Bacteria Run Wild, Defying Antibiotics

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March 2, 2004Bacteria Run Wild, Defying AntibioticsBy ABIGAIL ZUGER

 

A new chapter in the continuing story of antibiotic resistance is being written

in doctors' offices across the country, as a group of common bacteria rapidly

becomes resistant to the antibiotics that have been used to treat them for

decades.

 

The bacteria are called Staphylococcus aureus, or staph for short. Staph are the

most common cause of skin infections like boils and can also cause lung

infections, bloodstream infections and abscesses in the body's internal organs.

 

In hospitalized patients, infections caused by antibiotic-resistant staph have

been common for years. Among healthy people, though, antibiotic resistance in

staph has not been a big problem. Since the 1970's, doctors have routinely, and

successfully, treated staph infections in healthy patients with penicillin-like

drugs.

 

Not anymore. Office doctors who follow this practice now may find their patients

getting sicker instead of better.

 

Over the last year, Dr. John Gullett, an infectious disease specialist in

Abilene, Tex., has grown accustomed to getting calls for help from local doctors

who have used the usual antibiotics to no effect.

 

One doctor treated a high school football player " built like Charles Atlas " with

a standard oral antibiotic for a little boil in the groin. Even though the

teenager was the picture of health, the antibiotic did not work.

 

The boil, caused by resistant staph, grew into an large abscess tracking into

the leg, and the patient got sicker and sicker. Only when Dr. Gullett treated

him with an intravenous antibiotic generally reserved for desperately ill

hospitalized patients did he turn the corner.

 

Had the patient's first doctor been aware that the infection was caused by

resistant staph and chosen a different oral antibiotic, the entire episode might

have been milder.

 

Resistant staph, Dr. Gullet said, are " more invasive and more pervasive " than

the strains most primary care doctors are used to treating.

 

Dr. Gonzalo Ballon-Landa, an infectious disease specialist at Mercy Hospital in

San Diego, said he was " very concerned about what we are seeing. "

 

Dr. Ballon-Landa has treated clusters of infections from resistant staph in such

disparate groups as prisoners, homeless people, student nurses and football

players.

 

" Most doctors are just not aware of this, " said Dr. Bonnie Bock, an infectious

disease specialist in Newport Beach, Calif., who has treated resistant staph

infections in groups of secretaries, surfers and gay men.

 

Dr. Bock estimated that about two-thirds of the large staph abscesses she saw in

her office now were caused by the resistant bacteria.

 

Over all, staph infections are extremely common and often quite minor. Even

staph abscesses, if they are drained properly, may heal without requiring any

antibiotics at all. The new resistant staph can be treated with several common

antibiotics — just not the ones doctors are accustomed to using.

 

Still, the experts say that some infections caused by the new resistant staph

are unexpectedly aggressive, and delays in starting the right antibiotics may be

life-threatening.

 

" Staph infections are such a common problem that the emergence of infections

resistant to common antibiotics has important public health implications, " said

Dr. Daniel B. Jernigan, an epidemiologist at the federal Centers for Disease

Control and Prevention.

 

But the infections are so common that they are not reportable to the local or

federal public health authorities. Because of this, detective work to explain

the appearance of the new resistant staph in this country and track its progress

is just beginning.

 

The resistant staph was first recognized in the United States among children in

Chicago in the mid-1990's. In 1999, the disease control centers reported that

four children in the Midwest had died of infections with the new staph. Three of

them had initially been treated with the wrong antibiotics.

 

In the last several years, clusters of infections with the resistant staph have

been reported in jails and prisons in states around the country, including

California, Texas, Pennsylvania and Georgia. Clusters of skin infections have

also been reported among athletic team members and military recruits.

 

Pediatricians in Miami and Los Angeles have found that 20 percent to 30 percent

of the serious staph infections they see in nonhospitalized children are caused

by resistant strains. In Houston, rates in children have approached 50 percent.

 

In the spring of 2002, the health department in Los Angeles learned of a cluster

of resistant staph infections in a group of healthy newborn babies, followed in

rapid succession by an outbreak at the county jail that eventually involved more

than 1,000 inmates, a cluster of infections in a professional football team, and

a cluster of infections among gay men, said Dr. Elizabeth Bancroft, a medical

epidemiologist with the Los Angeles County Department of Health Services.

 

Although these infected groups had nothing at all to do with one another, the

bacteria that caused the infections in each group proved to be virtually

identical. Since 2002, the prevalence of the resistant staph in Los Angeles has

increased enormously, Dr. Bancroft said.

 

Like epidemiologists all over the country, Dr. Bancroft is puzzled by the origin

of the resistant staph and the way it can spread so quickly among such diverse

populations.

 

One clue may be the bacteria's tendency to " ping-pong " among people, she said.

In a study of children with infections caused by the new resistant staph, her

group found that roughly 30 percent had family members with similar infections

around the same time, suggesting that the staph was highly contagious and easily

passed from one person's skin to another's.

 

The one thing that newborns, children, prisoners and athletes have in common is

the degree of close body contact they maintain with those around them. They also

share common objects with their peers, toys and equipment, for example, or soap

and towels. They may have difficulty achieving optimal personal hygiene.

 

Close living, as in military barracks, also appears to be a risk factor for

infection with the resistant staph, as does having any kind of skin abrasion or

wound, even one as minor as chafing from underclothing or athletic equipment,

Dr. Jernigan said.

 

This winter, several fatal cases of pneumonia caused by the resistant staph

developed in children with influenza, presumably because the influenza infection

had damaged their lungs, allowing the staph to grow.

 

Experts are still grappling with the question of where the resistant staph came

from in the first place. It does not appear to have arisen in any of the most

common ways.

 

Antibiotic-resistant bacteria often develop when people take many antibiotics,

or frequent places like hospitals, where many antibiotics are used. The

antibiotics kill off the sensitive bacteria in people's mouths, intestines and

skin, and the bacteria that are naturally resistant to the antibiotics thrive,

and eventually predominate.

 

But this process, called " antibiotic pressure " cannot explain the emergence of

the new resistant staph, because among the general public where these infections

appear there is relatively little antibiotic use, and many people with these

infections have never taken antibiotics before.

 

Did the bacteria simply escape from hospitals, where antibiotic-resistant staph

have been a problem for years? A great deal of evidence suggests that they did

not, Dr. Jernigan said.

 

The outpatient strains are biologically different from hospital strains, and the

collections of genes that cause antibiotic resistance in the new strains are

quite different from those that cause it in the older strains.

 

Another ominous difference between the new resistant staph and the old hospital

strains is that the new staph strains appear far more likely to manufacture a

toxin that can destroy the white blood cells that normally fight off infection,

allowing the bacteria to eat through human tissue.

 

" The concern is that this or other toxins may be responsible for their increased

virulence, " said Dr. Franklin D. Lowy, a staph researcher at Columbia

University's College of Physicians and Surgeons in New York, who heads one of

five groups around the country financed by the disease control centers to study

the new staph.

 

" The organism also appears able to replicate more rapidly than others, which may

also cause more serious disease, " Dr. Lowy said.

 

As an example, he described a middle-aged woman with diabetes whom he cared for

recently. The woman developed pneumonia with the new staph, and wound up

spending months on a respirator in the intensive care unit, her lungs shredded

and useless from the infection.

 

Experts say that heightening doctors' awareness is crucial to tracking and

fighting the new staph.

 

Staph infections are so common that doctors often just prescribe an antibiotic

without bothering to drain collections of pus and take cultures. Now they may

need to take cultures routinely, and possibly change the usual antibiotics they

prescribe.

 

Patients, meanwhile, should know that mistaking a staph skin infection for an

insect bite, particularly a spider bite, is an extremely common mistake, said

Dr. Bancroft in Los Angeles, and may lead to delays in treatment.

 

A skin infection that worsens even with treatment should alert patients to the

possibility of drug resistance. The new staph is resistant to such common

antibiotics as Keflex and Rocephin. It is treated with antibiotics like Bactrim,

Vibramycin and Cleocin.

 

Hospitals curb antibiotic-resistant organisms by taking a variety of

precautions, including preventing an infected person from skin contact with

others, disinfecting shared objects, and sometimes using antiseptics like

chlorhexidine to rid the skin and other body sites of resistant staph.

 

It is possible, Dr. Jernigan said, that these measures may now be needed to

control resistant staph infections out of the hospital, too.

 

Copyright 2004 The New York Times Company

 

 

 

 

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