Nosocomial pneumonia in adult general medical and surgical patients at Christchurch Hospital.

AIMS: To determine the incidence, microbial cause, and outcome of nosocomial pneumonia in adult general medical and surgical patients at Christchurch Hospital. METHOD: A one-year prospective study of consecutive patients developing nosocomial pneumonia in a university-affiliated hospital. Expanded diagnostic laboratory testing was undertaken to identify the microbial cause of pneumonia. RESULTS: We recruited 126 patients, which represented an incidence of 6.1 per 1,000 admissions. Only 52 (41%) patients submitted sputum that satisfied the cytological screening criteria for testing. A microbial cause was identified in 47 cases (37%): the most common was Legionella spp. (sixteen cases), followed by Influenza A (six cases) and Staphylococcus aureus (four cases). We did not identify an environmental source of the Legionella species. Fourteen patients (11%) died as a consequence of pneumonia and nearly all of these had significant comorbidity. Renal impairment, alcohol excess, and severity of pneumonia were the most powerful predictors of a fatal outcome by univariate analysis. CONCLUSIONS: In most patients we did not identify a microbial cause of pneumonia; when we did, Legionella species were the most common, although this micro-organism has a long incubation period so some subjects may have acquired it before admission. These results guide preventative efforts, diagnostic testing and selection of antimicrobial therapy for nosocomial pneumonia in our hospital.

International multicenter evaluation of the clinical utility of a dipstick assay for detection of Leptospira-specific immunoglobulin M antibodies in human serum specimens.

We performed a multicenter evaluation of a robust and easily performed dipstick assay for the serodiagnosis of human leptospirosis. The assay is aimed at the detection of Leptospira-specific immunoglobulin M (IgM) antibodies. The study involved 2,665 serum samples collected from 2,057 patients with suspected leptospirosis in 12 countries on five continents with different levels of endemicity and different surveillance systems. The patients were grouped as laboratory-confirmed leptospirosis case patients and noncase patients based on the results of culturing and the microscopic agglutination test. Paired samples from 27.7% of the subjects were tested. Of the 485 case patients, 87.4% had a positive dipstick result for one or more samples. Of the 1,513 noncase patients, only 7.2% had a positive result. Whereas most (88.4%) of the positive samples from the case patients showed moderate to strong (2+ to 4+) staining in the dipstick assay, most (68.1%) of the positive samples from the noncase patients showed weak (1+) staining. The sensitivity of the dipstick assay increased from 60.1% for acute-phase serum samples to 87.4% for convalescent-phase samples. The specificities for these two groups of samples were 94.1 and 92.7%, respectively. The dipstick assay detected a broad variety of serogroups. The results of the dipstick assay were concordant (observed agreement, 93.2%; kappa value, 0.76) with the results of an enzyme-linked immunosorbent assay for the detection of specific IgM antibodies, a test which is often used in the laboratory diagnosis of current or recent leptospirosis. This study demonstrated that this easily performed dipstick assay is a valuable and useful test for the quick screening for leptospirosis; has a wide applicability in different countries with different degrees of endemicity; can be used at all levels of the health care system, including the field; and will be useful for detecting and monitoring outbreaks of leptospirosis.

Community acquired pneumonia: aetiology and usefulness of severity criteria on admission.

BACKGROUND: Community acquired pneumonia remains an important cause of hospital admission and carries an appreciable mortality. Criteria for the assessment of severity during admission have been developed by the British Thoracic Society (BTS). A study was performed to determine the sensitivity and specificity of a severity rule based on a modification of the BTS prognostic rules applied on admission, to compare severity as assessed by medical staff with the modified rule, and to determine the microbiological cause of community acquired pneumonia in Christchurch. METHODS: A 12 month study of all adults admitted to Christchurch Hospital with community acquired pneumonia was undertaken. Three hundred and sixteen consecutive patients with suspected community acquired pneumonia were screened for inclusion. Variables obtained from the history, examination, investigations, and initial treatment were examined for association with mortality. RESULTS: Two hundred and fifty five patients met the inclusion criteria. Their mean age was 58 years (range 18-97). A microbiological diagnosis was made in 181 cases (71%), Streptococcus pneumonia (39%), Mycoplasma pneumoniae (16%), Legionella species (11%), and Haemophilus influenzae (11%) being the most commonly identified organisms. Patients had a 36-fold increased risk of death if any two of the following were present on admission: respiratory rate > or = 30/min, diastolic BP < or = 60 mm Hg, urea > 7 mmol/l, or confusion. The severity rule identified 19 of the 20 patients who died and six of eight patients admitted to the intensive care unit as having life threatening community acquired pneumonia. The sensitivity of the modified rule for predicting death was 0.95 and the specificity 0.71. In 47 cases (21%) the clinical team appeared to underestimate the severity of the illness. CONCLUSIONS: The organisms responsible for community acquired pneumonia in Christchurch are similar to those reported from other centres except for Legionella species which were more common than in most studies. The modification of the BTS prognostic rules applied as a severity indicator at admission performed well and could be incorporated into management guidelines.

Use of the polymerase chain reaction to detect Legionella DNA in urine and serum samples from patients with pneumonia.

Legionella pneumonia can be difficult to diagnose. Existing laboratory tests for detecting Legionella species lack sensitivity or provide only a retrospective diagnosis. We used the polymerase chain reaction (PCR) with primers that amplify a 104-base pair segment of the coding region of the 5S tRNA gene to detect Legionella DNA in urine and serum samples from patients with pneumonia. Stored urine and serum samples from patients enrolled in two prospective studies of pneumonia were tested. Legionella DNA was detected in urine and/or serum samples from 18 (64%) of 28 patients with legionella pneumonia diagnosed by conventional tests, but it was not detected in urine or serum samples from 24 patients with pneumonia due to other organisms. The sensitivity of PCR improved to 73% if testing was restricted to samples taken within 4 days of the onset of symptoms. Detection of Legionella DNA in urine and serum promises to be a valuable tool for the rapid diagnosis of legionella pneumonia.

An outbreak of leptospirosis on a single farm in east Otago.

AIMS: To present an outbreak of leptospirosis on a dairy farm which had an unvaccinated herd. METHODS: Nine people working or living on the farm were tested for the presence of leptospira antibody by the microscopic agglutination test. Nineteen cows randomly selected, were also tested. RESULTS: Three human cases and one suspected case were detected over a one month period (December 1992-January 1993). Seventy-nine percent of the dairy herd tested had serological evidence of infection with L hardjo. CONCLUSIONS: Leptospirosis continues to be a major occupational problem in New Zealand. The importance of herd vaccination and the use of protective clothing during milking is emphasised.

Serological studies of legionellosis in New Zealand.

The service performed by the Legionella Reference Laboratory in New Zealand over the last 4 years is described. During this period the number of antigens used in the indirect fluorescent antibody test increased from 4 to 19. The percentage of patients diagnosed has risen concomitantly. Species or serogroups found particularly frequently included L. pneumophila serogroup (SG) 6, L. micdadei, L. jordanis and L. longbeachae SG 1. Cultural studies and direct fluorescent antibody (DFA) studies were also performed. In addition to other species or serogroups, L. dumoffii was isolated from a patient and L. oakridgensis was observed by DFA in a postmortem specimen.

Serological studies on patients with suspected legionellosis in New Zealand.

Specimens from 490 patients with suspected legionellosis from many parts of New Zealand were studied. Most of these were sera, but 36 specimens including material from lungs, pleural fluid and sputa were also examined. The sera were tested for the presence of antibodies to Legionella pneumophila serogroups 1 to 6 and Legionella micdadei. Serological evidence of legionellosis was found in 49 patients. Antibodies to L. pneumophila serogroup 6 predominated, while those to L. micdadei and L. pneumophila serogroup 1 were noted in smaller numbers. Antibodies to serogroups 2, 3, 4 and 5 of L. pneumophila were not often encountered.

Legionellosis due to Legionella pneumophila serogroup 6: report of three cases.

Three cases of legionellosis caused by Legionella pneumophila serogroup 6 are reported and a brief review of similar cases in New Zealand in 1982 is made. Legionellosis appears more common in New Zealand than was previously thought. In 1982 50% of reported cases occurred in the Wellington region and a uniquely high incidence of legionellosis due to serogroup 6 was observed.

The ecology of Escherichia coli in a maternity ward in Christchurch, New Zealand.

During one week, 594 strains of Escherichia coli were collected from the faeces of all mothers, babies and the hands of babies' attendants in a maternity ward in Christchurch Women's Hospital. The strains were serotyped for their 'O' and 'H' antigens, biotyped, and their antibiotic resistance patterns were determined. Very little spread was observed, compared with similar studies carried out in London a few years ago. This is ascribed to the fact that in Christchurch the mothers predominantly handled their own babies, whereas in London the nursing staff predominantly handled them.

O and H serotypes of Escherichia coli isolated from urinary tract infections.

Escherichia coli strains isolated from Christchurch women with symptomatic and asymptomatic bacteriuria were serotyped for both their "O" and "H" antigens with a complete set of antisera. Although the "O" types found in this survey conformed in general with the prevalence of "O" types observed in other parts of the world some differences were also noted. The serotypes associated with symptomatic infection showed differences with those from asymptomatic patients.