, oxygen, chemical oxygen demand, and temperature were significantly correlated with the quantification of carbapenem-resistant Enterobacteriaceae (CRE) at specific points in the WWTP. Interestingly, isolated K. pneumoniae harboring blaKPC-2 from the WWTPs were diverse and did not relate genetically to the hospital strains with which they were compared. In conclusion, these results confirm the worrying scenario of the dissemination and persistence of emerging contaminants such as CRGNB harboring blaKPC-2, and reinforce the need to establish strategies aimed at containing this problem using multifocal interventions.

Immune responses induced by inactivated vaccine against Aeromonas hydrophila in pacu, Piaractus mesopotamicus.

Aeromonas hydrophila is responsible for outbreaks of a severe infectious disease in fish farms around the world and is one of the major causes of economic losses to the neotropical fish farmers. This study assessed the induction of immune responses and protection against A. hydrophila in pacu, Piaractus mesopotamicus, vaccinated through intraperitoneal and immersion route with inactivated virulent strain. Fish were randomly distributed in three vaccinated groups: intraperitoneal (i.p.) route; immersion; and immersion + booster; and control group (unvaccinated). All vaccination protocols used the concentration of 1.7 × 108 CFU mL-1 of inactivated A. hydrophila., and an oil adjuvant was used for vaccine prepararion for i.p. route vaccination. Blood and skin mucus from 9 fishes per treatment were collected at 14, 28, 42 and 84 days post-vaccination (DPV) for determination of lysozyme concentration in skin mucus, as well as antibodies anti-A. hydrophila in blood serum and skin mucus. Fish were challenged at 84 DPV with homologous and virulent strain of A. hydrophila for evaluation of resistance against bacterial infection. The results demonstrated that vaccination with inactivated A. hydrophila suspension by i.p. or immersion resulted in significant increase of skin mucus lysozyme and specific antibody levels in serum and skin mucus, at 28 and 42 DPV, and this increase in innate and adaptive immunity remained significant in pacu vaccinated through i.p. route up to 84 DPV. Although no significant differences were observed in the survival study, pacu vaccinated through i.p. route presented 31,33% of relative percentage survival (RPS) in LD50-96h when compared unvaccinated fish challenged at 84 DPV. The results observed in this study indicate that vaccination programs with inactivated A. hydrophila, including booster doses by i.p. or immersion routes, could result in more effective protection in pacu against this bacteriosis, by increasing innate and adaptive mucosal and systemic immune responses.

Multidrug resistance and diversity of resistance profiles in carbapenem-resistant Gram-negative bacilli throughout a wastewater treatment plant in Colombia.

OBJECTIVES: Carbapenem-resistant Gram-negative bacilli (CRGNB) have been reported in different wastewater treatment plants (WWTPs) throughout the world; however, few studies have described the antimicrobial resistance profile in different CRGNB throughout WWTPs, information that would identify points of selection of resistant bacteria. The objective of this work was to characterize the resistance profile of CRGNB harbouring blaKPC-2 from a Colombian WWTP. METHODS: Six samples were taken from four points of a WWTP. CRGNB were selected in chromID® CARBA and identified by 16S rRNA. Carbapenemases were determined by polymerase chain reaction (PCR), and susceptibility was assessed using VITEK2. RESULTS: One hundred and forty-two CRGNB harbouring blaKPC-2 were detected: 41% corresponded to Aeromonas spp. (n = 58) and 59% to Enterobacteriaceae. To establish the resistance profile, 50% of the isolates were selected proportionally by family and sampling point (26 Aeromonadaceae and 45 Enterobacteriaceae). All Enterobacteriaceae showed resistance to carbapenems and penicillins + inhibitors, high percentages of resistance to ceftriaxone (88.9%), and ciprofloxacin (44.4%), and low resistance to other antibiotics (>30%). In Aeromonadaceae, 76.9% were resistant to ceftriaxone, 58% to carbapenems, and 65.4% to ciprofloxacin. Twenty-one resistance profiles were observed, the most common of which were resistant to penicillins + inhibitor, cephalosporins (third to fourth generation), and carbapenems (19%). The percentage of multidrug resistance was 91% and was similar at all points of the WWTP. CONCLUSIONS: The high frequency of multidrug resistance and great diversity of resistance profiles observed throughout the WWTP is of concern, and shows the role of WWTP as a reservoir and dissemination source of antimicrobial resistance to water sources.

Mionecrosis fulminante metastásica por Aeromonas caviae / Methastatic fulminant myonecrosis due to Aeromonas caviae

Resumen: Las especies de Aeromonas de la familia Aeromonadaceae son bacilos gramnegativos, anaerobios facultativos, citocromo oxidasa, catalasa e indol-positivo. Se encuentran naturalmente en el medio ambiente, pero principalmente en agua dulce y salina, asimismo, se han aislado de vegetales, carne, mariscos y alimentos procesados. Las infecciones de piel y tejidos blandos por Aeromonas spp son poco frecuentes. Se han reportado en el mundo infecciones en tejidos blandos secundarias a traumatismo local en contacto con tierra o agua, a intervención quirúrgica o a diseminación hematógena en enfermos inmunodeprimidos a partir de translocación bacteriana intestinal. De los casos reportados en humanos la gastroenteritis se manifiesta con mayor frecuencia; sin embargo, se han descrito infecciones extraintestinales de gravedad que ponen en peligro la vida, como septicemia, fascitis necrotizante y mionecrosis. Comunicamos un caso de mionecrosis fulminante por Aeromonas caviae que evolucionó desfavorablemente con desenlace fatal.

Abstract: The Aeromonas species of the Aeromonadaceae family are gram-negative bacilli, facultative anaerobes, cytochrome oxidase, catalase and indole-positive bacilli. They are found naturally in the environment, but they are mainly found in fresh and salt water, and they have been isolated from vegetables, meat, seafood and processed foods. Skin and soft tissue infections caused by Aeromonas spp are rare. Soft tissue infections secondary to local trauma in contact with soil or water have been reported in the world, in surgical intervention or in hematogenous dissemination in immunosuppressed patients from intestinal bacterial translocation. Of the cases reported in humans, gastroenteritis is the most frequent; however, life-threatening extraintestinal infections such as septicemia, necrotizing fasciitis, and myonecrosis have been reported. This paper reports a case of fulminating myonecrosis caused by Aeromonas caviae, which evolved unfavorably, unfortunately with a fatal outcome.