externalizing route.param() calls in Express.js

I want to extract some repetitive code into a single module in Node.js and Express.js

Together.js

var express = require('express');
var boom = require('express-boom');
var app = express();
var app.use(boom());    

app.param('user', function(request, reply, next, id){
    request.db.users.get(id, function(err, userInfo){
        if (err) reply.boom.badImplementation(err);
        else if (!userInfo || !userInfo.length) reply.boom.notFound();
        else {
            request.user = userInfo[0];
            next();
        }
    })
})

app.get('/api/users/:user', function(request, reply){
    reply.json(request.user);
});

app.listen(3000);

I have multiple routes I want to use this param conversion including: /users/:user, /api/users/:user, /checkout/:user/:barcode, etc. but each of the root routes (i.e. users, api, checkout) are in their own file and I am attaching them with app.use('/users', userRoutes);. As it is, I will have to put my user param conversion into EACH of these sub-route modules.

I would like to have an interceptors.js where I make all of the common param interceptor functions and only write them once. Here is an example of how I thought it would work.

app.js

var express = require('express');
var app = express();

app.use(require('./routes/interceptors'))

app.use('/users', require('./routes/users'));
app.use('/api', require('./routes/api'));
app.use('/checkouts', require('./routes/checkouts'));

app.listen(3000);

./routes/api.js

var express = require('express');
var api = express.Router();

api.get('/users/:user', function(request, reply){
    reply.json(request.user);
});

module.exports = api;

./routes/interceptors.js

var express = require('express');
var boom = require('express-boom');
var interceptors = express.Router();

var interceptors.use(boom());    

interceptors.param('user', function(request, reply, next, id){
    request.db.users.get(id, function(err, userInfo){
        if (err) reply.boom.badImplementation(err);
        else if (!userInfo || !userInfo.length) reply.boom.notFound();
        else {
            request.user = userInfo[0];
            next();
        }
    })
})

module.exports = interceptors;

There would of course be another file for each of checkout.js and users.js and they will be the same principal as api.js

When I do the above, the param interceptor is never run. No errors are throw that I can see.

Thank you all for any help you may provide, Rhett Lowe