Help Researchers Tackle Antimicrobial Resistance in Tuberculosis

Researchers at the University of Oxford are researching antibiotic resistance in Tuberculosis, and they want help reading MIC plates. You don’t have to fly to England, though–you can do it online! Visit the project Bash the Bug on Zooniverse to learn more, view a short tutorial, and get started.

You can read more about the Bash the Bug project here.

 

 

Antimicrobial Stewardship Down Under

If you’re an infectious disease/antimicrobial stewardship/microbiology geek, then the Australian blog AIMED is relevant to your interests. AIMED focuses on practical antimicrobial prescribing issues of relevance to hospital and community prescribers. It is supported by a local brains trust of General Practitioners, Pharmacologists, Pharmacists, Microbiologists and Infectious Disease Physicians. It also provides internet access to key Hunter New England resources for medical staff including guides to local antibiograms, infection control resources and personnel.

For those who don’t know, AIMED is an acronym for five principles that guide patient treatment with antimicrobials:

  • Antimicrobial selection and dosage
  • Indication for antimicrobial treatment
  • Microbiological assessment
  • Evaluate patient at 48-72 hours
  • Duration should be specified

If you’d like to learn more, check out their blog.

CMS Proposes Rule that Promotes Antibiotic Stewardship

In mid-June, CMS proposed a rule that, in part, will help promote antimicrobial stewardship in hospitals. The 60-day comment period is nearing its end, so if you have thoughts on this proposed rule, let them know.

CMS press release

 

Potential Antimicrobial Therapy Hiding in Plain Sight

Yesterday, Nature published a paper that might help in the fight against MRSA. In a nutshell, German researchers discovered that Staphylococcus lugdunensis–a common bacteria in commensal flora–produces a compound that reduces colonization with MRSA.

From the abstract:

“Notably, human nasal colonization by S. lugdunensis was associated with a significantly reduced S. aureus carriage rate, suggesting that lugdunin or lugdunin-producing commensal bacteria could be valuable for preventing staphylococcal infections.”

 

New Assay to Detect CRE Available

From the press release:

“The U.S. Food and Drug Administration today cleared for marketing the Xpert Carba-R Assay, an infection control aid that tests patient specimens to detect specific genetic markers associated with bacteria that are resistant to Carbapenem antibiotics.”

Read the Cepheid release here.

 

Carbapenem-Resistant Enterobacteriaceae Found in Rio de Janeiro’s Water

Recent studies conducted by Brazilian researchers found “super bacteria” in the waters where Olympic athletes will be competing. According to MercoPress, “The Brazilian group’s lead researcher, Renata Picao, said Rio’s “super bacteria” made its way into the city’s waterways through sewage from local hospitals, due to a lack of basic sanitation in the metropolitan area.”

A recent Lab Medicine podcast discusses laboratory testing for CRE. You can listen to it here.

Maryn McKenna writes extensively about antimicrobial resistance. You can watch to her recent TED talk (or read the transcript) to learn why the presence of CRE in Rio’s water is so concerning.

The World’s Most Ambitious Superbug

Researchers from the Walter Reed National Military Medical Center in Maryland discovered a strain of E. coli that carried 15 different genes that confer antibiotic resistance, including the resistance factor MCR, which confers resistance to colistin, a drug of last resort.

This particular E. coli was recovered from the urine of a 49-year-old woman.

The paper is currently available as an accepted manuscript posted online.

You can read Maryn McKenna’s report here.

 

Microbiology Case Study: 22 Year Old Male with Dysuria

A 22 year old male, treated for gonorrhea one month ago, presents with two days of dysuria and white penile discharge. He reported complete resolution of his symptoms with treatment. He has had sexual contact with 2 partners in the past month.

Cultures are taken and the following is seen on gram stain.

N. gonorrhoeae is a gram negative diplococci responsible for the disease of gonorrhea. Though most specimens for gonorrhea are received from sources suspected of having the disease, it should be noted that whenever dealing with a gram negative diplococci of unknown source, care should be taken, and the specimen should be handled under a hood for possible exposure to N. meningitidis.
N. gonorrhoeae is a gram negative diplococci responsible for the disease of gonorrhea. Though most specimens for gonorrhea are received from sources suspected of having the disease, it should be noted that whenever dealing with a gram negative diplococci of unknown source, care should be taken, and the specimen should be handled under a hood for possible exposure to N. meningitidis.

Seems like a clear cut case of gonorrhea, but given the patient’s history is this treatment failure, or likely reinfection?

The CDC has warned that rates of antibiotic resistant gonorrhea are on the rise. A once easily curable disease, is now becoming resistant to our mainstay treatment of ceftriaxone and azithromycin. Although cases have been reported, the majority of ‘failure of treatment’ scenarios are likely re-infection. Patients likely do not abstain until they are symptom free, or the partner may not be treated, leading to a reinfection of the patient. In the event of treatment failure, the CDC even recommends re-treating with the same ceftriaxone/azithromycin regiment. It is still recommended that a sample be taken for culture in the event that there is any concern over failure of treatment and possible antibiotic resistance.

Historically, testing for N. gonorrhoeae consisted of culture and gram stain, but the CDC now recommends testing for gonorrhea with nucleic acid amplification testing (NAAT). This test has improved sensitivity, less subjectivity and a much faster turnaround time than gram staining and culturing. It cannot, however, be used for test of cure, as the NAAT tests for DNA, which still may be present, even if the organisms have been killed within the host, leading to a false positive result.

When a clinician suspects gonorrhea, he or she should take care with what site the specimen is being collected from, and what sample is specifically needed. This lab is validated for only certain types of specimens, and it is important to communicate with the clinicians to ensure the proper specimens are being submitted.

The CDC states that the optimal samples should be vaginal swabs for women, and first catch urine for men. Great care should be used when collecting the ‘first catch urine’ as this is a dirty catch, and that some tests have specific requirements about quantity. For instance, at this lab, we require no more than 30 ml of urine. Any more volume could dilute the specimen which could cause a false negative result.

If a culture is required in the event of treatment failure, it is best if the clinician innoculates the sample directly onto Thayer Martin agar (or chocolate agar if that is all that is available). Given that N. gonorrhoeae is such a labile organism, it need special media to grow, and great care must be taken with transport. This lab recomends inoculating onto the Jembec plates (Thayer Martin media with a CO2 pellet) allowing survival during transport.

N. gonorrhoeae inoculated directley onto the Jembec plate
N. gonorrhoeae inoculated directly onto the Jembec plate
Cultures can also be innoculated onto chocolate agar. Notice the smaller grey colonies, which is the N. gonorrhoeae.  Notice the other colonies on the plate, as chocolate agar is not a selective medium.
Cultures can also be innoculated onto chocolate agar. Notice the smaller grey colonies, which is the N. gonorrhoeae. Notice the other colonies on the plate, as chocolate agar is not a selective medium.

In conclusion, although the majority of cases of gonorrhea treatment failure are likely to be due to re-infection, antibiotic resistance is still of growing concern and clinicians should know when a culture is necessary for antibiotic sensitivity testing. N. gonorrhoeae requires nutrient supplementation for growth, either on Thayer Martin media, or chocolate agar. Care must be taken when sampling and transporting the specimen. Clinicians also need to be aware of the requirements for sample collection for NAATs, as it is not always clear as to why one can’t simply run a test on a sample greater than 30 ml, or a clean catch urine.

-Rich Smith is a Pathology Student Fellow at University of Vermont Medical Center.

Wojewoda-small

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

Antimicrobial Testing–Are We Doing it Wrong?

Antibiotic resistance is a huge concern for microbiologists. In addition to stewardship programs and regulating agricultural use of antibiotics, is it time to re-examine clinical testing paradigms?

A recent study suggests that the typical way microbiologists test for antibiotic susceptibility–meuller-hinton plates and antibiotic disks–might be fallible. When his team tested Salmonella against polymyxin using typical methods, the organism tested sensitive; when the tested the same organism against the same antibiotic using medium that more closely resembled human cells, the organism tested resistant.

Bloomberg Business discusses the paper here. The article is worth your time, even if the info-graphic gives erroneous information (it mentions meuller-hinton broth instead of meuller-hinton agar plates).

An Interactive Tool to See Antibacterial Resistance Over Time

Do you need to know the percentage of Salmonella Typhi resistant to nalidixic acid in California in 2001? A resource now exists that can give you that answer.

The Centers for Disease Control (CDC) has released a tool called National Antimicrobial Resistance Monitoring System (NARMS) Now: Human Data, and it allows users to access antimicrobial resistance data based on year and geographical region. The interactive site tracks resistance for four bacteria that cause foodborne illness: Salmonella, Shigella, Campylobacter, and E. coli O157.