Dennis T Crouse

Antibiotic use in pregnancy and drug-resistant infant sepsis

OBJECTIVE We sought to evaluate the effect of antepartum and intrapartum antibiotic use on antimicrobial-resistant neonatal sepsis. STUDY DESIGN We analyzed perinatal outcomes for 8474 pregnancies (8593 live births) delivered at 6 hospitals. Data were collected regarding maternal antibiotic use and perinatal course, neonatal cultures, and outcomes. The diagnosis of confirmed neonatal sepsis required at least one positive blood or cerebrospinal fluid culture. Neonatal cultures were evaluated on the basis of the occurrence and timing of maternal antibiotic exposure. RESULTS There were 96 neonates with confirmed sepsis (11.2/1000 live births). Sepsis was 19.3-fold more common after preterm birth (57 vs 3. 1/1000; P <.001), with 76% of septic infants being delivered preterm. Forty-five percent of pathogens were ampicillin resistant. Ampicillin resistance increased with preterm birth (50% vs 26%; P =. 04), antepartum antibiotics (57% vs 34%; P =.03), intrapartum antibiotics (55% vs 28%; P <.01), and any prenatal antibiotic exposure (52% vs 22%; P =.01). Infection with an organism resistant to at least one maternal antibiotic was more common with intrapartum antibiotic exposure than with antepartum exposure only (57% vs 17%; P =.01). Regarding early-onset sepsis (n = 55), ampicillin resistance was more common with intrapartum antibiotics (50% vs 16%; P <.01), and resistance to at least one maternally administered antibiotic was more frequent with intrapartum exposure (56.7% vs 0%; P <.01). CONCLUSIONS Maternal antibiotic treatment is associated with neonatal sepsis by organisms resistant to ampicillin and to maternally administered antibiotics.

Interleukin-6, C-Reactive Protein, and Abnormal Cardiorespiratory Responses to Immunization in Premature Infants

Objective. We report our experience with routine immunization of 89 premature infants in the neonatal intensive care unit because 1) a substantial number of them developed abnormal clinical signs, and 2) all but one of those who received diphtheria, tetanus, and whole-cell pertussis (DTwP) vaccine responded with elevations of interleukin-6 (IL-6) and C-reactive protein (CRP) concentrations that are otherwise characteristic of bacterial disease. Methodology. We hypothesized that the elevated IL-6 and CRP levels were solely a response to immunization and that treatment with antibiotics was not necessary. We performed this study in two consecutive parts. In part 1, we prospectively evaluated 79 consecutive premature infants who were immunized with DTwP, Haemophilusb conjugate vaccine, hepatitis B vaccine, and inactivated polio vaccine, (Hib, HBV, and IPV). IL-6 and CRP were determined before immunization and every 12 hours on three occasions after immunization. In part 2, we studied an additional 10 infants who received acellular pertussis vaccine (DTaP) and who, 2 days later, received Hib, HBV, and IPV immunization simultaneously. We followed the same schedule of IL-6 and CRP determinations as in part 1. Results. In part 1, 24 infants (30%) developed abnormal cardiorespiratory signs within 24 hours after immunization. CRP and IL-6 values rose to abnormal levels after immunization in all but one infant; that infant was later shown to have a T-cell abnormality. In part 2, 3 infants had abnormal cardiorespiratory signs after simultaneous immunization with Hib, HBV, and IPV, but not after DTaP. IL-6 and CRP levels remained normal in all 10 infants. Conclusions. Part 1 demonstrates clearly the temporal relationship between IL-6 and CRP increments after DTwP, Hib, HBV, and IPV vaccines. In part 2 (DTaP was substituted for DTwP), there were no elevations of IL-6 or CRP, thus indicating that whole-cell pertussis component of DTwP was responsible for IL-6 and CRP elevations. Abnormal cardiorespiratory signs occurred frequently after immunizations in part 1, but they were unrelated to the magnitude of IL-6 and CRP elevations. The frequency of cardiorespiratory difficulty and its occasional severity suggest a need to monitor premature infants for ∼48 hours after routine immunization.

Genital Mycoplasmas Stimulate Tumor Necrosis Factor-|[alpha]| and Inducible Nitric Oxide Synthase Production from a Murine Macrophage Cell Line

Ureaplasma urealyticum and Mycoplasma hominis, two genital mycoplasmas, are the most common organisms isolated in the perinatal period and both either cause or are associated with poor perinatal outcomes. We speculate that these microbes could increase inflammation by stimulating macrophages to produce tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase because of their propensity to interact with the hosts immune system. To test this hypothesis, RAW 264.7 cells, a murine macrophage cell line, were coincubated for 16 h with either U. urealyticum or M. hominis, and LPS and sterile broth were used as controls. Lipopolysaccharide (LPS) and both mycoplasmas induced TNF-α production, which was concentration-dependent, whereas sterile broth had little effect. TNF-α production was not inhibited by the addition of polymyxin B, excluding the possibility of contaminating endotoxin in this effect. Inducible nitric oxide synthase was produced only in the presence of recombinant interferon-γ. We conclude that both viable and nonviable U. urealyticum and M. hominis are capable of TNF-α induction from murine macrophages and that LPS is not involved in this event. Also, the genital mycoplasmas are capable of stimulating inducible nitric oxide synthase production from murine macrophages. We speculate that the genital mycoplasmas produce perinatal disease by producing proinflammatory mediators by their interaction with inflammatory cells and either induce or act as a catalyst and augment inflammation which in turn leads to a poor pregnancy outcome.

Exogenous Bovine Surfactant Suppresses Tumor Necrosis Factor-α Release by Murine Macrophages Stimulated by Genital Mycoplasmas

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that appears to play a significant role in the development of neonatal chronic lung disease (CLD). Inflammation and CLD are also associated with respiratory tract colonization with genital mycoplasmas. The possible protective roles of surfactant in mitigating the inflammatory response to these microbes were investigated. Murine RAW 264.7 macrophages were preincubated with an exogenous surfactant and exposed overnight to sterile media, lipopolysaccharide (LPS), Mycoplasma hominis, or Ureaplasma urealyticum. Macrophages released TNF-alpha in response to challenge with LPS, U. urealyticum, and M. hominis in a concentration-dependent fashion. Surfactant suppressed LPS and M. hominis induced TNF-alpha production in a dose-dependent manner but suppressed U. urealyticum-mediated TNF-alpha production only at the higher dose tested. Similar effects were seen in hyperoxia (95% O2). Thus, exogenous bovine surfactant significantly inhibits the production of TNF-alpha by murine macrophages stimulated with genital mycoplasmas and bacterial LPS.

Immunomodulation by exogenous surfactant: Effect on TNF-α secretion and luminol-enhanced chemiluminescence activity by murine macrophages stimulated with group B streptococci

Group B streptococci (GBS) are important pathogens in neonatal sepsis and pneumonia. GBS stimulate alveolar macrophages to produce inflammatory cytokines and free oxygen radicals, which can damage the lungs. In several studies, use of exogenous surfactant in term babies has improved outcome related to sepsis and respiratory failure. The role(s) of exogenous surfactant in modulating the inflammatory response produced by this microbe was examined. Tumor necrosis factor alpha (TNF-alpha) production and luminol-enhanced chemiluminescence (LCL), a measure of respiratory burst, were investigated. For measuring TNF-alpha release, RAW 264.7 murine macrophages were pre-incubated with bovine surfactant and stimulated with either lipopolysaccharide, live or heat-killed GBS type Ia. LCL was measured after macrophages were pre-incubated with or without surfactant overnight, then stimulated with GBS or phorbol myristate acetate. Lipopolysaccharide and GBS stimulated TNF-alpha secretion from macrophages that was suppressed by exogenous surfactant in a dose-dependent fashion. GBS and phorbol myristate acetate also increased LCL from macrophages, which was significantly suppressed by pre-incubation of macrophages with exogenous surfactant. We conclude that GBS type Ia stimulates TNF-alpha release and LCL from RAW 264.7 cells and that these responses are suppressed by surfactant. Suppression of inflammatory mediators by exogenous surfactant might improve respiratory disease associated with GBS.

Pneumonitis Associated with Ureaplasma urealyticum in Children with Cancer

We describe 3 pediatric patients with cancer who had clinical and radiographic evidence of pneumonitis and for whom cultures of bronchoalveolar lavage fluid specimens yielded Ureaplasma urealyticum. Two of the patients died; for the surviving patient, clinical improvement coincided temporally with administration of erythromycin. Immunocompromised patients with pneumonitis of unclear etiology should have respiratory secretions cultured for mycoplasmas and should receive empiric therapy that includes a macrolide antibiotic.

Effect of Surfactant Phospholipid on TNF alpha release and Chemiluminescence Activity of Stimulated Murine Macrophages † 1483

TNFα is an important pro-inflammatory cytokine released by macrophages in response to various stimuli. The immunomodulatory effects of exogenous surfactant have been reported. Our previous studies indicate that Survanta® inhibits TNFα release from RAW 264.7, murine macrophages. We hypothesized that surfactant phospholipid, Dipalmytoyl, Phosphatidyl Choline (DPPC) played a major role in this suppression, since Survanta® does not contain any SP-A which is the other important component responsible for immunomodulation. We also studied luminol-induced chemiluminescence (LCL) activity from these macrophages and the effect of DPPC on LCL to understand the free oxygen radical production in the presence of various stimuli and surfactant phospholipids. We stimulated RAW 264.7 murine macrophages(106 cells/ml) with LPS (lipopolysaccharide)(10ng/ml,100ng/ml) and heat-killed Group B streptococci (GBS, 106cfu/ml) before and after incubation with DPPC (1mg/ml, 2mg/ml). The macrophages were stimulated for 16 hours at 37°C and 5% CO2 and supernatants were frozen at -70°C. TNFα was assayed using ELISA technique with a murine TNFα mini-kit(Endogen Inc.). In a different set of experiments, LCL was measured using a Tri-carb liquid scintillation analyzer. We incubated the macrophages(106cells/ml) with and without DPPC (2mg/ml) for 16 hours and then stimulated with PMA (phorbol myristate acetate)(10ng/ml) and GBS 106cfu/ml; luminol (1.44 mmol/l) was added to detect the LCL. Viability of macrophages remained unchanged after incubation with DPPC as determined by Trypan blue method. We found that murine macrophages released TNFα when stimulated with LPS (10ng, 100ng) and heat-killed GBS 106 cfu/ml. This release was significantly suppressed when incubated with 2mg/ml DPPC(p<.05), but only slightly suppressed with 1mg/ml DPPC. Conversely the LCL activity was higher in the macrophages incubated with DPPC (2mg/ml) as compared to macrophages incubated in plain media. Both PMA and GBS induced LCL which was maximum at 10 minutes after stimulation but decreased gradually to baseline by one hour. LCL activity was significantly higher in stimulated macrophages when pre-incubated with DPPC. The macrophages stimulated with PMA gave a higher response than GBS. We conclude that DPPC in exogenous surfactant suppress the release of TNFα from murine macrophages when stimulated by LPS and heat-killed GBS in a dose-dependent manner, but increases the LCL activity from both unstimulated and stimulated macrophages.

Interleukin-6 (IL-6), C-reactive protein (CRP), and Cardiorespiratory Responses to Primary Routine Immunization Series in Premature Infants with Bronchopulmonary Dysplasia (BPD) 1467

Interleukin-6 (IL-6), C-reactive protein (CRP), and Cardiorespiratory Responses to Primary Routine Immunization Series in Premature Infants with Bronchopulmonary Dysplasia (BPD) 1467

Effect of Dexamethasone on TNF alpha and Inducible Nitric Oxide Synthase(iNOS) Production from Mycoplasma-Stimulated Macrophages † 1432

Effect of Dexamethasone on TNF alpha and Inducible Nitric Oxide Synthase(iNOS) Production from Mycoplasma-Stimulated Macrophages † 1432

Suppressive Effect of Surfactant on TNFα Release from Murine Macrophages Stimulated by Live and Heat-Killed Group B Streptococci † 1350

Suppressive Effect of Surfactant on TNFα Release from Murine Macrophages Stimulated by Live and Heat-Killed Group B Streptococci † 1350