diff --git a/src/lib/mongo.js b/src/lib/mongo.js
index 18d24f3..c0004ae 100644
--- a/src/lib/mongo.js
+++ b/src/lib/mongo.js
@@ -1,4 +1,4 @@
-var Db = require('mongodb').Db;
+var MongoClient = require('mongodb').MongoClient;
 var MongoServer = require('mongodb').Server;
 var async = require('async');
 var config = require('./config');
@@ -27,25 +27,17 @@ var getDb = function(host, done) {
     }
   }
 
-  var mongoDb = new Db(config.database, new MongoServer(host, config.mongoPort, mongoOptions));
-
-  mongoDb.open(function (err, db) {
+  var connectionURI;
+  if (config.username) {
+    connectionURI = `mongodb://${encodeURIComponent(config.username)}:${encodeURIComponent(config.password)}@${host}:${config.mongoPort}/${config.database}`;
+  } else {
+    connectionURI = `mongodb://${host}:${config.mongoPort}/${config.database}`;
+  }
+  MongoClient.connect(connectionURI, mongoOptions, function(err, db) {
     if (err) {
       return done(err);
     }
-
-    if(config.username) {
-        mongoDb.authenticate(config.username, config.password, function(err, result) {
-            if (err) {
-              return done(err);
-            }
-
-            return done(null, db);
-        });
-    } else {
-      return done(null, db);
-    }
-
+    return done(null, db);
   });
 };
 
@@ -214,4 +206,4 @@ module.exports = {
   initReplSet: initReplSet,
   addNewReplSetMembers: addNewReplSetMembers,
   isInReplSet: isInReplSet
-};
+};
\ No newline at end of file