Inter-species geographic signatures for tracing horizontal gene transfer and long-term persistence of carbapenem resistance

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are an urgent global health threat. Inferring the dynamics of local CRE dissemination is currently limited by our inability to confidently trace the spread of resistance determinants to unrelated bacterial hosts. Whole-genome sequence comparison is useful for identifying CRE clonal transmission and outbreaks, but high-frequency horizontal gene transfer (HGT) of carbapenem resistance genes and subsequent genome rearrangement complicate tracing the local persistence and mobilization of these genes across organisms.

METHODS

To overcome this limitation, we developed a new approach to identify recent HGT of large, near-identical plasmid segments across species boundaries, which also allowed us to overcome technical challenges with genome assembly. We applied this to complete and near-complete genome assemblies to examine the local spread of CRE in a systematic, prospective collection of all CRE, as well as time- and species-matched carbapenem-susceptible Enterobacterales, isolated from patients from four US hospitals over nearly 5 years.

RESULTS

Our CRE collection comprised a diverse range of species, lineages, and carbapenem resistance mechanisms, many of which were encoded on a variety of promiscuous plasmid types. We found and quantified rearrangement, persistence, and repeated transfer of plasmid segments, including those harboring carbapenemases, between organisms over multiple years. Some plasmid segments were found to be strongly associated with specific locales, thus representing geographic signatures that make it possible to trace recent and localized HGT events. Functional analysis of these signatures revealed genes commonly found in plasmids of nosocomial pathogens, such as functions required for plasmid retention and spread, as well survival against a variety of antibiotic and antiseptics common to the hospital environment.

CONCLUSIONS

Collectively, the framework we developed provides a clearer, high-resolution picture of the epidemiology of antibiotic resistance importation, spread, and persistence in patients and healthcare networks.

In vivo commensal control of Clostridioides difficile virulence

Leveraging systems biology approaches, we illustrate how metabolically distinct species of Clostridia protect against or worsen Clostridioides difficile infection in mice by modulating the pathogen's colonization, growth, and virulence to impact host survival. Gnotobiotic mice colonized with the amino acid fermenter Paraclostridium bifermentans survive infection with reduced disease severity, while mice colonized with the butyrate-producer, Clostridium sardiniense, succumb more rapidly. Systematic in vivo analyses revealed how each commensal alters the gut-nutrient environment to modulate the pathogen's metabolism, gene regulatory networks, and toxin production. Oral administration of P. bifermentans rescues conventional, clindamycin-treated mice from lethal C. difficile infection in a manner similar to that of monocolonized animals, thereby supporting the therapeutic potential of this commensal species. Our findings lay the foundation for mechanistically informed therapies to counter C. difficile disease using systems biology approaches to define host-commensal-pathogen interactions in vivo.

Genomic Determination of Relative Risks for Clostridioides difficile Infection From Asymptomatic Carriage in Intensive Care Unit Patients

BACKGROUND

Clostridioides difficile infections (CDIs) are among the most prevalent hospital-associated infections (HAIs), particularly for intensive care unit (ICU) patients. The risks for developing active CDI from asymptomatic carriage of C. difficile are not well understood.

METHODS

We identified asymptomatic C. difficile carriage among 1897 ICU patients using rectal swabs from an existing ICU vancomycin-resistant enterococci (VRE) surveillance program. C. difficile isolates from VRE swabs, and from C. difficile-positive stool samples, were genome sequenced. Spatial-temporal data from hospital records assessed genomically identified clusters for potential transmission events.

RESULTS

Genomic analyses identified a diverse set of strains in infected patients and asymptomatic carriers. A total of 7.4% of ICU patients asymptomatically carried C. difficile; 69% of isolates carried an intact toxin locus. In contrast, 96% of C. difficile stool isolates were toxin encoding. CDI rates in asymptomatic carriers of toxin-encoding strains were 5.3% versus 0.57% in noncarriers. The relative risk for CDI with asymptomatic carriage of a toxin-encoding strain was 9.32 (95% confidence interval, 3.25-26.7). Genomic identification of clonal clusters supported analyses for asymptomatic transmission events, with spatial-temporal overlaps identified in 13 of 28 cases.

CONCLUSIONS

Our studies provide the first genomically confirmed assessments of CDI relative risk from asymptomatic carriage of toxin-encoding strains and highlight the complex dynamics of asymptomatic transmission in ICUs. Asymptomatic carriers are an active reservoir of C. difficile in the nosocomial environment. C. difficile screening can be implemented within existing HAI surveillance programs and has the potential to support infection-control efforts against this pathogen.

Interval analysis of blood filtration efficacy in novel device for autotransfusion in postpartum hemorrhage

Postpartum haemorrhage (PPH), the leading cause of maternal mortality, is particularly problematic in low resource settings where access to safe blood supplies and definitive medical treatment is limited. We describe the continued development of an autotransfusion device designed to treat PPH by collection, filtration and infusion of maternal blood. Previous study has demonstrated that the device effectively moves blood through a filtration apparatus and removes up to 97% of aerobic bacteria but had poor anaerobic bacteria reduction. In this study, we investigate the filtration efficacy of the device using configurations comprised of three different leukocyte depletion filter designs: the Pall Leukoguard RS leukocyte reduction filter (PLRF), the Haemonetics BPF4™ (BPF4) leukocyte reduction filter, and the Haemonetics SCRC Leukotrap® (SCRC) filter. All configurations performed well with reductions ranging from 49 to 98%. Configurations containing 2 Haemonetics SCRC Leukotrap^®filters (configuration 5 and 6) consistently reduced anaerobic bacteria by at least 73%. These results indicate that utilising a combination of SCRC and PLRF filters confers a high level of microbial filtration with improved removal of anaerobic organisms.

Silver-Coated Endotracheal Tubes Cleaned With a Mechanism for Secretion Removal

BACKGROUND

Biofilm on the surface of endotracheal tubes (ETTs) is associated with ventilator-associated pneumonia. The use of silver-coated ETTs has been suggested to reduce the occurrence of ventilator-associated pneumonia by preventing biofilm formation. However, mucus accumulation can reduce the antibacterial activity of silver-coated ETTs by isolating bacterial colonies from the silver surface. We hypothesized that, in mechanically ventilated subjects, periodic removal of secretions through the use of a cleaning device would enhance the antimicrobial properties of silver-coated ETTs and thus reduce bacterial colonization.

METHODS

Subjects were randomized to either standard suctioning (blind tracheal suctioning, control group) or blind tracheal suctioning plus cleaning maneuver every 8 h (treatment group). Tracheal aspirates were collected immediately before extubation for microbiological culture. After extubation, ETTs were collected for both cultural and non-cultural microbiological analysis and biofilm isolation.

RESULTS

39 subjects expected to be ventilated for > 48 h were enrolled; 36 ETTs (18 control, 18 treatment) and 29 tracheal samples (15 control, 14 treatment) were collected. Among the ETTs positive for bacterial colonization (15 vs 9, P = .18), cleaning maneuvers did not reduce microbial load, shown as the decimal logarithm of colony-forming units (CFU) per mL (1.6 ± 1.2 vs 0.9 ± 1.2 logCFU/mL, P = .15). There was a trend toward decreased biofilm deposition (439.5 ± 29.0 vs 288.9 ± 157.7 mg, P = .09) in the treated ETTs. No significant differences were observed in the number of positive tracheal aspirates (13 vs 10, P = .39) or in the microbial load (4.8 ± 4.0 vs 4.2 ± 3.8 logCFU/mL, P = .70) of tracheal secretions. Finally, no differences in the microbial load of Gram-positive organisms, Gram-negative organisms, or yeasts were found between the ETTs and tracheal aspirates of the 2 groups.

CONCLUSIONS

In 39 critically-ill subjects intubated with silver-coated ETTs, periodic cleaning maneuvers did not decrease bacterial colonization of the ETTs and did not lower respiratory tract colonization compared to the standard suctioning. (Clinicaltrials.gov registration NCT02120001.).

Acetobacter indonesiensis Pneumonia after Lung Transplantation

We report a case of Acetobacter indonesiensis pneumonia in a 51-year-old woman after bilateral lung transplantation. We found 2 other A. indonesiensis pneumonia cases reported in the literature. All 3 cases involved complex patients exposed to broad-spectrum antimicrobial drugs, suggesting that this pathogen may be opportunistic and highly drug-resistant.

MDSINE: Microbial Dynamical Systems INference Engine for microbiome time-series analyses

Predicting dynamics of host-microbial ecosystems is crucial for the rational design of bacteriotherapies. We present MDSINE, a suite of algorithms for inferring dynamical systems models from microbiome time-series data and predicting temporal behaviors. Using simulated data, we demonstrate that MDSINE significantly outperforms the existing inference method. We then show MDSINE’s utility on two new gnotobiotic mice datasets, investigating infection with Clostridium difficile and an immune-modulatory probiotic. Using these datasets, we demonstrate new capabilities, including accurate forecasting of microbial dynamics, prediction of stable sub-communities that inhibit pathogen growth, and identification of bacteria most crucial to community integrity in response to perturbations.

Staphylococcal enterotoxin P predicts bacteremia in hospitalized patients colonized with methicillin-resistant Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization predicts later infection, with both host and pathogen determinants of invasive disease.

METHODS

This nested case-control study evaluates predictors of MRSA bacteremia in an 8-intensive care unit (ICU) prospective adult cohort from 1 September 2003 through 30 April 2005 with active MRSA surveillance and collection of ICU, post-ICU, and readmission MRSA isolates. We selected MRSA carriers who did (cases) and those who did not (controls) develop MRSA bacteremia. Generating assembled genome sequences, we evaluated 30 MRSA genes potentially associated with virulence and invasion. Using multivariable Cox proportional hazards regression, we assessed the association of these genes with MRSA bacteremia, controlling for host risk factors.

RESULTS

We collected 1578 MRSA isolates from 520 patients. We analyzed host and pathogen factors for 33 cases and 121 controls. Predictors of MRSA bacteremia included a diagnosis of cancer, presence of a central venous catheter, hyperglycemia (glucose level, >200 mg/dL), and infection with a MRSA strain carrying the gene for staphylococcal enterotoxin P (sep). Receipt of an anti-MRSA medication had a significant protective effect.

CONCLUSIONS

In an analysis controlling for host factors, colonization with MRSA carrying sep increased the risk of MRSA bacteremia. Identification of risk-adjusted genetic determinants of virulence may help to improve prediction of invasive disease and suggest new targets for therapeutic intervention.

The villain team-up or how Trichomonas vaginalis and bacterial vaginosis alter innate immunity in concert

Objectives

Complex interactions of vaginal microorganisms with the genital tract epithelium shape mucosal innate immunity, which holds the key to sexual and reproductive health. Bacterial vaginosis (BV), a microbiome-disturbance syndrome prevalent in reproductive-age women, occurs commonly in concert with trichomoniasis, and both are associated with increased risk of adverse reproductive outcomes and viral infections, largely attributable to inflammation. To investigate the causative relationships among inflammation, BV and trichomoniasis, we established a model of human cervicovaginal epithelial cells colonised by vaginal Lactobacillus isolates, dominant in healthy women, and common BV species (Atopobium vaginae, Gardnerella vaginalis and Prevotella bivia).

Methods

Colonised epithelia were infected with Trichomonas vaginalis (TV) or exposed to purified TV virulence factors (membrane lipophosphoglycan (LPG), its ceramide-phosphoinositol-glycan core (CPI-GC) or the endosymbiont Trichomonas vaginalis virus (TVV)), followed by assessment of bacterial colony-forming units, the mucosal anti-inflammatory microbicide secretory leucocyte protease inhibitor (SLPI), and chemokines that drive pro-inflammatory, antigen-presenting and T cells.

Results

TV reduced colonisation by Lactobacillus but not by BV species, which were found inside epithelial cells. TV increased interleukin (IL)-8 and suppressed SLPI, likely via LPG/CPI-GC, and upregulated IL-8 and RANTES, likely via TVV as suggested by use of purified pathogenic determinants. BV species A vaginae and G vaginalis induced IL-8 and RANTES, and also amplified the pro-inflammatory responses to both LPG/CPI-GC and TVV, whereas P bivia suppressed the TV/TVV-induced chemokines.

Conclusions

These molecular host–parasite–endosymbiont–bacteria interactions explain epidemiological associations and suggest a revised paradigm for restoring vaginal immunity and preventing BV/TV-attributable inflammatory sequelae in women.

Effects of feminine hygiene products on the vaginal mucosal biome

Background

Over-the-counter (OTC) feminine hygiene products come with little warning about possible side effects. This study evaluates in-vitro their effects on Lactobacillus crispatus, which is dominant in the normal vaginal microbiota and helps maintain a healthy mucosal barrier essential for normal reproductive function and prevention of sexually transmitted infections and gynecologic cancer.

Methods

A feminine moisturizer (Vagisil), personal lubricant, and douche were purchased OTC. A topical spermicide (nonoxynol-9) known to alter the vaginal immune barrier was used as a control. L. crispatus was incubated with each product for 2 and 24h and then seeded on agar for colony forming units (CFU). Human vaginal epithelial cells were exposed to products in the presence or absence of L. crispatus for 24h, followed by epithelium-associated CFU enumeration. Interleukin-8 was immunoassayed and ANOVA was used for statistical evaluation.

Results

Nonoxynol-9 and Vagisil suppressed Lactobacillus growth at 2h and killed all bacteria at 24h. The lubricant decreased bacterial growth insignificantly at 2h but killed all at 24h. The douche did not have a significant effect. At full strength, all products suppressed epithelial viability and all, except the douche, suppressed epithelial-associated CFU. When applied at non-toxic dose in the absence of bacteria, the douche and moisturizer induced an increase of IL-8, suggesting a potential to initiate inflammatory reaction. In the presence of L. crispatus, the proinflammatory effects of the douche and moisturizer were countered, and IL-8 production was inhibited in the presence of the other products.

Conclusion

Some OTC vaginal products may be harmful to L. crispatus and alter the vaginal immune environment. Illustrated through these results, L. crispatus is essential in the preservation of the function of vaginal epithelial cells in the presence of some feminine hygiene products. More research should be invested toward these products before they are placed on the market.

Maternal intestinal flora and wheeze in early childhood

BACKGROUND

Increasing evidence links altered intestinal flora in infancy to eczema and asthma. No studies have investigated the influence of maternal intestinal flora on wheezing and eczema in early childhood.

OBJECTIVE

To investigate the link between maternal intestinal flora during pregnancy and development of wheeze and eczema in infancy.

METHODS

A total of 60 pregnant women from the Boston area gave stool samples during the third trimester of their pregnancy and answered questions during pregnancy about their own health, and about their children's health when the child was 2 and 6 months of age. Quantitative culture was performed on stool samples and measured in log(10)colony-forming units (CFU)/gram stool. Primary outcomes included infant wheeze and eczema in the first 6 months of life. Atopic wheeze, defined as wheeze and eczema, was analysed as a secondary outcome.

RESULTS

In multivariate models adjusted for breastfeeding, day care attendance and maternal atopy, higher counts of maternal total aerobes (TA) and enterococci (E) were associated with increased risk of infant wheeze (TA: OR 2.32 for 1 log increase in CFU/g stool [95% CI 1.22, 4.42]; E: OR 1.57 [95% CI 1.06, 2.31]). No organisms were associated with either eczema or atopic wheeze.

CONCLUSIONS AND CLINICAL RELEVANCE

In our cohort, higher maternal total aerobes and enterococci were related to increased risk of infant wheeze. Maternal intestinal flora may be an important environmental exposure in early immune system development.

Novel vaginal microflora colonization model providing new insight into microbicide mechanism of action

Several broad-spectrum microbicides, including cellulose sulfate (CS), have passed conventional preclinical and phase I clinical safety evaluation and yet have failed to protect women from acquiring HIV-1 in phase II/III trials. Concerns have been raised that current preclinical algorithms are deficient in addressing the complexity of the microflora-regulated vaginal mucosal barrier. We applied a novel microflora-colonized model to evaluate CS and hydroxyethylcellulose (HEC), which is used as a "universal placebo" in microbicide trials. Cervicovaginal epithelial cultures were colonized with normal vaginal microflora isolates representing common Lactobacillus species used as probiotics (L. acidophilus and L. crispatus) or Prevotella bivia and Atopobium vaginae, most prevalent in the disturbed microflora of bacterial vaginosis (BV). At baseline, all strains maintained constant epithelium-associated CFUs without inducing cytotoxicity and apoptosis. CS selectively reduced epithelium-associated CFUs and (to a lesser extent) planktonic CFUs, most significantly affecting L. crispatus. Inducing only minor changes in sterile epithelial cultures, CS induced expression of innate immunity mediators (RANTES, interleukin-8 [IL-8], and secretory leukocyte protease inhibitor [SLPI]) in microflora-colonized epithelia, most significantly potentiating effects of bacteria causing BV. In the absence of CS, all bacterial strains except L. acidophilus activated NF-κB, although IL-8 and RANTES levels were increased by the presence of BV-causing bacteria only. CS enhanced NF-κB activation in a dose-dependent manner under all conditions, including L. acidophilus colonization. HEC remained inert. These results offer insights into possible mechanisms of CS clinical failure. The bacterially colonized cervicovaginal model reveals unique aspects of microflora-epithelium-drug interactions and innate immunity in the female genital tract and should become an integral part of preclinical safety evaluation of anti-HIV microbicides and other vaginal formulations.

IMPORTANCE

This report provides experimental evidence supporting the concept that the vaginal microflora regulates the epithelial innate immunity in a species- and strain-specific manner and that topically applied microbicides may alter both the bacterial and epithelial components of this homeostatic interaction. Our data also highlight the importance of differentiating the effects of biomedical interventions on epithelium-associated versus conventional planktonic bacterial growth when assessing vaginal mucosal health and immunity.

In vitro antimicrobial susceptibility of Propionibacterium acnes isolated from acne patients in northern Mexico

BACKGROUND

Antimicrobials are essential in acne therapy. In the last decades, Propionibacterium acnes has become resistant to different antibiotics.

OBJECTIVE

To determine antimicrobial susceptibility patterns of P. acnes to frequently used drugs.

MATERIALS AND METHODS

Cutaneous lesion samples were obtained from 50 patients with acne vulgaris, which were cultured in anaerobic media to demonstrate the presence of P. acnes. After that, antimicrobial susceptibility tests to tetracycline, minocycline, doxycycline, erythromycin, azithromycin, clindamycin, trimethoprim/sulfamethoxazole (SXT) and levofloxacin were performed.

RESULTS

In the general study group, resistance to azithromycin was 82%, the most prevalent one (P < 0.05), followed by trimethoprim/sulfamethoxazole (68%) and erythromycin (46%). On the other hand, all strains isolated were susceptible to minocycline. Resistance bias were similar when subgroups with and without the previous antimicrobial therapy were performed, finding a low prevalence of resistance to tetracyclines and levofloxacin in both groups.

CONCLUSIONS

In our region, P. acnes is highly resistant to azithromycin, SXT, erythromycin and clindamycin; and being very susceptible to minocycline, levofloxacin and tetracycline, in vitro in both groups: with and without the previous antibiotic use. To our knowledge, high resistance prevalence to azithromycin and SXT has never been reported.

Enterobacteriaceae act in concert with the gut microbiota to induce spontaneous and maternally transmitted colitis

Disruption of homeostasis between the host immune system and the intestinal microbiota leads to inflammatory bowel disease (IBD). Whether IBD is instigated by individual species or disruptions of entire microbial communities remains controversial. We characterized the fecal microbial communities in the recently described T-bet(-/-) ×Rag2(-/-) ulcerative colitis (TRUC) model driven by T-bet deficiency in the innate immune system. 16S rRNA-based analysis of TRUC and Rag2(-/-) mice revealed distinctive communities that correlate with host genotype. The presence of Klebsiella pneumoniae and Proteus mirabilis correlates with colitis in TRUC animals, and these TRUC-derived strains can elicit colitis in Rag2(-/-) and WT adults but require a maternally transmitted endogenous microbial community for maximal intestinal inflammation. Cross-fostering experiments indicated a role for these organisms in maternal transmission of disease. Our findings illustrate how gut microbial communities work in concert with specific culturable colitogenic agents to cause IBD.

Persistence survey of toxic shock syndrome toxin-1 producing Staphylococcus aureus and serum antibodies to this superantigen in five groups of menstruating women

Background

Menstrual Toxic Shock Syndrome (mTSS) is thought to be associated with the vaginal colonization with specific strains of Staphylococcus aureus TSST-1 in women who lack sufficient antibody titers to this toxin. There are no published studies that examine the seroconversion in women with various colonization patterns of this organism. Thus, the aim of this study was to evaluate the persistence of Staphylococcus aureus colonization at three body sites (vagina, nares, and anus) and serum antibody to toxic shock syndrome toxin-producing Staphylococcus aureus among a small group of healthy, menstruating women evaluated previously in a larger study.

Methods

One year after the completion of that study, 311 subjects were recalled into 5 groups. Four samples were obtained from each participant at several visits over an additional 6-11 month period: 1) an anterior nares swab; 2) an anal swab; 3) a vagina swab; and 4) a blood sample. Gram stain, a catalase test, and a rapid S. aureus-specific latex agglutination test were performed to phenotypically identify S. aureus from sample swabs. A competitive ELISA was used to quantify TSST-1 production. Human TSST-1 IgG antibodies were determined from the blood samples using a sandwich ELISA method.

Results

We found only 41% of toxigenic S. aureus and 35.5% of non-toxigenic nasal carriage could be classified as persistent. None of the toxigenic S. aureus vaginal or anal carriage could be classified as persistent. Despite the low persistence of S. aureus colonization, subjects colonized with a toxigenic strain were found to display distributions of antibody titers skewed toward higher titers than other subjects. Seven percent (5/75) of subjects became seropositive during recall, but none experienced toxic shock syndrome-like symptoms.

Conclusions

Nasal carriage of S. aureus appears to be persistent and the best predicator of subsequent colonization, whereas vaginal and anal carriage appear to be more transient. From these findings, it appears that antibody titers in women found to be colonized with toxigenic S. aureus remained skewed toward higher titers whether or not the colonies were found to be persistent or transient in nature. This suggests that colonization at some point in time is sufficient to elevate antibody titer levels and those levels appear to be persistent. Results also indicate that women can become seropositive without experiencing signs or symptoms of toxic shock syndrome.

Diversity of the gut microbiota and eczema in early life

BACKGROUND

A modest number of prospective studies of the composition of the intestinal microbiota and eczema in early life have yielded conflicting results.

OBJECTIVE

To examine the relationship between the bacterial diversity of the gut and the development of eczema in early life by methods other than stool culture.

METHODS

Fecal samples were collected from 21 infants at 1 and 4 months of life. Nine infants were diagnosed with eczema by the age of 6 months (cases) and 12 infants were not (controls). After conducting denaturating gradient gel electrophoresis (DGGE) of stool samples, we compared the microbial diversity of cases and controls using the number of electrophoretic bands and the Shannon index of diversity (H') as indicators.

RESULTS

Control subjects had significantly greater fecal microbial diversity than children with eczema at ages 1 (mean H' for controls = 0.75 vs. 0.53 for cases, P = 0.01) and 4 months (mean H' for controls = 0.92 vs. 0.59 for cases, P = 0.02). The increase in diversity from 1 to 4 months of age was significant in controls (P = 0.04) but not in children who developed eczema by 6 months of age (P = 0.32).

CONCLUSION

Our findings suggest that reduced microbial diversity is associated with the development of eczema in early life.

Colonization of second-trimester placenta parenchyma

OBJECTIVE

The overtly healthy, nonpregnant uterus harbors bacteria, Mycoplasma and Ureaplasma. The extent of colonization remains elusive, as are relationships between isolated microorganisms, preterm labor and fetal inflammation.

STUDY DESIGN

Biopsy specimens of chorion parenchyma from 1083 placentas delivered before the beginning of the 28th week of gestation were cultured, and the placentas were examined histologically. The frequencies of individual microorganisms and groups of microorganisms were evaluated in strata of processes leading to preterm delivery, routes of delivery, gestational age, and placenta morphology.

RESULTS

Placentas delivered by cesarean section with preeclampsia had the lowest bacterial recovery rate (25%). Preterm labor had the highest rates, which decreased with increasing gestational age from 79% at 23 weeks to 43% at 27 weeks. The presence of microorganisms in placenta parenchyma was associated with the presence of neutrophils in the fetal stem vessels of the chorion or in the vessels of the umbilical cord.

CONCLUSION

The high rate of colonization appears to coincide with phenomena associated with preterm delivery and gestational age. The presence of microorganisms within placenta parenchyma is biologically important.

Hyaluronic acid binding peptides prevent experimental staphylococcal wound infection

Staphylococcus aureus is a major cause of surgical wound infections. The development of mechanisms of antimicrobial resistance by this and other bacterial pathogens has prompted the search for new approaches to treat infectious diseases. Hyaluronic acid binding peptides have been shown to modulate cellular trafficking during host responses and were assessed for their ability to treat and possibly prevent experimental surgical wound infections caused by S. aureus. Treatment with these peptides was highly efficacious in reducing the number of S. aureus cells at the wound site and ameliorated the inflammatory host response associated with these infections. These data suggest a novel approach for the treatment and prophylaxis of staphylococcal wound infections in the clinical setting.

TNFA-308G>A polymorphism influences the TNF-alpha response to altered vaginal flora

OBJECTIVE

To investigate the association between a tumor necrosis factor-alpha (TNF-alpha) gene polymorphism, vaginal TNF-alpha level, and microbial flora in pregnant women.

METHODS

Vaginal samples from 203 women at 18-22 weeks' gestation were analyzed for microflora. TNFA-308G>A polymorphism was analyzed by polymerase chain reaction and restriction endonuclease analysis and TNF-alpha concentration was determined by ELISA. Outcome data were subsequently obtained.

RESULTS

The vaginal TNF-alpha concentration was elevated in TNFA-308A carriers only in the presence of abnormal vaginal flora. A median TNF-alpha level of 10.94 pg/ml in TNFA-308A carriers with bacterial vaginosis (BV) was significantly higher than that of 1.77 pg/ml in TNFA-308A carriers without BV (P=.02), and 1.72 pg/ml in TNF-308G homozygotes with BV (P=.01).

CONCLUSION

The TNFA-308G>A polymorphism influences the local TNF-alpha response to altered vaginal microflora. This suggests that the nature of the host response to microbial invasion in the lower female genital is genetically determined.

Vaginal nitric oxide in pregnant women with bacterial vaginosis

PROBLEM

To evaluate vaginal nitric oxide (NO) production in response to alterations in the vaginal microbial flora.

METHOD OF STUDY

Cervicovaginal lavage samples from 206 women at 18-22 weeks of gestation were tested for NO, interleukin-1beta (IL-1beta), IL-1 receptor antagonist (IL-1ra), tumor necrosis factor-alpha and the inducible 70 kDa heat shock protein (hsp70). Bacterial vaginosis (BV) was diagnosed based on gram staining of vaginal smears.

RESULTS AND CONCLUSIONS

Elevated NO (>2.14 mmol/L) was associated with a diagnosis of BV (38% versus 11%, P < 0.008) as well as an increased median vaginal IL-1ra concentration (72.5 ng/ml versus 36.6 ng/ml, P = 0.041). Elevated vaginal NO was also associated with vaginal hsp70 and this relationship was independent of BV status or IL-1ra concentrations (P < 0.026). We conclude that vaginal hsp70 release in response to abnormal vaginal microflora may trigger NO production in an attempt to minimize the pathological consequences of this altered milieu.

Mode of delivery and cord blood cytokines: a birth cohort study

Background

The mechanisms for the association between birth by cesarean section and atopy and asthma are largely unknown.

Objective

To examine whether cesarean section results in neonatal secretion of cytokines that are associated with increased risk of atopy and/or asthma in childhood. To examine whether the association between mode of delivery and neonatal immune responses is explained by exposure to the maternal gut flora (a marker of the vaginal flora).

Methods

CBMCs were isolated from 37 neonates at delivery, and secretion of IL-13, IFN-γ, and IL-10 (at baseline and after stimulation with antigens [dust mite and cat dander allergens, phytohemagglutinin, and lipopolysaccharide]) was quantified by ELISA. Total and specific microbes were quantified in maternal stool. The relation between mode of delivery and cord blood cytokines was examined by linear regression. The relation between maternal stool microbes and cord blood cytokines was examined by Spearman's correlation coefficients.

Results

Cesarean section was associated with increased levels of IL-13 and IFN-γ. In multivariate analyses, cesarean section was associated with an increment of 79.4 pg/ml in secretion of IL-13 by CBMCs after stimulation with dust mite allergen (P < 0.001). Among children born by vaginal delivery, gram-positive anaerobes and total anaerobes in maternal stool were positively correlated with levels of IL-10, and gram-negative aerobic bacteria in maternal stool were negatively correlated with levels of IL-13 and IFN-γ.

Conclusion

Cesarean section is associated with increased levels of IL-13 and IFN-γ, perhaps because of lack of labor and/or reduced exposure to specific microbes (e.g., gram-positive anaerobes) at birth.

Prevalence of toxic shock syndrome toxin 1-producing Staphylococcus aureus and the presence of antibodies to this superantigen in menstruating women

Menstrual toxic shock syndrome (mTSS) is thought to be associated with colonization with toxic shock syndrome toxin 1 (TSST-1)-producing Staphylococcus aureus in women with insufficient antibody titers. mTSS has been associated with menstruation and tampon use, and although it is rare, the effects can be life threatening. It remains of interest because of the widespread use of tampons, reported to be about 70% of women in the United States, Canada, and much of Western Europe. This comprehensive study was designed to determine S. aureus colonization and TSST-1 serum antibody titers in 3,012 menstruating women in North America between the ages of 13 and 40, particularly among age and racial groups that could not be assessed reliably in previous small studies. One out of every four subjects was found to be colonized with S. aureus in at least one of three body sites (nose, vagina, or anus), with approximately 9% colonized vaginally. Eighty-five percent of subjects had antibody titers (> or =1:32) to TSST-1, and the vast majority (81%) of teenaged subjects (13 to 18 years) had already developed antibody titers. Among carriers of toxigenic S. aureus, a significantly lower percentage of black women than of white or Hispanic women were found to have antibody titers (> or =1:32) to TSST-1 (89% versus 98% and 100%). These findings demonstrate that the majority of teenagers have antibody titers (> or =1:32) to TSST-1 and are presumed to be protected from mTSS. These findings also suggest that black women may be more susceptible to mTSS than previously thought.

Association between vaginal 70-kd heat shock protein, interleukin-1 receptor antagonist, and microbial flora in mid trimester pregnant women

OBJECTIVE

This study investigated the association among the inducible 70-kd heat shock protein, cytokines, and microbial flora in the vagina in mid trimester pregnant women and subsequent preterm delivery.

STUDY DESIGN

Vaginal samples from 205 pregnant women, which were collected at 18 to 22 weeks of gestation, were analyzed for qualitative and quantitative vaginal microflora and for 70-kd heat shock protein, interleukin-1beta, interleukin-1 receptor antagonist, and tumor necrosis factor-alpha by enzyme-linked immunosorbent assay. Pregnancy outcome data were obtained subsequently.

RESULTS

The 70-kd heat shock protein was detected in 38 vaginal samples (18.5%). Its presence was associated with elevated vaginal pH, a diagnosis of bacterial vaginosis, and elevated interleukin-1 receptor antagonist levels (P < .001). Among women with bacterial vaginosis, 70-kd heat shock protein-positive subjects had a >80% increase in median vaginal concentration of interleukin-1 receptor antagonist (P < .05).

CONCLUSION

Vaginal 70-kd heat shock protein expression is associated with the down-regulation of the proinflammatory immune response to abnormal vaginal flora in mid trimester pregnant women.

Polymorphism in intron 2 of the interleukin-1 receptor antagonist gene, local midtrimester cytokine response to vaginal flora, and subsequent preterm birth

OBJECTIVE

This study investigated the association between polymorphism in intron 2 of the interleukin-1 receptor antagonist gene, midtrimester vaginal microflora, vaginal interleukin receptor antagonist and interleukin-1beta levels and subsequent spontaneous preterm birth.

STUDY DESIGN

Vaginal samples from 212 women, collected at 18-22 weeks' gestation, were analyzed for the polymorphism in intron 2 of the interleukin-1 receptor antagonist gene by polymerase chain reaction, qualitative and quantitative vaginal microflora, and interleukin-1beta and interleukin-1ra concentrations by enzyme-linked immunosorbent assay. Pregnancy outcome data were subsequently obtained.

RESULTS

Carriage of intron 2 of the interleukin-1 receptor antagonist allele 2 (IL1RN * 2) was associated with an elevated vaginal pH in black ( P < .001) and white ( P = .005) women, a reduced interleukin-1beta response to anaerobic Gram-negative rods and/or Gardnerella vaginalis ( P < .01), and a decreased rate of spontaneous preterm deliveries (6% versus 18%, P = .02). In black women, IL1RN * 2 carriage was associated with increased anaerobic Gram-negative rods, Mycoplasma, and Peptostreptococci and decreased Lactobacilli colonization.

CONCLUSION

IL1RN * 2 carriage was associated with a blunted proinflammatory interleukin-1beta response to abnormal vaginal flora. This property may decrease susceptibility to infection-related preterm birth.

Relationship between a toll-like receptor-4 gene polymorphism, bacterial vaginosis-related flora and vaginal cytokine responses in pregnant women

OBJECTIVE

The relationship between a single nucleotide polymorphism (TLR4 896 A > G) in the toll-like receptor-4 (TLR4) gene, qualitative and quantitative changes in vaginal micro-flora and vaginal interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1ra) concentrations in pregnant women were evaluated.

STUDY DESIGN

Qualitative and quantitative microbial methods were used to characterize vaginal micro-flora of 238 women at 18-22 weeks gestation. Polymerase chain reaction was used to determine TLR4 genotype. IL-1beta and IL-1ra concentrations in vaginal lavage samples were measured by ELISA.

RESULTS

The TLR4 variant was identified in 10.3% of women. Carriage of this variant was associated with a median increase in vaginal pH (P = 0.05), a greater than 10-fold increase in vaginal Gardnerella vaginalis levels (P < 0.0001) and a 10-fold increase in the vaginal concentration of three species of anaerobic Gram-negative rods, Prevotella, Bacteroides, and Porphyromonas (P = 0.08 ). Colonization with G. vaginalis and/or the anaerobic Gram-negative rods resulted in elevated vaginal IL-1 (P = 0.01) and IL-1ra (P < 0.0002) concentrations in women who were TLR4 896A homozygotes, but not in TLR4 896G carriers.

CONCLUSION

The TLR4 896 A > G polymorphism contributes to inter-individual differences in the vaginal immune defense against G. vaginalis and anaerobic Gram-negative rods.

A disproportionate increase in IL-1beta over IL-1ra in the cervicovaginal secretions of pregnant women with altered vaginal microflora correlates with preterm birth

OBJECTIVE

This purpose of this study was to investigate the association between vaginal microflora, concentrations of interleukin-1beta (IL-1beta), and its natural receptor antagonist (IL-1ra) in the cervicovaginal discharge, and spontaneous preterm birth. Study design Vaginal samples collected at 18 to 22 weeks' gestation from 207 women were analyzed to study qualitative and quantitative microbiologic aspects of vaginal microflora and IL-1beta and IL-1ra concentrations.

RESULTS

Among women colonized with anaerobic Gram-negative rods and/or Gardnerella vaginalis, an elevated IL-1beta concentration, or a diminished IL-1ra:IL-1beta ratio were associated with preterm delivery. A cut-off IL-1ra:IL-1beta ratio of <8632:1 optimally discriminated the subjects with subsequent spontaneous preterm deliveries from subjects who delivered at term, with a sensitivity of 78%, specificity of 51%, positive predictive value of 21%, and negative predictive value of 95%.

CONCLUSION

A disproportionate increase in IL-1beta over IL-1ra in response to vaginal colonization with anaerobic Gram-negative rods and/or G. vaginalis at 18 to 22 weeks' gestation is associated with spontaneous preterm delivery.

Quantitative microbiologic models for preterm delivery

Preterm delivery (PTD) is the leading cause of infant morbidity and mortality in the United States. An epidemiological association between PTD and various bacteria that are part of the vaginal microflora has been reported. No single bacterial species has been identified as being causally associated with PTD, suggesting a multifactorial etiology. Quantitative microbiologic cultures have been used previously to define normal vaginal microflora in a predictive model. These techniques have been applied to vaginal swab cultures from pregnant women in an effort to develop predictive microbiologic models for PTD. Logistic regression analysis with microbiologic information was performed for various risk groups, and the probability of a PTD was calculated for each subject. Four predictive models were generated by using the quantitative microbiologic data. The area under the curve (AUC) for the receiver operating curves ranged from 0.74 to 0.94, with confidence intervals (CI) ranging from 0.62 to 1. The model for the previous PTD risk group with the highest percentage of PTDs had an AUC of 0.91 (CI, 0.79 to 1). It may be possible to predict PTD by using microbiologic risk factors measured once the gestation period has reached the 20-week time point.

Nugent score related to vaginal culture in pregnant women

OBJECTIVE

To relate Gram-stained smears, using the Nugent criteria, to quantitative and qualitative vaginal cultures in pregnant women.

METHODS

Two independent evaluators using the Nugent criteria, a standardized method of Gram-stain interpretation designed to detect bacterial vaginosis, scored 104 vaginal smears from pregnant women. The quantitative and qualitative vaginal cultures were assessed at the same time and the results expressed as log(10) colony-forming units per gram of vaginal secretion. The Nugent scores were compared with the microbiologic findings.

RESULTS

The prevalence of normal, intermediate, or bacterial vaginosis vaginal flora as determined by Gram stain was 68%, 21%, and 11%, respectively. A comparison of the mean bacterial counts with the Nugent score showed a weak negative correlation for Lactobacillus species and a positive correlation for gram-variable and gram-negative rods. Additional analysis revealed a strong positive correlation between the mean bacterial counts analyses of Peptostreptococcus, a genus not included in the Nugent scoring system, and the Nugent score. In addition, the Prevotella counts correlated strongly with both the Nugent score and the Peptostreptococcus counts. The quantitative counts for Lactobacillus did not vary significantly among the three defined groups of vaginal microflora; however, significant increases in the concentrations of Gardnerella vaginalis and Prevotella were found as the Nugent score increased.

CONCLUSION

A strong correlation was found among the gram-variable and gram-negative genera comprised by the Nugent score. Peptostreptococcus also correlated strongly with the Nugent score and with the Prevotella counts, suggesting that this genus may play a role in determining vaginal health.

Laparoscopic myomectomy-an unusual cause of meralgia paresthetica

Meralgia paresthetica may be associated with diabetes, trauma, infection, and use of self-retaining retractors. Our patient experienced left upper thigh paresthesia after undergoing laparoscopic myomectomy with extensive dissection of the left retroperitoneal space. Neurologic evaluation confirmed meralgia paresthetica. The patient was observed for 4 months, by which time the neuropathy resolved spontaneously.

Evaluation of the AnaeroPack system for growth of clinically significant anaerobes

The AnaeroPack (Mitsubishi Gas Chemical America, Inc., New York, N.Y.) system was compared with the GasPak (Becton Dickinson Microbiology Systems, Cockeysville, Md.) system and a conventional anaerobe chamber to evaluate the ability of the AnaeroPack system to support the growth of clinically significant anaerobes. The AnaeroPack system requires no catalyst or water, produces no hydrogen, and is oxygen absorbing and carbon dioxide generating. It is simple to use and reduces preparation time to a minimum. One hundred forty clinical isolates obtained from various anatomic sites and 10 American Type Culture Collection type strains were evaluated. Isolates were plated on various media, and bacterial growth was examined after 24, 48, 72, and 168 h of incubation. Criteria for evaluation and comparison of systems included rate and quality of growth, colonial morphology, hemolytic reactions, and pigment production. Results indicate that the AnaeroPack system is highly effective in creating an anaerobic atmosphere. The AnaeroPack system never failed to reduce the methylene blue indicator, while the GasPak system failed 15% of the time. The rate or quality of growth achieved by the AnaeroPack system compared with that of established anaerobic culturing techniques was similar and significantly better for several genera including the Bacteroides fragilis group, Fusobacterium, Clostridium, and Peptostreptococcus. The AnaeroPack system appears to be an excellent alternative to established methods for generating an environment for anaerobic incubation.

19-Acetylenic-deoxycorticosterone inhibits 19-hydroxylase and 11 beta-hydroxylase activities in dispersed bovine zona fasciculata cells

19-Acetylenic-deoxycorticosterone (19-A-DOC) is believed to be a competitive irreversible inhibitor of the synthesis of 19-nor-deoxycorticosterone (19-nor-DOC), a potent mineralocorticoid implicated in some forms of human and animal hypertension. It has been shown to inactivate 11 beta/19-hydroxylase in hamster adrenal mitochondria. Dispersed bovine zona fasciculata cells were incubated for one hour with 1.5 x 10(-8) M ACTH and 0, 1, 10, or 100 microM 19-A-DOC and tritiated deoxycorticosterone (DOC) substrate. Steroids were separated using two sequential thin-layer chromatography systems and their tritium content was counted and corrected for recovery. The 19-A-DOC decreased synthesis of 19-hydroxydeoxycorticosterone, the precursor of 19-nor-DOC. The inhibitor also impaired 11-hydroxylation of DOC to form corticosterone. The data suggest that 19-A-DOC is an effective inhibitor of 11 beta/19-hydroxylase activity in dispersed bovine adrenal cells.

Mixed-effect models for predicting microbial interactions in the vaginal ecosystem

Three statistical models that predict microbial interactions within the vaginal environment are presented. A large data set was assembled from in vivo studies describing the healthy vaginal environment, and the data set was analyzed to determine whether statistical models which would accurately predict the interactions of the microflora in this environment could be formulated. During assembly of the data set, two new variables were defined and were added to the data set, that is, cycle (sequence of menstrual cycle) and flow stage (subdivision of cycle determined by day of menstrual cycle). Concentrations of total aerobic (includes facultative) bacteria, total anaerobic bacteria, and a Corynebacterium sp. were identified by correlation analysis as variables with significant predictors. By using a regression method with a backward elimination procedure, significant predictors of these outcome variables were identified as the concentrations of Lactobacillus spp., anaerobic Streptococcus spp., and Staphylococcus spp., respectively. For all three outcome variables, pH and flow stage were also identified as significant independent variables. Because some of the data in the data set are repeated measurements for a subject, a mixed-effect model that accounts for the random effects of repeated-measurement data fit best the data set for predicting interactions between various members of the vaginal microflora. The predictive accuracies of the three models were tested by a comparison of model-predicted outcome-variable values with actual mean in vivo outcome-variable values. From these results, we concluded that it is possible to accurately predict vaginal microflora interactions by using a mixed-effect modeling system. The application of this type of modeling strategy and its future use are discussed.

Quantitative and qualitative effects of douche preparations on vaginal microflora

OBJECTIVE

To determine the effect of douching on the quantitative and qualitative makeup of the vaginal microflora.

METHODS

We first evaluated the effect of douching with a solution of physiologic saline to determine the effect of washing the vaginal surface. Two douche preparations, one containing 0.04% acetic acid and one containing 0.30% povidone-iodine, were evaluated subsequently to determine whether any effects occurred in addition to those noted with saline. Duplicate vaginal swab samples were obtained at predetermined intervals from ten healthy volunteers for three sampling cycles before and after use of the douche preparations for various periods of time. Samples were analyzed for total facultative and obligately anaerobic bacterial populations.

RESULTS

The use of a douche preparation containing acetic acid caused a transient reduction of the total bacterial counts, with most of the change attributable to the effect of washing the surface of the vaginal vault as noted with physiologic saline. In contrast, the povidone-iodine preparation caused a significant reduction in total counts compared with those obtained after use of a physiologic saline solution by the same subjects (P = .02). Little change in the qualitative makeup of the vaginal microflora occurred.

CONCLUSION

The use of povidone-iodine douches decreases the numbers of the dominant bacterial species beyond those expected with other douches. In some individuals, such changes may allow rapid proliferation of potential pathogens during this altered state, increasing the risk of associated infections.

Normal vaginal microflora during use of various forms of catamenial protection

Although the effect of vaginal tampons on microbial flora during menstruation has been studied, the effects attributable to particular tampon fibers have received inadequate attention. The purpose of this report is to review previous studies and describe the results of laboratory tests that compare the effects of use of various tampons on the normal changes that occur in vaginal microflora during menstruation. Tampon and swab samples were obtained from volunteers on days 2, 4, and 21 after the start of menses. Statistical evaluation of the qualitative and quantitative data revealed that the same numerically dominant phenotypes were present regardless of sample type, sample time, or catamenial product. In general, total bacterial counts decreased during menstruation, and the total bacterial counts from tampon samples tended to be lower than those in concomitant swab samples. Predictable changes in total numbers of the dominant species were noted when the data were evaluated by day of menstrual cycle. Results indicate that the tampon type had little effect on the qualitative and quantitative composition of the vaginal microflora during the menstrual cycle.