Antibiotic Susceptibility Pattern of Escherichia coli Isolated from Out-patient Individuals Attending the University College Hospital (UCH), Ibadan, Nigeria

Joseph Omololu-Aso*

University College Hospital (UCH), Ibadan, Nigeria

*Corresponding Author:
Joseph Omololu-Aso
University College Hospital (UCH)
Ibadan, Nigeria
Tel: +2348033770933
Email: [email protected]

Received Date: January 07, 2017 Accepted Date: February 01, 2017 Published Date:February 22, 2017

Citation: Omololu-Aso J. Antibiotic Susceptibility Pattern of Escherichia coli Isolated from Out-patient Individuals Attending the University College Hospital (UCH), Ibadan, Nigeria. J Infec Dis Treat. 2017, 3:1.

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A retrospective review of culture media of urine, ascitic fluid, sputum, tracheal aspirate, wound biopsy, antral washouts and blood was taken. The aim of this study was to determine the prevalence and antimicrobial susceptibility of Escherichia coli from clinical sources. A total of 32 samples were analyzed for isolation and identification of bacteria and antimicrobial susceptibility testing. Escherichia coli were isolated from 14 (43.75%) samples. The E. coli co-infection was highly implicated in urine specimen (21.42%). The E. coli isolates showed resistance to ciprofloxacin (92.86%), cotrimozazole (92.86%) and ceftriazone (78.58%). Lower susceptibility was observed with oflaxacin (28.57%). Indiscriminate use of antibiotics should be discouraged. Regular hygiene methods should be advocated among community dwellers and hospital personnel.


Antibiotics resistant; Hospital; Escherichia coli; Urinary tract infections; Patients


Escherichia coli is the most common cause of urinary tract infections (UTIs) in humans and is a leading cause of enteric infections and systemic infections [1]. The systemic infections include bacteremia, nosocomial pneumonia, cholecystitis and infectious arthritis. E. coli is also a leading cause of neonatal meningitis [2].

Escherichia coli and related bacteria constitute about 0.1% of gut flora [3]. Faecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease also, E. coli majorly is responsible for a wide variety of hospital and community onset infections, affecting patients with normal immune systems as well as those with pre-existing conditions [4]. They often comprise most Gram negative bacteria found in clinical laboratories including the vast majority of urinary, blood culture and peritoneal isolates. Several variants or pathotypes of E. coli have been described as causing infections of the gastrointestinal system while other pathotypes cause infections outside the gastrointestinal system [5]. The pathogenic ability of E. coli is largely affordable by the flexible gene pool through the gain and loss of materials [6,7].

Antibiotic resistant isolates, especially those that are floroquinolones resistant and those producing extendedspectrum ß-lactamases have increased significantly during the 2000’s and in certain areas while many nosocomial and community-acquired E. coli are now resistant to several important antimicrobials [4]. A wide range of antimicrobial agents effectively inhibit the growth of E. coli. The β-lactams, fluoroquinolones, aminoglycosides and trimethoprim-sulfamethoxazole are often used to treat community and hospital infections associated with E. coli [3]. Clinical studies of antimicrobial therapy and the outcome of patients infected with carbapenemase-producing E. coli compared with patients infected with susceptible strains are limited and suggest worse clinical outcomes for patients with infections due to resistant isolates [8].

This study was designed to isolate, identify, and determine the susceptibility index of E. coli from clinical sources obtained from patients at the University College Hospital (UCH) Ibadan, Nigeria.

Materials and Methods

Sample collection

Clinical samples from patients diagnosed with various infections were obtained from the Microbiology Laboratories of the Department of Medical Microbiology and Parasitology, University College Hospital, Ibadan, Nigeria. The samples were collected on prepared agar slants.

Sample population

A total of 32 samples were taken from the Department of Microbiology and Parasitology of the University College Hospital (UCH), Ibadan, Nigeria and transferred to the Laboratories of the Department of Microbiology, Obafemi Awolowo University, Ile- Ife, Nigeria for subsequent culturing and biochemical tests.

Growth on Eosin Methylene Blue Agar (EMB)

Pinkish colonies on Mac Conkey agar were transferred on EMB agar. Greenish metallic sheen colonies on EMB were identified after incubation for 18-24 hours at 37°C. They were stored for future use.

Catalase test

The ability to produce catalase by the isolates was determined using hydrogen peroxide.

Bacterial Isolation and Identification

Culture plates from Deoxycholate agar (Oxoid, UK), MacConkey agar (Oxoid), nutrient agar, blood agar were used. The swab sticks used for the collection of the samples were streaked directly on the labeled agar plate and incubated at 37°C for 24 h. After incubation, cultures were examined for significant growth. Biochemical test were performed to identify microbes that could not be characterized by morphology. Biochemical tests applied were standard catalase test, citrate utilization, oxidase, Voges- Prokauer, indole production, motility, sucrose, maltose, lactose, nitrate reduction and mannitol [9].

Antibiotic Susceptibility Test

In vitro susceptibility of the isolates against antimicrobial agents was determined by the standard disc diffusion procedure. The following antibiotic discs were used: Augmentin (AUG; 30 μg), Ceftriazone (CRO; 30 μg), Nitrofuranoton (NIT; 300 μg), Gentamycin (GEN; 10 μg), otrimozazole (COT; 23.2 μg), Ofloxacin (OFL; 5 μg), Amoxycillin (AMX; 25 μg), Ciprofloxacin (CPX; 5 μg), Tetracycline (TET; 30 μg), Pefloxacin (PFX; 5 μg). The E. coli isolates were inoculated in nutrient broth and incubated at 37°C for 24 hours. The inoculum was transferred into the Mueller-Hinton agar plates. Antibiotic discs were carefully placed on the plates. Plates were incubated at 37° C for 18 to 24 hours. The zones of inhibition were measured, recorded and interpreted according to the Clinical Laboratory Standard Institute provided [10].

Results and Discussion

Out of the 32 clinical isolates in this investigation. 14 isolates were identified as Escherichia coli.

Table 1 shows the percentage distribution of the E. coli in relation to age and sex. Male individuals `which fall within the age range 61-70 constituted highest E. coli infection susceptible individuals of 3 (21.43%) followed by 2 (14.28%) females with age range of (0-10). The least E. coli infected persons were within the age range of (11-20) and (21-30) showing percentage constitution of (7.14%) respectively.

Age range Isolate code Total number of Patient samples Number of % Male Number of % Female
 0-10  CLS3  2  -  14.28
 11-20  CLS11  1  -  7.14
 21-30  CLS13  1  7.14  -
 31-40  CLS9  2  14.28  -
 41-50  CLS2  3  14.28  7.14
 51-60  CLS1  2  7.14  7.14
 61-70  CLS5  3  21.43  -

Table 1. Distribution of E. coli infections in relation to age and sex.

Table 2 showed the distribution of E. coli infection in polymicrobial association and variable medical diagnosis. Urinary tract infection 2 (14.28%) was predominantly associated with E. coli followed by other implicated clinical conditions ranging from Wound sepsis, Flame burns, Chronic sinusitis, Retroviral disease on ART, Jaundice, Chronic liver disease, Dysuria, Lower respiratory tract infection, Cough, Multiple myeloma, Tuberculosis and Known Hbs with haemolytic crisis which constituted 7.14% of the mixed culture infection (Table 3).

Case histories/E. coli infection Isolate codes Total number %
Wound sepsis CLS1 7.14
Flame burns CLS2 7.14
Chronic sinusitis CLS3 7.14
Retroviral disease on ART CLS4 7.14
Urinary tract infection CLS5 14.28
Urinary tract infection CLS9 -
Jaundice CLS6 7.14
Chronic liver disease CLS7 7.14
Dysuria CLS8 7.14
Lower respiratory tract infection CLS10 7.14
Cough CLS11 7.14
Multiple myeloma CLS12 7.14
Tuberculosis CLS13 7.14
Known Hbs with Haemolytic crisis CLS14 7.14

Table 2. Distribution of E. coli infection case histories.

Sources of Isolation Gender Age Diagnosis Isolate code Gram stain Growth on Mac Conkey Growth on EMB
Wound biopsy  M


Wound sepsis CLS1  -  +  +
Wound biopsy  M


Flame burns CLS2  -  +  +
Antral washouts  F


Chronic sinusitis CLS3  -  +  +
Sputum  F


Retroviral on ART CLS4  -  +  +
Urine  M


Urinary tract infection CLS5  -  +  +
Ascitic fluid  F


Jaundice CLS6  -  +  +
Sputum  M


Chronic liver disease CLS7  -  +  +
Urine  M


Dysuria CLS8  -  +  +
Urine  F


Urinary tract infection CLS9  -  +  +
Sputum  M


Lower respiratory tract infection CLS10  -  +  +
Sputum  F


Cough CLS11  -  +  +
Tracheal aspirate  F


Multiple myeloma CLS12  -  +  +
Sputum  M


Tuberculosis CLS13  -  +  +
Blood  F


Known Hbs with haemolytic crisis CLS14  -  +  +

Table 3. Cultural morphology of microorganism isolated from clinical sources.

The present study showed that the prevalence of E. coli was higher among the elderly 8 (57.14%) compared to young age patients 6 (42.85%). Overall prevalence of E. coli was equal for both sexes in the study area (Table 4). E. coli isolates from the female patients exhibited increased antibiotic resistance than isolates from male patients. The highest resistance was with nitrofurantoin, gentamycin, tetracycline and perfloxacin followed by cotrimoxazole with perfloxacin (Table 5). Least resistance was with ofloxacin. The highest susceptibility was with ceftriazone. Least susceptibility was with ceftriazone. Highest resistance was also with ofloxacin.

Citrate  -  -  -  -  -  -  -  -  -  -  -  -  -  -
Indole  +  +  -  +  +  +  +  +  +  +  +  +  +  +
Motility  +  +  -  +  +  +  +  +  +  +  +  +  +  +
Hydrogen sulphide  -  -  +  -  -  -  -  -  -  -  -  -  -  -
Catalase  +  +  +  +  +  +  +  +  +  +  +  +  +  +
MR  +  +  +  +  +  +  +  +  +  +  +  +  +  +
VP  -  -  -  -  -  -  -  -  -  -  -  -  -  -
Urease  -  -  -  -  -  -  -  -  -  -  -  -  -  -
De-mannitol  +  +  +  +  +  -  +  +  +  +  +  +  +  +
Lactose  +  +  +  +  +  -  +  +  +  +  +  +  +  +
Sucrose  +  +  +  +  +  -  +  +  +  +  +  +  +  +
Possible organism E. coli E. coli Proteus sp E. coli E. coli Proteus vulgaris E. coli E. coli E. coli E. coli E. coli E. coli E. coli E. coli

Table 4. Biochemical characterisation of miroorganism isolated from clinical source.

Antibiotics with disc potency Frequency %
Resistance Intermediate Susceptible Total
Augmentin (30 µg)  -  -  -  -
Ceftriazone (30 µg)  78.58  14.28  7.14  100
Nitrofuranton (300 µg)  100  0  0  100
Gentamycin (10 µg)  100  0  0  100
Cotrimozazole (23.2 µg)  92.86  7.14  0  100
Ofloxacin (5 µg)  57.15  14.28  28.57  100
 Ciprofloxacin (5 µg)  92.86  7.14  0  100
Amoxycillin (30 µg)  -  -  -  -
Tetracycline (30 µg)  100  0  0  100
Pefloxacin (5 µg)  100  0  0  100

Table 5. Frequency of antibiotic susceptibility of the E. coli isolated.

In the present study, 43.75% of the clinical samples which comprised E. coli showed polymicrobial association of isolates in many infections. This is in support of the findings of [11] on their investigation on urine culture. The present study showed the prevalence of drug resistant strains of E. coli being higher (92.85%) in comparison with previous studies carried out in Sudan. In this study, the prevalence of E. coli is relatively higher than those reported in neighboring countries such as in Egypt (87%) and in Ethiopia (74.6%) [11,12].

In this investigation, high resistance rates of E. coli was to certain first-line oral antimicrobial agents. These were amoxycillin (100%), cotrimozazole (92.85%) and tetracycline (100%) (Table 6). These findings represent alarming increased rates in resistant E. coli. These results are comparable to findings in other studies [13,14].

Number of Antibiotic(s) Antibiotic Resistance Pattern Frequency Total Number
1 NIT 4 (28.57%) 4 (28.57%)
1 (7.14%)
1 (7.14%)
2 (14.28%)
5 GEN/OFL/CPX/TET/PFX 1 (7.14%) 1 (7.14%)
1 (7.14%)
1 (7.14%)
1 (7.14%)
3 (21.42%)
1 (7.14%)
1 (7.14%)
8 CRO/NIT/GEN/COT/OFL/CPX/TET/PFX 1 (7.14%) 1 (7.14%)
TOTAL 13 (92.83%) 13(92.83%)

Table 6. Multiple Antibiotic Resistance Pattern of E. coli isolated from Clinical sources.

Resistance to fluoroquinolones varies geographically and is an emerging problem in both developed and developing countries [15,16]. In this study, it is observed that the E. coli isolates showed relatively high resistance to ciprofloxacin and is in support of reports of [17], whose findings advocated the appropriate use of fluoroquinolones in humans.

Whilst the third-generation Cephalosporin such as Ceftriaxone has been used to treat Gram-negative bacterial infections of various body sites [18], the current study showed high levels of resistance to ceftriaxone (78.25%) in E. coli. This might be as a result of Extended Spectrum Beta-Lactamases (ESBL) in the strains [19].

Lower susceptibility rates were observed with ceftriaxone (7.14%) and Ofloxacin (28.57%) while susceptibility to Cotrimozazole and Ciprofloxacin was 0%. Intermediate susceptibility was also observed with ceftriaxone (14.28%), Ciprofloxacin (7.14%) and Cotrimozazole (7.14%). However, it was observed that a particular isolate, was resistant to all the antibiotics used. This may be attributed to the prevailing usage and abuse of drugs in the area under study. The resistance to these drugs may be attributed to indiscriminate drugs usage.


The judicious use of antibiotic by the health professional and efforts to control procurement and use of antibiotics officially in the locality will probably help to limit the increasing rate of drug resistance in the pathogens. Also, it is imperative for optimal patient care that constant evaluation of antibiotic sensitivity pattern of pathogens for commonly used antimicrobial agents in a particular environment greatly maintained.


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