Nosocomial klebsiellas. II. Transfer in a hospital ward

During a 6-month period an epidemiological survey of the carriage of Klebsiella was conducted in a hospital ward where no outbreak of nosocomial infection occurred. In this endemic situation the regular sampling of several sites of patients, members of the nursing staff, and the environment, and the biotyping of Klebsiella made it possible to analyse the patterns of transmission between sites. There was abundant evidence for striking transmission of Klebsiella between the throat, hands, and faeces of patients. Transmission between patients seemed to be mainly through hands. The role of nurses' hands in transmission was not evident from this survey, probably due to the relatively long interval (a week) between samplings. Through the hands of patients, wash stands and the surrounding floor were contaminated with Klebsiella. The biotyping of Klebsiella facilitated the epidemiological analysis of the results.

Mechanisms of maternal-fetal transmission of hepatitis B virus

In a prospective study of maternal-fetal transmission of hepatitis B virus in 125 healthy mothers who were carriers of hepatitis B surface antigen (HBsAg), preliminary results showed that the most important determinant in such transmission was the presence of hepatitis B e antigen in the mother. HBsAg was detectable by solid-phase radioimmunoassay in 33% of amniotic fluid samples, 50% of cord blood samples, 71% of breast milk samples, and 95.3% of samples of gastric contents from newborns. The presence of HBsAg in gastric aspirate from the infants immediately after birth in almost all cases suggests a universal mechanism of infection by the oral route during delivery. In light of these findings, precautions such as possible elective cesarean section, routine gastric aspiration of the newborn, avoidance of breast-feeding, etc., should be taken to avoid perinatal transmission.

Transmission of swine dysentery by carrier pigs

Swine dysentery (SD) was transmitted to healthy pigs by contact with experimentally-induced carrier pigs. Carrier pigs were produced by exposure of specific pathogen-free (SPF) swine to swine acutely affected with SD. When carrier pigs became acutely affected with SD, they were allowed to recover naturally or were treated with dimetridazole or ronidazole. Recovery was based on disappearance of clinical signs of SD. At a given time after recovery, normal SPF swine were housed with the carriers in a disinfected isolation unit to determine the ability of carriers to transmit SD. In each of 3 experiments, carriers that had recovered and remained asymptomatic for 11 to 25 days transmitted SD to contacts in 14 to 51 days. In 2 experiments, pathogenic Treponema hyodysenteriae was isolated from carriers 12 days before clinical SD was observed in contacts. Carriers which had recovered and remained asymptomatic for 70 and 90 days transmitted SD to contacts in 1 of 3 experiments. Treponema hyodysenteriae was isolated only from contacts with clinical signs of SD. In 4 experiments, carriers that had been treated with nitroimidazole compounds and subsequently recovered for 19 to 44 days failed to transmit SD. Culture of fecal samples on trypticase soy agar with 5% bovine blood and 400 microgram of spectinomycin/ml was helpful in predicting the carrier state, but phase contact contact microscopy of wet fecal smears was not.

Investigations into the role of carrier animals in the spread of contagious bovine pleuropneumonia

An attempt was made to transmit contagious bovine pleuropneumonia (CBPP) from 22 animals recovered from artificial infection to healthy animals. Despite close contact and the imposition of a number of stresses no disease was transmitted. An unsuccessful attempt was made to reactivate old CBPP lesions by corticosteroid treatment, and by splenectomy. Four animals recovered from artificial infection did not become reinfected when put in contact with acute disease. Seven animals were reinoculated with Mycoplasmamycoides sub-species mycoides by endobronchial intubation. No clinical disease resulted. It is concluded that sequestra do not break down easily and that it is difficult to reinfect recovered animals. It is suggested that in field outbreaks of obscure origin, investigation should be thorough before it is concluded that an animal with an old sequestrum was responsible.

[Quantitative evaluation of the patterns of the mechanism of pathogenic streptococcal transmission]

In the course of a one week observation in the organized collective body with a daily bacteriological examination for streptococcus group A carrier state 20 infections were recorded per 70 risk man-days. Statistical analysis of conditions for the recipients' infection showed bedrooms to be the main site of streptococcus infection in the organized collective bodies. The most important role in the epidemic process belonged to healthy carriers capable of infecting sensitive recipients, with the potency of microbial foci in the pharynx and the nose of about 1000-2000 microbes per standard tampon. The greatest frequency of infection occured at a distance of from 1 to 1.2 m. Consequently, the main direction of prophylaxis of streptococcus infection at the collective bodies should be associated with measures directed to the source of infection (isolation and penicillin therapy of the patients, urgent antibiotics prophylaxis in case of threatening epidemic or at its initial period).

Hepatitis B surface antigen and chronic hepatitis in infants born to asymptomatic carrier mothers

Twenty-three infants born to asymptomatic hepatitis B surface antigen (HBSAg) carrier mothers were followed up to determine the vertical transmission of hepatitis B virus. Four infants became positive for HBSAg within four months after birth. Three showed hepatic dysfunction; liver biopsy specimens demonstrated mild chronic hepatitis in one and persistent hepatitis in another. In six infants followed up for more than six months after birth, antibody to HBSAg (anti-HBS) without antigenemia could be detected. Antigenemia of cord blood strongly suggested that hepatitis B viral infection of the infant would occur. HBSAg was also demonstrated in breast milk by radioimmunoassay in three cases. These findings indicate that vertical transmission of hepatitis B virus occurs in many infants born to asymptomatic HBSAg carrier mothers, and that some of them become persistent carriers or develop chronic hepatitis without showing any signs suggesting hepatic involvement.

Vertical transmission of hepatitis-B surface antigen

Transmission of Hepatitis B virus from mother to infant can cause a severe type of neonatal hepatitis. Comparing chronic carrier mothers with mothers who have acute hepatitis in pregnancy we find that the latter group present the greater risk to their infants. Differences in the presence of Hepatitis B core and Hepatitis B e antigen and antibody in the acute case and in the carrier state may expoain the differences observed in the transmission rates of two groups. In countries where the prevalence of the carrier state is high it appears that vertical transmission of the carrier state is also common. This pattern may be explained by differences in the geographical distribution of carriers of Hep B e antigen, which has been recently described as a virulance factor.

Carrier state of antibody and viruses in a mouse breeding colony persistently infected with Sendai and mouse hepatitis viruses

In a large-scale mouse breeder colony persistently infected with Sendai and mouse hepatitis viruses, most adult breeders 8 wk or more of age were shown to have antibodies to both viruses when monitored over a periof of 20 mo. Antibody to Sendai virus, apparently transmitted from the dam, was detected in 76% and 2% of mice aged 3 and 4 wk. respectively, and 64% and 100% of mice aged 6 and 8 wk, respectively. By seroconversion of sentinel cage-mates, a Sendai virus-carrier state was demonstrated with 6-wk-old mice but not with those either 4 wk or 10 wk of age, suggesting that breeder candidates about 6 wk of age may play an important role in establishing and perpetuating Sendai infection in this breeding colony. With mouse hepatitis virus, however, mice aged 4 wk or older seem to be effective transmitters of the virus, while some of these mice were found to have antibody to the virus.

New light on the transmissibility of viral hepatitis in dental practice and its control

Evidence of an increase in the nonparenteral spread of viral hepatitis is of much concern in dentistry and supports the need for sterilization of all instruments used in intraoral treatments. Methods for the rapid sterilization of all dental handpieces and air-water syringes are still inadequate for routine clinical use. It may be possible to improve surface disinfection of these items by more thorough, repeated cleansing with common disinfectants and by the use of stronger germicidal agents such as aldehydes. However, for handpieces and some other equipment, effective sterilization methods must be developed or the instruments must be modified so they can be safely and rapidly sterilized. Surface disinfectants that will destroy hepatitis viruses are needed for disinfection of the dental unit. The use of gloves is also an important consideration for the protection of both the dentist and his patient. The high attack rate of hepatitis among surgeons, as well as patient protection, make the wearing of gloves during surgery imperative. Evidence that aerosolborne viruses would be removed by filtered laminar air flow or by face masks is not available, but use of these devices reduces exposure of personnel to aerosols in general and appears to be highly desirable. Sterilization of all possible instruments is advocated for use in all institutions and dental offices. Careful monitoring of the effectiveness of sterilization also is advocated. These concepts and new information on which they are based should be incorporated into dental curriculums and continuing education courses for all dentists and auxiliary personnel.

Spread of Streptococcus pneumoniae in families. II. Relation of transfer of S. pneumoniae to incidence of colds and serum antibody

Factors that affect the spread of Streptococcus pneumoniae and the antibody responses associated with colonization were studied in 64 families for periods of eight to 52 weeks. Surveillance included daily recording of respiratory symptoms and bimonthly pharyngeal cultures for identification of the pneumococcal carrier state. Rhinovirus cultures were included for a portion of the study period. Intrafamilial carriage of a single type of S. pneumoniae and simultaneous spread to more than one family member were commonmspread often occurred in association with an upper respiratory tract infection; simultaneous transmission of S. pneumoniae and a rhinovirus was documented. Preexisting, type-specific serum antibody did not prevent acquisition of homotypic S. pneumoniae but did appear to shorten the duration of pharyngeal carriage. Sera of all 11 adults had greater than 150 ng of antibody nitrogen/ml of homotypic serum antibody (measured by a radioimmunoassay) before colonization. In contrast, only one of 13 preschool children had homotypic antibody concentrations of this magnitude before colonization. A threefold or greater rise in the concentration of homotypic antibody occurred in 13 of 24 children (54%) after acquisition of S. pneumoniae; the increase in antibody concentration was associated with illness in six of the children. On the other hand, acquisition of S. pneumoniae in adults was not associated with an increase in concentration of homotypic serum antibody.