Methicillin-resistant Staphylococcus aureus (MRSA) has become a common cause of skin infections and invasive infections in community dwellers in the United States since the late 1990s. Isolates characterized as USA300 by pulsed-field gel electrophoresis (PFGE) are the predominant strain type in these infections. USA100 and USA500 strains commonly cause health care-associated infections. We compared PFGE with a number of other methods of genotyping in a sample of 149 clinical MRSA isolates from the University of Chicago Medical Center. The 5 USA500 isolates yielded 3 spa types and 2 multilocus sequence types (MLSTs). Among the 24 USA100 isolates, 21 (88%) were of spa type t002, 19 (79%) were of ST5, 2 carried arcA and opp3, and 1 was Panton-Valentine leukocidin positive (PVL+). Among the 102 USA300 isolates, 96 (94%) were of ST8 and 94 (92%) were of spa type t008. The combination of traits that provided the best sensitivity (98%), specificity (97%), positive predictive value (PPV) (99%), and negative predictive value (NPV) (95%) for identifying USA300 isolates were the presence of the arcA gene and the presence of the PVL genes (area under the curve, 0.980; 95% confidence interval [CI], 0.955 to 1.0). PFGE did not delineate a homogeneous group of MRSA genetic backgrounds, as documented for other typing methods, particularly for USA500 and USA100 pulsotypes. Documenting the presence of arcA and PVL genes by PCR was an efficient and accurate means of identifying USA300 in a collection of MRSA isolates in which USA300 is common. None of the tested genotyping methods provided an accurate means of identifying the next most common PFGE-based backgrounds, USA100 and USA500.
Powassan virus; Minnesota; diagnostic tests; viruses; Suggested citation for this article: Neitzel DF; Lynfield R; Smith K. Powassan virus encephalitis; Minnesota; USA [letter]. Emerg Infect Dis [Internet]. 2013 Apr [date cited]. http://dx.doi.org/10.3201/eid1904.121651
Serotype predominance has shifted, and drug resistance is emerging.
bacteria; group B Streptococcus; GBS; neonatal GBS disease; invasive GBS disease; serotype IV; early-onset GBS disease; late-onset GBS disease; clindamycin resistance; streptococci; antimicrobial resistance; serotype; neonates; Minnesota; United States; capsular polysaccharide; CPS; prophylaxis
Prospective studies establishing the temporal relationship between the degree of inflammation and human influenza disease progression are scarce. To assess predictors of disease progression among patients with influenza A(H1N1)pdm09 infection, 25 inflammatory biomarkers measured at enrollment were analyzed in two international observational cohort studies.
Among patients with RT-PCR-confirmed influenza A(H1N1)pdm09 virus infection, odds ratios (ORs) estimated by logistic regression were used to summarize the associations of biomarkers measured at enrollment with worsened disease outcome or death after 14 days of follow-up for those seeking outpatient care (FLU 002) or after 60 days for those hospitalized with influenza complications (FLU 003). Biomarkers that were significantly associated with progression in both studies (p<0.05) or only in one (p<0.002 after Bonferroni correction) were identified.
In FLU 002 28/528 (5.3%) outpatients had influenza A(H1N1)pdm09 virus infection that progressed to a study endpoint of complications, hospitalization or death, whereas in FLU 003 28/170 (16.5%) inpatients enrolled from the general ward and 21/39 (53.8%) inpatients enrolled directly from the ICU experienced disease progression. Higher levels of 12 of the 25 markers were significantly associated with subsequent disease progression. Of these, 7 markers (IL-6, CD163, IL-10, LBP, IL-2, MCP-1, and IP-10), all with ORs for the 3rd versus 1st tertile of 2.5 or greater, were significant (p<0.05) in both outpatients and inpatients. In contrast, five markers (sICAM-1, IL-8, TNF-α, D-dimer, and sVCAM-1), all with ORs for the 3rd versus 1st tertile greater than 3.2, were significantly (p≤.002) associated with disease progression among hospitalized patients only.
In patients presenting with varying severities of influenza A(H1N1)pdm09 virus infection, a baseline elevation in several biomarkers associated with inflammation, coagulation, or immune function strongly predicted a higher risk of disease progression. It is conceivable that interventions designed to abrogate these baseline elevations might affect disease outcome.
The 2009 H1N1 pandemic strained healthcare systems. There was a need for supportive services, rapid antiviral access, and minimization of unnecessary healthcare contacts particularly face-to-face interactions. In response, the Minnesota Department of Health (MDH) launched a telephone-based nurse triage line (NTL) called the Minnesota FluLine coordinating all major MN healthcare systems with NTLs to form a single toll-free number triage service. Callers were evaluated for symptoms of influenza-like illness (ILI) and were prescribed an antiviral if indicated, using nurse administered protocols.
To determine caller outcomes, associated healthcare seeking, and satisfaction a telephone survey of Minnesota FluLine callers was conducted using a 5% random sample of those who completed the protocol and those who did not.
Of 6,122 callers with ILI who began the nurse protocol administered by the contract NTL, 1,221 people were contacted for the survey and 325 agreed to participate; response rate was 26%. Of those who completed the nurse protocol 73% said they would have sought healthcare without the Minnesota FluLine, 89% reported the service was moderately or very helpful, and 91% reported being satisfied or very satisfied. Of those not completing the protocol, 50% reported the service was moderately or very helpful and 50% reported being satisfied or very satisfied. 72% of qualitative responses to open-ended questions were positive regarding the MN FluLine. Cost to MDH for operating the Minnesota FluLine service was $331,226 to service 27,391 callers ($12.09/call).
The Minnesota FluLine diverted patients with mild ILI symptoms away from acute care visits at low cost and had a high rate of satisfaction among callers. Early intervention likely prevented morbidity and possibly additional cases. NTLs are powerful and flexible tools for pandemic response and should be considered as an important tool for future emergency responses.
Sepsis in the first 3 days of life is a leading cause of morbidity and mortality among infants. Group B Streptococcus (GBS), historically the primary cause of early-onset sepsis, has declined through widespread use of intrapartum chemoprophylaxis. We estimated the national burden of invasive early-onset sepsis (EOS) cases and deaths in the era of GBS prevention.
Population-based surveillance for invasive EOS was conducted in 4 of CDC’s Active Bacterial Core surveillance (ABCs) sites from 2005–2008. We calculated incidence using state and national live birth files. Estimates of the national number of cases and deaths were calculated, standardizing by race and gestational age.
ABCs identified 658 cases of EOS; 72 (10.9%) were fatal. Overall incidence remained stable during the three years (2005:0.77 cases/1,000 live births; 2008:0.76 cases/1,000 live births). GBS (~38%) was the most commonly reported pathogen followed by Escherichia coli (~24%). Black preterm infants had the highest incidence (5.14 cases/1,000 live births) and case fatality (24.4%). Non-black term infants had the lowest incidence (0.40 cases/1,000 live births) and case fatality (1.6%). The estimated national annual burden of EOS was approximately 3,320 cases (95% CI: 3,060–3,580) including 390 deaths (95% CI: 300–490). Among preterm infants, 1,570 cases (95% CI: 1,400–1,770; 47.3% of the overall) and 360 deaths (95% CI: 280–460; 92.3% of the overall) occurred annually.
The burden of invasive early-onset sepsis remains substantial in the era of GBS prevention and disproportionately affects preterm and black infants. Identification of strategies to prevent preterm births is needed to reduce the neonatal sepsis burden.
early-onset; neonatal sepsis; group B Streptococcus; disease burden
PCR detecting the protein D (hpd) and fuculose kinase (fucK) genes showed high sensitivity and specificity for identifying Haemophilus influenzae and differentiating it from H. haemolyticus. Phylogenetic analysis using the 16S rRNA gene demonstrated two distinct groups for H. influenzae and H. haemolyticus.
We described the outbreak investigation and control measures after the Minnesota Department of Health identified a cluster of tuberculosis (TB) cases among Guatemalan immigrants within three rural Minnesota counties in August 2008.
TB cases were diagnosed by tuberculin skin test followed by chest radiography and sputum testing for Mycobacterium tuberculosis (M. tuberculosis). We reviewed medical records, interviewed patients, and completed a contact investigation for each infectious case. We used isolate genotyping to confirm epidemiologic links between cases.
The index case was a six-month-old U.S.-born male with Guatemalan parents. Although he experienced four months of cough and fever, TB was not considered at two medical visits but was diagnosed upon hospitalization in May 2008. The presumed source of infection was a Guatemalan male aged 25 years who sang in a band that practiced in the infant’s house and whose pulmonary TB was diagnosed at hospitalization in June 2008, despite his having sought medical attention for symptoms seven months earlier. Among the 16 identified TB cases, 14 were outbreak-related. Three genetically distinct M. tuberculosis strains circulated. Of 150 contacts of the singer, 62 (41%) had latent TB infection and 13 (9%), including 10 children, had TB disease.
In this outbreak, delayed diagnoses contributed to M. tuberculosis transmission. Isolate genotyping corroborated the social links between outbreak-related patients. More timely diagnosis of TB among immigrants and their children can prevent TB transmission among communities in rural, low-incidence areas that might have limited resources for contact investigations.
Certain industries were overrepresented among employed adults with this disease.
influenza; pandemic (H1N1) 2009; viruses; hospitalizations; humans; occupational groups; health personnel; industry
In September 2008, the Council of State and Territorial Epidemiologists and the Centers for Disease Control and Prevention sponsored a meeting of public health and infection-control professionals to address the implementation of surveillance for multidrug-resistant organisms (MDROs)—particularly those related to health care-associated infections. The group discussed the role of health departments and defined goals for future surveillance activities. Participants identified the following main points: (1) surveillance should guide prevention and infection-control activities, (2) an MDRO surveillance system should be adaptable and not organism specific, (3) new systems should utilize and link existing systems, and (4) automated electronic laboratory reporting will be an important component of surveillance but will take time to develop. Current MDRO reporting mandates and surveillance methods vary across states and localities. Health departments that have not already done so should be proactive in determining what type of system, if any, will fit their needs.
Host genetic factors that modify risk of pneumococcal disease may help target future public health interventions to individuals at highest risk of disease. We linked data from population-based surveillance for invasive pneumococcal disease (IPD) with state-based newborn dried bloodspot repositories to identify biological samples from individuals who developed invasive pneumococcal disease. Genomic DNA was extracted from 366 case and 732 anonymous control samples. TagSNPs were selected in 34 candidate genes thought to be associated with host response to invasive pneumococcal disease, and a total of 326 variants were successfully genotyped. Among 543 European Americans (EA) (182 cases and 361 controls), and 166 African Americans (AA) (53 cases and 113 controls), common variants in surfactant protein D (SFTPD) are consistently underrepresented in IPD. SFTPD variants with the strongest association for IPD are intronic rs17886286 (allelic OR 0.45, 95% confidence interval (CI) [0.25, 0.82], with p = 0.007) in EA and 5′ flanking rs12219080 (allelic OR 0.32, 95%CI [0.13, 0.78], with p = 0.009) in AA. Variants in CD46 and IL1R1 are also associated with IPD in both EA and AA, but with effects in different directions; FAS, IL1B, IL4, IL10, IL12B, SFTPA1, SFTPB, and PTAFR variants are associated (p≤0.05) with IPD in EA or AA. We conclude that variants in SFTPD may protect against IPD in EA and AA and genetic variation in other host response pathways may also contribute to risk of IPD. While our associations are not corrected for multiple comparisons and therefore must be replicated in additional cohorts, this pilot study underscores the feasibility of integrating public health surveillance with existing, prospectively collected, newborn dried blood spot repositories to identify host genetic factors associated with infectious diseases.
Circulating strains of Staphylococcus aureus (SA) have changed in the last 30 years including the emergence of community-associated methicillin-resistant SA (MRSA). A report suggested staphylococcal toxic shock syndrome (TSS) was increasing over 2000–2003. The last population-based assessment of TSS was 1986.
Population-based active surveillance for TSS meeting the CDC definition using ICD-9 codes was conducted in the Minneapolis-St. Paul area (population 2,642,056) from 2000–2006. Medical records of potential cases were reviewed for case criteria, antimicrobial susceptibility, risk factors, and outcome. Superantigen PCR testing and PFGE were performed on available isolates from probable and confirmed cases.
Of 7,491 hospitalizations that received one of the ICD-9 study codes, 61 TSS cases (33 menstrual, 28 non-menstrual) were identified. The average annual incidence per 100,000 of all, menstrual, and non-menstrual TSS was 0.52 (95% CI, 0.32–0.77), 0.69 (0.39–1.16), and 0.32 (0.12–0.67), respectively. Women 13–24 years had the highest incidence at 1.41 (0.63–2.61). No increase in incidence was observed from 2000–2006. MRSA was isolated in 1 menstrual and 3 non-menstrual cases (7% of TSS cases); 1 isolate was USA400. The superantigen gene tst-1 was identified in 20 (80%) of isolates and was more common in menstrual compared to non-menstrual isolates (89% vs. 50%, p = 0.07). Superantigen genes sea, seb and sec were found more frequently among non-menstrual compared to menstrual isolates [100% vs 25% (p = 0.4), 60% vs 0% (p<0.01), and 25% vs 13% (p = 0.5), respectively].
TSS incidence remained stable across our surveillance period of 2000–2006 and compared to past population-based estimates in the 1980s. MRSA accounted for a small percentage of TSS cases. tst-1 continues to be the superantigen associated with the majority of menstrual cases. The CDC case definition identifies the most severe cases and has been consistently used but likely results in a substantial underestimation of the total TSS disease burden.
During the pandemic (H1N1) 2009 outbreak, Minnesota, New Mexico, and Oregon used several surveillance methods to detect associated deaths. Surveillance using unexplained death and medical examiner data allowed for detection of 34 (18%) pandemic (H1N1) 2009–associated deaths that were not detected by hospital-based surveillance.
Influenza A virus; H1N1; influenza; pandemic (H1N1) 2009; Minnesota; Oregon; New Mexico; unexplained deaths; coroners; medical examiners; death; fatal outcome; cause of death; mortality; surveillance; viruses; dispatch
It is not well understood why strains of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), a major cause of skin and soft tissue infections, became successful so quickly, overtaking the place of methicillin-sensitive S. aureus (MSSA) in many communities. To evaluate the genetic basis of differences in their virulence traits, 293 S. aureus isolates consisting of three cohorts, genotypically defined clinical CA-MRSA (n = 77), clinical MSSA (n = 103), and nasal carriage MSSA (n = 113), collected over a 19-year period in two Midwestern states in the United States, were (i) extensively genotyped and (ii) screened for 40 known virulence genes which included those for enterotoxins, leukocidins, hemolysins, and surface proteins and several newly identified putative toxin genes from the USA400 lineage of CA-MRSA. Genotypically, nasal carriage and clinical MSSA isolates were much more diverse than was the CA-MRSA group, which was found to be of USA400 lineage only. Virulence gene profiles of the three groups showed that CA-MRSA strains harbored significantly higher percentages (≥95%; P value, <0.05) of the sea, sec, sec4, seg2, seh, sek, sel, sel2, ear, ssl1, lpl10, lukSF-PV, lukD, lukE, and clfA genes than did the carriage and the clinical MSSA group (range, 0% to 58%). Genes of the enterotoxin gene cluster, seg, sei, sem, sen, and seo, were present in the clinical and carriage isolates but not in the CA-MRSA group. These results suggest that the presence of additional virulence factors in USA400 CA-MRSA strains compared to the nasal carriage and clinical MSSA strains probably contributed to their enhanced virulence.
In 2000, the Minnesota Department of Health (MDH) implemented active, sentinel site surveillance for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Data from 2000–2005 were analyzed to determine trends in case characteristics, pulsed-field types (PFTs), and antimicrobial susceptibilities including inducible clindamycin resistance (ICR).
Active sentinel site surveillance was initiated in 2000 at 12 hospital laboratories that served inpatients and outpatients. Patient medical records were reviewed to determine if they met the epidemiologic case criteria for CA-MRSA; isolates were obtained from patients meeting these criteria. The MDH Public Health Laboratory performed pulsed-field gel electrophoresis subtyping and antimicrobial susceptibility testing, including ICR.
The proportion of MRSA cases classified as CA increased from 11% to 33% (p<0.01). The proportion of cases with skin or soft tissue infections also increased compared with other infection types from 75% to 87% (p<0.01). During the surveillance period, USA300 replaced USA400 as the dominant PFT. With the change in dominant PFT, the proportion of isolates susceptible to erythromycin (45% to 13%, p<0.01) and ciprofloxacin (80% to 59%, p<0.01) decreased. The proportion of erythromycin-resistant/clindamycin-susceptible isolates with ICR (93% to 14%, p<0.01) decreased. The proportion of susceptible isolates also changed within the USA300 PFT; the proportion of isolates susceptible to erythromycin (33% vs. 3%) and the proportion susceptible to ciprofloxacin (67% to 62%) decreased significantly.
CA-MRSA increased dramatically from 2000 to 2005. Changes in the predominant PFT have impacted susceptibility profiles of CA-MRSA, including ICR. Continued surveillance is needed to monitor the changing epidemiology of CA-MRSA and to inform clinical decisions.
In October 2007, a cluster of patients experiencing a novel polyradiculoneuropathy was identified at a pork abattoir (Plant A). Patients worked in the primary carcass processing area (warm room); the majority processed severed heads (head-table). An investigation was initiated to determine risk factors for illness.
Methods and Results
Symptoms of the reported patients were unlike previously described occupational associated illnesses. A case-control study was conducted at Plant A. A case was defined as evidence of symptoms of peripheral neuropathy and compatible electrodiagnostic testing in a pork abattoir worker. Two control groups were used - randomly selected non-ill warm-room workers (n = 49), and all non-ill head-table workers (n = 56). Consenting cases and controls were interviewed and blood and throat swabs were collected. The 26 largest U.S. pork abattoirs were surveyed to identify additional cases. Fifteen cases were identified at Plant A; illness onsets occurred during May 2004–November 2007. Median age was 32 years (range, 21–55 years). Cases were more likely than warm-room controls to have ever worked at the head-table (adjusted odds ratio [AOR], 6.6; 95% confidence interval [CI], 1.6–26.7), removed brains or removed muscle from the backs of heads (AOR, 10.3; 95% CI, 1.5–68.5), and worked within 0–10 feet of the brain removal operation (AOR, 9.9; 95% CI, 1.2–80.0). Associations remained when comparing head-table cases and head-table controls. Workers removed brains by using compressed air that liquefied brain and generated aerosolized droplets, exposing themselves and nearby workers. Eight additional cases were identified in the only two other abattoirs using this technique. The three abattoirs that used this technique have stopped brain removal, and no new cases have been reported after 24 months of follow up. Cases compared to controls had higher median interferon-gamma (IFNγ) levels (21.7 pg/ml; vs 14.8 pg/ml, P<0.001).
This novel polyradiculoneuropathy was associated with removing porcine brains with compressed air. An autoimmune mechanism is supported by higher levels of IFNγ in cases than in controls consistent with other immune mediated illnesses occurring in association with neural tissue exposure. Abattoirs should not use compressed air to remove brains and should avoid procedures that aerosolize CNS tissue. This outbreak highlights the potential for respiratory or mucosal exposure to cause an immune-mediated illness in an occupational setting.
This study characterizes 1,984 methicillin-resistant Staphylococcus aureus (MRSA) isolates collected in 2005 and 2006 from normally sterile sites in patients with invasive MRSA infection. These isolates represent a convenience sample of all invasive MRSA cases reported as part of the Active Bacterial Core surveillance system in eight states in the United States. The majority of isolates were from blood (83.8%), joints (4.1%), and bone (4.2%). Isolates were characterized by pulsed-field gel electrophoresis (PFGE); SCCmec typing; susceptibility to 15 antimicrobial agents; and PCR analysis of staphylococcal enterotoxin A (SEA) to SEH, toxic shock syndrome toxin 1, and Panton-Valentine leukocidin. Thirteen established PFGE types were recognized among these isolates, although USA100 and USA300 predominated, accounting for 53.2% and 31.4% of the isolates, respectively. As expected, isolates from hospital onset cases were predominantly USA100, whereas those from community-associated cases were predominantly USA300. USA100 isolates were diverse (Simpson's discriminatory index [DI] = 0.924); generally positive only for enterotoxin D (74.5%); and resistant to clindamycin (98.6%), erythromycin (99.0%), and levofloxacin (99.6%), in addition to β-lactam agents. USA300 isolates were less diverse (DI = 0.566), positive for Panton-Valentine leukocidin (96.3%), and resistant to erythromycin (94.1%) and, less commonly, levofloxacin (54.6%), in addition to β-lactam agents. This collection provides a reference collection of MRSA isolates associated with invasive disease, collected in 2005 and 2006 in the United States, for future comparison and ongoing studies.
In Minnesota, incidence of invasive group B streptococcal disease was 3 times greater in older adults in long-term care facilities than in older adults in community settings (67.7/100,000 vs. 21.4/100,000) during 2003–2007. The overall case-fatality rate was 6.8%, and concurrent conditions were common among both groups.
Streptococcus agalactiae; streptococci; long-term care; antimicrobial resistance; elderly; microbial; Minnesota; USA; dispatch
We compared passive surveillance and International Classification of Diseases, 9th Revision, codes for completeness of staphylococcal toxic shock syndrome (TSS) surveillance in the Minneapolis–St. Paul area, Minnesota, USA. TSS-specific codes identified 55% of cases compared with 30% by passive surveillance and were more sensitive (p = 0.0005, McNemar χ2 12.25).
Staphylococci; bacteria; epidemiology; Staphylococcus aureus; toxic shock syndrome; surveillance; dispatch
Antibiotics are used for both group B streptococcal (GBS) prevention and treatment. Active population-based surveillance for invasive GBS disease was conducted in four states during 1996–2003. Of 3813 case-isolates, 91.0% (3471) were serotyped, 77.1% (2937) had susceptibility testing, and 46.6% (3471) had both. All were sensitive to penicillin, ampicillin, cefazolin, cefotaxime, and vancomycin. Clindamycin and erythromycin resistance was 12.7% and 25.6%, respectively, and associated with serotype V (P < .001). Clindamycin resistance increased from 10.5% to 15.0% (X2 for trend 12.70; P < .001); inducible clindamycin resistance was associated with the erm genotype. Erythromycin resistance increased from 15.8% to 32.8% (X2 for trend 55.46; P < .001). While GBS remains susceptible to beta-lactams, resistance to alternative agents such as erythromycin and clindamycin is an increasing concern.
Twenty-three isolates of group A streptococci (GAS) recovered from population-based invasive GAS surveillance in the United States were erythromycin resistant, inducibly clindamycin resistant, and lacked known macrolide resistance determinants. These 23 isolates, representing four different clones, contained a broad-host-range plasmid carrying the erm(T) methylase gene, which has not been detected in GAS previously.
We tested the feasibility of linking Active Bacterial Core surveillance, a prospective, population-based surveillance system for invasive bacterial disease, to a newborn dried blood spot (nDBS) repository. Using nDBS specimens, we resequenced CD46, putative host gene receptor for Neisseria meningitidis, and identified variants associated with susceptibility to this disease.
Active bacterial core surveillance; Neisseria meningitidis; blood spots; host gene; CD46; dispatch
Nursing home residents are at high risk for invasive GAS disease; clusters are common.
Nursing home residents are at high risk for invasive group A streptococcal (GAS) disease, and clusters of cases in nursing homes are common.To characterize the epidemiologic features of invasive GAS disease in nursing homes, we conducted active, statewide, population- and laboratory-based surveillance in Minnesota from April 1995 through 2006. Of 1,858 invasive GAS disease cases, 134 (7%) occurred in nursing home residents; 34 of these cases were identified as part of 13 clusters. Recognizing cases of GAS disease in nursing homes posed challenges. Measures to ensure identification of case-patients as residents of specific nursing homes need to be included in standard guidelines for the prevention and control of invasive GAS disease in this setting.
Streptococcus pyogenes; nursing home; epidemiology; outbreaks; infection control; research