The recovery of bacteria from the handpiece of a High School telephone. (Features).

Introduction

Telephones are a potential vector for infection; however, all the past studies of this phenomenon were done in hospital environments (Conzanitis, Grant, & Makela, 1978; Rafferty & Pancoast, 1984). A review of the literature showed that no similar studies have been done in a school setting.

School environments facilitate the spread of infection (Cardona, Bek, Mills, Isaacs, & Alperstein, 1999; Harley, Harrower, Lyon, & Dick, 2001). Several illnesses are common in a school environment. These include infected cuts and bruises, sports injuries, the common cold, diarrheal disease, and infectious mononucleosis. The sterilization techniques and antibacterial products found in a hospital are not present in a school building, despite the fact that a school is a heavily populated environment with inhabitants who are perpetually in close contact.

Two studies on bacterial contamination of telephones in hospitals have been published (Conzanitis et al., 1978; Rafferty & Pancoast, 1984). These studies generally show that bacteria from a human subject who has used a telephone can be found on telephones in hospitals. The two studies also find that the cultured bacteria were generally nonpathogenic and harmless to a healthy person. Numerous studies also have documented the spread of bacteria in daycare centers, where hygiene often is not good and many children are in close contact (Ang, 2000).

The purpose of this study was to determine whether public phones in a public school can become colonized with potentially pathogenic bacteria, thus enabling the spread of these bacteria through telephone use in a school environment.

Materials and Methods

The experiment was carried out on Monday November 6, 2000, at Montgomery Blair High School in Silver Spring, Maryland. The school is situated in a suburban middle-class neighborhood and is attended by approximately 3,000 students. Four indoor public pay phones are available for student use in the school. Bacterial cultures were obtained from these four telephone handpieces at 7 a.m. and 3 p.m. Two of the phones (phones 1 and 2) were located outside the auditorium. The other phones (phones 3 and 4) were located outside of the Student Activity Center, A fifth phone, the private phone of the school principal, was also included in the study as a control.

Culture procedures were as follows: A sterile cotton swab was dipped into sterile water, and the swab was then used to wipe the entire area of either the mouthpiece, the handle inset, or the earpiece of a telephone. The swab was slightly rotated several times to expose clean areas of the tip. Each swab that had cultured a telephone mouthpiece was streaked onto sheep-blood, chocolate, and MacConkey agar plates, in that order. The swabs that had cultured the telephone handle insets and the earpieces were streaked onto sheep-blood and MacConkey agar plates only All sampling and plating was done by the same individual. The telephones were made from plastic-type materials.

All of the agar plates were incubated at 5 percent carbon dioxide for 24 and 48 hours at 37[degrees]C and were analyzed for quantitative and qualitative data. Microscopic examination of Gram-stain preparations and, in some cases, biochemical identification were performed on the bacterial isolates (Murray, Baron, Pfaller, Trenover, & Yolken, 1993).

Results

A total of 1,919 colonies were counted on blood agar plates collected from all five phones in the morning (Table 1). In the afternoon, a total of 5,416 colonies were counted as collected from all five phones, at least a 2.8 times increase (Table 1). Since in three instances (phones 1, 3, and 5) the number of colonies was over 800 or 1000 and was uncountable, the ratio may in fact have been higher.

Out of a total of 15 observations (of the mouthpiece, the handle, and the earpiece combined), 10 observations (67 percent) documented an increase in the number of bacteria from morning to afternoon (Table 2). Eight observations showed a more than threefold increase in the amount of bacteria from morning to afternoon. Four observations had very little or no increase at all. Only one observation, of the handle of Phone 2, found a decrease from morning to afternoon in the number of bacteria.

The total number of different types of bacteria found on the telephones also increased form morning to afternoon (61 versus 45) (Table 1). Eight of the 15 observations (53.3 percent) found an increase in the number of types of bacteria from morning to afternoon (Table 3). Six of the 15 observations (40 percent) found no change in the number of types of bacteria. Only one observation showed a decrease, from six to three types of bacteria, from morning to afternoon (on the handle on Phone 2). The handles of all five telephones had more types of bacteria in the afternoon than any other part of the telephone (Table 1).

There was no difference between the results for the control phone and those for the other four, public, phones. The control phone had a significant increase in the number of bacteria on the mouthpiece, a smaller increase on the handle, and no increase on the earpiece. There was, however, almost no increase from morning to afternoon in the number of types of bacteria collected from the control phone. The control phone also had the lowest number of total types of bacteria in the morning and afternoon (Table 1).

Gram stains were made from several samples of collected bacteria, and several bacteria were biochemically identified. No growth was noted on any of the MacConkey agar plates. Most Gram stains observed included Gram-positive cocci in clusters or chains. There were also a few Gram-negative cocci in clusters and Gram-negative bacilli in chains. The bacteria that were completely identified were Staphylococcus species (haemolyticus, epidermidis, warneri, huminis, and auricolaris) (Table 1).

Discussion and Conclusion

This study demonstrated that the number of kinds of bacteria recovered from school public phones increased from morning to afternoon. The goal was to determine whether public phones in a school can become colonized with potentially pathogenic bacteria, thus enabling the spread of these bacteria through telephone use in a school environment. The data from the study showed two results: First, there was an overall increase in the total number of bacteria and the number of strains of bacteria from morning to afternoon. Second, the bacteria isolated were not pathogenic. The authors conclude that on the day of the experiment, there was no risk of acquiring pathogenic bacteria for any student who used the telephones. Under certain circumstances, however, the bacteria found on telephones could be dangerous to some students. To an individual who has a weak immune system or even a cut or abrasion, any bacterial contamination can prove detrimental.

Past literature relating to the problem of contamination of phones by bacteria includes studies of the bacteria found on telephones in a hospital. Rafferty and Pancoast (1984) found that only 7 percent of the phone handpieces contained potential pathogens, which included two instances of Staphylococcus aureus out of 114 cultured objects. Cozanitis et al. (1978) found that almost all hospital telephones showed some degree of bacterial contamination. In findings similar to those of the present study, coagulase-negative staphylococci were the predominant bacteria. These bacteria are normally found in the nostrils, in the mouth, and on the skin of humans and are considered non-pathogens. They can, however, cause serious disease such as bacteremia and endocarditis in patients following cardiac surgery and in the immunocompromised host (Cozanitis et al.)

In the study reported here, no pathogens were found on the telephone handpieces. This study is, however, just a quick snapshot of the bacteria that can be found on the telephones at Blair High School. Only four public telephones and one private phone were studied in the experiment. Moreover, the surfaces of the phones were evaluated only on a single day, once in the morning and once in the afternoon. It is conceivable that on any day a single person could contaminate a phone with potentially pathogenic bacteria that might cause serious illness. To prevent the spread of disease, certain precautions can be taken. Washing of hands before lunch and after bathroom use reduces the chances of being contaminated by or of contaminating others with pathogenic bacteria. While this experiment represents the bacteriology for a single day further studies are necessary to establish additional and more comprehensive conclusions concerning the bacteria found on telephones. Such studies would evaluate larger numbers of phones over a greater period of time.

TABLE 1

Bacteria Growth on Blood Agar Plates by Number and Colony Types from
Morning to Afternoon

                      Morning Bacteria
Phone     Piece      Total        Number
                    Number     of Types (a)

1         Mouth       39            4

1         Handle       2            2
1         Ear        300            3
2         Mouth       75            2


2         Handle     824            6
2         Ear          0            0

3         Mouth       36            4
3         Handle       9            2

3         Ear        140            4
4         Mouth        9            3
4         Handle      30            4
4         Ear        100            3
5 (b)     Mouth       83            3
5 (b)     Handle      32            2

5 (b)     Ear        240            3
Totals              1919            45

                  Morning Bacteria              Afternoon Bacteria
Phone     Comments                         Total          Number
                                          Number       of Types (a)

1                                         > 1000            5

1                                             46            4
1         G+ Staphylococcus haemolyticus   > 800            4
2         G+ cocci, clusters                  52            5


2         G- cocci, clusters                  55            3
2                                            456            4

3                                             35            4
3                                         > 1000            6

3                                            136            4
4                                            132            3
4                                            128            7
4                                            216            3
5 (b)                                     > 1000            3
5 (b)                                        120            3

5 (b)                                        240            3
Totals                                      5416            61

                  Afternoon Bacteria
Phone     Comments


1         G- rods, Staphylococcus warneri,
          Staphylococcus auricolaris
1
1
2         G- bacilli, chains; G- cocci,
          clusters; G+ cocci, chains;
          clusters
2         G+ cocci, clusters
2         Staphylococcus huminis; G+ cocci,
          clusters
3
3         G+ cocci, clusters; G- cocci,
          clusters
3
4
4         G-bacilli
4
5 (b)
5 (b)     Staphylococcus epidermidis,
          Staphylococcus warneri
5 (b)
Totals

(a) Type = bacteria of distinct morphological colonial and Gram-stain
appearance.

(b) Phone 5 = control phone.

G+ = Gram positive.

G- = Gram negative.

TABLE 2

Number of Changes in the Amount of Bacteria from Morning to Afternoon

            Number of Increases  Number of Decreases  No Changes
                in Bacteria          in Bacteria

Mouthpiece           3                    1               1
Handle               4                    1               0
Earpiece             3                    0               2
Totals              10                    2               3

TABLE 3

Number of Changes in the Number of Bacteria Types from Morning to
Afternoon

            Number of Increases  Number of Decreases  No Changes
             in Bacteria Types    in Bacteria Types

Mouthpiece           2                    0               3
Handle               4                    1               0
Earpiece             2                    0               3
Totals               8                    1               6

Acknowledgements: The authors acknowledge the assistance of Michael Kravitz and Lillian Miller at Montgomery Blair High School and of Thomas B. Elliot, Ph.D.

REFERENCES

Ang, L.H. (2000). Outbreak of giardiasis in a daycare nursery. Communicable Disease and Public Health, 3, 212-213.

Cardona, M., Bek, M.D., Mills, K., Isaacs, D., & Alperstein, G. (1999). Transmission of tuberculosis from a seven-year-old child in a Sydney school, Pediatric Child Health, 35(4), 375-378.

Cozanitis, D.A., Grant, J., & Makela, P. (1978). Bacterial contamination of telephones in an intensive care unit. Anaesthesist, 27, 439-442.

Harley D., Harrower, B., Lyon, M., & Dick, A. (2001). A primary school outbreak of Pharyngoconjunctival fever caused by adenovirus type 3. Communicable Diseases Intelligence, 25(1), 9-12.

Murray P.R., Baron, E.J., Pfaller, M.A., Trenover, P.C., & Yolken, R.H. (1993). Manual of clinical microbiology (5th ed.). Washington, DC: American Society for Microbiology 

Rafferty, K.M., & Pancoast, S.J. (1984). Brief report: Bacteriological sampling of telephones and other hospital staff hand-contact objects. Infection Control, 5(11), 533-535.

Corresponding Author: Itzhak Brook, 4431 Albemarle St., NW Washington, DC 20016. E-mail: <[e-mail]>.