**5. Use of immunoglobulins in the treatment of neonatal sepsis**

86 Neonatal Bacterial Infection

Amato et al. (24) investigated serial IgG and IgM serum levels during the neonatal period in two groups of non-septic, preterm infants treated prophylactic with IVIG. Twenty-two very low birth weight infants (mean gestational age 31.8 weeks and mean birth weight 1265 g with a range of 1001 - 1500g) and 12 extremely low birth weight infants < 1000g (mean gestational age 28.6 weeks and mean birth weight 910g) received at random three standard doses of IVIG (0.5 g/kg/day) or IVIGAM (IgM enriched preparation) (5 ml/kg/day). IgG and IgM concentrations were assayed by rate nephelometry before treatment and at day 3, 5, 7, 14 and 28 of life. At any time IgG levels were higher in the IVIG very low birth weight group and no difference was observed in the extremely low birth weight group. IgM levels were higher at day 3 and 5 in the IVIGAM very low birth weight group and until day 7 in the extremely low birth weight group. The authors concluded that their findings indicate a wide

Supplementation of the preterm serum with either intravenous immunoglobulin or IgMenriched immunoglobulin did not change the results of phagocytosis rates (percentage of neutrophils phagocytosing group B streptococci in vitro in infants < 32 weeks of gestation

In a rat model marked neutropenia, complete depletion of the neutrophil storage pool, and death within 48 hours were observed in newborn rats intrapulmonically inoculated with type III group B streptococci (26). Intraperitoneal administration of 225 mg of IVIG immediately after intrapulmonic inoculation of GBS significantly lessened the degree of neutropenia and prevented depletion of the neutrophil storage pool and death. No effect of IVIG on neutrophil production was observed in vitro or in vivo in normal neonatal rats injected with IVIG. IVIG, however, markedly hastened release of neutrophils from the reserves into the blood and hastened the arrival of neutrophils at the site of the bacterial injection. Specific antibody to GBS, as opposed to a nonspecific IgG effect, appeared to be responsible for the improvements in neutrophils kinetics and for survival of the animals.

In animal experiments following administration of IVIGAM endotoxemia was induced by intraperitoneal inoculation of a sublethal dose of Escherichia coli and subsequent intravenous administration of an antimicrobial agent (27). Prophylactic administration of IVIGAM was found to significantly attenuate the antibiotic-induced increase in endotoxin activity as compared to the albumin control group. These experimental results suggested that in endotoxaemia the polyclonal immunoglobulin preparation had a prophylactic protective effect on the acute phase responses and reduced the cardiodepressant effects of

The pharmacokinetics and safety of IVIG were examined in thirty neonates with suspected sepsis who were randomly assigned either to a treatment (receiving either 250, or 500, or 1,000 mg/kg of IVIG plus antibiotics) or control (antibiotics alone) group (28). The 500 mg/kg dose produced a rise in total IgG for greater than 8 and in group B streptococcus typespecific IgG for greater than 4-14 days. The type-specific antibody elevation varied with the amount of pathogen-specific antibody and dose of IVIG. Pharmacokinetic analysis suggested a biphasic elimination curve and a terminal elimination half-life of 24.2 days. No

range of IgG and IgM kinetics in the healthy premature infant.

and adult controls) significantly (25).

Escherichia coli septicaemia.

toxicity was observed (28).

Polyvalent immunoglobulin preparations are widely used as adjunctive therapy for sepsis or septic shock, but their efficacy is still a matter of debate. In 2007 Kreymann et al. (30) conducted a systematic review summarizing data on adults and neonates separately. In neonates, 12 trials (31-42) involving 710 patients were published. The estimate of the pooled effect on mortality was RR = 0.56 (95% CI 0.42– 0.74, p <.0001). Five studies (32,35,37,39,41) involving 352 patients were performed with the IgGAM preparation. The range of the cumulative dose of IgG was 0.57– 0.76 g/kg birth weight plus 0.09–0.12 g/kg birth weight IgA and 0.09–0.12 g/kg birth weight IgM. In this subgroup, the estimate of the pooled effect was RR = 0.50 (95% CI 0.34–0.73), equivalent to a 50% relative reduction in mortality (*p* < .0003). The study effects were comparable, and the test of heterogeneity was not significant. The study of El Nawawy (32) reported a significant reduction of mortality, the other four a positive trend (35,37,39,41). Polyvalent immunoglobulin preparations containing only IgG were evaluated in seven trials (31,33,34,36,38,40,42) involving 358 patients. The cumulative dose of IgG was 0.5–3 g/kg birth weight. The estimate of the pooled effect for this subgroup was RR = 0.63 (95% CI 0.42– 0.96), equivalent to a 37% relative reduction in mortality (p < .03). The test of heterogeneity was not significant. One study (38) reported a significant reduction in mortality, three studies reported a positive trend (31,33,42), and two studies (34,40) showed no effect. One trial (36) showed a duplication of mortality; one neonate died in the control group and two in the treatment group. Comparing the two treatment modalities, a small and insignificant difference in favour of IgGAM was observed (z = 0.80, p ≤ .42). Kreymann et al. (30) found a negative correlation with the severity of illness (as measured by the mortality of the control groups) in neonates; however, this held true only when the results reported by Chen (36) were included: In this study, an exceptionally low mortality in the control group was observed (1 of 28, respectively, 3.6%), which was doubled in the treatment group (2 of 28, respectively, 7.1%). If these results were omitted, the correlation lost significance. Additionally the authors found no correlation with the dosage of immunoglobulins administered.

In adults and children, Kreymann et al. (30) found a strong trend in favour of IgGAM over IgG preparations with a 34% and 15% reduction of the risk to die, respectively, compared to an even higher 50% and 37% relative reduction of mortality in neonates, respectively. In

neonates and especially preterm infants, therapy with polyclonal immunoglobulins should be understood much more as a substitutional therapy than as an adjunctive therapy as for adults or older children (43). Comparing the two treatment modalities (IgGAM vs. IgG) in neonates, Kreymann et al. (30) only found a slight difference without statistical significance. A major limitation of this meta-analysis is the inclusion of the study of El Nawawy (32), who originally included infants of 1 to 24 months of age hospitalized at a pediatric intensive care unit, of which 50 were proven septic patients. This study strongly influenced study results favouring immunoglobulin therapy.

Immunoglobulins in the Prevention and Treatment of Neonatal Sepsis 89

**6. Use of immunoglobulins in the prevention of neonatal sepsis** 

Medicine (50,51) with divergent results and the latest Cochrane Review (52).

The cumulative relative risk reduction was 0.7 (CI 95% 0.5-0.9).

There have been published a lot of studies and reviews on the preventive use of IVIG in preterm infants and I herewith report ("pars pro toto") two multicenter randomized, double-blind, placebo-controlled trial published early in the New England Journal of

Baker et al. (50) included 588 infants with a birth weight of 500 - 1750 g and age of 3 - 7 days from six centres in the U.S. between 1987 and 1988. The trial was randomized, double-blind, placebo-controlled with 287 infants having received 500 mg/kg of IVIG at enrolment (age 3 to 7 days), one week later, and then every 14 days until a total of five infusions had been given or until hospital discharge, whichever came first, and 297 controls having received an equal volume of a sterile solution of 5 % albumin and 0.9 % sodium chloride. Outcomes included proven infection - clinical findings of sepsis and at least one of the following: a positive blood culture of either bacteria or fungi (the isolation of a pathogen from a normally sterile other body site or urine obtained by suprapubic or bladder catheterization, or the isolation of virus from an infant with clinical deterioration), necrotizing enterocolitis stage II or III, intraventricular haemorrhage grade 1 to 4, bronchopulmonary dysplasia, death, and total days in hospital. There were 50 episodes of sepsis among 287 infants (17.4%) in the IVIG group and 75 episodes of sepsis among 297 infants (25.3%) in the placebo group.

In a prospective, multicenter, two-phase controlled trial, Fanaroff et al. (51) stratified 2416 infants according to birth weight (501 to 1000 g and 1001 to 1500 g) and randomly assigned to an IVIG (n = 1204) or a control group (n = 1212). Control infants were given placebo infusions during phase 1 of the study (n = 623) but were not given any infusions during phase 2 (n = 589). Infants weighing 501 to 1000 g at birth were given 900 mg of immune globulin per kilogram of body weight, and infants weighing 1001 to 1500 g at birth were given a dose of 700 mg per kilogram. The immune globulin infusions were repeated every 14 days until the infants weighed 1800 g, were transferred to another center, died, or were sent home from the hospital. Nosocomial infections of the blood, meninges, or urinary tract occurred in 439 of the 2416 infants (18.2 %): 208 (17.3 %) in the immune globulin group and 231 (19.1%) in the control group (relative risk, 0.91; CI 95% 0.77 to 1.08). Septicemia occurred in 15.5% of the immune globulin recipients and 17.2% of the controls. The predominant organisms included gram-positive cocci (53%), gram-negative bacilli (22.4%), and candida species (16%). Adverse reactions were rarely observed during the infusions. Immune globulin therapy had no effect on respiratory distress syndrome, bronchopulmonary dysplasia, intracranial hemorrhage, the duration of hospitalization, or mortality. The incidence of necrotizing enterocolitis was 12% in the immune globulin group and 9.5" in the control group. Thus, the authors concluded that the prophylactic use of IVIG failed to reduce the incidence of hospital-acquired infections in very-low-birth-weight infants (51).

The prophylactic administration of intravenous immunoglobulins (IVIG) to prevent nosocomial infections has been studied in >5,000 neonates from 19 studies enrolled in randomised controlled trials (52). The results of these meta-analyses showed a statistically

Ohlsson and Lacy (44) recently reviewed IVIG for suspected or subsequently proven infection in neonates including randomized or quasi-randomized controlled trials comparing IVIG treatment to placebo or no intervention in newborn infants below 28 days of age. They found 10 studies meeting their inclusion criteria that differed to the above mentioned analysis (30) by additional including the small study of Christensen et al. (45) and a new study by Ahmend et al. (46) and not including the studies by El Nawawy (32), Gökalp (38), and Gunes (31).The results showed a statistically significant reduction in mortality in cases of proven and also of suspected infection with a NNT of 10 infants (95% CI; 6, 33) to avoid one death.

IVIG preparations with high concentrations of antibodies to bacteria that are commonly isolated from neonates in specific local settings or geographical areas may be more effective in reducing adverse outcomes (44). However, the use of antistaphylococcal immunoglobulins to prevent staphylococcal infection in very low birth weight infants has recently been reviewed and is currently not recommended (47).

A very recent study published by the International Neonatal Immunotherapy Study (INIS) Collaborative group enrolled 3493 infants with birth weight less than 1500g receiving antibiotics for suspected or proven serious infection and randomly assigned them to receive two infusions of either IgG immune globulin (at a dose of 500 mg per kilogram of body weight) or matching placebo 48 hours apart (48). The researchers found no significant between-group difference in the rates of death or major disability at the age of two years (39 and 39%, respectively). Similarly, there were no significant differences in the rates of secondary outcomes including the incidence of subsequent sepsis episodes. In the 2-years follow-up of the study participants there were no differences in the rates of major or nonmajor disability or of adverse events. Thus, IgG IVIG was not found to be helpful in diminishing the risk of major complications or adverse outcomes in neonates with suspected or proven sepsis. The duration of hospital stay also did not differ between groups (48).

The clinical efficacy of IgM-enriched IVIG (currently there is only one preparation available, Pentaglobin®) has been reviewed by Norrby-Teglund et al. (49) for both adult and paediatric/neonatal patients. The authors concluded that patients most likely to benefit are Gram-negative septic shock patients. Therefore it is important to emphasize that selection of study patients as well as microbiological aetiology are of high relevance affecting the efficacy of IVIG.
