MICROORGANISMS FOUND IN AIR-CONDITIONED BUILDINGS

ABSTRACT

Air-conditioners are temperature cooling equipment used in modifying air temperature of homes, offices, and industries for various reasons. Nevertheless, such artificial environment may be favourable to bacteria and fungi which may bring health risks to users, either by hypersensitivity or infections. The microorganisms found in air-conditioned buildings were examined in Umuahia, Abia State, Nigeria using the sedimentation technique. Five bacterial species were isolated and they include Staphylococcus aureus (24%), Klebsiella spp (24%), Micrococcus spp (12%), Bacillus spp (16%) and Escherichia coli (24%). Also, four fungal species were isolated and they include Aspergillus niger (31.25%), Aspergillus flavus (31.25%), Rhizopus stolonizer (31.25%), and Rhodotorula spp (6.25%). Staphylococcus aureus, Escherichia coli, and Klebsiella spp were predominant and the most frequently encountered bacteria having the highest percentage of occurrence while Aspergillus niger, Aspergillus flavus, and Rhizopus stolonizer were the most frequently encountered fungi with the highest percentage of occurrence. The results from the statistical analysis showed significant differences (P < 0.05). Ability of the isolates to access and inhabit air-conditioned buildings call for frequent cleaning of air-conditioners to guarantee their safe use as a means of achieving air quality.

TABLE OF CONTENTS

Title Page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgement ﾿            iv

Table of Contents ﾿ v

List of Tables ﾿ vii

Abstract ﾿ viii

CHAPTER ONE

1.0 ﾿ Introduction ﾿ 1

1.1 ﾿ Time of the year when air-conditioners are used in Nigeria ﾿ 2

1.2 ﾿ Aim and Objectives ﾿ 3

CHAPTER TWO

2.0 ﾿ Literature Review ﾿ 4

2.1 ﾿ Advantages of air-conditioners ﾿ 7

2.2 ﾿ Disadvantages of air-conditioners ﾿ 8

2.3 ﾿ Microorganisms found in air-conditioned buildings ﾿ 8

2.3.1 ﾿ Fungi ﾿ 8

2.3.2 ﾿ Bacteria ﾿ 9

2.4 ﾿ Health implication of air-conditioned building ﾿ 9

2.4.1 ﾿ Hypersensitivity Diseases ﾿ 10

2.4.2 ﾿ Infectious Diseases ﾿ 11

CHAPTER THREE

3.0 ﾿ Material and methods ﾿ 12

3.1 ﾿ Study area ﾿ 12

3.2 ﾿ Sample collection ﾿ 12

3.3 ﾿ Media preparation ﾿ 13

3.3.1 ﾿ Nutrient agar ﾿ 13

3.3.2 ﾿ Mannitol salt agar ﾿ 13

3.3.3 ﾿ MacConkey agar ﾿ 14

3.3.4 ﾿ Potato dextrose agar ﾿ 14

3.4 ﾿ Sterilization of materials ﾿ 14

3.5 ﾿ Isolation and morphological study of bacteria ﾿ 14

3.6 ﾿ Isolation and taxonomic study of fungi ﾿ 15

3.7 ﾿ Bacterial identification ﾿ 15

3.7.1 ﾿ Gram Staining ﾿ 15

3.7.2 ﾿ Biochemical characterization of bacteria ﾿ 16

3.7.2.1 ﾿ Indole production test ﾿ 16

3.7.2.2 ﾿ Catalase test ﾿ 16

3.7.2.3 ﾿ Oxidase test ﾿ 17

3.7.2.4 ﾿ Methyl red test ﾿ 17

3.7.2.5 ﾿ Voges Proskauer test ﾿ 17

3.7.2.6 ﾿ Coagulase test ﾿ 18

3.7.2.7 ﾿ Motility test ﾿ 18

3.8 ﾿ Fungal identification ﾿ 18

3.8.1 ﾿ Cell morphology ﾿ 18

3.8.2 ﾿ Cultural morphology ﾿ 19

3.9 ﾿ Statistical analysis ﾿ 19

CHAPTER FOUR

4.0 ﾿ Results ﾿ 20

CHAPTER FIVE

5.0 ﾿ Discussion, Conclusion and Recommendations ﾿ 28

5.1 ﾿ Discussion ﾿ 28

5.2 ﾿ Conclusion ﾿ 31

5.3 ﾿ Recommendation ﾿ 32

REFERENCES

APPENDIX I: Statistical table

APPENDIX II: Pictures of plates

LIST OF TABLES

TABLE                           TITLE                                                                  PAGE NUMBER

1  ﾿ Site characteristics of the various locations ﾿       ﾿      22

2 ﾿ Total viable count of isolated microorganisms ﾿      23

3 ﾿ Identification and characterisation of bacterial isolates ﾿      24

4 ﾿ Identification and characterisation of fungal isolates ﾿      25

5 ﾿ Percentage of occurrence of bacteria found in air-conditioned buildings ﾿      26

6 ﾿ Percentage of occurrence of fungi found in air-conditioned buildings ﾿      27