split a string by the last patterns

I have some data like this:

vtab = read.table(textConnection("uid=123455,ou=usuarios,ou=gm,dc=intra,dc=planej,dc=gov,dc=de  
                                 uid=123456,ou=bsa,dc=plant,dc=gov,dc=de  
                                 uid=123457,ou=reg,ou=regfns,dc=sero,dc=gov,dc=de  
                                 uid=123458,ou=reg,ou=regbhe,dc=sero,dc=gov,dc=de    
                                 uid=123459,ou=sede,ou=regbsa,dc=sero,dc=gov,dc=de    
                                 uid=123450,ou=reg,ou=regbhe,dc=sero,dc=gov,dc=de"))   

I would like split this data. Firstly split the data in two groups including just the uid= number and the third last description in dc=. Like thus:

     [,1]         [,2]      
[1,] "123455"   "plant" 
[2,] "123456"   "planej" 
[3,] "123457"   "sero" 
[4,] "123458"   "sero" 
[5,] "123459"   "sero" 

Any helps are enjoyed :-)