Probable mother to infant transmission of Pneumocystis jiroveci from an HIV-infected woman to her HIV-uninfected infant

Role of Inflammation in Virus Pathogenesis during Pregnancy

Viral infections during pregnancy lead to a spectrum of maternal and fetal outcomes, ranging from asymptomatic disease to more critical conditions presenting with severe maternal morbidity, stillbirth, preterm birth, intrauterine growth restriction, and fetal congenital anomalies, either apparent at birth or later in life. In this article, we review the pathogenesis of several viral infections that are particularly relevant in the context of pregnancy and intrauterine inflammation. Understanding the diverse mechanisms employed by viral pathogens as well as the repertoire of immune responses induced in the mother may help to establish novel therapeutic options to attenuate changes in the maternal-fetal interface and prevent adverse pregnancy outcomes.

Current antimicrobial management of community-acquired pneumonia in HIV-infected children

INTRODUCTION

Community-acquired pneumonia is a leading cause of morbidity and mortality amongst HIV-infected infants and children. Polymicrobial infection is common and, due to the difficulties in confirming the etiology of pneumonia, empiric broad-spectrum antimicrobial therapy is frequently used.

AREAS COVERED

The author based this article on literature identified from PubMed. The author's search terms included: pneumonia, community-acquired pneumonia, HIV, children. The articles reviewed included original studies, recent review articles and current guidelines on the management of pneumonia in HIV-infected children. The microbiological etiology and the empiric and pathogen-specific antimicrobial therapy of community-acquired pneumonia in HIV-infected and HIV-exposed infants and children are also discussed.

EXPERT OPINION

There are many changing epidemiological factors impacting antimicrobial management of community-acquired pneumonia in the context of HIV infection in infants and children. These include vaccination strategies, antimicrobial prophylaxis, emerging drug-resistant pathogens, and recognition of the importance of viruses and tuberculosis in the etiology of community-acquired pneumonia. Further research is needed on optimal amtimicrobial management strategies in HIV-exposed uninfected children, and HIV-infected children receiving antiretroviral therapy.

Excess respiratory viral infections and low antibody responses among HIV-exposed, uninfected infants

OBJECTIVE

HIV-exposed uninfected (HEUs) infants have frequent severe infection, hospitalization, and death. We performed a serologic investigation to determine the role of common childhood respiratory pathogens in the excess incidence of infections in HEUs.

DESIGN

Prospective cohort study of mother-infant pairs.

METHODS

Among 247 HEUs and 88 HIV-unexposed uninfected (HUU) infant-mother pairs, we measured maternal antibodies to respiratory syncytial virus (RSV) and pneumococcus (PNC 1, 5, 6B, 14); infant antibodies to RSV, influenza A (flu), parainfluenza viruses (1, 2, 3), and PNC 1, 5, 6B, and 14 were measured at 0 and 6 months, and antitetanus antibodies at 6 months.

RESULTS

HIV-infected mothers had higher RSV and lower PNC antibody concentrations at delivery than uninfected mothers. Transplacental transfer of maternal antibodies, particularly for RSV, was lower in HEUs compared with HUUs. At birth, HEUs had higher concentrations of anti-RSV antibodies than HUUs, but lower antibodies to the other respiratory agents. At 6 months, HEUs had significantly higher proportions of seroconversions and higher antibody concentrations against parainfluenza viruses 1, 2, and 3. There were no significant differences in seroconversions to flu and RSV, but antibody concentrations to RSV were six-fold lower in HEUs versus HUUs at 6 months. Antibody responses to at least two doses of tetanus vaccine were also six-fold lower in HEUs compared with HUUs.

CONCLUSION

Six-month-old HEUs had a higher incidence of respiratory viral infections than HUUs. In addition to the low passive protection from maternal antibodies, low antibody responses of HEUs may contribute to increased morbidity and mortality.

Maternal HIV and Paediatric Lung Health

With improved prevention of mother to child transmission of HIV, paediatric HIV disease is less common. However, the number of HIV exposed but uninfected infants is growing. Exposure to maternal HIV impacts infant respiratory health through an increase in known risk factors such as increased preterm birth and low birth weight, suboptimal breastfeeding, increased psychosocial stressors and increased exposure to infective pathogens. Exposure to the HIV virus and altered maternal immune environment result in immunologic changes in the infant that may contribute to respiratory disease risk. HIV exposed infants are at increased risk for severe pneumonia with poorer outcomes compared to unexposed infants. Maternal ART and optimal nutrition, including breastfeeding in high infective disease burden settings, reduce morbidity and mortality in HIV exposed infants and should be prioritized. The impact of exposure to maternal HIV on normal lung growth and risk for chronic respiratory disease is unknown and warrants further investigation.

Risk Factors for Presumed Bacterial Pneumonia Among HIV-uninfected Children Hospitalized in Soweto, South Africa

BACKGROUND

Pneumonia is a leading cause of child morbidity and death. Data on risk factors can guide prevention efforts. Within a study on pneumococcal conjugate vaccine effectiveness, we investigated risk factors for presumed bacterial pneumonia (PBP).

METHODS

PBP cases were human immunodeficiency virus (HIV) uninfected children with lower respiratory tract infection and consolidation on chest radiograph or nonconsolidated infiltrate with C-reactive protein ≥40 mg/L hospitalized at Chris Hani Baragwanath Academic Hospital (CHBAH) in Soweto. Age-matched community controls were identified using CHBAH birth records ±1 week of case birth date. Data were analyzed using conditional logistic regression.

RESULTS

A total of 889 PBP cases (median age 9 months) were matched to 2628 controls. Crowding was a significant risk factor among well-nourished children (adjusted odds ratio [aOR]: 2.29, 95% confidence interval [CI]: 1.89-2.78), but not in those with low weight-for-age. Malnutrition was associated with PBP; strength of association was highest in the absence of crowding (aOR: 6.68, 95% CI: 4.74-9.42). Exclusive breastfeeding was protective only among HIV-unexposed children (aOR: 0.65, 95% CI: 0.54-0.78). Self-reported maternal HIV infection was a risk factor among children exclusively breastfeed up to 4 months (aOR: 2.33, 95% CI: 1.53-3.55). Having indoor tap water was protective (aOR: 0.65, 95% CI: 0.54-0.78), whereas a primary care giver who smoked was a risk factor (aOR: 5.15, 95% CI: 2.94-9.03).

CONCLUSIONS

Our findings confirm several known pneumonia risk factors and highlight complex interactions between factors, including HIV exposure, breastfeeding, malnutrition and crowding. Improved housing, reduced secondhand smoke exposure and HIV prevention among women of reproductive age could lessen the child pneumonia burden.

HIV-Exposed Uninfected Infants Show Robust Memory B-Cell Responses in Spite of a Delayed Accumulation of Memory B Cells: an Observational Study in the First 2 Years of Life

Improved HIV care has led to an increase in the number of HIV-exposed uninfected (HEU) infants born to HIV-infected women. Although they are uninfected, these infants experience increased morbidity and mortality. One explanation may be that their developing immune system is altered by HIV exposure, predisposing them to increased postnatal infections. We explored the impact of HIV exposure on the B-cell compartment by determining the B-cell subset distribution, the frequency of common vaccine antigen-specific memory B cells (MBCs), and the levels of antibodies to the respective antigens in HEU and HIV-unexposed uninfected (HUU) infants born to uninfected mothers, using flow cytometry, a B-cell enzyme-linked immunosorbent spot assay, and an enzyme-linked immunosorbent assay, respectively, during the first 2 years of life. For the majority of the B-cell subsets, there were no differences between HEU and HUU infants. However, HIV exposure was associated with a lower proportion of B cells in general and MBCs in particular, largely due to a lower proportion of unswitched memory B cells. This reduction was maintained even after correcting for age. These phenotypic differences in the MBC compartment did not affect the ability of HEU infants to generate recall responses to previously encountered antigens or reduce the antigen-specific antibody levels at 18 months of life. Although HIV exposure was associated with a transient reduction in the proportion of MBCs, we found that the ability of HEU infants to mount robust MBC and serological responses was unaffected.

HIV-exposed, uninfected infants: new global challenges in the era of paediatric HIV elimination

The number of infants infected with HIV is declining with the rise in interventions for the elimination of paediatric HIV infection, but the number of uninfected infants exposed to HIV through their HIV-infected mothers is increasing. Interest in the health outcomes of HIV-exposed, uninfected infants has grown in the past decade, with several studies suggesting that these infants have increased mortality rates, increased infectious morbidity, and impaired growth compared with HIV-unexposed infants. However, heterogeneous results might reflect the inherent challenges in studies of HIV-exposed, uninfected infants, which need large populations with appropriate, contemporaneous comparison groups and repeated HIV testing throughout the period of breastfeeding. We review the effects of HIV exposure on mortality, morbidity, and growth, discuss the immunological abnormalities identified so far, and provide an overview of interventions that could be effective in this susceptible population. As the number of infants infected with HIV declines, the health needs of HIV-exposed, uninfected infants should be prioritised further, to ensure that post-2015 Sustainable Development Goals are achieved.

Pneumocystis pneumonia in South African children diagnosed by molecular methods

Background

Pneumocystis pneumonia (PCP) is an important cause of hospitalization and mortality in HIV-infected children. However, the incidence of PCP has been underestimated due to poor sensitivity of diagnostic tests. The use of polymerase chain reaction (PCR) for pneumocystis has enabled more reliable diagnosis. This study describes the incidence, clinical features and outcome of PCP in South African children diagnosed using PCR.

Methods

A prospective study of children hospitalised in South Africa with suspected PCP was done from November 2006 to August 2008. Clinical, laboratory and radiological information were collected. Lower respiratory tract specimens were obtained for PCP immunofluorescence (IF), real- time PCR for pneumocystis, bacterial and mycobacterial culture. Nasopharyngeal aspirates were taken for immunofluorescence (IF), real-time PCR for pneumocystis and PCR for respiratory viruses. A blood specimen for bacterial culture and for cytomegalovirus PCR was taken. Children were followed for the duration of their hospitalisation and the outcome was recorded.

Results

202 children [median (interquartile range, IQR) age 3.2 (2.1– 4.6) months] were enrolled; 124 (61.4%) were HIV infected. PCP was identified in 109 (54%) children using PCR, compared to 43 (21%) using IF and Grocott staining (p < 0.0001). Most PCP cases (88, 81%) occurred in HIV-infected children. All 21 cases (19%) occurring in HIV- negative children had another risk factor for PCP. On logistic regression, predictive factors for PCP were HIV infection, lack of fever, high respiratory rate and low oxygen saturation whilst cotrimoxazole prophylaxis was protective (OR 0.24; 95% CI 0.1 to 0.5; p < 0.002). The case fatality of children with PCP was higher than those without PCP (32.1% versus 17.2%; relative risk 1.87; 95% confidence interval (CI) 1.11 – 3.15). Amongst HIV-infected children, a CD4 less than 15% was the only independent predictor of mortality.

Conclusions

The diagnostic yield for PCP is more than 2.5 times higher on PCR than other detection methods. PCP is a very common cause of severe hypoxic pneumonia and is associated with high mortality in HIV-infected African infants.

Humoral immune responses to Pneumocystis jirovecii antigens in HIV-infected and uninfected young children with pneumocystis pneumonia

Background

Humoral immune responses in human immunodeficiency virus (HIV)-infected and uninfected children with Pneumocystis pneumonia (PcP) are poorly understood.

Methods

Consecutive children hospitalized with acute pneumonia, tachypnea, and hypoxia in South Africa were investigated for PcP, which was diagnosed by real-time polymerase chain reaction on lower respiratory tract specimens. Serum antibody responses to recombinant fragments of the carboxyl terminus of Pneumocystis jirovecii major surface glycoprotein (MsgC) were analyzed.

Results

149 children were enrolled of whom 96 (64%) were HIV-infected. PcP occurred in 69 (72%) of HIV-infected and 14 (26%) of HIV-uninfected children. HIV-infected children with PcP had significantly decreased IgG antibodies to MsgC compared to HIV-infected patients without PcP, but had similar IgM antibodies. In contrast, HIV-uninfected children with PcP showed no change in IgG antibodies to MsgC, but had significantly increased IgM antibodies compared to HIV-uninfected children without PCP. Age was an independent predictor of high IgG antibodies, whereas PcP was a predictor of low IgG antibodies and high IgM antibodies. IgG and IgM antibody levels to the most closely related MsgC fragments were predictors of survival from PcP.

Conclusions

Young HIV-infected children with PcP have significantly impaired humoral immune responses to MsgC, whereas HIV-uninfected children with PcP can develop active humoral immune responses. The children also exhibit a complex relationship between specific host factors and antibody levels to MsgC fragments that may be related to survival from PcP.

Antibody responses to vaccination among South African HIV-exposed and unexposed uninfected infants during the first 2 years of life

HIV-exposed but uninfected (HEU) infants born to HIV-infected mothers from areas in the world with a high burden of infectious disease suffer higher infectious morbidity and mortality than their HIV unexposed uninfected (HUU) peers. Vaccination provides protection from infection. The possibility exists that altered response to vaccination contributes to the higher rate of infection in HEU than in HUU infants. While short-term, cross-sectional studies support this notion, it is unclear whether or not HEU infants develop long-term protective immune responses following the WHO extended program on immunization (EPI). Vaccine-specific antibody responses were compared between HEU and HUU infants from 2 weeks until 2 years of age in a longitudinal South African cohort. Total IgG and antibodies specific for Bordetella pertussis, Haemophilus influenzae type b (Hib), tetanus toxoid, hepatitis B virus (HepB), and measles virus were measured at multiple time points throughout the first 2 years of life. Prevaccine antibodies (maternal antibodies passively acquired) specific for tetanus were lower in HEU than in HUU infants, while prevaccine antibodies to HepB were higher in HEU than in HUU infants. Both groups responded similarly to tetanus, Hib, and HepB vaccination. HEU demonstrated stronger pertussis vaccine responses, developing protective titers 1 year earlier than HUU patients, and maintained higher anti-tetanus titers at 24 months of age. Vaccine-induced antibodies to measles virus were similar in both groups at all time points. Our results suggest that the current EPI vaccination program as practiced in South Africa leads to the development of vaccine-specific antibody responses that are equivalent in HEU and HUU infants. However, our data also suggest that a large fraction of both HEU and HUU South African infants have antibody titers for several infectious threats that remain below the level of protection for much of their first 2 years of life.

High incidence of invasive group B streptococcal infections in HIV-exposed uninfected infants

OBJECTIVES

The occurrence of an unusual number of group B streptococcal (GBS) infections in HIV-exposed uninfected (HEU) infants who were followed in our center prompted this study. The objective of this study was to describe and compare the incidence and clinical presentation of GBS infections in infants who were born to HIV-infected and -uninfected mothers.

METHODS

All cases of invasive GBS infections in infants who were born between 2001 and 2008 were identified from the database of HEU infants and from the microbiology laboratory records. The medical charts of all infants with GBS infection were reviewed.

RESULTS

GBS invasive infections were described for 5 (1.55%) infants who were born to 322 HIV-infected mothers who delivered in our center. The incidence of GBS infections during the same period was 16 (0.08%) of 20 158 infants who were born to HIV-uninfected mothers. One HEU infant presented a recurrent infection 28 days after completion of treatment for the first episode. Late-onset infection was more frequent in HEU infants (5 of 6 vs 2 of 16 episodes in the control population). The diseases were also more severe in HEU infants with 5 of 6 sepsis or sepsis shock in HEU infants versus 10 of 16 in control subjects, and most HEU infants had leukopenia at onset of infection.

CONCLUSIONS

The incidence of GBS infection was significantly higher in HEU infants than in infants who were born to HIV-uninfected mothers. These episodes of GBS sepsis in HEU infants were mostly of late onset and more severe than in the control population, suggesting an increased susceptibility of HEU infants to GBS infection.

Pneumocystis pneumonia in South African children with and without human immunodeficiency virus infection in the era of highly active antiretroviral therapy

BACKGROUND

Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in human immunodeficiency virus (HIV)-infected African children.

AIM

The aim of this study was to investigate the incidence and outcome of PCP in South African children living in a high HIV-prevalence area in the context of a free, available antiretroviral therapy program.

METHODS

Sequential children hospitalized with hypoxic pneumonia were prospectively enrolled from November 2006 to August 2008. Sociodemographic, historical, clinical, and outcome data were collected. A nasopharyngeal aspirate and lower respiratory tract sample (induced sputum or bronchoalveolar lavage) were submitted for PCP immunofluorescence. Lower respiratory tract samples were also investigated for bacterial, mycobacterial, and viral pathogens.

RESULTS

A total of 202 children were enrolled; 124 (61.4%) were HIV-infected; 34 (16.8%) were HIV-exposed but uninfected and 44 (21.8%) were HIV-unexposed. Among HIV-exposed children, 70 (44.3%) had participated in the Prevention of Mother to Child Transmission program, but only 18.4% were taking trimethoprim-sulfamethoxazole prophylaxis. PCP occurred in 43 children (21.3%) of whom 33 (76.7%) were HIV-infected. The case fatality of children with PCP was higher than those without PCP (39.5% vs. 21.4%; relative risk, 1.85; 95% confidence interval, 1.15-2.97; P = 0.01).

CONCLUSIONS

PCP is a common cause of hypoxic pneumonia and mortality in HIV-infected South African infants. Underuse of the Prevention of Mother to Child Transmission program and failure to institute trimethoprim-sulfamethoxazole prophylaxis in HIV-exposed children identified through the program are important obstacles to reducing PCP incidence.

Severe infections in HIV-exposed uninfected infants: clinical evidence of immunodeficiency

We describe the clinical and basic immunological findings of eight HIV-exposed uninfected infants hospitalized with serious infectious morbidity and referred for immunological evaluation. The median age at presentation was 5.5 (1.5-15) months. Infections included Pneumocystis jiroveci pneumonia (three), cytomegalovirus colitis with perforation (one), Pseudomonas sepsis (two), hemorrhagic varicella (one) and Group A streptococcal meningitis and endocarditis (one). Five required intensive care, four for assisted ventilation and one for post-surgical care. Follow-up to 36 months suggested resolution of a transient immunodeficiency in two infants, one of whom had CD4 and the other B-cell depletion. Further studies are indicated in HIV-exposed uninfected infants.

Effect of age, polymicrobial disease, and maternal HIV status on treatment response and cause of severe pneumonia in South African children: a prospective descriptive study

BACKGROUND

HIV-related pneumonia is the main cause of paediatric hospital admissions in southern Africa. We aimed to measure predictors of treatment failure and the cause of non-responsive pneumonia in children admitted to hospital with severe pneumonia in Durban, South Africa.

METHODS

We investigated 358 children aged 1-59 months who presented with WHO-defined severe or very severe pneumonia. Children were recruited irrespective of HIV status and started on a standard antimicrobial regimen of benzylpenicillin and gentamicin. All infants also received high-dose trimethoprim-sulfamethoxazole. The primary outcome measure was treatment failure at 48 h.

FINDINGS

242 (68%) children were HIV infected, 41 (12%) HIV exposed, uninfected, and 75 (21%) HIV uninfected. Failure to respond by 48 h was predicted by age under 1 year (adjusted odds ratio 6.38, 95% CI 2.72-14.91, p<0.0001), very severe disease (2.47, 1.17-5.24, p=0.0181), HIV status (HIV infected 10.3, 3.26-32.51; HIV exposed, uninfected 6.02, 1.55-23.38; p=0.0003), and polymicrobial disease (one organism 2.06, 1.05-4.05; two organisms 10.75, 4.38-26.36; p<0.0001) on logistic regression analysis. All children with three organisms failed treatment. 72/110 treatment failures had at least two organisms isolated. Three of nine HIV-exposed, uninfected infants, 29/74 HIV-infected, but no HIV-uninfected infants who failed study therapy had Pneumocystis jirovecii pneumonia.

INTERPRETATION

For children younger than 1 year, the WHO guidelines are inadequate and need to be revised since both HIV-infected and HIV-exposed, uninfected infants had more treatment failures than did HIV-uninfected infants. Polymicrobial disease is an important reason for treatment failure, and we need to identify rapid low-cost diagnostic methods to assist clinicians.

Emerging infections and pregnancy

A key component of the response to emerging infections is consideration of special populations, including pregnant women. Successful pregnancy depends on adaptation of the woman's immune system to tolerate a genetically foreign fetus. Although the immune system changes are not well understood, a shift from cell-mediated immunity toward humoral immunity is believed to occur. These immunologic changes may alter susceptibility to and severity of infectious diseases in pregnant women. For example, pregnancy may increase susceptibility to toxoplasmosis and listeriosis and may increase severity of illness and increase mortality rates from influenza and varicella. Compared with information about more conventional disease threats, information about emerging infectious diseases is quite limited. Pregnant women's altered response to infectious diseases should be considered when planning a response to emerging infectious disease threats.

Pneumocystis jiroveci pneumonia in a patient with rheumatoid arthritis as a complication of treatment with infliximab, anti-tumor necrosis factor alpha neutralizing antibody

We report that a-63-year-old woman developed Pneumocystis jiroveci pneumonia (PCP) as a complication from treatment with infliximab for rheumatoid arthritis. Although there was neither symptoms of dyspnea nor typical observations on a chest X-ray examination, low levels of oxygen saturation and findings of high-resolution chest computed tomographic scanning suggested a possibility of interstitial pneumonia. A polymerase chain reaction-based detection of Pneumocystis jiroveci in induced sputum allowed an early diagnosis of PCP and subsequent effective treatment.