INTRODUCTION:

Ear infection is an inflammation of the ear and ear discharge is one of the most common manifestations of ear infection¹^,². It has various forms, most commonly occurring in children presenting in the form of otitis media.

Due to the shorter length of the Eustachian tube, the higher frequency of ear infections in children is more horizontal in children than in adults ³^,⁴.About 65-330 million individuals worldwide suffer from ear infections, and 60% of them suffer from hearing impairment.

Otitis media is a middle ear infection, typically associated with an upper respiratory tract infection. It may occur at any age But 60-80 percent of cases are children^5,6.

Asymptomatic or symptomatic otitis media infections can be present. Symptoms such as moderate to severe pain, ear rash discharge (pus), irritation and sometimes fever are characterized by acute symptomatic infections. Sources of ear infections include bacteria, viruses and fungi, with the most common cause being bacteria. Otitis media can be classified into 2 groups according to clinical presentation: Acute otitis media (AOM), Chronic suppurative otitis media (CSOM)^{7, 8}.

Several bacterial species have been linked to the infection, such as Pseudomonas aeruginosa, Proteus vulgaris, Proteus mirabilis and Staphylococcus aureus^9,10. Highly resistant strains of both gram-positive and gram-negative bacteria, such as extended spectrum beta lactamase (ESBL), can inhibit the most effective antibiotics. ^{11, 12}.

Bacteriology of aural discharge:

Bacteria can be aerobic (e.g. Pseudomonas aeruginosa, Escherichia coli, S. aureus, Streptococcus pyogenes, Proteus mirabilis, Klebsiella species) or anaerobic (e.g. Bacteroides, Peptostreptococcus, Proprionibacterium)^{(13, 14)}. In chronic suppurative otitis media (CSOM) cases. Bacteria are rarely present in the skin of the external canal, but are likely to proliferate if trauma, inflammation, laceration or high humidity occurs ^{15, 16}.

MATERIALS AND METHODS:

This is a cross sectional study conducted in Al-Kindy Teaching Hospital / Baghdad /Iraq. Swabs taken for 225 patients suffering from aural discharge were tested for culture and sensitivity for the duration of two years 2018-2019. Aural discharge is cultured by inoculating it into blood, MacConkey, chocolate and Sabouraud agars (for fungi).

Inclusion criteria:

Any patient with otorrhea for two weeks or more.

Exclusion criteria:

1. Patients with otitis externa

2. Patients with tympanostomy tubes

3. Immunocompromised patients

4. patients with other medical conditions that may affect interpretation of the effect of investigational drugs

5. Patients on any medications that may affect the interpretation (e.g., inhaled steroids).

After obtaining the formal approval from the Scientific and Ethical Committee in Al-Kindy College of Medicine, University of Baghdad, a verbal and written consent from each patient was taken. Randomization, Blinding were assured Aural swabs from patients with aural discharge were collected from ear in ENT department and MacConkey agar plates. Bacteria were identified by using Gram staining. Antimicrobial sensitivity testing was done on Mueller Hinton agar using Modified Kirby Bauer disc diffusion technique. 0.5 McFarland turbidity test inoculums were used as a standards were for comparison. The suitable antimicrobial discs used for Gram negative bacteria and gram positive. After keeping the appropriate antibiotics, the plates were incubated at 35C for the time of 16-18 hours. The zone of inhibition was measured and interpreted according the Clinical and Labarotary Standards Institute (CLSI).

The antibiotic susceptibility and resistance is assessed by (Kirby-Bauer Method) by using commercially obtained disks for the following antibiotics: CRO

CAZ =ceftazidime, CFM=cefotaxime, ATM=aztreonam, CFP=cefipime, FOX=cefoxitine, AZM=azithromycin, TMP=trimethoprime, CIP=ciprofloxacin, VAN=vancomycin, AK=amikacin, GN=gentamycin

The results were measured focusing on several demographic parameters which are age, sex. The type of pathogen whether bacterial or fungal in relation to its antibiotics results of culture and sensitivity.

The results were illustrated in frequencies and percentages using EXCEL software. Statistical analysis was conducted with Chi-Square test by implementing Graph-Pad 8 software and P value < 0.05 was used as level of significance.

RESULTS:

225 patients were recruited in this study comprising 108 males and 117 females. Their age and sex distribution are illustrated in Figure 1. The highest frequency is in the 11-20 years age group.

Figure 1: Frequency distribution of cases of ear infections according to sex and age groups. The highest frequency is in 11-20 yr age group. There is no statistical significance, p= 0.23

Then, by analyzing the percentage of pathogens involved in ear infections we have found that the highest percentage is for Pseudomonas aeruginosa (51%), followed by Staph. aureus (20%), Proteus vulgaris (11%), fungal infections (9%), Klebsiella pneumonia (4%), Enterobacter aerogenes (2%), E.coli (2%) and Streptococcus pneumoniae (1%).

Figure 2: Pie chart representing the percentage of various pathogens involved in ear infections. The highest percentage is for Pseudomonas aeruginosa representing 51% of cases.

Table 1: Various pathogens involved in samples of aural swabs and their pattern of antibiotic resistance in terms of frequency and percentage of resistance.

	*Pseudomonas aeruginosa*		*Proteus vulgaris*		*Staph. aureus*		*E. coli*		*Streptococcus pneumonia*		*Klebsiella pneumonia*		*Enterobacter* *aerogenes*
	No. of cases	%	No. of cases	%	No. of cases	%	No. of cases	%	No. of cases	%	No. of cases	%	No. of cases	%
CRO	3	27.27	1	16.67	3	50.0	3	100.0	0	0.00			1	0.00
CAZ	19	28.79	3	23.08	4	80.0	4	100.0	1	100.00	3	100.0	1	0.00
CFM	42	89.36	1	25.00	3	75.0	2	100.0			0	0.00	1	100.
ATM	13	19.7	2	25.00	1	25.0	2	66.67			1	33.33	1	0.00
CFP	11	31.43	0	0.00	1	25.0	1	100.0			0	0.00	2	0.00
FOX	14	82.35	2	22.22	0	0.00					0	0.00
AZM	2	28.57	2	18.18	1	8.33	0	0.00			1	50.0
TMP	1	50.0	1	33.33	2	25.00	1	0.00			0	0.00
CIP	18	36.0	4	50.00	4	26.67	2	100.0			2	66.67
VAN			0	0.00	1	3.23
AK	16	21.33	1	5.88	1	6.67	0	0.00			1	14.29	2	0.00
GN	36	38.71	10	41.67	2	6.25	2	50.0	1	100.00	2	25.00	0	0.00

Looking deep into the causative pathogens and their resistance patterns we would get table 1, which illustrates details of their resistance patterns to various antibiotics in terms of frequency and percentage.

· Pseudomonas aeruginosa pattern of resistance shows the least resistance to aztreonam, azithromycin and amikacin.

· Regarding Proteus vulgaris resistance pattern it shows the least resistance to cefepime, vancomycin and amikacin.

· Staphylococcus aureus shows the least resistance patterns toward cefoxitin, vancomycin, gentamycin and amikacin.

· E.coli shows the least resistance pattern toward azithromycin, amikacin , trimethoprime.

· Streptococcus pneumonia shows high resistance toward gentamycin and ceftazidime.

· Klebsiella pneumonia shows the least resistance toward cefotaxime, cefoxitine, cefipime and trimethoprime.

· Enterobacter aerogenes show no resistance to all the available antibiotics in the test.

DISCUSSION:

The emerging problem of antimicrobial resistance is rapidly growing that day by day we have less arsenal of antibiotics to combat the new “superbugs” responsible for resistant infections.

Thus, we have conducted a study to explore the recent patterns of pathogens responsible for ear infections and their expressed antibiotic resistance.

In terms of age and sex distribution, the commonest age is in 11-20 years old which is compatible with international studies¹⁷^,¹⁸. However, there is no statistical significance as measured by Chi-Square test.

Pseudomonas aeruginosa represents the biggest share; 51%. This is compatible with a study reporting the pseudomonas as the main culprit pathogen accounting for 37% of cases, followed by Staph aureus 14%¹⁹^,²⁰.

Regarding Pseudomonas aeruginosa, Proteus vulgaris and Staph aureus, we had got good number of samples to get clear picture about their antibiotics resistance patterns.

Thus, we can say that in case of aural infection with Pseudomonas aeruginosa, the antibiotics of choice are: aztreonam, amikacin, ceftriaxone. Similar results, in another study, were obtained regarding the high efficacy of amikacin (resistance 8.3%) while regarding ceftriaxone and aztreonam which they didn’t show to be effective as the resistance was 96.6% and 100%, respectively^{19, 21}. This could be explained by the higher number of samples in the latter study.

While in case of aural infection with Proteus vulgaris, we should first think of using cefipime, vancomycin and amikacin.

For Staph. aureus aural infections, the first-choice antibiotics are cefoxitin, vancomycin, gentamycin and amikacin.

E.coli treatment could be successful when we use azithromycin or amikacin or trimethoprime.

Similar results were obtained regarded amikacin (resistance 5.7%), while trimethoprime was reported to show high resistance 71.4%⁽¹³⁾. This difference in results could be explained by the higher number of samples in the latter study.

The last three bacterial species, Streptococcus pneumonia, Klebsiella pneumonia and Enterobacter aerogenes results are not very relevant because of low number of samples that we couldn’t come out with clear view of the resistance patterns.

Cefotaxime is a highly effective 3^rd generation cephalosporin that was reported to be effective against Pseudomonas aeruginosa in early studies²²^,²³. It was introduced to Iraq several decades ago. However, in the present study it didn’t show to be very effective against Pseudomonas nor Proteus. This can be attributed to extensive unjustified use of antibiotics.

The same thing can be said about gentamycin which has shown to be not effective against E.coli although it is Gram –ve and Gentamycin is 1^st choice Gram –ve antibiotic²⁴.

CONCLUSION:

Choosing the proper antibiotic in any bacterial infection is of tremendous importance. However, reassessment of antibiotic resistance profiles over regular intervals is vital and should be regarded as a routine task. Since pseudomonas aeruginosa is the most common cause of ear infection, it should be considered in every single case and treated accordingly with the proper antibiotics like aztreonam, amikacin and ceftriaxone.

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Received on 11.01.2021 Modified on 03.02.2021

Research J. Pharm. and Tech 2021; 14(12):6503-6506.

DOI: 10.52711/0974-360X.2021.01124