Part V—Eureka! Mark cautiously pushed open the door to the microbiology lab and
ID: 213650 • Letter: P
Question
Part V—Eureka! Mark cautiously pushed open the door to the microbiology lab and glanced around the room. He could just make out the top of Anne’s head, barely visible behind several tall stacks of multi-hued bacteriological media as she bent over a culture. “Don’t these people ever sleep?” he wondered, simultaneously admitting to himself that his night had not been exactly restful. Mark cleared his throat, hoping to get her attention without appearing too eager. Anne looked up, smiled, and set aside the culture she had been examining. “Any new information on those nursery cultures, Ms. Mosel?” “Oh, yes, of course, Dr. Maddison. We called the report up to the fl oor earlier this morning. Let me show you what we found.” She pulled a microscope slide from a small cardboard box and placed it under her microscope. “Take a look for yourself.” Mark sat down and began to scan the slide. Spread out across it was a sea of round purple spheres that looked like those he had seen on yesterday’s slide of the lesions. “So many,” he observed. “Yes,” Anne responded. “This smear was taken from a culture plate, so there will be a large number of organisms. Here are the plates, if you’d like to have a look.” Mark picked up the sheep blood plate fi rst. It was covered with round, opaque creamy colonies. He held the plate up to the light to get a better look and noticed that there was a halo around each tiny colony where the sheep blood appeared to be missing from the agar. The plate labeled “PEA” looked nearly identical. Mark sniffed the plate, enjoying the scent, which reminded him of the Rose Milk lotion his grandmother used to use. Finally, he picked up the lavender plate labeled “MAC” and held it up to the light. Except for the tracks left in the pattern of the microbiologist’s inoculating needle, the plate looked completely barren. “We performed catalase testing on the isolate,” interjected Anne. “You should have seen the way it bubbled! We have a rapid agglutination test in this laboratory that we used instead of the coagulase test. This isolate was a strong positive. There’s no doubt about its identity now, is there?” Mark closed his eyes and rubbed his temples in an attempt to dislodge the buried bits of information. “Why, it looks for all the world like Staphylococcus aureus!” he said, surprised by the confi dence of his answer. “Exactly!” replied Anne. “We have antimicrobial susceptibility testing already set up and running. Using our automated system, we may have the results available later today.” “Great day in the morning!” Mark jumped up from his seat, grabbed the shoulders of a very startled Anne Mosel, and planted a kiss right in the middle of her forehead. He then turned, tossed open the laboratory door, and trotted down the hallway toward the medical library. Back in the library, Dr. Maddison went straight to the small pile of reference books he had been working with the previous evening. Choosing a likely looking volume entitled Pediatric Infectious Disease, he looked up Staphylococcus aureus in the index. There were about a dozen pages listed. “Hmmm, impetigo is less generalized than these babies are showing… food poisoning in breast-fed babies just doesn’t sound right at all….” Mark continued to fl ip pages, more and more impatiently. Abruptly, he turned a page and met the gaze of a newborn staring unfl inchingly out at him. Except for the tiny hat stenciled with the name of an unknown hospital, the newborn could have been one of his patients in the nursery. The baby was pictured lying in a crib naked except for the hat. There was an angry looking rash extending from the baby’s groin upward to above his umbilicus. The skin had peeled away from the rash, leaving a moist, bright red surface. The caption read “Neonatal Staphylococcal Scalded Skin Syndrome.” “Hmmm,” Mark muttered. “I know that staphylococci can cause some wicked wound infections, but why the rash?” He scanned the chapter looking for information about the disease mechanism. “Of course. There’s a toxin, an exfoliatin, that’s causing the skin to peel away.” He continued reading: When treating staphylococcal scalded skin syndrome, the fi rst goal is to stabilize the patient through measures such as rehydration. Elimination of the offending S. aureus is the next goal. Most commonly, and in more serious cases, intravenous antibiotics are administered, including beta-lactamase resistant penicillins, fi rst generation cephalosporins, macrolides, and aminoglycosides. With treatment, the prognosis for children is excellent. “Time to write some orders!” Dr. Maddison pushed back his chair and strode down the hall toward the nursery. As he entered, he could see that Bill Alkin was there trying to soothe Mrs. Levi. The Willis parents were still staring mournfully down into the twins’ isolettes. Nurse Benoit glanced resignedly at him. “Good morning, everyone! How are our patients doing today?” Mark walked over to the Levi baby’s chart and fl ipped it open. “Good news, Mrs. Levi, we have a diagnosis for Lilly, and I am prescribing a medication that should have her skin back to its former beauty in just a few days. Mr. and Mrs. Willis, your little ones should be on the mend very soon, too.” Mark pulled Bill aside and discreetly murmured, “We still need to work with the health department to trace the source for this organism. I’d like to collect nasal swabs from anyone who has had contact with these babies. Clinic staff, including myself, are the most likely source.” Bill’s eyes darted furtively to the others in the room as he whispered, “You won’t mention this to anyone else, of course.” He placed his hand on Mark’s shoulder. “I knew we could count on you, Mark.” “Sure, Bill. Thanks,” Mark answered wryly. The nursery phone rang and Mark walked over to answer it. He could hear static and then, faintly in the background, Dr. Elridge’s voice. “Mark, is that you? I only have a few seconds on this line. I’ve just returned from the summit! I’m having the time of my life! How is everything there?” “Well, hello, Explorer! Everything’s under control here, Jullie. I’ll fi ll you in when you get home. Have a great time!” Questions 1. Many people, especially healthcare workers, carry Staphylococcus aureus in the anterior nares. How, then, are infections passed from these caregivers to their patients? How can transmission be prevented? 2. Tracing the source of an outbreak of Staphylococcus aureus often involves a technique known as phage typing. What is phage typing, and how could it help to understand an individual outbreak?
Explanation / Answer
Staphylococcus aureus is an important source for hospital borne infection which spreads in patients. They are usually found at the anterior nares. They are mainly spread from caregivers to pateints by sneezing, or inhaling the droplets containing the pathogen, or by direct contact and though the use of contaminated object like medical devices.
To prevent the spread of Staphylococcus aureus several strategies can be taken. Such as-
1. Using gloves where required and proper washing of hands with soap and disinfactant after touching contaminated objecs or inbetween visiting pateints.
2. Using of nose and mouse protection while visiting pateints.
3.Proper hygenic handeling of used material from pateints.
4. isolation of infected pateint .
2.Viruses which can infect bacteria are called bacteriophage or phage. Now, sometimes a single type of phage can only attack a partcular strain of bacteria. The method which is then used to identify that particular species in presence of bacteriophage is called phage typing. To perform phage typeng mixed bacterial population were grown of agar medium and the areas are marked in a petridish. Next phages are added as drops on the bacterial colony and dried for specific time. If a particular phage is able to infect a single strain pf bacteria, there will be presence of a ring like structure aroung that bacteria colony.