New Carbenicillin-Hydrolyzing β-Lactamase (CARB-7) from Vibrio cholerae Non-O1, Non-O139 Strains Encoded by the VCR Region of the V. cholerae Genome

Abstract

In a previous study, an analysis of 77 ampicillin-nonsusceptible (resistant plus intermediate categories) strains of Vibrio cholerae non-O1, non-O139, isolated from aquatic environment and diarrheal stool, showed that all of them produced a ␤-lactamase with a pI of 5.4. Hybridization or amplification by PCR with a probe for bla TEM or primers for bla CARB gene families was negative. In this work, an environmental ampicillinresistant strain from this sample, ME11762, isolated from a waterway in the west region of Argentina, was studied. The nucleotide sequence of the structural gene of the ␤-lactamase was determined by bidirectional sequencing of a Sau3AI fragment belonging to this isolate. The gene encodes a new 288-amino-acid protein, designated CARB-7, that shares 88.5% homology with the CARB-6 enzyme; an overall 83.2% homology with PSE-4, PSE-1, CARB-3, and the Proteus mirabilis N29 enzymes; and 79% homology with CARB-4 enzyme. The gene for this ␤-lactamase could not be transferred to Escherichia coli by conjugation. The nucleotide sequence of the flanking regions of the bla CARB-7 gene showed the occurrence of three 123-bp V. cholerae repeated sequences, all of which were found outside the predicted open reading frame. The upstream fragment of the bla CARB-7 gene shared 93% identity with a locus situated inside V. cholerae's chromosome 2. These results strongly suggest the chromosomal location of the bla CARB-7 gene, making this the first communication of a ␤-lactamase gene located on the VCR island of the V. cholerae genome.

Integrons: Past, Present, and Future

“…These include an RNA methyltransferase and a phosphotransferase (116). A number of cassettes recovered from chromosomal integrons have significant homology to known antibiotic resistance genes (9), and various gene cassettes from Vibrio can be demonstrated to confer resistance phenotypes (117)(118)(119)(120).…”

Cholera Vibrios of nonO1/nonO139 Serogroups in Etiology of Acute Intestinal Infections: Current Situation in Russia and Around the World

“…Обращает на себя внима-ние частая встречаемость антибиотикорезистентных штаммов в водных объектах. В последние годы они были зарегистрированы в Индии, Китае, Вьетнаме, Индонезии, Марокко, бассейне Карибского моря, Мексике, России [8,24,32,38,54]. У ряда из них с помощью ПЦР выявлены гены β-лактамаз, детер-минанты устойчивости к ампициллину, неомицину, стрептомицину, сульфаметизол-сульфадиазину [24,54].…”

“…Некоторые индийские штаммы также содержали интегроны класса 1 на плазмидах [54]. У штамма из Аргентины ген β-лактамазы (также измененный) был выявлен в области мегаинтегрона VCR [38]. Наличие МГЭ и мегаинтегрона создает благоприятные усло-вия для успешного горизонтального переноса генов от штамма к штамму и не исключает дальнейшего нарастания числа резистентных, что вызывает необ-ходимость эффективного выбора средств этиотроп-ной терапии НАГ-инфекций.…”

Microbiological investigation of Escherichia coli isolates from cloacal and feacal swabs of broiler chickens for extended spectrum beta lactamase (ESBL) enzymes

“…Pathogenic bacteria (including Escherichia coli) that produce ESBL show resistance to a wide variety of β-lactams and some non-β-lactam drugs including fluoroquinolones, aminoglycosides and sulphamethoxazoles [5]. Failure to the therapeutic effectiveness of cephalosporins in clinical medicine has been attributed to ESBLproducing microorganisms [6]; and organisms producing these all important enzymes (ESBL) have been reported in both community and clinical environments. Escherichia coli are a widely studied bacterium and harmless microorganism that thrive in the gut of animals (humans and poultry birds inclusive).…”