Microbiological Study of Otitis media

NANDAN SINGH RADHA BHASKAR

Hyderabad

Microbial infections of the middle ear are of fairly common occurrence. They are characterised by Chronicity and are generally refractory to ordi- nary treatment. Variation in the pat tern of aetiological agents causing ottitis have been reported by various workers. (Friedman 1952, Tulsidas et al 1954, Lewis and Grey 1957, L a x m i p a t i a n d Bhaskaran 1962, Sri- nivasan 1958). The present communi- cation deals with the aetiological agents and their antibiotic susceptibility.

Materials and Methods

Cases showing suppuration of long standing durat ion in which there were no signs of acu!e inflammation with the presenting symptom of ear dis- charge varying from this mucopurulent to thick fowl swelling, were selected for investigation. Three hundred (300) such cases attending the ENT out-

Dr. Nandan Singh, Asst. Prof. Microbiology G.M.C. Dr. Radha Bhaskal, MD. Professor Microbiology G.M.C. From the Department of Microbiology, Gandhi Medical College, Hyderabad.

Received for publication on 4.9.71.

patient Department of Gandhi Hos- pital Secunderabad, were selected for study. Ear discharge was carefully collected using a sterile cotton swab and inoculated on Blood agar, Mac- Conkey agar, Robertson's cooked meat medium and Sabouraud aga r slope with chloramphenicol. A smear was examined by Gram ' s stain and a wet smear by lacto-phenol cotton blue for fungal elements. Sabouraud's slopes were incubated at room temperature for 2-3 weeks and growth observed everyday. After overnight incubation at 37~ growth on various other incu- lated media was studied. Single colony sub-cultures and smears were made for identification of the organism Coagulase test, sugar formentat ion tests, biochemical tests etc. were per- formed wherever applicable, Antibio- tic sensitivity tests were also done simultaneously using various antibiotics with standard concentrations of the antibiotic by disc method (Cruick- shank, 1965).

Out of three hundred (300) swabs cultured 68 (22.670) were mixed infec- tions and 232 (77.4~) due to one type of organism.

161

Table I showing the various organisms isolated S. No. Name of organism isolated Number Percentage

1. Staphylococcus aureus 150 40.7% 2. Staphylococcus albus 20 5.5% 3. Streptococcus pyogenes 18 4.9% 4. Escherichia coli 30 8.2Yo 5. Klebsiella aerogenes 18 4.9% 6. Proteus vulgaris 76 20.6% 7. Proteus mirabilis 8 2.2% 8. Proteus morgani 6 1.6% 9. Proteus rettgeri 4 1.1%

10. Pseudomonas pyocyaneus 26 7.1% 11. Alkaligenes faecalis 2 0.5% 12. Aspergillus fumigatus 4 1.1~ 13. Aspergillus 2 0.5% 14. Mucor species 2 05% 15. Penicillium species 2 0.5%

Total 368 100%

Staphylococci it is seen from table E coli (8.2%), Pseudomonas Pyoeya- I, were isolated from 46.2% of cases, neus (7.1~ and 10 strains of fungi followed by Proteus species (25%), were also encountered.

Table lI showing the age incidence of otitis cases III

Age group Number Per- of cases centage

0-10 years. 148 49.3% 11-20 years. 68 22.7% 21-30 years. 38 12.6% 31-40 years. 26 8.7% 41-50 years. 20 6.7% Total 300 100 %

Table II shows maximum incidence in the 1st and second decade of life, thereafter a gradual decline is noted in higher age groups.

Out of 300 (three hundred)cases analysed 168 (56%) were in males and

0 / 132 (44/0) were females, showing a preponderance in males.

Table No. III showing the sensitivity pattern of various Organisms towards the antibiotics tested

Number Percentage Number Percentage Sensitive Sensitive Resistant Resistant

1. Penicillin 40 13.3% 260 86.7% 2. Streptomycin 192 64 % 108 36% 3. Orisul 10 3.3~ 290 96.7% 4. Furacin 225 85~'o 75 15% 5. Chlorampenicol 260 86.7%. 40 13.3% 6. Demethylochoretetracycline 195 65~ 105 35% 7. Tetracycline hydrochloride 174 58% 126 42% 8. Synermycin 189 63~ 11l 37% 9. Erythromycin 156 52% 144 48%

10. Polymyxin-B 264 88% 36 12% 11. Ampicillin 204 68% 96 32~ 12. Rovamycin 171 57% 129 43% 13. Soframycin 234 78~ 66 22%

162 Ind. J. Otol. Vol. XXIV, No. 4, December 1972

Discussion

Hayes and Hall (1948) found Pseudomonas and Proteus as predomi- nant organisms causing ottitis. ~fhey are usually associated other organisms mostly Gram Positive ones. Srinivasan (1958) found Staphylococcus, Proteus and Pyocyaneus as common in-vaders. Staphylococcus aureus was the most frequent organism, in the present study causing otitis. This was found by Anand et al (1971) but it differs from the observations of others (Laxmipati and Bhaskaran 1965, Arya

Mohapatra 1966, Gulati etal 1969). Table I shows various workers report- ing different organisms as commonly responsible for the infections. There is general agreement on the occurance of infections caused by Proteus Sp., PS, Pyocyaneus and Staphylococcus aureus. These three organisms can be held as the most common Trio of aetiological agents of Otitis. But present study points out the frequency o f Staphylococcal infections.

Otitis caused by Betahaemolytic Streptococcus used to be responsible for 90'/0 of infections before, but use of antibiotics has changed the picture. Streptococcal infections have decreased and Staphylococcal infections have increased, which is in conformity with our findings. Otitis caused by Pseudo- monas and Proteus species has become a problem of treatment as they gene- rally do not respond favourably des- pite sensitivity tests (Mawson 1963). Our experience is also similar.

The incidence of otitis media, in our series, was most common in the 1st decade of life and gradually declin- ed thereafter; being common in males than females as reported by Arya & Mohapatra (1966). In this study no strict anaerobes were isolated in all the eases studied indicating that anaerobic bacteria are not commonly responsible for Otitis (Friedman 1957). There are reports of sterile cultures (5-30%) from middle ear infections, may be

due to some bactericidal or bacterics- tatic properties of the middle ear effu- sions on many strains of organisms (Sirala 1956). No such sterile culture were obtained in the present series. Tuberculous otitis media is usually due to a focus of infection elsewhere in the body (Hollender 1950).

The sensitivity pattern of various organisms isolated in the order of pre- ference was as follows :

1. Polymyxin B, 2. ChIorampheni- col, 3. Furacin, 4. Soframycin (Framy- cetin Sulphate), 5. Ampicillin, 6. Demethyl chlorotetracycline, 7. Strep- tomycin, 8. Synermycin, 9. Tetracyc- line hydrochloride, 10. R~vamycin, 11. Erythromycin, 12. Penicillin, and 13. Orisul. The sensitivity to antibiotics resembles that reported by Gulati etal (1969) but differs from those of Tulsidas etal (1954) and Anand etal (1971). The choice of the antibiotic appears to be chlorampheni- col and PoIymyxin-B for systemic, and polymyxin-B, chloramphenicol, Furacin Soframycin for topical use. Swanson and Baker (1944) have reported the efficacy oflargedoses of penicillin in cases of Otitis. But the picture is changed now after all these years of indiscriminate use of antibiotics. Peni- cillin which used to be the drug of choice for cases of otitis is now least effective. (Anand etal 1971). Lewis and Gray (1957) have shown the superiority of chloramphenicol with which we agree. Palva and Holtstrem 1965) showed the efficacy of Polymyxin B as found in our study.

Routine incubation of ear swabs on Sabouraud's agar revealed 2.6~, Positive cultures of fungi causing oto- mycosis. These cultures were repea- tedly isolated from the same patients prooving that they were not contami- nants. Fungus infection was seen in cases having some sort of dermatitis either eczematous or Seborrheic. Therefore routine inoculation of Sabouraud's dextrose agar with ehlora-

Microbiological Study/Singh & Bhaskar 163

mphenicol is indicated for revealing cases affected with fungal infections of the ear, which fact has not been noted in the recent works. It may be asserted that where there are no faci- lities of vitro culture and sensitivity tests, Chloramphenic~l, and Polymyx- in-B for systemic and Chlorampheni- col, Polymyxin-B, Furacin or Framyce- tin Sulphate for local use could be safely recommended.

Summary & Conclusions

1. Staphylococcus aureus has been found to be the mgst frequent cause of ottitis followed by Proteus and Pyocya- n e u s .

2. The antibiotics of choice was found to be Polymyxin-B, Chloram- phenicol and Soframycin in the majo- rity of cases.

3. Fungous infections of the ear have been found to occur with increas- ing frequency and a need for aware- ness of such infections is indicated.

Acknowledgements

We are thankful to Dr. N.R.V. Swamy, Superintendent Gandhi Hospi- tal Secunderabad for allowing us to publish this work. Our thanks a r e due" to Dr. Uday Prasad for providing clinical material.

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164 Ind. J. Otol. Vol. XXIV, No. 4, December 1972