This document summarizes a student's presentation on a project isolating, characterizing, and analyzing antibiotic resistance of Staphylococci bacteria from indoor air samples collected from student halls of residence at Obafemi Awolowo University, Nigeria. A total of 26 Staphylococci isolates were recovered from the air samples. Biochemical testing showed that 46% were DNase positive and 54% were DNase negative. Antibiotic susceptibility testing found resistance rates of 0%, 15.4%, and 38.5% to Ciprofloxacin, Gentamicin, and Tetracycline respectively. The presentation concludes that air contamination poses a health risk and calls for improved hygiene and ventilation to reduce

1. JOURNAL CLUB MONTHLY PRESENTATION
AT THE
TRAINING AND CLINICAL TRIAL CENTER (TCC) , ISTH, NIGERIA.
COORDINATOR:
DR D. U. EHICHIOYA.
PRESENTED BY:
MR ADEYEMI KAYODE.
PROJECT CARRIED OUT AT: THE DEPARTMENT OF MICROBIOLOGY, OAU, ILE IFE, NIGERIA (2017).
Isolation, Characterization, and Antibiotics Resistance Profile of Staphylococci from Indoor Air of the
Students’ Halls of Residence at the Obafemi Awolowo University, Ile Ife, Nigeria.

2. Background of the Study
The safety of the only readily consumable and unfiltered part of the
biosphere; the air has been a public health concern (Horneck, Klaus
and Mancinelli, 2010).
Most especially in its probable containment of pathogenic air-borne
microorganisms such as the genus of Staphylococci (Kozajda, Jeżak
and Kapsa, 2019).
This concern is more important in an enclosed and densed
populated region as the students' hall of residence of the Obafemi
Awolowo University.

3. A high number of communicable diseases in the World had been reported to be from aerosol origin, in which
causative microbial agents are mainly transmitted via sneezing, coughing or talking from an infected
individual, or air current from a reservoir (Jill, 2017).
(Qian and Zheng, 2018)
The characteristics and antibiotics profile of the staphylococci isolated in the Students’ hostel can be used to
evaluate the overall hygiene, and public health safety of the study sites.
Airborne Transmission of Infectious Agents

4. METHODOLOGY: Study location
(AmShield, 2020)
Samples were collected from indoor air of the reading rooms of eight (8)
undergraduate, and one (1) postgraduate students' hostels at the University.
At the time of collection, the average atmospheric parameters of the
university as reported by the Ile-Ife Air Quality Index (AQI) and Nigeria Air
Pollution, AirVisual, 2017 were;
 Relative Humidity: 75%
 Wind speed: 12km/hr, and
 Atmospheric pressure: 1016mb.

5. SAMPLING TECHNIQUES
Indoor airborne microorganisms were collected on open
sterile Mannitol Salt Agar plates; a solid impingement
method as described by Omeliansky (Awad, & Mawla,
2012).
Sample collection was carried out between the period of
09:00 and 14:00 Nigerian local time for a period of six
weeks (December 6th to January 18th, 2017). The plates
were transferred immediately to the laboratory for 48
hours incubation at 370C.
(Malakpet, 2020)

6. CHARACTERIZATION AND ISOLATION OF STAPHYLOCCOCCI
The estimation of the total number of halophilic bacteria colonies forming unit per
unit cubic meter per minute in the reading rooms was done using CFU/m3/min =
𝟓𝟎𝟎𝟎𝟎𝑨
𝑺𝑻
(Awad, & Mawla, 2012).
All cocci, Gram positive colonies that appeared clustered on oil immersion
microscopy with tiny, yellowish, or whitish macroscopic appearance on Mannitol
plates were counted and recorded as presumptive Staphylococci.
Biochemical tests carried out for further characterization include catalase, and
Dnase tests.

7. Antibiotics susceptibility test on presumptive staphylococci isolates
Samples were initially resuspended in sterile physiological saline solution and standardized to
0.5McFarland turbidity index with the use of colorimeter on a wavelength of 590nm.
The disk diffusion method was used for the antibiotic susceptibility testing. The following antibiotics were
used
5µg/mL of Ciprofloxacin,
30µg/mL tetracycline, and
10µg/mL gentamicin (Habdiscs ABTEK biological limited, Liverpool).
The diameter of the zone of growth inhibition revealed the level of susceptibility of the isolate to the
antibiotics in reference to the Clinical Laboratory Standards Institute (CLSI) guidelines (CLSI, 2017).

8. RESULT: MORPHOLOGICAL, AND BIOCHEMICAL
The Total mannitol fermenting halophiles recorded from
each hostel on the culture plates were in the range of 126
– 4204 CFU/m3/min, with one of the female
undergraduate hostel having the lowest and the highest
from one of the male undergraduate hostel.
From this, a total number of twenty-six (26)
staphylococci isolates were recovered. These isolates
were all were catalase-positive, 46% were DNase positive,
while 54% were DNase negative.
Morphological and biochemical characteristics of selected
Staphylococci isolates.
CODE Gram Cocci Cluster Catalase DNase
16 –18 + + + + +
19 + + + + -
20 + + + + +
21 + + + + -
22 + + + + +
23 + + + + -
24 + + + + +
25- 27 + + + + -
28 –29 + + + + +
30 + + + + -
31 –32 + + + + +
33- 37 + + + + -
38 –40 + + + + +
41 + + + + -

9. RESULT: ANTIBIOTICS SUSCEPTIBILITY PROFILE
100% 84.60% 61.50%
0% 0% 0%0%
15.40%
38.50%
0%
20%
40%
60%
80%
100%
120%
Ciprofloxacin Gentamicin Tetracycline
Susceptible Isolates Intermediate Isolates
Antibiotics Profile of the isolated Staphylococci.
 It was found that 0%, 15.4%, and 38.5% of the tested isolates were resistant to Ciprofloxacin,
Gentamicin, and Tetracycline, respectively.
 While about 3.8% of the isolates were resistant to both Gentamicin and Tetracycline.

10. DISCUSSION
This result revealed an occurrence of diversity in the number of microorganisms in the air at different
locations as indicated by Samuel and Abayneh (2014).
The susceptibility of 93.4% to ciprofloxacin is supported by Taddesse group (Taddesse et al., 2014) as
compared to 100% obtained in this study.
Also, from Bhatt et al., 2014, a 85% susceptibility of Staphylococci isolates to gentamicin is in line with the
84.6% obtained in this study.
It is also noticed that the result of the 62% susceptibility to tetracycline in this study is in line with that of
Foozieh et al., 2018’s recorded 67% rate.

11. DISCUSSION CONTD
As stated by Spellberg, and Gilbert that it is not difficult to
develop a model to predict the future antibiotics resistance
these ever-evolving bacteria will have if antibiotics
stewardship is not duly followed (Spellberg and Gilbert,
2014).
Therefore, a non-linear regression was used to predict the
future rate of resistance of the air-borne Staphylococci
isolates used in this study.
Resistance index ranging from 0 to 1 (R),
R = 15(7Y2 – 243Y – 332),
Where Y is the number of years since first use of the antibiotics.
y = -0.0133x2 + 1.4669x + 36
R² = 1
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25 30 35 40
Yrssincefirstuse
Resistance Rate (%)
 Regression and Correlation Analysis Between Resistance
Pattern and Antibiotics Age Since First Use

12. Conclusion and recommendation
The high range of bacteria count and the presence of antibiotics resistance Staphylococci recovered
from these reading rooms is a potential risk to the health of the users and an indication of air
contamination.
Considering the future adaptation of microorganisms to yet-to-made antibiotics, search for novel
means to antimicrobial discovery which will serve as supplement to antimicrobials with different
approaches to management of infection that will not necessarily kill the microbes should be
encouraged.
In references to the study location, immediate intervention is needed to be taken to maintain hygiene
of the reading rooms and the environs, especially in Education Trust Fund Hall.
The university should therefore increase the number of reading rooms to reduce overcrowding and
improve cross ventilation system within the rooms.

13. REFERENCES
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2. Awad, A.H, & Mawla, H.F. (2012). Sedimentation with the Omeliansky Formula as an Accepted Technique for Quantifying Airborne Fungi.
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6. Horneck, G, Klaus, D. and Mancinelli, R, 2010. Space Microbiology. Microbiology and Molecular Biology Reviews, 74(1), pp.121-156.
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9. Malakpet, 2020. Mannitol Salt Agar Plate At Best Price In Hyderabad, Telangana | Labline Trading Company. [online] Tradeindia.com. Available at:
<https://www.tradeindia.com/fp5130280/Mannitol-Salt-Agar-Plate.html> [Accessed 7 October 2020].
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