Occurrence of Moraxella catarrhalis isolated from respiratory tract Infection

During the period from November 2011 to February 2012, 96 (69.1 %) isolates of M. catarrhalis were isolated from 139 outpatients of both sex (85 male and 54 female ) with respiratory tract infection (either Tonsilities , Otitis media , Sinusitis ,or Pneumonia) admitted to or presenting at two hospitals in Al-Najaf governorate. TheM.catarrhalis appeared to be the most frequent microorganism isolated in this study, which had percentage 75.6% (96) , followed by Streptococcus pneumonia, Staphylococcusaureus,and Hemophilusinfluenzae in 15.7 % (20) , 6.3% (8) ,and 2.4% (3),respectively .M.catarrhalis isolates had high frequency of isolate in throat swabs than other samples .In this study , only 14(14.6%) isolates of M. catarrhalis were produced sidrophores by growing on M9 medium .In addition, there were 72 (75%) isolates of M.catarrhalis appeared to adhere with the epithelial cells and all isolates show resistance to complement.The phenotypic resistance of 40 Moraxella catarrhalis isolates to 11 commonly used antimicrobial agents by using Kirby-Bauer disk diffusion method. All isolate of M. catarrhaliswere appeared to show highest rate of resistance( 100%) to Penicillin and Ampicillin .Similarly, the isolate exhibited high rate of resistance to Amoxicillin (95%) and Cefotaxime(72.5%) and mild resistance to Ciprofloxacinand Cephalothin in 62.5% for each, Cloramphinicol (57.5%), 52.5% of isolate showed resistance to Gentamicin and Trimethoprim .Whereas no one of isolates show resistance to (Ampicillin +Cloxacillin) and Tetracyclin. In the present study 15 M. catarahalis isolates show MIC ofPenicillin at 512 μg/ml(ie.had highest concentration MIC) while 4 isolate show MIC of Ampicillin at 512 μg/ml.Phenotypic assay was performed to determine the presence of β-lactamase enzyme by using nitrocefin disk . while in genotypic β-lactamase assay, thebro-1 gene found in 25 (62.1%) isolates, whilebro-2 gene was presented only in 3 (7.5%) isolates.