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Microbiological burden of public transport vehicles.

INTRODUCTION

As part of living in society, many common spaces are shared with other people. This makes it possible to spread diverse microorganisms that can lead to infections. People who use public transport can pass bacteriological, virological, or fungal infections to other people (Rusin et al. 2002). The greatest risk for infectious diseases in these vehicles is that people sit close together in a closed environment and breathe the same air (Yatagan 1991; Furuya 2007; Edelson and Phypers 2011). These vehicles can become a significant source of microorganisms when passengers do not close their mouths when coughing and sneezing. Handles, seats, anchors, floors, and windows are areas that can host infectious microorganisms.

For this reason, detailed internal cleaning of public transportation vehicles, which thousands of people use every day, is an important issue. In Istanbul, public transport services are mainly run by Istanbul Electricity Tramway and Tunnel Businesses (IETT). According to IETT's official website, the institution serves in Istanbul with 4558 public and private buses and 334 metrobuses. The number of buses is about 5000, which means there are 3,440,000 passengers every day. IETT buses and other vehicles are reported to be cleaned to provide healthier environment for passengers (IETT 2015).

In our study, the microbiological burden of vehicles was evaluated in order to determine the role of public transportation vehicles in the transmission of microorganisms that can cause significant infections in humans.

MATERIALS AND METHODS

Sample collection

In this study, we investigated the microbiological burden of public transport such as trams, metrobuses, and buses, which are frequently used in daily life. A total of 60 samples were taken from the handles of these vehicles. Samples were taken from vehicles by morning and evening by swap method.

Swab method

The samples were taken with swap, which is the popular testing method. In a 10x10 cm area, sampling was. Swaps were placed in a tube containing Amies agar gel transport media and brought to the laboratory for analysis.

Microbiological analysis

All the collected swap samples were analyzed to detect the presence of total bacterial and fungal count. The microbial species S. aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella sp. and Enterococcus sp. were investigated, as suggested in The United States Pharmacopeia (USP). Each sample was weighed aseptically and diluted in pH 7 phosphate buffer and Tryptic Soy Broth (Difco). Serial dilutions of the samples were homogenized in phosphate buffer and spread on duplicate Tryptic Soy Agar (Difco) and Sabouraud Dextrose Agar (Difco). Plates were incubated at 37[degrees]C 48h and 25[degrees]C 5-7 days. At the end of the incubation, emergent colonies were counted and the numbers of colony forming units (CFU/ml) were determined. Tryptic Soy Broth was incubated at 37[degrees] C 24h. After incubation, samples were spread on Mannitol Salt Agar (Oxoid), Baird-Parker Agar (Difco), Cetrimide Agar (Difco), MacConkey Agar (Difco), Eozine Methylene Blue Agar (Difco), Fluid Tetrathionate Medium (Difco), Xylose-Lysine Deoxycholate Agar (Difco), Bismuth Sulfite Agar (Difco) and Enterococcosel Agar (Difco) to determine the presence of specific microorganisms according to pharmacopeia (USP 2009). Plates were incubated at 37[degrees]C 24h and identification was performed after microscopic examination and biochemical identification.

RESULTS

Microbiological analysis

Sixty samples taken from the handles belonging to 10 different trams, metrobuses and buses in the morning and evening were microbiologically examined.

Determination of total aerobic bacteria and fungus numbers in the samples belonging to the trams and the isolated microorganisms

A total number of bacteria and fungi counts and isolates determined in the samples belonging to the trams in the morning and evening were summarized in Tables 1 and 2. The total number of bacteria for one of the samples taken in the morning, the total number of bacteria in the eight samples taken in the evening and the total number of fungi in one sample were found high.

Determination of total aerobic bacteria and fungus numbers in the samples belonging to metrobuses and the isolated microorganisms

A total number of bacteria and fungi counts and isolates determined in the samples belonging to the metrobus in the morning and evening were summarized in Tables 3 and 4. Eight of the samples taken in the morning and seven of the samples taken in the evening were found to have a high total number of bacteria.

Determination of total aerobic bacteria and fungus numbers in the samples belonging to buses and the isolated microorganisms

A total number of bacteria and fungi counts and isolates determined in the samples belonging to the buses in the morning and evening were summarized in Tables 5 and 6. The total number of bacteria in the six samples taken in the morning and the total number of fungi in one sample were found to be high. The total number of bacteria and fungi in the all samples taken in the evening were also high.

DISCUSSION

Public transportation vehicles facilitate the spread of various pathogens that can cause frequent infections in the community. These vehicles are vectors of colds, flu, and bronchitis in winter months. Many public transport vehicles carry passengers well above their capacity, especially in the morning and evening hours. This leads to the spread of disease among people using these vehicles. To ensuring proper hygiene, these vehicles must be inspected regularly.

Hand-touch sites can become contaminated with bacteria and become fomites for the transmission of bacteria between humans. Such sites can provide a reservoir for community-associated bacteria in high-prevalence areas [Brook and Brook (1994); Rusin et al. (2002); Simoes et al. (2011); Zhou and Wang (2013)]. Stepanovic et al. (2008) recently reported a high frequency of methicillin-resistant, coagulase-negative staphylococci but no MRSA contaminating hand-touch sites on public transportation vehicles in Serbia (Stepanovic et al. 2008). Otter and French determined total aerobic counts in 118 hand-touch surfaces on buses, trains, stations, hotels, and public areas of a hospital in central London. S. aureus isolates were identified (Otter and French 2012).

According to the information provided by the IETT General Directorate, vehicles that serve millions of people every day have a detailed interior and exterior cleaning to provide a more healthy environment for the passengers. It is stated that these routine cleanings are carried out every day by 4:00 am as the vehicles are readied for morning service. It is also stated that the vehicles are subjected to detailed disinfection treatment once a week, thus making the vehicles safe from microbiological contamination (IETT 2015).

When we compared the results of the samples taken in morning and evening by public transportation vehicles, it was determined that the samples taken in the evening from all vehicles were much higher than the counts of the samples taken in the morning for aerobic bacteria and fungus counts.

In particular, the total aerobic bacteria counts of the samples taken in the morning from the buses were high so daily cleaning procedures were insufficient. In addition, the isolation of pathogens such as S. aureus, Staphylococcus and Enterococcus in the specimens shows that these vehicles may be important sources of infection.

The presence of S. aureus in these vehicles is of great importance for both hospital-acquired and community-acquired infections. Transmission is usually through direct contact or droplet contact. In humans, skin inflammation can lead to various organ infections such as wound infections, urinary tract infections, pneumonia or poisoning (Bilgehan 1992; Gurler 2008; Winston and Chambers 2009). Enterococci are among the leading endocarditis agents and may cause various infections such as bacteremia, salpingitis, endometritis, peritonitis, biliary tract infections, intraabdominal abscess, and sometimes meningitis (French 2010).

We have found that the microbial load in public transportation vehicles is high. It has also been shown that these vehicles can be an important source of contamination for many community-based infections. Our results suggest that these vehicles need to be cleaned, disinfected and tested more often. In addition, those who use these vehicles could prevent many diseases with proper hand washing techniques.

REFERENCES

* Bilgehan H (1992). Klinik Mikrobiyoloji Ozel bakteriyoloji ve Bakteri Infeksiyonlari. Baris Yayinlari Fakulteler Kitabevi, Izmir.

* Brook J, Brook I (1994). Recovery of organisms from the handrails of escalators in the public metro rail system in Washington, D.C. J Environ Health 57: 13-14.

* Edelson PJ, Phypers M (2011). TB transmission on public transportation: a review of published studies and recommendations for contact tracing. Travel Med Infect Dis 9: 27-31. [CrossRef]

* Furuya H (2007). Risk of transmission of airborne infection during train commute based on mathematical model. Environ Health Prev Med 12: 78-83. [CrossRef]

* French GL (2010). The continuing crisis in antibiotic resistance. Int J Antimicrob Agents 36: 3-7. [CrossRef]

* Gurler B (2008). Istanbul Universitesi Tip Fakultesi Tibbi Mikrobiyoloji-3: Nobel Kitabevleri, Istanbul.

* Istanbul Elektrik Tramvay ve Tunel Isletmeleri Genel Mudurlugu (IETT), Internet Sitesi http://www.iett.gov.tr.

* Otter JA, French GL (2012). Community-associated meticillinresistant Staphylococcus aureus: the case for a genotypic definition. J Hosp Infect 81: 143-148. [CrossRef]

* Rusin P, Maxwell S, Gerba C (2002). Comparative surface-to-hand and fingertip-to-mouth transfer efficiency of gram-positive bacteria, Diversity of Staphylococcus spp. in public transit 207 gram-negative bacteria, and phage. J Appl Microbiol 93: 585-592. [CrossRef]

* Simoes RR, Aires-de-Sousa M, Conceicao T, Antunes F, Martins da Costa P Lencastre H (2011). High prevalence of EMRSA-15 in Portuguese public buses: a worrisome finding. PLoS One 6: 1-5. [CrossRef]

* Stepanovic S, Cirkovic I, Djukic S, Vukovic D, Svabic-Vlahovic M (2008). Public transport as a reservoir of methicillin-resistant staphylococci. Lett Appl Microbiol 47: 339-341. [CrossRef]

* USP 32- NF 27. (2009) Microbial Limit Tests. The United States Pharmacopeia.

* Winston LG, Chambers HF (2009). Antimicrobial resistance in Staphylococci: Mechanisms of resistance and clinical implications. Mayers D, (ed). Antimicrobial Drug Resistance Mechanisms of Drug Resistance. Vol.1, Humana Press, pp. 735-748. [CrossRef]

* Yatagan E (1991) Bulasici Hastaliklar ve Epidemiyoloji. 2. Baski, Sekav, Istanbul.

* Zhou F, Wang Y (2013). Characteristics of antibiotic resistance of airborne Staphylococcus isolated from metro stations. Int J Environ Res Public Health 10: 2412-2426. [CrossRef]

Ayse Seher Birteksoz Tan (*), Gamze Erdogdu

Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Istanbul University, 34116, Istanbul, Turkey

(*) Address for Correspondence: Ayse Seher Birteksoz Tan, e-mail: seherbirteksoz@hotmail.com

Received: 07.08.2017

Accepted: 22.08.2017

Cite this article as: Birteksoz Tan AS, Erdogdu G (2017). Microbiological burden of public transport vehicles. Istanbul J Pharm 47 (2): 52-56.

DOI: 10.5152/IstanbulJPharm.2017.008
Table 1. The total aerobic bacteria, fungi counts and isolated
microorganisms in the samples taken from the trams in the morning

                                     Total Fungal
Sample    Sample   Total Bacterial      Count             Isolated
Area        No      Count (cfu/mL)     (cfu/mL)        Microorganisms

            1      -                 -                       -
            2      2x[10.sup.1]      3x[10.sup.1]           KNS
            3     <1x[10.sup.1]      -             Enterococcus spp, KNS
            4      -                 -                      KNS
Handles     5      1x[10.sup.1]      -                    S.aureus
            6      -                 -                      KNS
            7      6.28 x[10.sup.5]  -                       -
            8      -                 2x[10.sup.1]            -
            9      6x[10.sup.1]      -                      KNS
           10      5x[10.sup.1]      -                Enterococcus spp

Table 2. The total aerobic bacteria, fungi counts and isolated
microorganisms in the samples taken from the trams in the evening

                                    Total Fungal
Sample    Sample  Total Bacterial     Count             Isolated
Area        No     Count (cfu/mL)    (cfu/mL)        Microorganisms

            1     2.8 x[10.sup.3]   3x[10.sup.1]             -
            2     3.4x[10.sup.2]    -                    S.aureus
            3     1.83x[10.sup.3]   1.34x[10.sup.3]      S.aureus
            4     -                 2.5x[10.sup.1]           -
Handles     5     1.14x[10.sup.3]   -                        -
            6     2.2x[10.sup.2]    1x[10.sup.1]             -
            7     2.62 x[10.sup.3]  -                Enterococcus spp,
            8     -                 -                        -
            9     1.25x[10.sup.6]   -                        -
           10     3.12x[10.sup.5]   5x[10.sup.1]         S.aureus

Table 3. The total aerobic bacteria, fungus counts and isolated
microorganisms in the samples taken from the metrobuses in the morning

                                    Total Fungal
Sample    Sample  Total Bacterial      Count            Isolated
Area        No     Count (cfu/mL)     (cfu/mL)       Microorganisms

            1     5.1x[10.sup.4]         -                  -
            2     6.25x[10.sup.5]        -                 KNS
            3     3.6x[10.sup.5]         -        Enterococcus spp, KNS
            4     4.26x[10.sup.5]        -                 KNS
Handles     5     3.83x[10.sup.5]        -                 KNS
            6     2.6x[10.sup.4]         -                 KNS
            7     5.42x[10.sup.5]        -                  -
            8     6.25 x[10.sup.6]       -                  -
            9     4.[10.sup.1]           -              S.aureus
           10     4.5.[10.sup.1]         -              S.aureus

Table 4. Total aerobic bacteria, fungus counts and isolated
microorganisms in the samples taken from the metrobuses in the evening

                                    Total Fungal
Sample    Sample  Total Bacterial      Count          Isolated
Area        No     Count (cfu/mL)     (cfu/mL)     Microorganisms

            1     3.22x[10.sup.5]        -              KNS
            2     8.21x[10.sup.4]        -              KNS
            3     -                 2x[10.sup.1]        KNS
            4     7.11x[10.sup.5]        -              KNS
Handles     5     -                      -              KNS
            6     2.64x[10.sup.5]   2x[10.sup.1]        KNS
            7     -                      -              KNS
            8     3.24 x[10.sup.5]       -              KNS
            9     6.14x[10.sup.5]        -              KNS
           10     2.13.[10.sup.5]        -              KNS

Table 5. The total aerobic bacteria, fungus counts and isolated
microorganisms in the samples taken from the buses in the morning

                                    Total Fungal
Sample    Sample  Total Bacterial      Count             Isolated
Area        No     Count (cfu/mL)     (cfu/mL)        Microorganisms

            1     2.6x[10.sup.2]         -               S.aureus
            2     3x[10.sup.1]           -          Enterococcus spp,
            3     1.2x[10.sup.2]         -        Enterococcus spp, KNS
            4     1.3x[10.sup.2]         -         Enterococcus spp,KNS
Handles     5     1x[10.sup.1]           -        Enterococcus spp, KNS
            6     7x[10.sup.1]           -        Enterococcus spp, KNS
            7     4x[10.sup.1]           -        Enterococcus spp, KNS
            8     1.8 x[10.sup.4]        -        Enterococcus spp, KNS
            9     5.6x[10.sup.2]         -        Enterococcus spp, KNS
           10     9x[10.sup.2]     1.7x[10.sup.3] Enterococcus spp, KNS

Table 6. The Total aerobic bacteria, fungus counts and isolated
microorganisms in the samples taken from the buses in the evening

                                    Total Fungal
Sample    Sample  Total Bacterial      Count             Isolated
Area        No     Count (cfu/mL)     (cfu/mL)        Microorganisms

            1     3.83x[10.sup.5]  2.6x[10.sup.2]        S.aureus
            2     3.14x[10.sup.5]  3.2x[10.sup.2]        S.aureus
            3     6.81x[10.sup.4]  1.3x[10.sup.2]   Enterococcus spp,
                                                         S.aureus
            4     7.11x[10.sup.5]  1.5x[10.sup.2]        S.aureus
Handles     5     1.24x[10.sup.4]  1.4x[10.sup.2]        S.aureus
            6     2.4x[10.sup.6]   3.25x[10.sup.4]  Enterococcus spp,
                                                         S.aureus
            7     1.3x[10.sup.4]   1.09x[10.sup.2]       S.aureus
            8     7.1x[10.sup.5]   6.1x[10.sup.5]        S.aureus
            9     3.25x[10.sup.4]  1.37x[10.sup.4]       S.aureus
           10     1.71x[10.sup.5]  1.59x[10.sup.2]       S.aureus
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Title Annotation:Original Article
Author:Tan, Ayse Seher Birteksoz; Erdogdu, Gamze
Publication:Journal of the Faculty of Pharmacy of Istanbul University
Date:Aug 1, 2017
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