Factors influencing the analysis of secondary prevention of pertussis

The aim of this study was to evaluate factors that influenced the spread of pertussis in secondary contacts after household exposure. The data were acquired during a prospective household-contact study into the efficacy of an acellular vaccine. The spread of the disease was monitored with respect to various case definitions of pertussis, socio-economic factors, household composition, and antibiotic therapy. A total of 453 index cases had contact with 173 unvaccinated children aged from 6 to 47 months. Depending on the clinical case definition, the attack rates (AR) in children with a laboratory-confirmed Bordetella infection increased from 55% for the WHO definition to 69%, when a less stringent definition was used. AR in children were independent of age and gender. The social status of the family had no significant influence on the AR in children. Erythromycin treatment of the index case reduced the AR from 64% to 51% (p = 0.08). These factors should be taken into consideration when studies into the secondary prevention of pertussis by acellular vaccines are initiated.

Epidemiologic aspects and diagnostic criteria for a protective efficacy field trial of a pertussis vaccine

Pertussis was a major childhood disease in parts of West Germany in 1990. Before a prospective household contact trial into the efficacy of an acellular pertussis vaccine was undertaken, the epidemiology of the disease was studied in one area. This study showed that pertussis had an annual incidence of 4%-6% in the first 6 years of life. During the trial, a total of 1223 pertussis cases were diagnosed by laboratory methods. Isolation rates of Bordetella organisms varied by the pediatrician who did the nasopharyngeal swab and decreased with time required for swab transport. Analysis of the serologic results showed that if IgG and IgA anti-pertactin antibodies had been considered, overall sensitivity would have been only marginally increased. Several pertussis patients had antibodies to parapertussis antigens, indicating a lack of complete cross-protection. The serologic response in secondary household contacts differed by vaccination status. However, this difference was unlikely to have influenced the point estimate of efficacy of the acellular vaccine.

Acellular pertussis vaccines: the rationale for an efficacy trial in Germany

After concern about the safety of diphtheria-tetanus toxoid-whole cell pertussis vaccines (DTPw), the recommendation to vaccinate children with DTPw was withdrawn in 1974 in the former West Germany. This led pertussis cases to increase to an estimated 100,000 annually. Despite renewal of the vaccination recommendation in 1991, vaccine use remained low. The German health care structure assures regular contact between most children and pediatricians. This enabled the conduct of a large efficacy trial with a diphtheria-tetanus toxoid-acellular pertussis (DTPa) vaccine. Because a placebo-controlled trial was not ethically possible, a prospective household contact study with a blinded clinical follow-up was done. Possible study participants were screened by their pediatrician, who also initiated diagnostic procedures. Clinical follow-up was done by another locally based but independent and blinded physician. Vaccine efficacy was calculated to be 89% (95% confidence interval, 76.6%-94.6%). None of the identified confounding factors biased results in favor of the DTPa vaccine.

Analysis of proteins encoded by the ptx and ptl genes of Bordetella bronchiseptica and Bordetella parapertussis

Bordetella pertussis is the only bacteria] species which is known to produce pertussis toxin (PT); however, both Bordetella bronchiseptica and Bordetella parapertussis contain regions homologous to the ptx genes of B. pertussis that encode the toxin subunits. After finding that several children with B. parapertussis infections exhibited modest antibody titers to PT, we examined the ptx genes of both B. parapertussis and B. bronchiseptica to determine whether they would encode stable, functional proteins even though their promoters are thought to be inactive under the conditions that have been examined. We inserted a functional promoter directly upstream of the ptx-ptl region of both species and examined culture supernatants of the resulting strains for PT activity. Biologically active PT was found in the culture supernatants of both engineered species. The toxin encoded by the B. parapertussis ptx genes appeared more labile in culture supernatants than did toxin produced by either B. pertussis or the engineered strain of B. bronchiseptica. This lability might be due to the lack of a full-length S2 subunit. We also investigated the ptl genes of these species, which are necessary for the secretion of this toxin, and found that both B. bronchiseptica and B. parapertussis contain at least certain of these genes, including ptlE and ptlF. Moreover, B. bronchiseptica appeared to contain all essential ptl genes since the introduction of a functional promoter directly upstream of the ptx-ptl region resulted in both production and efficient secretion of toxin. These results indicate that despite a number of amino acid changes in the sequences of the toxins, the toxins encoded by B. bronchiseptica and B. parapertussis are active.

Pertussis in adults: frequency of transmission after household exposure

Although pertussis in adults is well documented, opinions differ about incidence of adult disease and about the role of adults as reservoirs of infection. We made use of a prospective household contact study of an acellular pertussis vaccine to collect data about pertussis in adults. All members of families with an index case of pertussis were monitored for respiratory symptoms, and pertussis was confirmed by laboratory tests. In 122 households, 104 children (85%) and 18 adults (15%) were the source of pertussis. These households consisted of 265 adults (aged 19-83 years), in 84 of whom (31%) pertussis was confirmed. Of these 84, 81% had respiratory symptoms for 21 days or more. The spread of pertussis was independent of whether a child (74/104) or an adult (14/18) was the index case. Most adult index cases had no pertussis recall (odds ratio 11.8). The overall attack rate in adult contacts was 0.267 and was independent of the social status and the size of the family and of a pertussis recall, although it differed significantly between women and men (p < 0.05). Erythromycin treatment of the index case reduced the attack rate significantly (p < 0.05). Patients whose first pertussis episode dated back more than 20 years had similar symptoms and attack rates to patients without a recall. We conclude that adults are often involved in the spread of pertussis, and that they can be susceptible to reinfection 20 years after a first pertussis episode.

[Efficacy of acellular pertussis vaccines]

Acellular vaccines against pertussis could be developed because various virulence factors of B. pertussis have been characterized. Acellular pertussis vaccines should retain the efficacy but have lower side effects, as compared to the conventional whole-cell vaccine. Lacking any correlate of antibacterial resistance, the efficacy of the vaccines had to be tested in large field trials. Such trials have been conducted and are being conducted in various European and in one African country. These trials used different designs, and various different vaccines were tested. All available efficacy data show that acellular pertussis vaccine can effectively protect against typical pertussis. It also seems probable that the efficacy of vaccines, which contain more than two pertussis components may be better than a vaccine containing pertussis toxoid or pertussis toxoid with filamentous hemagglutinin. A three-component acellular pertussis vaccine has been licensed for use in primary vaccination in infants in Germany in early 1995.

Isolation of a Bordetella avium-like organism from a human specimen

The isolation of a strain of Bordetella for which the species could not be determined but which most closely resembled Bordetella avium is reported. The strain was isolated in mixed culture from an ear swab of a patient suffering from chronic otitis media. The bacterium showed the typical biochemical reactions of Bordetella avium but differed in antimicrobial resistance pattern, protein and fatty acid composition, and DNA-DNA and DNA-rRNA hybridization. Further studies will clarify the taxonomic status of this strain within the Bordetella-Alcaligenes ribosomal RNA cluster.

Symptoms and complications of pertussis in adults

There is increasing evidence that pertussis occurs frequently in adults, but there is limited information on the clinical course of this disease beyond childhood. A household contact study on the efficacy of an acellular pertussis vaccine was used to study the symptoms of pertussis in adults. Among 257 patients with pertussis identified in 121 families during a two-year period in one study center with a low whole-cell pertussis-vaccine uptake, 79 (30.7%) were adults, aged 19-83 years (mean age: 36 years) with a 1:1.8 male to female ratio. Ninety-one percent of the adults suffered from coughing (mean duration: 54 days), and in 80% this cough lasted > or = 21 days. Whoops were rare (8%), whereas cough followed by vomiting and/or choking (53%) and cough disturbing sleep (52%) were common. This is the first report to describe sweating attacks as symptom of pertussis (14%). Pharyngeal symptoms (37%), influenza-like symptoms (30%), sneezing attacks (22%), hoarseness (18%), sinus pain (16%) and headaches (14%) were also observed. Various complications were seen in 23% of the patients. In order to minimize the spread of the organism, microbiological diagnostics should be vigorously applied to all symptomatic contacts of a patient with pertussis but also to all patients with long lasting cough-irrespective of age.

Bordetella hinzii sp. nov., isolated from poultry and humans

A polyphasic taxonomic study that included DNA-rRNA hybridizations, DNA-DNA hybridizations, DNA base ratio determinations, whole-cell protein and fatty acid analyses, and an examination of classical phenotypic characteristics was performed in order to classify human and veterinary isolates that resemble Bordetella avium. Twelve poultry isolates and two human isolates were assigned to a new species, for which we propose the name Bordetella hinzii. The position of this organism in the family Alcaligenaceae and various genotypic, phenotypic, and chemotaxonomic characteristics are described.

[Streptococcal myositis in children: four case histories]

We report about four children, who suffered from myositis caused by beta-hemolytic group A streptococci (GAS). The cases were observed during the last 12 months, and differed much in severity. Soft tissue infections caused by GAS are reported with increasing frequency from the USA, Australia and Europe. They occur in hitherto healthy children and young adults, mostly without a predisposing trauma. In children, a preceding varicella infection is often found. Some patients develop a streptococcal toxic shock syndrome with a letality of 20-50%. The bacteria, which can be isolated from normally sterile body sites, are morphologically inconspicuous, and are mostly of the serological type M1 or M3.

Role of pertussis toxin in causing symptoms of Bordetella parapertussis infection

Whooping cough can be caused by either Bordetella pertussis or Bordetella parapertussis. Although the two species share an almost complete DNA identity, Bordetella parapertussis does not produce pertussis toxin, which is thought to be the main virulence factor of Bordetella pertussis. In order to elucidate the role of pertussis toxin in causing the typical symptoms of whooping cough, clinical information from 33 patients with culture-positive Bordetella parapertussis infection was collected and compared to that from 331 patients with infection caused by Bordetella pertussis. Isolated strains of Bordetella parapertussis lacked pertussis toxin expression, as was demonstrated by negative tests for histamine sensitization. This was further substantiated in vivo by a significantly lower leukocyte count in the parapertussis group as compared to the pertussis group. Frequencies of typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting, were almost identical in the two groups. Nocturnal coughing and contact anamnesis were noted more often in the Bordetella pertussis group. Children in the parapertussis group were significantly more often vaccinated with whole-cell pertussis vaccine than children infected with Bordetella pertussis. The results indicate that pertussis toxin may not play a decisive role in causing the typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting.

[Sexually transmitted diseases by agents other than viruses and treponema]

The current concepts about sexually transmitted diseases (STD)--excluding syphilis and viral STD--are presented in a condensed form. The focus of attention is directed to complications or sequelae of these infections, and to the epidemiology of STD.

[Hepatitis viruses and pregnancy]

Infections with hepatitis virus A, B, C, D or E can also be observed during pregnancy. Furthermore, pregnant carriers of hepatitis B virus, occurring at various frequencies in different populations, represent an important source of infection. The course and the outcome of hepatitis A, B, C and D do not seem to be significantly affected by pregnancy. A fulminant hepatitis E, however, which is observed only rarely in Europe, can be induced by pregnancy and labor. Fetal malformations have not been attributed to any hepatitis virus. A perinatal transmission of hepatitis B virus often occurs, whereby the circulating HBe antigen or the amount of viral DNA in blood can be used as prognostic markers. Perinatal transmission of hepatitis C virus has also been documented; its frequency, however, seems to be less than 10%. A general screening of pregnant women for HBs antigen is suitable in interrupting transmission of hepatitis B virus. Children born from hepatitis B virus carriers should receive a postpartal passive-active immunization.

[Epidemic occurrences of multiresistant Acinetobacter baumannii strains in a neonatal intensive care unit]

In a period of nine months (May 1991 to January 1992), 39 infants were colonized with Acinetobacter baumannii in a paediatric intensive care unit. Colonization was observed mainly in premature infants, weighing between 680 g and 2,000 g, who were artificially ventilated. Shortly after birth, A. baumannii was isolated regularly from tracheal washings, and less frequently from other material, such as gastric juice, catheter tips, and umbilical swabs. In older children or adults, the bacteria were found only in very low frequency. In the intensive care unit, A. baumannii could be isolated from tap water, sinks, water traps of the ventilation devices, the inner wall of incubators, and from the hands of medical personnel. Patients strains of A. baumannii, and those isolated monitoring the intensive care unit had an identical biochemical profile and a similar pattern of antimicrobial resistance, as well as a similar reaction in other typing methods. Anti-infective measures are discussed.

[Acellular pertussis vaccines]

Each vaccine is normally rated according to its efficacy and to the frequency and severity of unwanted side effects. The efficacy of whole-cell pertussis vaccines is beyond doubt, its frequent side effects, however, stimulated research into less reactogenic acellular vaccines. Several acellular pertussis vaccines of different composition have been developed. All of these produced significantly less local and systemic side effects, as compared to the conventional whole-cell vaccine. Various epidemiological data strongly suggest the efficacy of these vaccines. An equivalence of protective efficacy between whole-cell vaccines and acellular pertussis vaccines can, however, only be documented in controlled field trials, which are now ongoing in several countries.

[The epidemiology of whooping cough]

Due to a low acceptance of active immunisation against Bordetella pertussis, whooping cough continues to be a frequent childhood disease in parts of Germany. The age distribution in the lower Rhine area showed a peak incidence at 4.3 years of age, whereas 11% of all cases were observed in infants, and 6% were observed in adults. A significant sex difference was not found in children suffering from pertussis; in adult patients, however, women were more often affected. Whooping cough occurred during the whole year, its peak incidence was found during early winter. In children, paroxysmal coughing fits, vomiting and whooping were the primary symptoms of disease; adults and infants, however, developed these symptoms only in reduced frequency. About 25% of all cases showed an atypical course, and could only be diagnosed by laboratory tests. While leukocyte count and ESR did not have diagnostic significance, a combination of microbiological and serological tests showed a high diagnostic sensitivity and specificity. In contrast to the former GDR and to most European neighbours, the former Federal Republic overrated the side effects of active vaccination as compared to the various risks of natural infection. This resulted in a decline of vaccine acceptance to less than 10% in several areas of the former FRG. It is anticipated that the altered recommendation in favour of vaccination, and especially the future application of acellular vaccines with less side effects, will result in the elimination of whooping cough in all areas of Germany.

[Outbreak of a nosocomial infection of SHV2-beta-lactamase-containing Klebsiella pneumonia strains in an operative intensive care unit]

Resistant strains of Klebsiella pneumoniae were found in increasing frequency as a cause of nosocomial infection in an intensive care unit between July and October 1990. The isolated strains had an almost identical biochemical profile, showed a similar pattern of antibiotic resistance, and produced type SHV2-broad-spectrum betalactamase. Thus, it was assumed that the isolates were copies of identical strains, causing an outbreak of nosocomial infections. The bacteria were resistant to third-generation cephalosporins, such as cefotiam, cefotaxime and ceftriaxone, and also to aminoglycosides and acylaminopenicillins. Approximately half of the strains were resistant to ceftazidim and aztreonam. The bacteria were sensitive in vitro to ciprofloxacin, imipenem, latamoxef and cefotetan. During three months, 10% (11) of all patients became infected; four of these patients (36%) died from septicemia. After conventional hygiene programs had failed to stop the outbreak, the intensive care unit was closed and disinfected, a measure, which effectively interrupted the infection.

[Whooping cough in adults]

Within a period of four years the diagnosis of pertussis was made in 169 adults (105 women, 64 men; mean age 35.8 [18-79] years). based on symptoms, specific antibodies and bacteriological examination of nasopharyngeal swabs (in 53). The findings were compared with those obtained in a control group of 2,771 children (1,381 females, 1,390 males; mean age 4.3 years). In the adult the dominant symptom was persisting cough, at times convulsive, while the other symptoms, characteristic in children, of rib retraction and vomiting were significantly less common in adults (retraction: 3% vs 40%; vomiting 12% vs 59%). A history of contact was elicited in only 17% of adults (38% in children). Confirmation of the diagnosis was obtained by growing Bordetella pertussis from a nasopharyngeal swab (6 of 53 patients [11%]; in children 45%), or finding significantly elevated antibody concentration or titre rise of specific antibodies against B. pertussis (IgG: 81% vs 68%; IgA: 91% vs 73%; IgM: 44% vs 72%). Half the adult patients were aged between 20 and 35 years. Contrary to the sex distribution of pertussis in children, significantly more women than men contracted the infection (P less than 0.01). It is concluded that even in adults pertussis should be considered in the differential diagnosis of persisting cough.

Histomorphology of experimental listeriosis

This paper is a survey of the histomorphology of experimental listeriosis based on cooperative studies performed within the past ten years. The influence of various parameters of the infectious agent (pathogenic Listeria monocytogenes serovar 4b, nonpathogenic Listeria innocua serovar 6b etc.) as well as of the host (euthymic NMRI-mice conditioned with dextran sulfate 500 or cyclosporin A, athymic nude mice etc.) on the course, morphology and outcome of the Listeria infection was investigated. From the experimental models used and the studies performed much could be learned concerning the factors that determine the histomorphological manifestations of listeriosis in humans.

Alteration of non-specific resistance to infection with Listeria monocytogenes

The experimental infection of murine hosts with Listeria monocytogenes is often used as a model for cell-mediated immunity. However, the natural immunity or non-specific resistance to listeriosis can be influenced by the parasite itself and also by a wide array of endogenous and exogenous host factors. The most important host factor in inbred mouse strains is their genetically determined susceptibility or resistance to Listeria monocytogenes. Secondly, the age of the mice is crucial for the outcome of infection. Resistance is only slowly developed by newborn mice, while aged mice possess an increased non-specific resistance as compared to young adult animals. Resistance is further influenced by the nutritional status, by pregnancy or by a simultaneous second antigenic stimulation. Regarding exogenous factors, macrophage blocking agents can totally abolish the resistance to listeriosis, while a lot of immunomodulating agents, such as BCG, killed Bordetella pertussis or Propionibacterium acnes organisms, lipopolysaccharides, suramin etc., can either increase or decrease the resistance. The mononuclear phagocyte system seems to be the main target of all these immunomodifiers. The timing between listeria infection and application of the immunomodulator determines the effect on non-specific resistance. A simultaneous injection of parasite and immunomodulator results in a decrease of resistance, while the application of immunoadjuvants several days before infection can dramatically increase the resistance to listeriosis. The delicate equilibrium of the mononuclear phagocyte system must therefore be taken into account, when infection with Listeria monocytogenes is used to test for immune-modifying agents, which are intended for use in humans or animals.

[Effect of anti-D prevention on the incidence of irregular erythrocyte antibodies in pregnant patients]

The immunohaematology results found during antenatal care from 1963-1981 were used to try to answer the question whether and how much the anti-D-prophylaxis, which was started in 1967 and was given to German and foreign pregnant women post partum or after abortion, had affected the frequency of immunization to D and other erythrocyte antigens. The results allow the following statements: 1. From 1973-3 or 4 years after the general introduction of anti-D prophylaxis-until 1981, a continuously sustained decline in the frequency of anti-D in the German pregnant women was found. This could not be found in the corresponding group of foreign pregnant mothers. 2. Additionally, a statistically significant reduction in the frequency of anti-D + C could only be found in the German group. 3. After 1973, other erythrocyte antibodies in combination with anti-D were only found sporadically. A rise in the frequency of other erythrocyte antibodies, such as anti-C, was not observed. 4. The frequency of "non-anti-D antibodies" was significantly higher in the foreigners than in the German group during the whole observation period. This was due to the significant increase in anti-Lea, anti-Leb, anti-H, anti-P1 and the nonidentifiable antibodies in the foreign group.

[The significance of "nonpathogenic" Corynebacteria as a cause of opportunistic infections]

A lot of corynebacterial species, summarized as "diphtheroids" has its normal habitat on the human skin. Consequently, these bacteria are often isolated from various clinical materials and mostly regarded as indeginous flora. The same bacteria, however, can cause serious infections, when the balance between host and microorganisms is impaired. Multiresistant corynebacteria group JK are used as an example to describe the development of such infections. Central venous catheters and other plastic devices can facilitate the entry of the bacteria. Simultaneously, resistant strains of corynebacteria benefit from a concurrently administered antimicrobial chemotherapy. Subsequently, these bacteria can be found as a cause of septicemia, endocarditis, wound infection, osteomyelitis, peritonitis and meningitis. The antimicrobial chemotherapy is hampered by the extreme resistance and vancomycin is the only antibiotic of choice. Colonization or infection of the single patient can be differentiated by clinical criteria only. According to the individual risk, a microbiological monitoring can be helpful in the early detection of colonization and infection.