Evaluation of the spectrum of bacteria encountered in patients with chronic suppurative otitis media with their antibiotic sensitivity pattern

: Objectives: The aim of this study was to determine the most frequent bacteria that cause chronic suppurative otitis media(CSOM) and their sensitivity to various antimicrobials so that an appropriate therapy can be started promptly while awaiting the results of the culture and sensitivity of the isolate to various antibiotics. Methodology : This study was conducted at Alforat teaching hospital in Najaf city at the ear-nose-throat (ENT) department from December 2010 to April 2011. The swab was taken from ear discharge before starting the antibiotics and cultured on MacConckey agar(Oxoid, England) and blood agar(HiMedia, India).Gram positive bacteria were identified on the bases of colony morphology ,Gram staining, catalase test and coagulase test while the Gram negative bacteria were identified by oxidase test and API 20E(API BioMerieux, France). The sensitivity of the isolates to various antibiotics was tested by Kirby Bauer disk diffusion technique. Results : The study showed that females are more prone to get the infection than males in a ratio of 1.8: 1 and the frequent ages liable for infection lie between 3months – 15 year, also it revealed that the gram negative bacteria were more frequent in causing the infection than gram positive bacteria in a ratio of 2.64 :1 and Pseudomonas aeruginosa was the most frequent species that causes CSOM then Staphylococcus aureus and Proteus mirabilis. Pseudomonas aeruginosa was more sensitive to ciprofloxacin than to gentamicin, Staphylococcus aureus also showed more sensitivity to ciprofloxacin than gentamicin, while Proteus mirabilis had the same degree of sensitivity to those 2 antibiotics. Conclusions : 1-Children are more prone to be infected with CSOM because of their small Eustachian tube and low immunity. 2-Gram negative bacteria were more common in causing the infection than gram-positive bacteria in this study. 3-Pseudomonas aeruginosa was the most frequent bacteria that cause CSOM then Staphylococcus aureus and Proteus mirabilis. 4-Pseudomonas aeruginosa was more sensitive to ciprofloxacin


Abstract:
Objectives: The aim of this study was to determine the most frequent bacteria that cause chronic suppurative otitis media(CSOM) and their sensitivity to various antimicrobials so that an appropriate therapy can be started promptly while awaiting the results of the culture and sensitivity of the isolate to various antibiotics.Methodology: This study was conducted at Alforat teaching hospital in Najaf city at the ear-nose-throat (ENT) department from December 2010 to April 2011.The swab was taken from ear discharge before starting the antibiotics and cultured on MacConckey agar(Oxoid, England) and blood agar(HiMedia, India).Gram positive bacteria were identified on the bases of colony morphology ,Gram staining, catalase test and coagulase test while the Gram negative bacteria were identified by oxidase test and API 20E(API BioMerieux, France).The sensitivity of the isolates to various antibiotics was tested by Kirby Bauer disk diffusion technique.Results: The study showed that females are more prone to get the infection than males in a ratio of 1.8: 1 and the frequent ages liable for infection lie between 3months -15 year, also it revealed that the gram negative bacteria were more frequent in causing the infection than gram positive bacteria in a ratio of 2.64 :1 and Pseudomonas aeruginosa was the most frequent species that causes CSOM then Staphylococcus aureus and Proteus mirabilis.Pseudomonas aeruginosa was more sensitive to ciprofloxacin than to gentamicin, Staphylococcus aureus also showed more sensitivity to ciprofloxacin than gentamicin, while Proteus mirabilis had the same degree of sensitivity to those 2 antibiotics.Conclusions: 1-Children are more prone to be infected with CSOM because of their small Eustachian tube and low immunity.2-Gram negative bacteria were more common in causing the infection than gram-positive bacteria in this study.3-Pseudomonas aeruginosa was the most frequent bacteria that cause CSOM then Staphylococcus aureus and Proteus mirabilis.4-Pseudomonas aeruginosa was more sensitive to ciprofloxacin than to gentamicin despite the fact that gentamicin is known to be effective against gram negative bacteria

INTRODUCTION
Chronic suppurative otitis media (CSOM) is a perforated tympanic membrane with persistent drainage from the middle ear.It is defined as chronic otorrhea (i.e., lasting >6-12 wk) through a perforated tympanic membrane [1,2] ,it occurs as a complication of acute otitis media [3] .Detection of middle ear by pneumatic otoscopy is key in establishing the diagnosis [4] , CSOM differs from chronic serous otitis media in that chronic serous otitis media is a middle ear effusion without perforation that is reported to persist for more than 1-3 months [5] .CSOM is a common infection in both developing and industrialized countries [6] .It causes considerable morbidity and is a major global cause of hearing impairment in children [7] Because fluid buildup behind the tympanic membrane can cause poor transmission of sound waves [8] .Moreover, it may lead to serious intracranial and extracranial complications like mastoiditis and meningitis [9] .Antibiotics have produced an overall decline in the frequency of complications of OM relative to the preantibiotic time.However, severe complications still occur and may be associated with high mortality [10] .In order to avoid serious complications an active and prompt approach in the management of chronic suppurative otitis media is mandatory [11] .However, in order to start appropriate therapy according to the causative organisms and its sensitivity to various antibiotics we have to wait for 48-72 hrs for the culture and sensitivity report.Delaying the therapy for 2 to 3 days may further aggravate symptoms of the patient or may contribute to long term complications.Despite being so common there are still many questions and controversies concerning the best treatment option for patients suffering from chronic ear infections.The aim of this study was to determine the most frequent bacteria that cause chronic suppurative otitis media and their sensitivity to various antimicrobials so that an appropriate therapy can be started promptly while awaiting the results of the culture and sensitivity of the isolate to various antibiotics.Once the result of the culture is available, the antibiotic being given to the patient may be modified if required.

PATIENTS AND METHODS:
This study was conducted at Alforat teaching hospital in Najaf city at the earnose-throat (ENT) department from December 2010 to April 2011 .In the study a total of 51 patients of age between(3months-55 years) who were having discharge from one or both ears with tympanic membrane perforation for a duration of (1month-1.5year)were included .

Exclusion criteria:
Current febrile illness, current antibiotic use, allergy to a specific antibiotic, recent ear surgery, congenital ear, or hearing problems.

Method
The swab was taken from ear discharge before starting the antibiotics and cultured on MacConckey agar(Oxoid, England) and blood agar(HiMedia, India) and incubated aerobically and anaerobically at 37 C for 24-48 hrs.Gram positive bacteria were identified on the bases of colony morphology, Gram staining, catalase test and coagulase test while the Gram negative bacteria were identified by oxidase test and API 20E(API BioMerieux, France) according to the method of McFadden [12] .The sensitivity of the isolates to various antibiotics was tested by Kirby Bauer disk diffusion technique in accordance with the Clinical and Laboratory Standards institute (CLSI) guidelines (table 1-Antibiotic types and concentrations).

RESULTS:
A total of 51 patients were included in the study of which 33 (64.7%) were females and 18 (35.3%)were males.Female to male ratio was 1.8: 1.The mean age of the patients were 27.63 years and the age of the patients ranged between 3 months and 55 years(figure-1 the age distribution of the patients).The percentage was considered in determining the results in this study.

DISCUSSION
Chronic suppurative otitis media (CSOM) and various complications associated with the disease are among the most common conditions seen by the otologist, pediatrician and the general practitioner.It is a persistent disease and often causes irreversible local destruction of middle ear [13].
In this study, CSOM was found mostly among children and in young adults (Figure -1).Same results were obtained by Wariso BA [14] , Poorey VK [15] and World Health Organization-2004 [9] .This may be due to multiple reasons as young children and infants have low resistance and also because of relative short and straight Eustachian tube (inner ear tube).Females were more commonly affected than males and it is also supported by a study carried by Loy AHC [16] .In contrast to this some studies showed opposite trend reported male 57.3% and female 42.7% [17] and this can be due to geographical variation.This study shows that Pseudomonas aeruginosa was the commonest organism isolated in chronic suppurative otitis media followed by Staphylococcus aureus and then Proteus mirabilis.Klebsiella and E. coli were also found(figure-2).As Pseudomonas aeruginosa was the most prevalent microorganism is also supported by Wariso BA [14] , Loy AHC [16], , Sharma S et al [18] , and Yeo SG et al [19] .However different results were obtained by other studies (Anwar -us-Salam [20] and Ahmed B et al [21] ), this could be due to variation in microorganisms in different locality and effect of climate [22] .
Flouroquinolones have a broad range of activity and it is found to be active against Pseudomonas aeruginosa.It inhibits the bacterial DNA replication and transcription.64% of Pseudomonas aeruginosa isolates in this study were sensitive to ciprofloxacin(40% to ciprofloxacin ,24% to both ciprofloxacin and gentamicin) , 61.54% of Staphylococcus aureus isolates were sensitive to it (23.08% to ciprofloxacin , 38.46% to both ciprofloxacin and gentamicin) and 49.7% of Proteus

DISCUSSION
Chronic suppurative otitis media (CSOM) and various complications associated with the disease are among the most common conditions seen by the otologist, pediatrician and the general practitioner.It is a persistent disease and often causes irreversible local destruction of middle ear [13].
In this study, CSOM was found mostly among children and in young adults (Figure -1).Same results were obtained by Wariso BA [14] , Poorey VK [15] and World Health Organization-2004 [9] .This may be due to multiple reasons as young children and infants have low resistance and also because of relative short and straight Eustachian tube (inner ear tube).Females were more commonly affected than males and it is also supported by a study carried by Loy AHC [16] .In contrast to this some studies showed opposite trend reported male 57.3% and female 42.7% [17] and this can be due to geographical variation.This study shows that Pseudomonas aeruginosa was the commonest organism isolated in chronic suppurative otitis media followed by Staphylococcus aureus and then Proteus mirabilis.Klebsiella and E. coli were also found(figure-2).As Pseudomonas aeruginosa was the most prevalent microorganism is also supported by Wariso BA [14] , Loy AHC [16], , Sharma S et al [18] , and Yeo SG et al [19] .However different results were obtained by other studies (Anwar -us-Salam [20] and Ahmed B et al [21] ), this could be due to variation in microorganisms in different locality and effect of climate [22] .
Flouroquinolones have a broad range of activity and it is found to be active against Pseudomonas aeruginosa.It inhibits the bacterial DNA replication and transcription.64% of Pseudomonas aeruginosa isolates in this study were sensitive to ciprofloxacin(40% to ciprofloxacin ,24% to both ciprofloxacin and gentamicin) , 61.54% of Staphylococcus aureus isolates were sensitive to it (23.08% to ciprofloxacin , 38.46% to both ciprofloxacin and gentamicin) and 49.7% of Proteus

DISCUSSION
Chronic suppurative otitis media (CSOM) and various complications associated with the disease are among the most common conditions seen by the otologist, pediatrician and the general practitioner.It is a persistent disease and often causes irreversible local destruction of middle ear [13].
In this study, CSOM was found mostly among children and in young adults (Figure -1).Same results were obtained by Wariso BA [14] , Poorey VK [15] and World Health Organization-2004 [9] .This may be due to multiple reasons as young children and infants have low resistance and also because of relative short and straight Eustachian tube (inner ear tube).Females were more commonly affected than males and it is also supported by a study carried by Loy AHC [16] .In contrast to this some studies showed opposite trend reported male 57.3% and female 42.7% [17] and this can be due to geographical variation.This study shows that Pseudomonas aeruginosa was the commonest organism isolated in chronic suppurative otitis media followed by Staphylococcus aureus and then Proteus mirabilis.Klebsiella and E. coli were also found(figure-2).As Pseudomonas aeruginosa was the most prevalent microorganism is also supported by Wariso BA [14] , Loy AHC [16], , Sharma S et al [18] , and Yeo SG et al [19] .However different results were obtained by other studies (Anwar -us-Salam [20] and Ahmed B et al [21] ), this could be due to variation in microorganisms in different locality and effect of climate [22] .
Flouroquinolones have a broad range of activity and it is found to be active against Pseudomonas aeruginosa.It inhibits the bacterial DNA replication and transcription.64% of Pseudomonas aeruginosa isolates in this study were sensitive to ciprofloxacin(40% to ciprofloxacin ,24% to both ciprofloxacin and gentamicin) , 61.54% of Staphylococcus aureus isolates were sensitive to it (23.08% to ciprofloxacin , 38.46% to both ciprofloxacin and gentamicin) and 49.7% of Proteus mirabilis isolates were sensitive to it(33.3% to ciprofloxacin ,16.4% to both ciprofloxacin and gentamicin).In general 54.9% of total cases in this study were sensitive to ciprofloxacin whereas in other studies 90% of Pseudomonas aeruginosa isolates were sensitive to it(Anwar-us-Salam [20] , Aslam MA [23] and Gul AA [24] ).37.25% of the total isolates were sensitive to the aminoglycoside derivative; gentamicin that interferes with bacterial protein synthesis while 62.75% of them were resistant to it, this indicates the increasing resistance of the microorganisms against this antibiotic, Sensitivity of Pseudomonas aeruginosa to gentamicin came in second place after ciprofloxacin in this study despite the fact that aminoglycosides are more effective against gram negative bacteria, this is may be related to the inappropriate duration and dose of antibiotics and this result was supported by Yeo SG et al [19] and Ahmed S et al [25] .Sensitivity of Staphylococcus aureus to ciprofloxacin was also higher than its sensitivity to gentamicin this was agreed by Lodhi M et al [26] .

CONCLUSIONS:
1-Children are more prone to be infected with CSOM because of their small Eustachian tube and low immunity.
2-That pseudomonas aeruginosa was the most frequent bacteria that cause CSOM then Staphylococcus aureus and Proteus mirabilis.In general gram negative bacteria were more common in causing the infection than gram positive bacteria in the current study.3-pseudomonas aeruginosa was more sensitive to ciprofloxacin than to gentamicin despite the fact that gentamicin is known to be effective against gram negative bacteria including pseudomonas aeruginosa propably because of antibiotic miss use and genetic mutation of pseudomonas aeruginosa .