How bugs become superbugs

CNN's Elizabeth Cohen explains how superbugs are formed when bacteria become resistant to antibiotics.

Posted: Aug 8, 2018 9:56 PM
Updated: Aug 8, 2018 10:24 PM

In hospitals, one bacterial species is becoming increasingly tolerant to the alcohols used in hand sanitizers, according to research published Wednesday in the journal Science Translational Medicine.

Globally, hospitals use isopropyl or ethyl alcohol-based disinfectants, such as hand rubs, to prevent patients from becoming sick from many germs. These are the same active ingredients found in hand sanitizers available for personal use and at schools -- but that doesn't mean people should give up on them.

The bacterium Enterococcus faecium resides in our guts, but if encountered in a hospital, it can cause various complicated infections affecting the abdomen, skin, urinary tract and blood. This particular bug is a member of the Enterococci family, which ranks as the fourth and fifth leading cause of sepsis, a life-threatening bloodstream infection, in North America and Europe, respectively.

Many hospital-acquired infections have decreased or been kept in check by Australia's strict hygiene practices that rely on alcohol-based hand sanitizers. Yet drug-resistant E. faecium infections have increased in Australian hospitals over time, according to the study authors.

This alarming pattern prompted them to investigate whether E. faecium might be developing resistance to the alcohols used in hand rubs.

Another form of resistance

The researchers analyzed 139 bacterial samples from two Melbourne hospitals collected over 19 years ending in 2015. They studied how well each sample survived when exposed to diluted isopropyl alcohol.

The isolates gathered after 2009 were, on average, more tolerant to the alcohol compared with bacteria taken from before 2004, the researchers discovered. Conducting mice experiments and further analysis, they also saw that alcohol-tolerant bacterial samples harbored several genetic mutations involved in metabolism, which made them better equipped to live in the gut.

Although the results suggest that microbes can adapt to alcohols and other ingredients found in disinfectants, this conclusion cannot be drawn until more research is done, the researchers warn.

"There are two things we are working on," said Tim Stinear, a co-author of the study and professor at the University of Melbourne. "One is understanding exactly how the bacteria are becoming more tolerant. ... The second is what's going on in other parts of the world, and we are working with colleagues around the world to address that."

One-third of all enterococcal infections in Australian hospitals are caused by E. faecium, according to Stinear and his co-authors. Of these, 90% were ampicillin-resistant strains, and half of those were resistant to vancomycin, another common antibiotic. Even when doctors try a higher-grade antibiotic to treat such illnesses, the outcome may be further drug resistance -- and a longer-lasting infection for the patient.

Study co-author Paul Johnson, an infectious diseases professor and director of research at Austin Health in Melbourne, said that when it comes to preventing certain outbreaks, including vancomycin-resistant enterococci, hospitals might need to use more than standard precautions such as hand hygiene.

"We might need to specifically add additional control measures," he said. Such measures could include using an additional bacteria-killing agent, such as chlorhexidine, to sanitize hands in some medical care settings.

True perhaps in hospitals, but the same might not apply to the world at large.

Don't throw away the hand sanitizer

"The bottom line is, this is a really good study," said James Scott, a professor at the Dalla Lana School of Public Health at the University of Toronto.

"It's one of these things that microbiologists thought might happen for a long time, but no one really bothered to test it," said Scott, who did not participate in the research. Now, he said, it's "pretty clear" that alcohol-resistance does happen.

Yet, he added, the results might not translate to the everyday use of hand sanitizers.

"The germs that were tested in this study are really hospital-based germs, not the kind of thing you would encounter in the community routinely," he said. In the community, people use hand sanitizers to kill germs that spread foodborne illness, such as listeria and salmonella.

"The hospital situation is very different," he said, explaining that in the closed environment of a hospital with highly susceptible patients, there's an opportunity for organisms to evolve. "It can lead over time to a growth in resistance."

"Rubbing alcohol has long been used in medicine as a disinfectant for skin surfaces and environmental surfaces," Scott said. "It has been generally thought that rubbing alcohol was fairly safe from the emergence of resistance amid susceptible germs. This interesting and carefully done study refutes that assumption."

Scientists have known for a long time that rubbing alcohol is not a universal disinfectant, because a number of important germs are highly resistant to disinfection by alcohol, he said. One example: "Clostridium difficile, an agent of serious diarrheal disease responsible for hospital outbreaks."

"It is important for people to understand that this study is specifically concerned with one particular germ that is increasingly implicated in hospital-acquired infections," Scott said. "This study really only applies to the specific environment of hospitals, and I'm confident that alcohol-based disinfectants will continue to remain highly effective in general use."

Mississippi Coronavirus Cases

Data is updated nightly.

Cases: 319704

Reported Deaths: 7369
CountyCasesDeaths
DeSoto22276267
Hinds20677421
Harrison18407317
Rankin13880282
Jackson13689248
Madison10249224
Lee10056176
Jones8464167
Forrest7827153
Lauderdale7260242
Lowndes6509150
Lamar634888
Lafayette6310121
Washington5420137
Bolivar4837133
Panola4669110
Oktibbeha466098
Pearl River4604147
Marshall4573105
Warren4440121
Pontotoc425373
Union415777
Monroe4155135
Neshoba4061179
Lincoln4008112
Hancock386687
Leflore3515125
Tate342486
Sunflower339491
Pike3369111
Alcorn325972
Scott320174
Yazoo314171
Adams307486
Itawamba305178
Copiah299966
Coahoma298784
Simpson298189
Tippah291968
Prentiss283861
Leake271974
Marion271280
Covington267283
Wayne264442
Grenada264087
George252051
Newton248663
Tishomingo231568
Winston229981
Jasper222148
Attala215073
Chickasaw210559
Holmes190374
Clay187854
Stone187833
Tallahatchie180041
Clarke178980
Calhoun174132
Yalobusha167840
Smith164034
Walthall135347
Greene131833
Lawrence131024
Montgomery128643
Noxubee128034
Perry127138
Amite126342
Carroll122330
Webster115032
Jefferson Davis108033
Tunica108027
Claiborne103130
Benton102325
Humphreys97533
Kemper96629
Franklin85023
Quitman82216
Choctaw79118
Wilkinson69532
Jefferson66228
Sharkey50917
Issaquena1696
Unassigned00

Alabama Coronavirus Cases

Cases: 548323

Reported Deaths: 11288
CountyCasesDeaths
Jefferson809531565
Mobile42066826
Madison35663525
Tuscaloosa26162458
Shelby25595254
Montgomery25081612
Baldwin21839313
Lee16265176
Calhoun14718325
Morgan14626285
Etowah14171363
Marshall12449230
Houston10764288
Elmore10295213
Limestone10182157
St. Clair10160251
Cullman9941201
Lauderdale9596249
DeKalb8967189
Talladega8458184
Walker7335280
Autauga7230113
Blount6944139
Jackson6922113
Colbert6414140
Coffee5627127
Dale4929114
Russell454941
Chilton4472116
Franklin431083
Covington4273122
Tallapoosa4136155
Escambia401780
Chambers3726124
Dallas3607156
Clarke352961
Marion3242106
Pike314078
Lawrence3129100
Winston283572
Bibb268464
Geneva257581
Marengo250665
Pickens236862
Barbour234659
Hale226878
Butler224071
Fayette218162
Henry193843
Cherokee187245
Randolph187044
Monroe179341
Washington170439
Macon162951
Clay160159
Crenshaw155657
Cleburne153244
Lamar146537
Lowndes142054
Wilcox127030
Bullock124242
Conecuh113430
Coosa111429
Perry108626
Sumter105732
Greene93534
Choctaw62025
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We continue to monitor a tropical disturbance in the Gulf of Mexico. This will be in heavy rainfall two locations across the southeast over the course of the weekend, and flooding rainfall could be in tow as well. Things are looking better for Father’s Day itself, thankfully.
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