Etiology of acute lower respiratory tract infection in Central Australian Aboriginal children.

BACKGROUND: Aboriginal children in central Australia have attack rates for acute lower respiratory tract infection (ALRI) that are similar to those in developing countries. Although mortality rates are much lower than in developing countries, morbidity is high and ALRI is still the leading cause of hospitalization. However, there are no data on the etiology of ALRI in this population. METHODS: We prospectively studied 322 cases of ALRI in 280 Aboriginal children admitted to the hospital. Blood, urine and nasopharyngeal aspirate samples were examined for evidence of bacterial, viral and chlamydial infection. RESULTS: The combination of blood culture, viral studies and chlamydial serology provided at least 1 etiologic agent in 170 of 322 (52.5%) cases. Assays for pneumolysin immune complex and pneumolysin antibody increased etiologic diagnosis to 219 (68.0%). Blood cultures were positive in 6% but pneumolysin immune complex and pneumolysin antibody studies were positive in one-third of cases. Evidence of viral infection was present in 155 (48%) of cases compared with 12% in controls (P < 001). There were only 7 possible cases and 2 definite cases of Chlamydia trachomatis and 3 cases of Chlamydia pneumoniae. Coinfection was common in these children. CONCLUSION: These findings have implications for both standard treatment protocols and vaccine strategies. The high rate of coinfection may make it difficult to develop simple clinical predictors of bacterial infection. In the setting of a developed country with efficient patient evacuation services, management algorithms that focus on disease severity and need for hospital referral will be most useful to health staff in remote communities. Pneumococcal conjugate vaccines will be required to reduce the high attack rate of pneumococcal disease.

Bacterial colonization of the nasopharynx predicts very early onset and persistence of otitis media in Australian aboriginal infants.

Otitis media (OM) develops in the first months of life and persists throughout childhood in many rural Aboriginal children. We have followed Aboriginal and non-Aboriginal infants from birth to determine the relationship of the early onset of OM to nasopharyngeal colonization with respiratory pathogens. Aboriginal infants were colonized with multiple species of respiratory bacteria (Moraxella catarrhalis, Haemophilus influenzae, Streptococcus pneumoniae) at a rate of 5% per day and the timing of colonization predicted the onset of persistent OM in individual Aboriginal infants. Non-Aboriginal infants became colonized by M. catarrhalis alone at the slower rate of 1% per day and experienced transient episodes of OM in the absence of colonization. We attribute early bacterial colonization in most Aboriginal infants to high rates of cross-infection due to overcrowding, poor hygiene and high rates of bacterial carriage. Early age of infection and the multiplicity of bacterial types may contribute to prolonged carriage and to eustachian tube damage leading to persistent OM. Thus Aboriginal infants are "otitis-prone" and might qualify for prophylactic antibiotics.

Upper airway carriage by Haemophilus influenzae and Streptococcus pneumoniae in Australian aboriginal children hospitalised with acute lower respiratory infection.

When nasopharyngeal secretions from 171 Australian Aboriginal children hospitalized with acute lower respiratory tract infections (ALRI) were cultured selectively for Streptococcus pneumoniae and Haemophilus influenzae, 136 (79.5%) and 151 (88.3%) children yielded 166 and 254 isolates of S. pneumoniae and H. influenzae, respectively. In colonized subjects multiple populations of S. pneumoniae (20% of carriage-positive patients) and H. influenzae (55%) were common. Pneumococci belonging to 27 types or groups were identified. H. influenzae serotype b colonized 16.4% of all children studied. More than one half of 152 children tested were excreting antibiotics at the time of admission to hospital. Significantly fewer children with serum antibiotic residues were colonized with S. pneumoniae than were antibiotic free children. Antibiotic usage had no measurable impact on the isolation rate of H. influenzae.

Streptococcal update. A microbiology perspective.

The streptococci remain important human pathogens despite it being nearly 60 years since sulphonamides were introduced. Rheumatic fever and post glomerulonephritis are common diseases in the Aboriginal community, and a new invasive disease, toxic shock-like syndrome, is also caused by Group A Streptococcus. Group B, first described over 50 years ago in obstetric wards remains the primary neonatal pathogen despite attempts to eliminate this organism from the genital tract of the carrier mother. A major concern in paediatrics is the relatively poor response to the current pneumococcal vaccines. Australian researchers are playing a major role in developing a new vaccine with high antigenicity against all of the 100 odd serotypes of S pneumoniae. The oral streptococci are now recognised as important opportunistic pathogens and the pathogenesis is well defined. Disturbing reports from different geographical regions alert us to the antibiotic resistance in some of the streptococci once thought of as sensitive bacteria, for example, Group A has shown resistance to erythromycin, the pneumococcus to penicillin and beta-lactam antibiotics and the aminoglycosides have been ineffective against the enterococci due to plasmid-borne genes.

An outbreak of serotype 1 Streptococcus pneumoniae infection in central Australia.

An outbreak of serotype 1 Streptococcus pneumoniae infection involving both adults and children occurred in central Australia during the winter months of 1991. Eighteen patients, mainly Aboriginal men, presented with culture-positive serotype 1 bacteraemic pneumonia. In this group, 11 of 12 adults for whom medical records were available were alcohol dependent. Thirteen children who were separately studied were hospitalised with acute lower respiratory tract infection: none had bacteraemia but all had upper airway colonisation by type 1 pneumococci. Antibiotics taken by 8 of the 13 children before admission to hospital may have compromised the isolation of type 1 pneumococci from blood cultures. Since the availability of antibiotics, epidemic pneumococcal infection is infrequent and has not been reported in Australia. In three outbreaks of type 1 disease recorded elsewhere crowding and alcoholism were identified as contributory factors. In the 16 month period before this outbreak none of 162 strains of pneumococci isolated from blood (32 strains) and nasopharyngeal secretions (130 strains) from Aborigines with acute lower respiratory tract infection and meningitis in the Alice Springs region were serotype 1 organisms.

Comparison of a blood-free medium and a filtration technique for the isolation of Campylobacter spp. from diarrhoeal stools of hospitalised patients in central Australia.

Single specimens of diarrhoeal stool from 676 patients, mostly aboriginals aged less than 5 years, admitted to Alice Springs Hospital, central Australia, for diarrhoea between Sept. 1988 and Feb. 1989, were examined for Campylobacter spp. by culture on a blood-free medium with selective supplement (BFM; Oxoid) and blood agar overlaid with a membrane filter (FM). Campylobacter spp. were isolated on either BFM or FM or both from 225 patients. Campylobacter spp. were isolated on BFM alone from 75 patients and on FM alone from 213 patients (p less than 0.001; chi 2 test). Most campylobacters isolated on BFM were C. jejuni. All C. jejuni subsp. doylei, all "C. upsaliensis" except one, all C. laridis, C. fetus subsp. fetus and several uncharacterised Campylobacter isolates were isolated on FM only. C. jejuni was isolated on BFM but not FM from several patients, and vice versa. Serotyping of C. jejuni and C. coli isolated from both media showed the serotypes recovered from the two media to be different in some patients. In some patients concurrent infection with several species or serotypes (up to five) of Campylobacter, or both, was shown for the first time by the use of FM. We conclude that the use in combination of a selective medium and a non-selective medium with a filtration technique are better than either medium alone for the isolation of Campylobacter spp.

Neurological melioidosis: seven cases from the Northern Territory of Australia.

Pseudomonas pseudomallei, which causes melioidosis, is most commonly associated with pulmonary infection. We describe seven patients who developed a neurological syndrome as the predominant manifestation of melioidosis: this syndrome was characterized by peripheral motor weakness (mimicking Guillain-Barré syndrome), brain-stem encephalitis, aseptic meningitis, and respiratory failure. Neurological melioidosis occurred in the absence of demonstrable foci of infection in the central nervous system (CNS) in five of six patients whose cerebrospinal fluid was available for culture. Computed tomography and magnetic resonance imaging of the brain and spinal cord of these patients were not suggestive of pyogenic infection, although the latter procedure detected brain-stem encephalitis. Autopsy findings in one case confirmed brain-stem encephalitis without evidence of direct bacterial infection. The clinical presentation of neurological melioidosis includes features of an exotoxin-induced neurological syndrome, with profound neurological disease occurring in the absence of apparent direct infection of the CNS. This syndrome appears to be a newly recognized clinical presentation of melioidosis.

Serotype distribution of Campylobacter jejuni and Campylobacter coli isolated from hospitalized patients with diarrhea in central Australia.

Campylobacter jejuni and/or Campylobacter coli was cultured from 218 of 1,078 patients of all age groups admitted to Alice Springs Hospital, Alice Springs, central Australia, between July 1988 and June 1989 for treatment of diarrhea. One hundred sixty-six Campylobacter colonies from 127 patients were subjected to O serotyping by using the Penner typing scheme. All except 29 colonies could be serotyped. A total of 46 serotypes were identified, and the predominant serotypes were O:8, 17, O:22, O:1,44, and O:19. A large proportion of colonies reacted with more than one antiserum, and nine serotypes had antigenic compositions not observed previously. Several patients had multiple infections with more than one serotype, and some patients were shown for the first time to be infected with up to three different serotypes. Repeated reinfections with different serotypes were seen in some patients. In some patients, provided it was not due to reinfection with the same serotype, long-term excretion of the same serotype was seen, and for the first time, one patient showed evidence of excretion of the same serotype for up to 73 days.

A prospective single-blind trial of minocycline and doxycycline in the treatment of genital Chlamydia trachomatis infection in women.

A total of 2124 women who attended the Richmond Family Planning Association Clinic in Melbourne consecutively were screened for the presence or absence of Chlamydia trachomatis. One hundred and three women were found to have Chl. trachomatis infection of the cervix and were invited to participate in a clinical trial of minocycline and doxycycline for the treatment of chlamydial infection. A 10-day course of either drug resulted in a negative result of a chlamydial culture for all patients at the follow-up assessment, which occurred between 11 days to 12 weeks after the therapy. Minocycline and doxycycline showed equal effectiveness in the eradication of mycoplasmas in over 80% of the treated patients. Minocycline appeared to have a slight advantage with respect to the resolution of the gynaecological symptoms that were associated with the chlamydial infection. The number of adverse events that were recorded during the trial was similar for both treatment regimens. Gynaecological symptoms were associated with chlamydial infection in approximately 50% of the women in the study. The lack of association between chlamydial infection and gynaecological symptoms has led to the instigation of routine testing for the presence of Chlamydia spp. in young women who have more than one sexual partner.

Microbiological profile of the cervix in 1,000 sexually active women.

One thousand consecutive women who attended the Richmond Family Planning Association Clinic and who were to undergo a vaginal examination were asked to participate in a large prospective microbiological study. Participants were questioned about their sexual activity during the previous 12 months and any apparent signs of sexually transmitted disease. On examination the cervix was inspected for evidence of inflammation, ectopy or discharge and cervical swabs were taken microbiological assessment. Chlamydia trachomatis was isolated in 5.1% of women tested while Ureaplasma urealyticum and Mycoplasma hominis were found in 48.8% and 16.4% of women respectively. Significant associations were found between the number of sexual partners during the previous 12 months and the incidence of all 3 organisms. The carriage rate of the genital mycoplasmas was significantly affected by the type of contraception. In addition the association between the presence of the genital mycoplasmas and pelvic and cervical abnormalities was determined.

The prevalence of Chlamydia trachomatis in a young, sexually-active population.

A prospective study was carried out to determine the prevalence of Chlamydia trachomatis among 1000 sexually-active women at the Family Planning Association Clinic in Melbourne. This organism was isolated from the cervices of 5.1% of screened women. The women were surveyed about their sexual and gynaecological history, and symptoms of discharge or pain. It was found that women who gave positive results for the presence of Chlamydia were younger, and had commenced intercourse at an earlier age. Risk factors of multiple sexual partners, cervical ectopy and symptoms of urethritis were identified. We recommend that women who have more than one sexual partner should ask their partners to use condoms or, failing this, undergo annual screening for Chlamydia by immunofluorescent staining.

PIP: A prospective study was conducted over the December 11, 1985-May 29, 1986, period to determine the prevalence of "Chlamydia trachomatis" among 1000 sexually-active women at Melbourne's (Australia) Family Planning Association Clinic. An epidemiological and clinical history was recorded on a code sheet for study participants. Patients' ages, weights, coitarches, numbers of sexual partners during the last 12 months, and lengths of association with their present partners were recorded along with current contraceptive usage and the results of the last Papanicolaou smear-test. Patients also were asked about the presence of any symptoms of sexually-transmitted disease (STD). The appearance of the cervix was ascertained on speculum examination. Cervical specimens were taken from all women for microbiological assessment. 995 patients completed the patient record form. In 994 of these women, satisfactory swabs were taken for microbiological examination. The patients ranged in age from 15-50 years with a mean age of 25.4. The age at 1st intercourse (coitarche) ranged from 12-30 years and the number of sexual partners during the last 12 months from none to more than 10 partners. 573 (57.6%) women were using oral contraceptives (OCs), 141 (14.2%) no contraception, 101 (10.2%) an IUD, 118 (11.9%) a barrier method, and the remainder a progestagen-only pill, an injectable contraceptive agent, sterilization, or natural contraceptive methods. The previous cervical cytology was available for 775 (77.9%) women; 625 (80.6%) of these showed no abnormal cells. Of the 150 smear-tests that showed some abnormality, only 10 tests demonstrated dysplastic lesions. The rest were indicative of infection or a benign abnormality. Of the 994 cervical swabs, 51 (5.1%) swabs grew Chlamydia trachomatis. 42 swabs gave positive results of both immunofluorescence staining and culture; 9 swabs gave positive results of culture alone. An association between other factors and the presence or absence of Chlamydia was determined. When the ages of patients were compared, patients whose swabs gave positive results for Chlamydia were significantly younger than those whose swabs gave negative results. The women whose swabs gave positive results for Chlamydia began intercourse at a significantly younger age. The prevalence of Chlamydia trachomatis in a young sexually-active population was 5.1%; the group with multiple partner was identified as being at high risk (9.3% positive results). In trying to identify women with an increased risk of carrying Chlamydia, 5 factors appeared relevant: younger age at coitarche; a younger age; more than 1 sexual partner during the previous 12 months; symptoms of urethritis; and the presence of cervical ectopy.

Transfer of a chromosomal locus responsible for mucoid colony morphology in Pseudomonas aeruginosa isolated from cystic fibrosis patients to P. aeruginosa PAO.

The locus responsible for mucoid colony morphology in five independent clinical isolates of Pseudomonas aeruginosa from cystic fibrosis patients have been transferred by means of pM060-mediated conjugation to the genetically characterised strain P. aeruginosa PAO. Genetic mapping has shown that in all five strains the locus is on the chromosome between 89' and 94', although it is not possible to say that the same locus is involved in each case. The way is now open for a more detailed genetic analysis of the loci responsible for mucoid colony morphology.

Methicillin-resistant Staphylococcus aureus in neonatal nurseries. Two years' experience in special-care nurseries in Melbourne.

Methicillin-resistant Staphylococcus aureus has become an important nosocomial pathogen in the four special-care nurseries in Melbourne during the past two years. Once introduced into a nursery, it can spread rapidly unless specific precautions are taken to prevent it. It has been responsible for a number of serious infections in susceptible infants who have required treatment with the potentially toxic antibiotic agent, vancomycin. Because of the interdependence of the four special-care nurseries, a coordinated approach to infection control is required to minimise the spread of the organism and the associated increased morbidity.

Epidemic of hospital-acquired infection due to methicillin-resistant Staphylococcus aureus in major Victorian hospitals.

During 1979, the Victorian Health Commission received reports of a rising proportion of methicillin-resistant Staphylococcus aureus (MRSA) isolates from an increasing number of institutions. At least 31 metropolitan hospitals were involved, and six of these reported MRSA totaling between 20% and 40% of all Staph. aureus isolates. Since that time, the problem has continued. In some university teaching hospitals, strains of MRSA now cause from 200 to 300 new cases of hospital-acquired infection each year. Sepsis occurs mainly in patients who underwent surgery, premature neonates and in the immunocompromised or debilitated patients. The organism involved is multiresistant. Recent isolates show increasing resistance, particularly against gentamicin, chloramphenicol and, more lately, fusidic acid and rifampicin. Only vancomycin can be relied upon for empirical treatment. There is concern that increasing use of vancomycin will select vancomycin-resistant strains of MRSA, so that, in the near future, there may no longer be any effective antibiotic therapy against hospital staphylococci.

Plasmid-determined tobramycin and gentamicin resistance in strains of Pseudomonas aeruginosa from two Sydney hospitals.

Strains of Pseudomonas aeruginosa resistant to gentamicin, tobramycin, streptomycin, and sulphonamide have been isolated from patients at two Sydney hospitals. The multiple resistance of all these strains was due to a transmissible plasmid. The significance of the identification of this plasmid, in this variety of strains and at two hospitals, for the treatment of Ps. aeruginosa infections is discussed.