Exploring extended-spectrum beta lactamase resistance in Vibrio parahaemolyticus and Vibrio cholerae within the tropical mangrove ecosystem of southwest India.

Multidrug-resistant pathogenic vibrios are a crisis of concern as they cause multiple illnesses, including gastroenteritis in humans and acute hepatopancreatic necrosis in aquaculture. In the current study, we investigated the prevalence of the beta-lactamase gene CTX-M-group 1 in Vibrio spp. (Vibrio cholerae and Vibrio parahaemolyticus) from the water and sediment of urban tropical mangrove ecosystems of Kerala, southwest India. A total of 120 isolates of Vibrio spp. were tested for antibiotic susceptibility to 14 antibiotics. In water, ampicillin resistance was very high in isolates of V. cholerae (94.1%, n = 17) and V. parahaemolyticus (89.1%, n = 46). 26.9% of V. parahaemolyticus and 14.2% of V. cholerae harbored the CTX-M-group 1 gene in water samples. Compared to V. cholerae, the CTX-M-group 1 gene was exclusively hosted by V. parahaemolyticus (49%) in sediment samples. A significant difference in the prevalence of the CTX-M-group 1 gene was observed among Vibrio spp. in both water and sediment samples (p < 0.05). The results revealed the presence of multidrug-resistant and beta-lactamase harboring Vibrio spp. in mangrove ecosystems, which may have evolved as a consequence of the misuse and abuse of broad-spectrum antibiotics as prophylaxis in human health care and aquaculture.

Heavy metal accumulation analysis using bivalve, sponge, sea urchin, and gastropod species as bioindicators.

A comparative assessment of heavy metal accumulation potential in four distinct marine benthic bioindicators: the bivalve Perna perna, the sponge Callyspongia fibrosa, the sea urchin Tripneustes gratilla, and the gastropod Purpura bufo were conducted. These organisms were collected from the same location, and the concentration of ten heavy metals was analyzed in water, sediment and various body parts of the organisms. The bioaccumulation potential was evaluated using the bio-water accumulation factor and bio-sediment accumulation factor. There was significant variation in the bioaccumulation potential of each organism with respect to different metals. The sponge proved to be a reliable indicator of Cd with a highest concentration of 2.60 µg/g. Sea urchin accumulated high concentrations of Cr (16.98 µg/g) and Pb (4.80 µg/g), whereas Cu was predominant (21.05 µg/g) in gastropod, followed by bivalve (17.67 µg/g). The concentration of metals in hard parts was found to be lower than in the tissues.

Prevalence of Extended-Spectrum Beta-Lactamase Resistance and CTX-M-Group 1 Gene in Escherichia coli from the Water and Sediment of Urbanized Mangrove Ecosystems of Kerala.

The study aimed to determine the prevalence of extended-spectrum ß-lactamase resistance and CTX-M-group 1 gene in Escherichia coli from the water and sediment of three urbanized mangrove ecosystems of Kerala. A total of 119 E. coli isolates were screened for antibiotic susceptibility to 16 antibiotics. According to the phylogenetic analysis of E. coli isolates, nonpathogenic group A and pathogenic group D (29.4% and 23.5%) were the predominant phylotypes found in water samples. The most frequent phylotypes found in sediment samples were nonpathogenic groups A and B1 (27.9% and 26.4%). The highest incidence of antibiotic resistance in E. coli was against cefotaxime and colistin (100%). A significant difference in the prevalence of CTX-M-group 1 gene was observed among E. coli isolates in water samples (p < 0.05). The results indicate a high prevalence of ß-lactamase harboring E. coli in the mangrove ecosystems that can hamper mangrove-dependent aquaculture practices and human health.

Comparative analysis of temporal variation of heavy metal accumulation by two sea urchin species from a harbour region, including pre and post COVID 19 lock down period.

Sea urchins are marine invertebrates belonging to phylum Echinodermata, recognized as relevant biological tool for assessing environmental pollution. In the present study, we assessed the bioaccumulation potential of different heavy metals by two sea urchin species, Stomopneustes variolaris Lamarck, 1816 and Echinothrix diadema Linnaeus, 1758, collected from a harbour region, along the south west coast of India, during four different sampling periods for 2 years, from the same sea urchin bed. Heavy metals like Pb, Cr, As, Cd, Co, Se, Cu, Zn, Mn and Ni were analysed from water, sediment and different body parts of sea urchins, such as shell, spine, tooth, gut and gonad. The sampling periods also included the pre and post COVID 19 lockdown period during which the harbour activities were closed. The bio-water accumulation factor (BWAF), bio-sediment accumulation factor (BSAF) and the metal content/test weight index (MTWI) were calculated, in order to compare the bioaccumulation of metals by both the species. The results showed that S. variolaris had higher bioaccumulation potential than E. diadema, for metals like Pb, As, Cr, Co and Cd especially in the soft body parts like gut and gonad. The hard parts of S. variolaris like shell, spine, and tooth also accumulated more Pb, Cu, Ni and Mn than E. diadema. Following the lockdown period, there was a decline in the concentration of all heavy metals in water, whereas in sediment, Pb, Cr, and Cu levels were reduced. The gut and gonad tissues of both the urchins showed a decrease in the concentration of most of the heavy metals following the lockdown phase and no significant reduction was observed in the hard parts. This study reveals the use of S. variolaris as an excellent bioindicator of heavy metal contamination in the marine environment which can be employed for coastal monitoring programs.