OTOLOGY M. Tayyar Kalcioglu Æ Orhan Ozturan Æ Riza Durmaz Elif Aktas In vitro efficacy of the successive or staggered use of eardrops Received: 8 December 2004 / Accepted: 6 June 2005 / Published online: 22 November 2005 Ó Springer-Verlag 2005 Abstract Chronic suppurative otitis media is still a sig- nificant health problem. Several topical agents such as antibacterials, steroids and acid media eardrops are widely used alone or in combination to control active otorrhea and obtain a dry ear. Patients frequently ask if there is any benefit or loss in the effect of these due to their use in a successive or staggered manner. This question led us to design this in vitro study to investigate the effect of the acetic acid solution and dexamethasone sodium phosphate on the antimicrobial effects of some ototopical antibiotics during their successive or staggered usage. Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli were used for testing the antimicrobial activities of the selected antibi- otic drops. Six microliters of acetic acid solution and dexamethasone sodium phosphate were used alone or together with 6 ll each of ciprofloxacin HCl, tobramycin and ofloxacin solution. Drops were placed on Whatman no. 1 paper disks with a diameter of 6 mm, and the disks were placed onto Mueller-Hinton agar plates on which bacteria had been swabbed over the entire surface. After overnight incubation of the plates at 35°C, the diameters of the inhibition zones were recorded. There was no antibacterial effect in response to either acid solution or dexamethasone used alone. The inhibition zones of the antibiotics did not change with either steroid or acid media solution added onto the antibiotic disks alone or together. Acid solution or steroids should be preferred to use in combination with antibacterial otic drugs in in- vivo settings; no negative or positive effects were seen in in-vitro conditions. Therefore, prescribed eardrops can be used in a successive or staggered manner without any influence on the treatment results. Keywords Eardrops Æ Ciprofloxacin Æ Tobramycin Æ Ofloxacin Æ Acid media Æ Steroid Æ Chronic suppurative otitis media Introduction Chronic suppurative otitis media (CSOM) is a com- monly encountered chronic inflammation of the middle ear and mastoid process with a perforated tympanic membrane and discharge. It is still a significant health problem, especially in developing countries. Conserva- tive medical treatment of CSOM is necessary to control active otorrhea, because most of the surgeons prefer a dry ear before surgery. Major bacterial pathogens iso- lated from CSOM include Staphylococcus aureus, Pseu- domonas aeruginosa, Proteus sp. and Escherichia coli [9, 16, 17, 18]. Vartiainen and Vartiainen [29] reported that bacteriological findings showed no statistically sig- nificant difference between child and adult patients. Management of CSOM with ototopical agents is a common practice among otolaryngologists and pedia- tricians. According to Lundy and Graham’s study [19], 84% of the otolaryngologists use ototopical preparations for otorrhea if the patient has a perforation. A similar result from Nelson’s [22] study showed that pediatricians also prescribe ototopical medications in 79%. Several ototopical agents such as antibacterial, ste- roid and acid media eardrops are widely used for CSOM, either alone or in combinations [1, 2, 8, 12, 15, 20, 27, 28]. The effects of the eardrops used for the elimination of the pathogen bacteria depend on their antibacterial spectrum. Irrigation of the external ear canal with acid media solutions is thought to change the pH media of the ear canal and interrupt the growth of the bacteria by affecting the amino acids, which causes alterations in the three-dimensional structures of the M. T. Kalcioglu (&) Æ O. Ozturan Department of Otorhinolaryngology, Inonu University, 44069 Malatya, Turkey E-mail: mtkalcioglu@hotmail.com Tel.: +90-422-3410660/4607 Fax: +90-422-3410128 R. Durmaz Æ E. Aktas Department of Clinical Microbiology, Inonu University, Malatya, Turkey Eur Arch Otorhinolaryngol (2006) 263: 395–398 DOI 10.1007/s00405-005-1014-2