Genomic Analysis of a Pan-Resistant Isolate of Klebsiella pneumoniae, United States 2016.

Antimicrobial resistance is a threat to public health globally and leads to an estimated 23,000 deaths annually in the United States alone. Here, we report the genomic characterization of an unusual Klebsiella pneumoniae, nonsusceptible to all 26 antibiotics tested, that was isolated from a U.S. PATIENT: The isolate harbored four known beta-lactamase genes, including plasmid-mediated blaNDM-1 and blaCMY-6, as well as chromosomal blaCTX-M-15 and blaSHV-28, which accounted for resistance to all beta-lactams tested. In addition, sequence analysis identified mechanisms that could explain all other reported nonsusceptibility results, including nonsusceptibility to colistin, tigecycline, and chloramphenicol. Two plasmids, IncA/C2 and IncFIB, were closely related to mobile elements described previously and isolated from Gram-negative bacteria from China, Nepal, India, the United States, and Kenya, suggesting possible origins of the isolate and plasmids. This is one of the first K. pneumoniae isolates in the United States to have been reported to the Centers for Disease Control and Prevention (CDC) as nonsusceptible to all drugs tested, including all beta-lactams, colistin, and tigecycline.IMPORTANCE Antimicrobial resistance is a major public health threat worldwide. Bacteria that are nonsusceptible or resistant to all antimicrobials available are of major concern to patients and the public because of lack of treatment options and potential for spread. A Klebsiella pneumoniae strain that was nonsusceptible to all tested antibiotics was isolated from a U.S. PATIENT: Mechanisms that could explain all observed phenotypic antimicrobial resistance phenotypes, including resistance to colistin and beta-lactams, were identified through whole-genome sequencing. The large variety of resistance determinants identified demonstrates the usefulness of whole-genome sequencing for detecting these genes in an outbreak response. Sequencing of isolates with rare and unusual phenotypes can provide information on how these extremely resistant isolates develop, including whether resistance is acquired on mobile elements or accumulated through chromosomal mutations. Moreover, this provides further insight into not only detecting these highly resistant organisms but also preventing their spread.

Meningococcal carriage among Georgia and Maryland high school students.

BACKGROUND: Meningococcal disease incidence in the United States is at an all-time low. In a previous study of Georgia high school students, meningococcal carriage prevalence was 7%. The purpose of this study was to measure the impact of a meningococcal conjugate vaccine on serogroup Y meningococcal carriage and to define the dynamics of carriage in high school students. METHODS: This was a prospective cohort study at 8 high schools, 4 each in Maryland and Georgia, during a school year. Students at participating schools received quadrivalent meningococcal conjugate vaccine that uses diphtheria toxoid as the protein carrier (MCV4-DT). In each state, 2 high schools were randomly assigned for MCV4-DT receipt by students at the beginning of the study, and 2 were randomly assigned for MCV4-DT receipt at the end. Oropharyngeal swab cultures for meningococcal carriage were performed 3 times during the school year. RESULTS: Among 3311 students, the prevalence of meningococcal carriage was 3.21%-4.01%. Phenotypically nongroupable strains accounted for 88% of carriage isolates. There were only 5 observed acquisitions of serogroup Y strains during the study; therefore, the impact of MCV4-DT on meningococcal carriage could not be determined. CONCLUSIONS: Meningococcal carriage rates in US high school students were lower than expected, and the vast majority of strains did not express capsule. These findings may help explain the historically low incidence of meningococcal disease in the United States.

Diversity of factor H-binding protein in Neisseria meningitidis carriage isolates.

Several meningococcal vaccines under development for prevention of serogroup B disease target the factor H-binding protein (FHbp), an immunogenic lipoprotein expressed on the surface of Neisseria meningitidis. Based upon sequence and phylogenetic analyses, FHbp can be classified into 3 protein variants (1, 2 or 3) or 2 subfamilies (A or B). The potential effect of FHbp-containing vaccines on meningococcal carriage is not known. We determined the diversity of FHbp among a population of carriage isolates obtained from Georgia and Maryland high school students in 1998 and 2006-2007. Analysis of the fHbp gene sequence from 408 carriage isolates identified 30 different FHbp protein sequences. The majority of carriage isolates harbored FHbp proteins belonging to variant 2/subfamily A. Association between FHbp proteins and genetic lineage was observed among the carriage isolates. However, split decomposition analysis, together with tests of linkage disequilibrium and pairwise homoplasy suggest recombination at fHbp contribute to allelic diversity. Of note, the FHbp proteins in serogroup B vaccines under development are either absent or not well represented in this carriage population. The FHbp genetic repertoire observed in carriage isolate populations will be useful in understanding the potential impact of FHbp-containing vaccines on meningococcal carriage.

Cost-effectiveness of different strategies for amplified Mycobacterium tuberculosis direct testing for cases of pulmonary tuberculosis.

We conducted a decision analysis to assess and compare four algorithms for amplified Mycobacterium tuberculosis direct (MTD) testing of respiratory specimens in terms of cost-effectiveness. The most cost-effective strategy was one in which smear-positive specimens but not smear-negative specimens were diluted prior to MTD testing.

Specimen dilution improves sensitivity of the amplified Mycobacterium tuberculosis direct test for smear microscopy-positive respiratory specimens.

Specimen dilution has been proposed as a strategy to minimize amplified Mycobacterium tuberculosis direct (MTD) test inhibition (N. Pollock, J. Westerling, and A. Sloutsky, Am. J. Clin. Pathol. 126:142-147, 2006; A. Sloutsky, L. L. Han, and B. G. Werner, J. Clin. Microbiol. 42:1547-1551, 2004). We evaluated the impact of respiratory specimen dilution on MTD test accuracy in a public health laboratory. The difference in MTD test sensitivity between the dilution and conventional methods was 15.9% (P = 0.001) for smear microscopy-positive specimens and -3.6% (P = 0.38) for smear microscopy-negative specimens.

Use of the amplified mycobacterium tuberculosis direct test in a public health laboratory: test performance and impact on clinical care.

BACKGROUND: The Amplified Mycobacterium tuberculosis Direct Test (MTD; Gen-Probe; San Diego, CA) is a nucleic-acid amplification test for rapid pulmonary tuberculosis (PTB) diagnosis. In a routine public health setting, test accuracy and impact on clinical decisions are unknown. METHODS: Retrospectively, we evaluated MTD accuracy and impact on clinical decisions in a public health setting. To estimate MTD accuracy, mycobacterial culture was used as the "gold standard." To evaluate MTD impact on clinical decisions, concordance of clinician presumptive diagnosis (at time of MTD and smear availability) and definitive diagnosis, and duration of nonindicated tuberculosis therapy were determined for smear-positive PTB suspects in a period of MTD availability (MTD group) and a prior period of MTD nonavailability (non-MTD group). RESULTS: A total of 1,151 respiratory specimens from 638 PTB suspects were analyzed. MTD sensitivity, specificity, positive predictive value, and negative predictive value were 91.7%, 98.7%, 96.7%, and 96.5% overall, respectively; and 98.7%, 97.8%, 98.7%, and 97.8% for smear-positive patients; and 62.2%, 98.9%, 85.2%, and 96.1% for smear-negative patients. In the MTD group, concordance between definitive and clinician presumptive diagnoses was 78% (95% confidence interval [CI], 64 to 88%), similar to that for the non-MTD group (79%; 95% CI, 68.4 to 89.6%). However, concordance between definitive diagnosis and the MTD test was 98% (95% CI, 94.1 to 100%). Median duration of nonindicated tuberculosis treatment was 6 days for the MTD group vs 31 days for the non-MTD group (p = 0.002). CONCLUSION: In this public health setting, MTD was accurate and rapidly detected more than half of the smear-negative PTB cases. For smear-positive PTB suspects, MTD had excellent concordance with definitive diagnosis, but clinicians often inappropriately initiated TB therapy despite a negative MTD result.

Effect of human immunodeficiency virus-1 infection on treatment outcome of acute salpingitis.

OBJECTIVE: To examine the effect of human immunodeficiency virus (HIV)-1 infection on treatment outcome of laparoscopically verified acute salpingitis. METHODS: Women aged 18-40 years with laparoscopically verified acute salpingitis received antibiotic therapy that included cefotetan 2 g intravenously and doxycycline 100 mg orally every 12 hours and laparoscopically guided drainage of tuboovarian abscesses of 4 cm or more. Clinical investigators blinded to HIV-1 serostatus used predetermined clinical criteria, including calculation of a clinical severity score and a standard treatment protocol to assess response to therapy. RESULTS: Of the 140 women with laparoscopically confirmed acute salpingitis, 61 (44%) women had mild, 38 (27%) had moderate, and 41 (29%) had severe disease (ie, pyosalpinx, tuboovarian abscesses, or both). Fifty-three (38%) were HIV-1-infected. Severe disease was more common in HIV-1-infected in comparison with HIV-1-uninfected women (20 [38%] compared with 21 [24%], P = .02). Defined as time of hospital discharge or 75% or more reduction in baseline clinical severity score, HIV-1-infected women with severe (6 days [4-16] compared with 5 days [3-9], P = .09) but not those with either mild (4 days [2-6] compared with 4 days [2-6] P = .4) or moderate salpingitis (4 days [3-7] compared with 4 days [3-6] P = .32) tended to take longer to meet criteria for clinical improvement. The need for intravenous clindamycin or additional surgery was not different in HIV-1-infected and uninfected cases (15 [28%] compared with 18 [21%], P = .3). CONCLUSION: Although HIV-1 infection may prolong hospitalization in women with severe salpingitis, all women hospitalized with acute salpingitis responded promptly to antibiotic therapy and surgical drainage regardless of HIV-1 infection status. LEVEL OF EVIDENCE: II-2.

Failure to control an outbreak of multidrug-resistant Streptococcus pneumoniae in a long-term-care facility: emergence and ongoing transmission of a fluoroquinolone-resistant strain.

OBJECTIVES: To characterize risk factors associated with pneumococcal disease and asymptomatic colonization during an outbreak of multidrug-resistant Streptococcus pneumoniae (MDRSP) among AIDS patients in a long-term-care facility (LTCF), evaluate the efficacy of antimicrobial prophylaxis in eliminating MDRSP colonization, and describe the emergence of fluoroquinolone resistance in the MDRSP outbreak strain. DESIGN: Epidemiologic investigation based on chart review and characterization of SP strains by antimicrobial susceptibility testing and PFGE and prospective MDRSP surveillance. SETTING: An 80-bed AIDS-care unit in an LTCF PARTICIPANTS: Staff and residents on the unit. RESULTS: From April 1995 through January 1996, 7 cases of MDRSP occurred. A nasopharyngeal (NP) swab survey of all residents (n=65) and staff (n=70) detected asymptomatic colonization among 6 residents (9%), but no staff. Isolates were sensitive only to rifampin, ofloxacin, and vancomycin. A 7-day course of rifampin and ofloxacin was given to eliminate colonization among residents: NP swab surveys at 1, 4, and 10 weeks after prophylaxis identified 1 or more colonized residents at each follow-up with isolates showing resistance to one or both treatment drugs. Between 1996 and 1999, an additional 6 patients were diagnosed with fluoroquinolone-resistant (FQ-R) MDRSP infection, with PFGE results demonstrating that the outbreak strain had persisted 3 years after the initial outbreak was recognized. CONCLUSIONS: Chemoprophylaxis likely contributed to the development of a FQ-R outbreak strain that continued to be transmitted in the facility through 1999. Long-term control of future MDRSP outbreaks should rely primarily on vaccination and strict infection control measures.

Etiology of persistent tubo-ovarian abscess in Nairobi, Kenya.

OBJECTIVE: To study the microbial etiology of tubo-ovarian abscess (TOA). METHODS: We recruited 11 women in Nairobi, Kenya who failed antibiotic therapy alone and required surgical drainage of a presumptive TOA. Pus from the nine abscesses and two pyosalpinges were collected and cultured for aerobic, facultative and anaerobic microorganisms. RESULTS: Eleven women suspected of having a TOA were hospitalized and treated for a median of 6 days (range 3-14 days) prior to surgical drainage of the abscess. Nine (82%) specimens were culture positive. Aerobes were present in all nine specimens. Seven of the nine positive cultures (78%) were polymicrobial and five of the polymicrobial cultures contained both anaerobes and aerobes. Anaerobic Gram-negative bacilli (Prevotella sp., Porphyromonas sp. and Bacteroides sp., Escherichia coli) and Streptococcus sp. (S. viridans and S. agalactiae) were the most common microorganisms isolated. Neisseria gonorrhoeae and Chlamydia trachomatis were not isolated by culture or detected by polymerase chain reaction. CONCLUSIONS: In Kenya, persistent TOAs are associated with endogenous flora similar to that normally found in the gastrointestinal tract.

Molecular subtyping to detect human listeriosis clusters.

We analyzed the diversity (Simpson's Index, D) and distribution of Listeria monocytogenes in human listeriosis cases in New York State (excluding New York City) from November 1996 to June 2000 by using automated ribotyping and pulsed-field gel electrophoresis (PFGE). We applied a scan statistic (p