Error in SQLAlchemy with Integer: "object() takes no parameters"

I suddenly started seeing an error in my Python SQLAlchemy application and I can't figure out what's causing it. My code looks like this:

from sqlalchemy import create_engine
from sqlalchemy import Column
from sqlalchemy import ForeignKey
from sqlalchemy import Integer
from sqlalchemy import MetaData
from sqlalchemy.ext.declarative import declarative_base

def loadConnection(connection_string, echo=False):
    engine = create_engine(connection_string, echo=echo)
    Base = declarative_base(engine)
    Session = sessionmaker(bind=engine)
    session = Session()
    return session, Base

connection = yaml.load('connection.yaml')
session, Base = loadConnection(connection['connection'], connection['echo'])

class Foo(Base):
    __tablename__ = 'foo'
    id = Column(Integer(11), primary_key=True)

And when I run this script I get the following error:

Traceback (most recent call last):
  File "ephem/database_interface.py", line 52, in <module>
    class Foo(Base):
  File "ephem/database_interface.py", line 54, in Foo
    id = Column(Integer(11), primary_key=True)
TypeError: object() takes no parameters

I am using SQLAlchemy 0.9.1. My backend is MySQL running on the localhost. As far as I can tell by inspecting with pdb connection, session, Base, Column, and Integer all seem normal.