Molecular characterization of Vibrio cholerae O1 outbreak strains in Miri, Sarawak (Malaysia)

Resistance of Vibrio cholera to antibiotics that inhibit cell wall synthesis: A systematic review and meta-analysis

Objective: Cholera is a challenging ancient disease caused by Vibrio cholera (V. cholera). Antibiotics that prevent cell wall synthesis are among the first known antibiotic groups. Due to its high consumption, V. cholera has developed resistance to the majority of antibiotics in this class. Resistance to recommended antibiotics for the treatment of V. cholera has also increased. In light of the decrease in consumption of certain antibiotics in this group that inhibit cell wall synthesis and the implementation of new antibiotics, it is necessary to determine the antibiotic resistance pattern of V. cholera and to employ the most effective treatment antibiotic. Method: An comprehensive systematic search for relevant articles was conducted in PubMed, Web of Science, Scopus, and EMBASE through October 2020. Stata version 17.1 utilized the Metaprop package to execute a Freeman-Tukey double arcsine transformation in order to estimate weighted pooled proportions. Results: A total of 131 articles were included in the meta-analysis. Ampicillin was the most investigated antibiotic. The prevalence of antibiotic resistance was in order aztreonam (0%), cefepime (0%), imipenem (0%), meropenem (3%), fosfomycin (4%), ceftazidime (5%), cephalothin (7%), augmentin (8%), cefalexin (8%), ceftriaxone (9%), cefuroxime (9%), cefotaxime (15%), cefixime (37%), amoxicillin (42%), penicillin (44%), ampicillin (48%), cefoxitin (50%), cefamandole (56%), polymyxin-B (77%), carbenicillin (95%) respectively. Discussion: Aztreonam, cefepime, and imipenem are the most efficient V. cholera cell wall synthesis inhibitors. There has been an increase in resistance to antibiotics such as cephalothin, ceftriaxone, amoxicillin, and meropenem. Over the years, resistance to penicillin, ceftazidime, and cefotaxime, has decreased.

Antimicrobial resistance in Vibrio cholerae O1/O139 clinical isolates: a systematic review and meta-analysis

OBJECTIVES

Vibrio cholerae O1/O139 is responsible for cholera epidemics; that remains a huge public health menace across the globe. Furthermore, an increasing resistance rate among V. cholerae strains has been reported around the world. Therefore, the objective of this meta-analysis was to evaluate the weighted pooled resistance (WPR) rates in clinical V. cholerae O1/O139 isolates based on different years, areas, antimicrobial susceptibility testing, and resistance rates.

RESEARCH DESIGN AND METHODS

: We searched the studies in PubMed, Scopus, Embase, and Web of Science (until January 2020). Statistical analyses were conducted using STATA software (ver. 14.0).

RESULTS

: A total of 139 studies investigating 24062 V. cholerae O1/O139 isolates were analyzed. The majority of the studies originated in Asia (n=102). The WPR rates were as follows: azithromycin 1%, erythromycin 36%, ciprofloxacin 3%, cotrimoxazole 79%, doxycycline 7%, tetracycline 20%. There was increased resistance to cotrimoxazole, ciprofloxacin, and tetracycline during the 1980 to 2020 years.

CONCLUSIONS

: Temporal changes in antibiotic resistance rate found in this study demonstrated the critical continuous surveillance of antibiotic resistance. Also, ciprofloxacin, azithromycin, gentamicin, cephalexin, imipenem, ofloxacin, and norfloxacin were found to be the best antibiotics against V. cholera, with the highest and the lowest effectiveness resistance rate.

Detection of Cholera Toxin-Producing Vibrio cholerae in Phytoplankton from Santubong and Samariang Estuaries

Many cholera outbreaks worldwide were associated with cholera toxin-producing Vibrio cholerae. The bacteria are ubiquitous in aquatic environment, whilst phytoplankton is associated with adaptation of the Vibrio species. This study was conducted to detect cholera toxin-producing Vibrio cholerae, and to determine association of the selected water physicochemical parameters with the number of the bacteria. In this study, a total of ten phytoplankton samples were collected at Santubong and Samariang Estuaries in Kuching, Sarawak. Water physicochemical parameters (temperature, pH and salinity) were recorded. Vibrio bacteria were cultivated on thiosulfate citrate bile-salts sucrose selective agar and analysed for cholera toxin-producing Vibrio cholerae using polymerase chain reaction by targeting ctxA gene that encodes for virulence cholera enterotoxin subunit A. The result revealed that a range of 1.0 × 107 – 8.0 × 107 CFU/ml of yellow colonies growing on the thiosulfate citrate bile-salts sucrose agars. Inversely, no samples were positive with cholera toxin-producing Vibrio cholerae. The physicochemical parameters at Samariang Estuary were more associated with the number of bacteria in the samples compared to Santubong Estuary.

Multiple Antibiotic Resistance (MAR), Plasmid Profiles, and DNA Polymorphisms among Vibrio vulnificus Isolates

Sixty strains (n = 60) of Vibrio vulnificus were examined for their multiple antibiotic resistance (MAR) index, plasmid profiles, and DNA polymorphisms. Thirty-seven strains (n = 37) were isolated from cockles (Anadara granosa) in Malaysia, while 23 (n = 23) isolates were isolated from clams (Mercenaria mercenaria) in Qatar. All isolates were resistant to two or more of the antibiotics tested, with the most common resistances were demonstrated towards penicillin (93%), ampicillin (70%), cephalothin (65%), clindamycin (66%), vancomycin (64%), and erythromycin (51%). The antibiotic that experienced the least resistance was kanamycin (6%), and all isolates were susceptible to cefoperazone, streptomycin, and tetracycline. The MAR index for the V. vulnificus isolated from Malaysia and Qatar, possessed similar values which ranged from 0.2 to 0.7, respectively. Plasmid analysis demonstrated that 65% of V. vulnificus strains harbored plasmids, while 35% were not. Nineteen (P1–P19) plasmids profiles were observed. No specific cluster or group was observed although they were isolated from different sample sources and locations by phylogenetic analysis using GelCompar II software at an 80% similarity level. Results demonstrated the high MAR index and genomic heterogeneity of V. vulnificus, which are of great concern to the human health of those who have consumed cockles and clams from the study area.

Antibiotic resistance and plasmid profiling of Vibrio spp. in tropical waters of Peninsular Malaysia

Vibrio species isolated from four different sampling stations in the west coast of Peninsular Malaysia were screened for their antimicrobial resistance and plasmid profiles. A total of 138 isolates belonging to 15 different species were identified. Vibrio campbellii, V. parahaemolyticus, V. harveyi, and V. tubiashii were found to predominance species at all stations. High incidence of erythromycin, ampicillin, and mecillinam resistance was observed among the Vibrio isolates. In contrast, resistance against aztreonam, cefepime, streptomycin, sulfamethoxazole, and sulfonamides was low. All the Vibrio isolates in this study were found to be susceptible to imipenem, norfloxacin, ofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and oxytetracycline. Ninety-five percent of the Vibrio isolates were resistant to one or more different classes of antibiotic, and 20 different resistance antibiograms were identified. Thirty-two distinct plasmid profiles with molecular weight ranging from 2.2 to 24.8 kb were detected among the resistance isolates. This study showed that multidrug-resistant Vibrio spp. were common in the aquatic environments of west coast of Peninsular Malaysia.

Cholera outbreaks in South-East Asia

This chapter highlights the cholera situation in South Asia and the Bay of Bengal region, the original 'homeland' of cholera. A detailed discussion of cholera outbreaks in individual countries in South-East Asia follows. The countries of the World Health Organization (WHO) SEARO (South-East Asia Region) region are discussed first, followed by discussions about the other countries in South-East Asia that do not fall within the purview of the WHO SEARO classification of the member countries of the region. Therefore, the chapter attempts to provide a comprehensive yet precise outline of the major cholera outbreaks that have occurred in the region over the years.

The role of Vibrio cholerae genotyping in Africa

Toxigenic Vibrio cholerae, the causative agent of the disease cholera, is prevalent in the African continent from the 1970s when the seventh pandemic spread from Asia to Africa. In the past decade, cholera has caused devastating outbreaks in much of Africa, illustrated by the recent cholera epidemics in Zimbabwe and regions of central Africa. Given the extent of cholera in Africa, a robust and efficient surveillance system should be in place to prevent and control the disease in this continent. Such a surveillance system would be greatly bolstered by use of molecular typing techniques to identify genetic subtypes. In this review, we highlight the role that modern molecular typing techniques can play in tracking and aborting the spread of cholera.

The Study of Genetic Relationship Among Third Generation Cephalosporin-resistant Salmonella enterica Strains by ERIC-PCR

Background and Objectives:

Salmonella is an important food-borne pathogen responsible for disease in humans and animals. The aim of this study was to investigate the genetic relationship among third generation cephalosporin-resistant Salmonella enterica strains by Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR.

Methods:

The study included all Salmonella isolates obtained from clinical cases in a pediatric hospital in Tehran, Iran during 2006 to 2009. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute. The genetic relationship between third generation cephalosporins-resistant Salmonella enterica strains was determined using ERIC-PCR.

Results:

Of 136 Salmonella enterica isolates recovered from pediatric patients, six isolates including four Salmonella enterica serotype Infantis and two Salmonella enterica serotype Enteritidis showed an extended-spectrum cephalosporins resistant phenotype. ERIC-PCR differentiated Salmonella enterica serotypes Infantis and Enteritidis into 2 distinct clusters arbitrarily named as E1 and E2. Profile E1 was found in two Salmonella enterica serotype Enteritidis isolates, and profile E2 was found in four Salmonella enterica serotype Infantis isolates.

Conclusion:

Extended-spectrum cephalosporins resistant Salmonella could be attributed to a few predominant serotypes including Enteritidis and Infantis in this study. Genetic analysis using ERIC-PCR showed that closely related clones are responsible for the occurrence of extended-spectrum cephalosporins resistant Salmonella infection in Tehran.

Design of a multiplex PCR method for detection of toxigenic-pathogenic in Vibrio cholerae

OBJECTIVE

To study virulence and regulatory genes (hlyA, ctxB, tcpI) in clinical strains of Vibrio cholerae (V. cholerae), simultaneously.

METHODS

Three important genes, tcpI, hlyA and ctxB were used for detection of toxigenic and pathogenic V. cholera by chain reaction assay method.

RESULTS

According to the results of the PCR, the incidence of hlyA, tcpI, and ctxB genes in clinical isolates was obtained as 94.7% (72 sample), 90.8% (69 sample), and 92.1% (70 sample), respectively. Five strains possessed all genes except ctxB, six strains possessed all genes except tcpI, four strains possessed all genes except hlyA, one strain possessed only hlyA and 60 strains contained a combination of three genes, Including hlyA, ctxB and tcpI.

CONCLUSIONS

Result show that this method could be reliable to detect toxigenic-pathogenic strains of V. cholerae in Iran.

Human impact on the microbiological water quality of the rivers

Microbiological contamination is an important water-quality problem worldwide. Human impact on this category of contamination is significant and several human-related activities, and also the population explosion, have affected and are still affecting dramatically the aquatic environment. Extensive industrialization and agriculture have led to increased pollution and hydromorphological changes in many river basins. The Danube river is one of the most affected by these changes where human involvement is undeniable, and subsequently, the Danube Delta Biosphere Reserve became one of the most vulnerable ecosystems. This review is an attempt to analyse the microbiological contamination and to identify the major role human activities play in altering the water quality of the rivers.

Genotypic characterization of Vibrio cholerae isolates using several DNA fingerprint techniques

Serious pandemics of cholera have occurred throughout the known history of mankind, especially in India, which is a motherland for cholera disease. For the last 20 years several DNA-based typing methods have been employed to study the clonal relatedness between Vibrio cholerae isolates irrespective of their geographical locations. Traditional typing methods, such as biochemical tests, phage typing, serotyping, biotyping and antimicrobial susceptibility tests, have produced reliable and informative data regarding V. cholerae for a long time. Gradually molecular typing techniques have taken the place of traditional typing methods because they produce the same results upon repeat testing of V. cholerae strain. In this article we focus on the discriminatory power of different DNA fingerprint techniques that are generally used to know the homogeneity and heterogeneity among different V. cholerae isolates.

Multidrug resistant Vibrio cholerae O1 El Tor carrying classical ctxB allele involved in a cholera outbreak in South Western India

Cholera is a fatal diarrheal disease characterized with enormous fluid loss through stools. A total of 41 Vibrio cholerae isolates collected from a recent cholera outbreak in Solapur, South Western India were found to belong to serogroup O1, biotype El Tor and serotype Ogawa. Molecular analysis revealed the prevalence of different toxigenic and pathogenic genes in the isolates. All the isolates harboured rstR(El)(Tor) allele indicating the presence of CTXΦ(El)(Tor). However, cholera toxin (ctxB) gene sequencing and a ctxB allele specific PCR of the isolates confirmed the presence of ctxB of classical biotype. The antibiogram profile revealed the resistance for several antibiotics including nalidixic acid, polymyxin B, streptomycin, sulfamethoxazole, trimethoprim, rifampicin and vibriostatic agent 2,4-diamino-6,7-diisopropylpteridine (O/129). All the isolates were PCR positive for class 1 integron and SXT elements also. Fingerprinting analysis revealed the clonal relationship among the outbreak isolates. The results suggested the involvement of multidrug resistant V. cholerae El Tor biotype isolates having ctxB gene of classical biotype in the cholera outbreak.

Molecular evidence of cholera outbreak caused by a toxigenic Vibrio cholerae O1 El tor variant strain in Kelantan, Malaysia

A total of 20 Vibrio cholerae isolates were recovered for investigation from a cholera outbreak in Kelantan, Malaysia, that occurred between November and December 2009. All isolates were biochemically characterized as V. cholerae serogroup O1 Ogawa of the El Tor biotype. They were found to be resistant to multiple antibiotics, including tetracycline, erythromycin, sulfamethoxazole-trimethoprim, streptomycin, penicillin G, and polymyxin B, with 35% of the isolates being resistant to ampicillin. All isolates were sensitive to ciprofloxacin, norfloxacin, chloramphenicol, gentamicin, and kanamycin. Multiplex PCR analysis confirmed the biochemical identification and revealed the presence of virulence genes, viz., ace, zot, and ctxA, in all of the isolates. Interestingly, the sequencing of the ctxB gene showed that the outbreak strain harbored the classical cholera toxin gene and therefore belongs to the newly assigned El Tor variant biotype. Clonal analysis by pulsed-field gel electrophoresis demonstrated that a single clone of a V. cholerae strain was responsible for this outbreak. Thus, we present the first molecular evidence that the toxigenic V. cholerae O1 El Tor variant has invaded Malaysia, highlighting the need for continuous monitoring to facilitate early interventions against any potential epidemic by this biotype.

Evaluation of VcA VNTR as a strain-typing and phylogeny study method of Vibrio cholerae strains

This study attempted to examine the relatedness between RAPD-PCR, PFGE and VcA VNTR results with those of conventional phage typing of V. cholerae strains and to evaluate VcA VNTR as an indispensable molecular-typing tool that accomplishes the urgent need for effective epidemiological surveillance. All the O1 El Tor strains were predominantly clustered into phage type T27 with the new phage-typing scheme. Using RAPD-PCR, a total of 69 O1 El Tor strains were grouped under 16 different electrophoretic patterns. A total of 33 pulsotypes were identified in these strains by PFGE. VcA VNTR revealed high VcA polymorphism in all V. cholerae strains incorporated in this study. Our results underline the considerable potential of VcA VNTR analysis as a tool for molecular typing of V. cholerae.

A large cholera outbreak due to a new cholera toxin variant of the Vibrio cholerae O1 El Tor biotype in Orissa, Eastern India

A total of 32 Vibrio cholerae isolates were collected during a recent large cholera outbreak in Eastern India. Biochemical and serological studies revealed that all of the isolates belonged to serogroup O1, biotype El Tor, serotype Ogawa. Two multiplex PCR assays confirmed the presence of various toxigenic and pathogenic genes - ace, ctxAB, hlyA, ompU, ompW, rfbO1, rtx, tcp, toxR and zot - in all of the isolates. Sequencing of the ctxB gene from the isolates revealed a novel mutation in the gene. Sequencing also confirmed the presence of altered cholera toxin B of the classical biotype in all of the El Tor isolates, suggesting infection of isolates by classical CTXPhi. The molecular diversity of V. cholerae isolates studied by enterobacterial repetitive intergenic consensus sequence PCR, BOX-PCR and randomly amplified polymorphic DNA analysis uniformly showed the clonal relationship among the outbreak V. cholerae O1 isolates. The results of this study suggest that cholera-causing V. cholerae strains are constantly evolving in epidemic areas, highlighting the potential of the emergence of more virulent strains.

Application of duplex-PCR in rapid and reliable detection of toxigenic Vibrio cholerae in water samples in Thailand

Toxigenic Vibrio cholerae, the cause of cholera, is a native flora of the aquatic environment which is transmitted through drinking water and still remains the leading cause of morbidity and mortality in many developing countries including Thailand. The culture method (CM), which is routinely used for assessing water quality, has not proven as efficient as molecular methods because the notorious pathogen survives in water mostly in a non-culturable state. We employed duplex-polymerase chain reaction (duplex-PCR) for detection of tcpA and ctxA genes in toxigenic V. cholerae, and compared PCR detection with CM in various waters of Khon Kaen Municipality, Thailand. We also evaluated the effect of different pre-PCR conditions on the results of ctxA and tcpA detection including: 1) water filtered and enriched in alkaline peptone water (APW) for 3 h before PCR, 2) water filtered without enrichment before PCR, and 3) use of only enrichment in APW for 6 h before PCR. Of the 96 water samples (taken from waste-water, potable and waste-water from patients' houses, and from rivers) tested, 48 (50%) were positive for ctxA and tcpA by duplex-PCR, whereas only 29 (30%) were positive for V. cholerae by CM. Of the 29 V. cholerae isolated by CM, 2 (7%) were toxigenic V. cholerae belonging to serovar O1, while the rests were non-O1/ non-O139. Results revealed, therefore, that ctxA and tcpA-targeted duplex PCR is more sensitive than CM for detection of toxigenic V. cholerae from water samples because CM detected much less toxigenic V. cholerae than the non-toxigenic V. cholerae. Template DNA as low as 100 fg or 23 cells of V. cholerae in the water sample was detected in duplex PCR. Pre-PCR filtration followed by enrichment for 3 h significantly increase in the efficiency of duplex-PCR detection of toxigenic V. cholerae.

Antibiotic resistance and plasmid profile of environmental isolates of Vibrio species from Mai Po Nature Reserve, Hong Kong

In this study, three environmental isolates of Vibrio species were isolated from water and sediment samples of Mai Po Nature Reserve, Hong Kong SAR. They were identified to be Vibrio cholerae MP-1, Vibrio aestuarianus MP-2 and Vibrio vulnificus MP-3 by both biochemical test and subsequent full-length 16S rDNA sequencing. Both disc diffusion susceptibility test and microplate dilution technique were used to investigate the antibiotic resistance profile of these three bacteria. Results from both assays were in generally good agreement. All three isolates were strongly resistant to beta-lactam family of antibiotics while susceptible to tetracycline, chloramphenicol, nalidixic acid and streptomycin. In addition, V. cholerae MP-1 was very tolerant to high concentration of vibriostatic agent O/129 to 40 microg/ml, at which the growth of V. aestuarianus MP-2 and V. vulnificus MP-2 was completely inhibited. A small naturally occurring plasmid was found in V. cholerae MP-1 while no plasmid was detected in the other two bacteria. This study suggests that Mai Po Nature Reserve harbors bacteria of unique characteristics that warrant further investigation.

Application of PCR-Based DNA Fingerprinting Techniques for the Genetic Differentiation of Vibrio cholerae Non-01/Non-0139 Isolates from Kuching, Sarawak

Fifty-four Vibrio cholerae non-01/non-0139 isolates were evaluated for their genetic diversity via randomly amplified polymorphic DNA-PCR (RAPD-PCR), enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and BOX-PCR assays. Based on the various PCR fingerprints, the V. cholerae isolates were successfully differentiated into 39 types by RAPD-PCR, 43 types by ERIC-PCR, and 38 types by the BOX PCR, with the overall average polymorphic distances observed to be at 0.593, 0.527 and 0.504, respectively. The Simpson’s index of diversity of the isolates based on the fingerprinting analyses indicated that these DNA fingerprinting methods have high discriminatory power 0.986 (RAPD-PCR), 0.992 (ERIC-PCR) and 0.983 (BOX-PCR), and could be used independently or as supplements to other methods for the epidemiological investigation of the V. cholerae from water and seafood sources. The dendrograms constructed also showed that the V. cholerae isolates were clustered into several main clusters and sub-clusters, suggesting that different strains were circulating in the water environment and in the seafood sources. We conclude that molecular genotyping of V. cholerae isolates from surface water and seafood samples in Kuching, Sarawak (Malaysia) enabled high level observation of clonal diversity within V. cholerae isolates, and is directly applicable for the molecular epidemiological studies of the V. cholerae isolates.

Application Of The Multiplex Polymerase Chain Reaction (M-PCR) For The Screening Of Vibrio Spp. From Rivers In Kuching, Sarawak

The present study was conducted to investigate the occurrence of Vibrio spp. from selected rivers in Kuching,Sarawak (Malaysia) using Multiplex Polymerase Chain Reaction (m-PCR). During the 6-month study period,19 samples were collected monthly from 7 rivers, followed by simultaneous detection of three Vibrio spp.,Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, in a single tube PCR reaction. Three sets ofprimers targeting the thermolabile (tl), outer membrane protein (ompW) and hemolysin/cytolysin genes(vulCulsl) of V. parahaemolyticus, V. cholerae and V. vulnificus, respectively, were used. The results indicatedthat V. parahaemolyticus was the predominant species, occurring approximately 60.9% throughout thesampling period, followed by V. cholerae (23.1%) and V. vulnificus (16.0%). The months of July andDecember were found to be the months where all three Vibrio spp. were found to be at higher frequencies inthe river samples. Results analyzed also indicated that the rivers with the highest prevalence of the three Vibriospp. were Tambak Sejingkat, followed by Sungai Jernang and Sungai Tabuan. We conclude that m-PCR is apowerful and useful tool for the rapid and simultaneous detection of V. parahaemolyticus, V. cholerae and V.vulnificus from the riverine environments without the need for isolation and culturing. Furthermore, thismethod is highly specific, and could be applied in diagnostic laboratories for larger scale epidemiologicalinvestigations of Vibrio spp.