Hospital superbugs that cause sepsis and meningitis could be hitching a ride on mobile phones

Hospital superbugs that cause sepsis and meningitis could be hitching a ride on mobile phones, allowing them to escape out of healthcare settings and into the community, according to research presented at MLS Future Forum earlier this year.

Khyati Sharma, an undergraduate at Birmingham City University,  presented her research in a poster at the Future Forum, which was held at the ICC Birmingham on March 31 to April 2 with the support of Applied Microbiology International.

Khyati says her findings underscore the need for better awareness around phone hygiene and antimicrobial resistance surveillance outside of traditional hospital settings.

“In 2024, as part of my undergraduate research at Birmingham City University (BCU), I worked on a study to investigate the prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-Es) on mobile phones that are a potential but under-explored abiotic factor for transmitting and spreading antimicrobial resistance in community settings,” she said.

Mobile phones

“I collected and analysed bacterial swab samples from mobile phones belonging to BCU Biomedical Sciences students and staff, aiming to compare bacterial abundance between mobile phones at BCU.

“My findings revealed significant variation in bacterial loads across different phones, indicating that phones being exposed to clinical environments may act as vectors for the spread of ESBL-Es into the wider community. This highlighted a possible route for hospital-associated antimicrobial-resistant bacteria to disseminate beyond healthcare settings. ESBL-E can persist on skin and mobile phones, facilitating their transmission in community. However, quantitative data examining community-associated ESBL-E on mobile phones remain limited.”

Role of skin

A second focus of the study was the role of human skin as a medium for transmission, she said.

“Given the frequent and prolonged contact between hands and mobile phones, I hypothesised that the skin could serve as a favourable environment for ESBL-Es to survive, colonise, and potentially transfer to the human body. My results supported this by demonstrating a higher bacterial abundance on skin.”

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The study addresses the real-world issue of antimicrobial resistance by focusing on ESBL-Es, which are classified by the World Health Organisation as one of the most challenging and high-priority pathogens. 

While ESBL-Es are typically associated with hospital settings, their presence in the community, though limited, can still pose serious health risks including sepsis, meningitis and increased morbidity and mortality rates.

Potential carriers

“Given that mobile phones are used daily by people of all ages, they can act as potential carriers for these resistant bacteria. Although previous studies have shown the presence of ESBL-Es on mobile phones, my study aimed to go further by exploring how transmission might occur by investigating the role of skin to act as a route for bacterial transfer,” Khyati said.

“My findings confirmed low levels of ESBL-Es on phones in the community, but even small amounts on such widely used devices highlight a risk that should not be ignored. The study contributes to understanding how ESBL-Es may spread outside hospital settings and why everyday hygiene practices matter in preventing antimicrobial resistance.”

Swab samples were collected from personal mobile phoneS (front and back), skin (thumb and palm) and community mobile phones of participants from BCU’s Biomedical Sciences course. Samples were collected using sterile PBS-moistened swabs and processed using 10-fold serial dilutions. 

Bacterial methods

These were then plated on Tryptic Soy Agar (TSA) for general bacterial growth and replica plated onto MacConkey (MAC) and Brilliance ESBL agar to isolate Gram-negative and ESBL-producing bacteria. Plates were incubated at 37°C, and colony morphology was used to identify bacterial species. 

A disc diffusion assay was also conducted to assess the antibiotic resistance profile of the ESBL-E isolates where six antibiotic discs - ampicillin, amoxycillin, meropenem, penicillin, gentamicin and colistin sulphate were selected for antimicrobial susceptibility testing.  

The antibiotics were selected based on their clinical relevance and activity against ESBL-Es. Penicillin was included to assess whether its known resistance in ESBL-E, as reported in previous studies, would be observed in the isolates in my study. Colistin sulphate was selected for its effectiveness against a broad range of Gram-negative bacteria. 

Additionally, gentamicin, amoxycillin and ampicillin were chosen due to their common use and susceptibility profiles in ESBL-E infections, while meropenem was included as it is the recommended empirical treatment for ESBL-E associated infections.

Isolated bacteria

Escherichia coli (52%) and Klebsiella pneumoniae (35.2%) were the most isolated bacteria based on colony morphology, consistent with previous literature. Replica plating showed a noticeable reduction in bacterial growth on MAC and ESBL agars compared to TSA, confirming selective isolation. This was expected, as previous studies have shown that Gram-positive bacteria are more prevalent in community environments. Their thicker peptidoglycan cell wall structure provides resistance and enables them to survive more effectively on dry surfaces compared to Gram-negative bacteria. 

The study found that bacterial viability varied weekly and between surfaces, with the skin often showing higher bacterial and ESBL-E counts than the mobile phone. Although ESBL-Es were present in low abundance, their detection across various samples suggests mobile phones may act as a reservoir for these resistant bacteria, and skin contact could facilitate their transmission.

In community samples, one mobile phone had the highest total bacterial count with over 3000 CFU/mL and only 30 CFU/mL ESBL-E viability, while another had the highest ESBL-E viability with 90 CFU/mL and demonstrated 400 CFU/mL on TSA, indicating that bacterial load does not always correlate with resistance risk. 

Antimicrobial susceptibility testing 

Antimicrobial susceptibility testing revealed resistance to ampicillin, amoxicillin, and penicillin, while meropenem and gentamicin remained effective. This was done by comparing the zone of inhibition of antibiotics with the zone diameter breakpoints according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) These findings contribute to growing evidence that even limited levels of ESBL-Es on everyday items like mobile phones could play a role in their spread within the community.

“There were a few things that genuinely surprised me during my study. In the initial stages of testing, I couldn’t detect any ESBL-Es on my samples, which was discouraging at first, especially because students on another project, who were investigating MRSA, were able to identify their target bacteria quite quickly,” Khyati said.

“Since they were working with Gram-positive bacteria, which tend to survive more easily on dry surfaces, it highlighted the difference in environmental resilience between Gram-positive and Gram-negative bacteria.

Surprising finds

“What really surprised me was how comparatively rare ESBL-Es appeared to be in community settings. I came to understand that their survival and transmission are much more dependent on specific environmental conditions such as temperature, skin nutrients and adaptable pH, which likely limits their abundance outside hospital settings. 

“However, as I progressed with my research, I adapted an improvised technique called replica plating to transfer previously established bacterial colonies from TSA to MAC agar. This approach was adopted to elevate the bacterial viability on MAC which may occur due to its selective components such as bile salts and crystal violet. These components can inhibit the growth of bacteria that have adapted to less selective environments such as mobile phone surfaces where conditions are relatively mild. 

“With this technique, I did begin to detect more ESBL-producing bacteria. It was both surprising and concerning that even a small presence of ESBL-Es in the community can be a serious public health threat, due to their resistance to commonly used ß- lactam antibiotics. That really reinforced the importance of monitoring and understanding how these pathogens may spread through everyday items like mobile phones.”

Transmission vectors

The results of this study highlight the important role of mobile phones as potential reservoirs and transmission vectors for ESBL-producing Escherichia coli (ESBL-E. coli) in the community, she said.

“Although Klebsiella pneumoniae was detected, it did not show ESBL production in this study, further emphasising the unique role of E. coli strains in the spread of resistance. Even though the levels of ESBL-E detected were relatively low, their presence on commonly used items such as phones is concerning due to their ability to resist multiple antibiotics and cause severe infections such as UTIs and sepsis. 

“This has real-world implications, as even minimal exposure can contribute to the spread of antimicrobial resistance (AMR), especially in community settings where hygiene protocols are less stringent than in clinical environments.

Watch the thumb

“The comparison of bacterial viability between phones and skin also showed that skin can act as a mediator in transferring bacteria from mobile devices to the human body. The thumb, which frequently contacts phone screens, showed higher bacterial viability due to favourable conditions such as warmth, moisture, and skin nutrients. 

“Conversely, the back of the phone showed more viability than the palm, possibly due to skin defences like acid production and frequent handwashing. This supports the idea that personal habits and environmental conditions directly influence the risk of transmission. 

“The significantly lower growth of Gram-negative bacteria and ESBL-E compared to total bacterial counts also reflects the resilience of Gram-positive bacteria on human skin and dry surfaces but does not eliminate the public health risk posed by even small amounts of resistant Gram-negative organisms.”

AMR in community

The study’s antimicrobial susceptibility results further underline the seriousness of ESBL-E presence in the community, Khyati added. 

“Resistance to commonly used antibiotics like penicillin, ampicillin, and amoxicillin limits treatment options and may lead to prolonged infections and hospital stays. While meropenem and gentamicin remained effective in this study, emerging resistance to aminoglycosides raises concern over narrowing therapeutic options.

“To build on the findings of this study, future research should include molecular confirmation of ESBL-E using techniques such as polymerase chain reaction (PCR). This would help detect specific resistance genes like CTX-M gene to detect genes associated with ESBL-producing bacteria. Molecular characterisation would provide a clearer understanding of resistance patterns and support the development of more targeted and effective treatments.

Next steps

“Another important step would be to expand the sample size and population diversity. This study focused on a small group from the BCU Biomedical Sciences department, which limits how broadly the findings can be applied. Future studies should involve participants from different backgrounds, age groups, and professions to gain a more accurate picture of ESBL-E prevalence and transmission in the community.

“A larger, more diverse dataset combined with genetic testing would strengthen the findings, improve public health awareness, and support strategies to reduce the spread of antimicrobial resistance.”

This study was conducted as part of Khyati’s undergraduate research project at Birmingham City University (BCU). It was led under the supervision and guidance of Dr Isabella Romeo-Melody, whose support and expertise were invaluable throughout the project. The University provided the necessary facilities, and the study was fully supported by BCU as part of the Biomedical Sciences programme. 

“I also received important assistance from the laboratory technicians, who ensured that all reagents, media, and equipment were available and properly maintained throughout the study, allowing me to carry out the practical work safely and efficiently,” she said.