91. Establishing Proof of Concept for a Bivalent RSVpreF Subunit Vaccine for Maternal Immunization

Background

Respiratory syncytial virus (RSV) is a major cause of infant morbidity and mortality worldwide and could be preventable by vaccination in pregnancy.

Methods

We conducted a randomized, placebo-controlled phase 2b trial evaluating safety, immunogenicity, and potential efficacy of a bivalent RSV prefusion F vaccine (RSVpreF) in pregnant women and their infants. Participants were randomized between 24- and 36-weeks’ gestation to receive 120 or 240 µg RSVpreF, with or without aluminum hydroxide, or placebo.

Results

This final analysis includes 579 women and 572 infants in 4 countries (Argentina, Chile, South Africa, and the US); 462 (79.8%) women received RSVpreF. Postvaccination reactions, most commonly injection site pain, fatigue, and myalgia, were generally mild-to-moderate. Adverse events (AEs) in the month following vaccination (maternal) or birth (infant) were mostly anticipated events in pregnancy and the neonatal period, respectively, and were similar between vaccine and placebo groups. No AEs were considered related to vaccination.

For all RSVpreF groups, 50% neutralizing titers for both RSV-A and RSV-B rose sharply by 2 weeks after vaccination. At delivery occurring a mean of ∼8 weeks later, geometric mean titer (GMT) ratios for combined RSV-A/B between vaccine and placebo recipients’ infants were 10.9 to 13.6. Transplacental transfer ratios (all groups) were 1.39 to 1.83. Infant GMTs were higher in infants whose mothers had received RSVpreF versus placebo through 6 months of life; the estimated half-life of infant combined 50% RSV-A/B neutralizing titers was 41 days. Infants of women immunized across the range of assessed gestational ages had similar cord blood titers and transplacental transfer ratios. Observed efficacy (95% CI) against medically attended and severe medically attended infant RSV lower respiratory tract illness (LRTI) through 180 days in an exploratory analysis was 84.7% (21.5%, 97.6%) and 91.5% (-5.6%, 99.8%), respectively.

Conclusion

RSVpreF was well-tolerated in pregnant women, elicited robust neutralizing responses with efficient transplacental transfer, and has the potential to prevent infant RSV LRTI.

Disclosures

Eric A. F. Simões, MD, M.B., B.S., DCH, Abbvie: DSMB|Astra Zeneca: Grant/Research Support|Bill and Melinda Gates Foundation: Grant/Research Support|Bill and Melinda Gates Foundation: DSMB|GSK Inc.: DSMB|Johnson and Johnson: Grant/Research Support|Merck Inc: Advisor/Consultant|Merck Inc: Grant/Research Support|Nivavax: Grant/Research Support|Pfizer Inc: Advisor/Consultant|Pfizer Inc: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Shabir A. Madhi, MBBCh, FCPaeds, MMed, PhD, AstraZeneca: Funding to institution for conduct of study Kimberly J. Center, M.D., Pfizer: Employee|Pfizer: Stocks/Bonds Jose M. Novoa Pizarro, MD, AstraZeneca: Grant/Research Support|Medimmune: Grant/Research Support|MSD: Grant/Research Support|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support Kena A. Swanson, Ph.D., Pfizer: employee of Pfizer David Radley, MS, Pfizer: Employee|Pfizer: Stocks/Bonds Stephanie B. McGrory, B.S.N., Pfizer: Employee|Pfizer: Stocks/Bonds Emily A. Gomme, Ph.D., Pfizer: Stocks/Bonds Daniel A. Scott, MD, Pfizer: Employee|Pfizer: Stocks/Bonds Kathrin U. Jansen, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds William C. Gruber, MD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Alejandra C. Gurtman, M.D., Pfizer: employee of Pfizer.

Prefusion F Protein-Based Respiratory Syncytial Virus Immunization in Pregnancy

BACKGROUND

Respiratory syncytial virus (RSV), a major cause of illness and death in infants worldwide, could be prevented by vaccination during pregnancy. The efficacy, immunogenicity, and safety of a bivalent RSV prefusion F protein-based (RSVpreF) vaccine in pregnant women and their infants are uncertain.

METHODS

In a phase 2b trial, we randomly assigned pregnant women, at 24 through 36 weeks' gestation, to receive either 120 or 240 μg of RSVpreF vaccine (with or without aluminum hydroxide) or placebo. The trial included safety end points and immunogenicity end points that, in this interim analysis, included 50% titers of RSV A, B, and combined A/B neutralizing antibodies in maternal serum at delivery and in umbilical-cord blood, as well as maternal-to-infant transplacental transfer ratios.

RESULTS

This planned interim analysis included 406 women and 403 infants; 327 women (80.5%) received RSVpreF vaccine. Most postvaccination reactions were mild to moderate; the incidence of local reactions was higher among women who received RSVpreF vaccine containing aluminum hydroxide than among those who received RSVpreF vaccine without aluminum hydroxide. The incidences of adverse events in the women and infants were similar in the vaccine and placebo groups; the type and frequency of these events were consistent with the background incidences among pregnant women and infants. The geometric mean ratios of 50% neutralizing titers between the infants of vaccine recipients and those of placebo recipients ranged from 9.7 to 11.7 among those with RSV A neutralizing antibodies and from 13.6 to 16.8 among those with RSV B neutralizing antibodies. Transplacental neutralizing antibody transfer ratios ranged from 1.41 to 2.10 and were higher with nonaluminum formulations than with aluminum formulations. Across the range of assessed gestational ages, infants of women who were immunized had similar titers in umbilical-cord blood and similar transplacental transfer ratios.

CONCLUSIONS

RSVpreF vaccine elicited neutralizing antibody responses with efficient transplacental transfer and without evident safety concerns. (Funded by Pfizer; ClinicalTrials.gov number, NCT04032093.).

Safety and immunogenicity of a novel hexavalent group B streptococcus conjugate vaccine in healthy, non-pregnant adults: a phase 1/2, randomised, placebo-controlled, observer-blinded, dose-escalation trial

BACKGROUND

Group B streptococcus (GBS) is a major cause of invasive disease in young infants. Infants born to women with sufficient pre-existing anti-GBS capsular IgG antibodies are at reduced risk of GBS disease, making maternal immunisation a potential strategy for prevention. We aimed to assess the safety and immunogenicity of a novel hexavalent (serotypes Ia, Ib, II, III, IV, and V) GBS conjugate vaccine (GBS6).

METHODS

This phase 1/2, placebo-controlled, observer-blinded, dose-escalation trial, was done at four clinical research centres in the USA (Kentucky, Georgia, and two sites in Utah). Healthy, non-pregnant adults aged 18-49 years were randomly assigned using an interactive, web-based response technology system. Within each dose group (low, medium, or high), participants in sentinel cohorts were randomly assigned 2:2:1 and expanded cohort participants were randomly assigned 4:4:1 to receive GBS6 with aluminium phosphate (AlPO₄), GBS6 without AlPO₄, or placebo (saline control). One 0·5 mL dose of either saline placebo or 5 μg capsular polysaccharide per serotype in the low-dose group, 10 μg capsular polysaccharide per serotype in the medium-dose group, or 20 μg capsular polysaccharide per serotype in the high-dose group was administered by intramuscular injection into the deltoid muscle on day 1. The primary outcome was safety up to 6 months after vaccination, including the proportion of sentinel cohort participants with clinical laboratory abnormalities at 1 week, the proportion of all participants reporting solicited local reactions, systemic events, or use of antipyretic or pain medication within 14 days, adverse events up to 1 month, and medically attended or serious adverse events up to 6 months. The secondary outcome was GBS immunogenicity (serotype-specific IgG geometric mean concentrations at 1 month). This study is registered with ClinicalTrials.gov, NCT03170609.

FINDINGS

Between June 5, 2017, and June 25, 2018, 365 participants were randomly assigned and 364 (52 in each dose group) were vaccinated and included in the safety analysis. Unsolicited adverse events were reported by 15 (29%) participants in the 5 μg with AlPO₄ group, 13 (25%) in the 5 μg without AlPO₄ group, 22 (42%) in the 10 μg with AlPO₄ group, 12 (23%) in the 10 μg without AlPO₄ group, 25 (48%) in the 20 μg with AlPO₄ group, 21 (40%) in the 20 μg without AlPO₄ group, and 20 (38%) in the placebo group. The most common unsolicited adverse events were in the system organ class of infections and infestations in any dose or formulation of GBS6 (ranging from six [12%] in the 10 μg without AlPO₄ group to 15 [29%] in the 20 μg with AlPO₄ group and placebo group). Three participants reported at least one serious adverse event during the study, one each in the 5 μg GBS6 with AlPO₄ group (diabetic ketoacidosis, two events; resolved), 10 μg GBS6 with AlPO₄ group (died by suicide), and 20 μg GBS6 with AlPO₄ group (metrorrhagia; resolved). None of these serious adverse events were considered related to the vaccine. 11 of the 365 participants were excluded from the evaluable immunogenicity population, including one participant who did not receive the vaccine, and ten who at 1 month after vaccination were withdrawn for various reasons. GBS serotype-specific IgG geometric mean concentrations increased by 1 week after vaccination for all GBS6 groups, peaked at 2 weeks, stabilised by 1 month, and declined gradually but remained higher than placebo at 6 months.

INTERPRETATION

GBS6 was well tolerated in healthy adults and elicited robust immune responses for all dose levels and formulations that persisted 6 months after vaccination. This study supports further evaluation of GBS6 in pregnant women.

FUNDING

Pfizer.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease After Introduction Into Routine Pediatric Use

BACKGROUND

In 2010, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced 7-valent PCV (PCV7) for protection against invasive pneumococcal disease (IPD). This study used laboratory surveillance data to examine the effect of PCV13 on IPD before and after PCV13 introduction among children aged 6 weeks to <6 years and those aged ≥6 weeks.

METHODS

Observational laboratory-based IPD surveillance data were compared for the periods May 2010-April 2018 and May 2008-April 2010 (the PCV7 period) using a database of Kaiser Permanente Northern California (KPNC) members with laboratory-confirmed IPD.

RESULTS

Among children aged 6 weeks to 6 years, overall IPD incidence decreased from 11.57 per 100 000 during the PCV7 period to 4.09 per 100 000 after PCV13 introduction; PCV13-type IPD incidence decreased from 5.12 to 0.84 per 100 000. Non-PCV13-serotype IPD did not change significantly in this age group (PCV7 period, 1.71 per 100 000 and after PCV13, 2.52 per 100 000). Of cases occurring in this group, bacteremia was the most common clinical diagnosis. Across all ages, IPD decreased from 9.49 to 6.23 per 100 000 and PCV13-type IPD decreased from 4.67 to 1.89 per 100 000, changes being mostly due to decreases in serotypes 19A and 7F. IPD caused by non-PCV13 serotypes did not change (3.34 and 3.35 per 100 000). Overall, pneumococci isolated after PCV13 introduction had increased susceptibility to penicillin, cefotaxime, and ceftriaxone.This prospective, laboratory-based surveillance study in Kaiser Permanente Northern California members examined annual IPD incidence before and after PCV13 introduction. In children aged 6 weeks to <6 years, IPD caused by PCV13 serotypes decreased significantly (84%) during the surveillance period.

CONCLUSIONS

IPD incidence decreased further in every age group after PCV13 introduction, suggesting both direct vaccination effects in the infant population and indirect effects in adults.

CLINICAL TRIALS REGISTRATION

NCT01128439.

National impact of 13-valent pneumococcal conjugate vaccine on ambulatory care visits for otitis media in children under 5 years in the United States

OBJECTIVE

The 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) were approved in the US in 2000 and 2010, respectively, for active immunization against invasive disease caused by all vaccine serotypes and otitis media (OM) caused by 7 serotypes common to both vaccines, starting at ∼6 weeks of age. This study assessed the impact of PCV13 on OM by evaluating changes in US ambulatory care visit rates between the period before PCV7 (1997-1999), during PCV7 (2001-2009), and after the introduction of PCV13 (2011-2013) among US children <5 years old.

METHODS

This ecological study used US National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey data. Trend analyses using weighted least-squares regression and mean visit rates were calculated for OM and two control endpoints not likely to be related to either vaccine (skin rash and trauma).

RESULTS

Among children <5 and < 2 years old, the observed reduction in OM visit rates was 22% (95%CI: 12%-32%) and 24% (95%CI: 13%-35%) when comparing PCV13 to PCV7 periods, and 41% (95%CI: 30%-52%) and 48% (95%CI: 37%-59%) when comparing PCV13 to pre-PCV7 periods. Visit rates for skin rash and trauma remained stable.

CONCLUSION

Significant reductions in US ambulatory care visit rates for OM were observed among children aged <5 years after introduction of PCV13 compared to the periods before and during PCV7; reductions were greatest among children <2 years old. The reductions beyond the PCV7 period support the effectiveness of the vaccine's 6 additional serotypes in preventing OM.

Effectiveness of 13-valent pneumococcal conjugate vaccination for protection against acute otitis media caused by Streptococcus pneumoniae in healthy young children: a prospective observational study

BACKGROUND

With wide use of the seven-valent pneumococcal conjugate vaccine (PCV7) for protection against acute otitis media caused by Streptococcus pneumoniae serotypes included in the vaccine, efficacy testing for the 13-valent vaccine (PCV13) was not feasible. We aimed to assess the effectiveness of PCV13 in preventing acute otitis media caused by the six serotypes in PCV13 that were not in PCV7.

METHODS

We did a longitudinal observational study in healthy children seen as outpatients in a private paediatric practice in Rochester, NY, USA. Children aged up to 30 months who had received the full primary series of PCV13 with other recommended vaccines were eligible to participate and were followed up to age 30-36 months to identify episodes of acute otitis media, during which we collected middle-ear fluid (MEF) by tympanocentesis. We assessed MEF for the serotypes common to PCV7 and PCV13 (4, 6B, 9V, 14, 18C, 19F, and 23F) and the six additional serotypes specific to PCV13 (1, 3, 5, 6A, 7F, and 19A). As controls, we included children enrolled in a longitudinal study in the study centre from Oct 1, 2007, to Sept 30, 2009, who had been vaccinated with PCV7, had MEF prospectively collected at the onset of acute otitis media, and been followed up until age 30 months. The primary outcome was the effectiveness of PCV13 to prevent acute otitis media caused by pneumococci expressing the six capsular serotypes not included in PCV7 (1, 3, 5, 6A, 7F, and 19A). This study is registered with ClinicalTrials.gov, number NCT01199016.

FINDINGS

From Sept 28, 2010, to Sept 30, 2013, we enrolled 239 children (123 [51%] boys and 116 [49%] girls; median age 6·3 months [IQR 6·1-8·6]) in the PCV13 cohort, and 162 completed the study. Of 348 children (184 [53%] boys and 164 [47%] girls; 6·5 months [6·1-9·1]) included in the PCV7 cohort, 248 completed follow-up. 223 MEF samples were obtained at onset of acute otitis media from 90 children in the PCV13 cohort. 53 (24%) of 223 samples were culture positive for S pneumoniae, compared with 89 (31%) of 284 samples in the PCV7 cohort (p=0·06). Four (8%) of 53 samples in the PCV13 cohort contained pneumococci expressing one of the additional PCV13 capsular serotypes, compared with 46 (52%) of 89 samples in the PCV7 cohort, giving a relative reduction of 86% (95% CI 61-94, p=0·0010). The greatest reduction in MEF samples was in serotype 19A (two [4%] in the PCV13 cohort vs 46 [52%] in the PCV7 cohort; relative reduction 91% [58-97, p=0·0010]).

INTERPRETATION

PCV13 prevents acute otitis media caused by S pneumoniae expressing serotypes included in the vaccine.

FUNDING

Pfizer.

Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) formulated with 2-phenoxyethanol in multidose vials given with routine vaccination in healthy infants: An open-label randomized controlled trial

BACKGROUND

This open-label randomized controlled trial in infants compared safety, tolerability, and immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) formulated with the preservative 2-phenoxyethanol (2-PE) in a multidose vial (MDV) to the current PCV13 without 2-PE in a single-dose syringe (SDS).

METHODS

Gambian infants were randomized 1:1 to receive PCV13 as either MDV or SDS at ages 2, 3, and 4months. Serotype-specific antipneumococcal antibody responses and opsonophagocytic activity ([OPA]; subset) were measured at age 5months. Noninferiority was declared if the lower bound of the 97.5% CI for the difference (MDV-SDS) in proportions of subjects achieving IgG concentrations ≥0.35μg/mL (primary endpoint) was greater than -10%. IgG geometric mean concentrations (GMCs) were noninferior if the lower limit of the two-sided 97.5% CI of the geometric mean ratio (MDV vs SDS) was greater than 0.5. Reactogenicity and other adverse events were collected.

RESULTS

500 participants were randomized and vaccinated; 489 (MDV: n=245; SDS: n=244) completed the trial. Noninferiority of MDV was demonstrated for all serotypes as measured by percentage of subjects achieving antibody responses above ≥0.35μg/mL. IgG GMCs (coprimary endpoint) also demonstrated noninferiority of MDV; OPA results supported these findings. Safety and tolerability were comparable between groups.

CONCLUSIONS

PCV13 in MDV was safe and immunogenic when administered according to the routine schedule to infants. MDV was noninferior to SDS for all 13 pneumococcal serotypes. Comparable immunogenicity and safety profiles of PCV13 MDV and SDS suggest PCV13 MDV can help optimize vaccination in resource-limited settings. ClinicalTrials.gov NCT01964716 https://clinicaltrials.gov/ct2/show/NCT01964716.

13-valent pneumococcal conjugate vaccine (PCV13) in preterm versus term infants

OBJECTIVES

This study evaluated the immune response and safety profile of 13-valent pneumococcal conjugate vaccine (PCV13) in preterm infants compared with term infants.

METHODS

This Phase IV, open-label, 2-arm, multicenter, parallel-group study enrolled 200 healthy infants (preterm, n = 100; term, n = 100) aged 42 to 98 days. All subjects received PCV13 at ages 2, 3, 4 (infant series), and 12 (toddler dose [TD]) months, together with routine vaccines (diphtheria-tetanus-acellular pertussis, hepatitis B, inactivated poliovirus, and Haemophilus influenzae type b vaccine and meningococcal group C conjugate vaccine).

RESULTS

Most subjects achieved an anticapsular immunoglobulin G (IgG) antibody concentration ≥ 0.35 μg/mL for all serotypes: >85% after the infant series (except preterm infants for serotypes 5, 6A, and 6B) and >97% after TD (except for serotype 3). Preterm infants had overall lower IgG geometric mean concentrations compared with term infants; however, geometric mean fold increases after TD were similar for all serotypes. Opsonophagocytic activity results were consistent with IgG results and titers increased after TD in both groups for all serotypes, including serotype 3. PCV13 was generally well tolerated, with similar safety profiles in all preterm subgroups.

CONCLUSIONS

Immune responses were lower in preterm infants than in term infants. However, the majority of subjects in both groups achieved both pneumococcal serotype-specific IgG antibody levels after the infant series that exceeded the World Health Organization-established threshold of protection and functional antibody responses. Responses were uniformly higher after TD, reinforcing the importance of a timely booster dose. PCV13 was well tolerated regardless of gestational age.

Multicenter surveillance of Streptococcus pneumoniae isolates from middle ear and mastoid cultures in the 13-valent pneumococcal conjugate vaccine era

BACKGROUND

Streptococcus pneumoniae is a common cause of otitis media (OM) in children; mastoiditis remains an important complication of OM. Limited data are available on the impact of the 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal otitis.

METHODS

Investigators from 8 children's hospitals in the United States prospectively collected pneumococcal isolates from middle ear or mastoid cultures from children from 2011 to 2013. Serotype and antibiotic susceptibilities were determined and PCV13 doses for children documented.

RESULTS

Over the 3-year period, the proportion of isolates included in PCV13 (plus a related serotype) decreased significantly (P = .0006) among the middle ear/mastoid isolates (2011, 50% [74/149]; 2012, 40.5% [47/116]; 2013, 29% [34/118]). The number of serotype 19A isolates in 2013 (n = 12, 10.2% of total) decreased 76% compared with the number of 19A isolates in 2011 (n = 50, 33.6% of total). Of the children from whom serotype 19A was isolated (n = 93), 55% had previously received <3 doses of PCV13. The most common non-PCV13 serotypes for the combined years were 35B (n = 37), 21 (n = 20), 23B (n = 20), 15B (n = 18), 11 (n = 17), 23A (n = 14), 15A (n = 14), and 15C (n = 14). The proportion of isolates with a penicillin minimal inhibitory concentration >2 µg/mL decreased significantly over the 3 years (2011, 22% [35/154]; 2012, 20% [24/118]; 2013, 10% [12/120]; P < .02).

CONCLUSIONS

The number of pneumococcal isolates and the percentage of isolates with high-level penicillin resistance from cultures taken from children with OM or mastoiditis for clinical indications have decreased following PCV13 use, largely related to decreases in serotype 19A isolates.

Prevenar™ vaccination: Review of the global data, 2006

The 7-valent pneumococcal conjugate vaccine, Prevenar, was first licensed in the United States in 2000 for the prevention of invasive pneumococcal disease (IPD) caused by the serotypes included in the vaccine. It is presently approved in more than 70 countries, and more than 100 million doses of vaccine have been distributed to date. Within 1 year of routine use in the US, incidence of vaccine-serotype IPD had fallen dramatically among children younger than 2 years, with indirect effects noted among other age groups as well. The most recent data available from the US demonstrates that vaccine-serotype IPD has declined by 94% among the age group recommended for vaccination, and indirect effects have been documented in every unvaccinated age group, including among neonates and young infants. Additionally, declines in other pneumococcal-associated respiratory tract diseases have been reported, highlighting the extended benefits of a Prevenar vaccination program. Subsequently, the vaccine has been introduced into the national immunization programs of several other countries, including Canada, Australia, and The Netherlands. While an increase in disease caused by serotypes not included in the vaccine has been observed ("replacement disease"), the overall impact of this increase has, to date, been small in comparison to the substantial reduction in overall disease burden that has resulted since Prevenar introduction.

Streptococcus pneumoniae: description of the pathogen, disease epidemiology, treatment, and prevention

Streptococcus pneumoniae causes significant morbidity and mortality. Children younger than 2 years and individuals older than 65 years experience the highest rates of pneumococcal disease. Efforts to treat pneumococcal disease have been complicated by increasing resistance to antimicrobials. Prevention efforts have included the pneumococcal polysaccharide vaccines and the pneumococcal conjugate vaccines, with use of these vaccines targeted to those at highest risk for disease. Information and background on S. pneumoniae and pneumococcal disease are provided. Vaccines targeted at this pathogen are reviewed, and the clinical trials that evaluated their safety, efficacy, and effectiveness are summarized. Also provided are recommendations for use of these vaccines.

Decreased vancomycin susceptibility of coagulase-negative staphylococci in a neonatal intensive care unit: evidence of spread of Staphylococcus warneri

Coagulase-negative staphylococci (CoNS) are important pathogens in premature neonates; decreasing glycopeptide susceptibility has been observed among these isolates. The epidemiology of colonization with CoNS, the organisms' vancomycin susceptibilities, and genetic relatedness were studied over 6 months in a tertiary-care neonatal unit. A total of 321 isolates of CoNS were isolated. Seventy-five percent of the infants were colonized at admission, and virtually all were colonized thereafter. Common species were Staphylococcus epidermidis (69%), S. warneri (12%), S. haemolyticus (9.7%), and S. hominis (5.6%). A total of 3.9% of CoNS isolates had decreased vancomycin susceptibility (DVS) (MICs > 2.0 microg/ml); isolate recovery was associated with a stay in a neonatal intensive care unit for >28 days (P = 0.039), vancomycin exposure (P = 0.021), and S. warneri colonization (P < 0.0001). Nine of 12 (75%) CoNS with DVS were S. warneri, had enhanceable high-level resistance in vitro, were indistinguishable or closely related by pulsed-field gel electrophoresis, and were different from 29 vancomycin-susceptible S. warneri isolates. Epidemiological analysis suggested unsuspected nosocomial spread. Species determination in certain settings may aid in the understanding of emerging nosocomial problems.