Recent developments in detection and enumeration of waterborne bacteria: a retrospective minireview

Abstract

Waterborne diseases have emerged as global health problems and their rapid and sensitive detection in environmental water samples is of great importance. Bacterial identification and enumeration in water samples is significant as it helps to maintain safe drinking water for public consumption. Culture‐based methods are laborious, time‐consuming, and yield false‐positive results, whereas viable but nonculturable (VBNCs) microorganisms cannot be recovered. Hence, numerous methods have been developed for rapid detection and quantification of waterborne pathogenic bacteria in water. These rapid methods can be classified into nucleic acid‐based, immunology‐based, and biosensor‐based detection methods. This review summarizes the principle and current state of rapid methods for the monitoring and detection of waterborne bacterial pathogens. Rapid methods outlined are polymerase chain reaction (PCR), digital droplet PCR, real‐time PCR, multiplex PCR, DNA microarray, Next‐generation sequencing (pyrosequencing, Illumina technology and genomics), and fluorescence in situ hybridization that are categorized as nucleic acid‐based methods. Enzyme‐linked immunosorbent assay (ELISA) and immunofluorescence are classified into immunology‐based methods. Optical, electrochemical, and mass‐based biosensors are grouped into biosensor‐based methods. Overall, these methods are sensitive, specific, time‐effective, and important in prevention and diagnosis of waterborne bacterial diseases.

Early detection and classification of live bacteria using time-lapse coherent imaging and deep learning

“…However, this traditional culture-based detection method requires the colonies to grow to a certain macroscopic size for visibility, which often takes 24-48 h in the case of bacterial samples. Alternatively, molecular detection methods 14,15 based on, e.g., the amplification of nucleic acids, can reduce the assay time to a few hours, but they generally lack the sensitivity for detecting bacteria at very low concentrations, e.g., 1 colony forming unit (CFU) per 100-1000 mL, and are not capable of differentiating between live and dead microorganisms 16 . Furthermore, there is no EPA-approved nucleic acid-based analytical method 17 for detecting coliforms in water samples.…”

Presence of Human Enteric Viruses, Protozoa, and Indicators of Pathogens in the Bagmati River, Nepal

“…Although diverse groups of waterborne pathogens are present in river water [ 17 ], the lack of standardized techniques and high costs mean it is almost impossible to detect all the waterborne pathogens simultaneously [ 18 ]. Consequently, routine monitoring of fecal indicator bacteria is traditionally used to provide correlative information on human enteric viruses and protozoa.…”

Fluorescent Materials With Aggregation-Induced Emission Characteristics for Array-Based Sensing Assay

“…However, the suitable growth conditions differ among bacteria, and some bacteria are very difficult to grow; thus, this method only works well on common bacteria with wellknown growth conditions and becomes impotent for bacteria that are difficult to culture. A number of biochemical kits are also available for bacteria identification, such as carbohydrate test, enzyme test, immunological test, protein and nucleic acid sequences, and typing method, which are too expensive and time-consuming for routine bacteria identification (Noble and Weisberg, 2005;Ahmed et al, 2014;Law et al, 2014;Deshmukh et al, 2016). As mentioned previously, array-based sensing is powerful in identifying subjects with subtle differences in a complex environment, so research effort has been devoted to the development of sensor arrays for identification of bacteria.…”