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