Enable the invalid Foundation 6 input via JS/jQuery

Question

I’m developing a logins registration form.

The login must be unique. Every time a login is typed in the field the onblur event makes a connection in ajax where it is checked if in the database there is such login typed.

This form is made in Foundation 6. Follow the form code.

It turns out that when the login in the database is identified, I cannot make the form 'lock' until the user enters a valid login. I did in jQuery activating the error classes of the fields but, even so, the user can proceed with the registration.

Is there any way to activate the Foundation 6 form error via JS/jQuery?

HTML: (Foundation 6)

    <form method="POST" name="contrato" action="teste.php" target="_blank" data-abide novalidate>
          <label id="labelTeste" for="teste">Login do Usuário *
            <input name="teste" pattern="[A-Za-z]{3}[.][A-Za-z]{3}" maxlength="100" id="teste" type="text" placeholder="nome.sobrenome" aria-describedby="helpLoginUsuario" required>
            <span id="spanTeste" class="form-error"> Campo obrigatório</span>
          </label>
          <p class="help-text" id="helpTeste">Login do usuário</p>
    </form>

JS/jQuery/Ajax:

$('#teste').on('blur', function(){
        var url = 'ajax/teste.php';
        var usuario = $('#teste').val();
        $.ajax({
            type : 'post',
            data : {
                "usuario" : usuario
            },
            url : url,
            cache : false,
            dataType : 'html',
            timeout : 120000,
            success : function(data) {
                if(data > 0)
                {
                    $('#labelTeste').addClass('is-invalid-label');
                    $('#teste').attr('data-invalid', '');
                    $('#spanTeste').addClass('is-visible');
                    $('#spanTeste').text('Este usuário já existe, por favor, utilize outro!');
                }   else {
                    $('#labelTeste').removeClass('is-invalid-label');
                    $('#teste').removeAttr('data-invalid');
                    $('#spanTeste').removeClass('is-visible');
                    $('#spanTeste').text('Campo obrigatório');
                    $('#helpTeste').text('Usuário válido!');
                }
            },
        });
    });