Clinical impact of methicillin resistance on outcome of patients with Staphylococcus aureus infection: a stratified analysis according to underlying diseases and sites of infection in a large prospective cohort.

OBJECTIVE: This study was conducted to identify the predictors of mortality and to evaluate the impact of methicillin resistance on outcome in patients with Staphylococcus aureus infection according to underlying conditions and type of infection. METHODS: An observational cohort study including 4949 patients with S. aureus infection was conducted. We compared data from patients with MRSA infection with those with MSSA infection. RESULTS: The 30-day mortality rate of MRSA group was significantly higher than that of MSSA group (15.6% vs. 6.2%, P < 0.001). However, MRSA infection was not found to be independent risk factor for mortality after adjusting for other variables (OR = 1.03, 95% CI = 0.80-1.32). When we analyzed patients with S. aureus bacteremia (n = 709), MRSA infection was found to be significantly associated with mortality in multivariate analysis (Adjusted OR = 1.69, 95% CI = 1.15-2.49). When the 30-day mortality rates were compared according to underlying diseases, the 30-day mortality rate of MRSA group was significantly higher than that of MSSA group in patients with malignancy or renal diseases. MRSA infection was also found to be one of the independent risk factors for mortality in patients with malignancy (adjusted OR = 1.69, 95% CI = 1.06-2.70) and in those with renal disease (adjusted OR = 1.70, 95% CI = 1.0-2.89), after adjustment for host variables. CONCLUSIONS: Methicillin resistance adversely affected the outcome of patients with S. aureus infection, in patients with cancer or renal disease and in those with S. aureus bacteremia, although MRSA infection was not found to be significantly associated with higher mortality in overall patient population.

Epidemiology and clinical outcomes of community-acquired pneumonia in adult patients in Asian countries: a prospective study by the Asian network for surveillance of resistant pathogens.

Appropriate antimicrobial treatment of community-acquired pneumonia (CAP) should be based on the distribution of aetiological pathogens, antimicrobial resistance of major pathogens, clinical characteristics and outcomes. We performed a prospective observational study of 955 cases of adult CAP in 14 hospitals in eight Asian countries. Microbiological evaluation to determine etiological pathogens as well as clinical evaluation was performed. Bronchopulmonary disease (29.9%) was the most frequent underlying disease, followed by cardiovascular diseases (19.9%), malignancy (11.7%) and neurological disorder (8.2%). Streptococcus pneumoniae (29.2%) was the most common isolate, followed by Klebsiella pneumoniae (15.4%) and Haemophilus influenzae (15.1%). Serological tests were positive for Mycoplasma pneumoniae (11.0%) and Chlamydia pneumoniae (13.4%). Only 1.1% was positive for Legionella pneumophila by urinary antigen test. Of the pneumococcal isolates, 56.1% were resistant to erythromycin and 52.6% were not susceptible to penicillin. Seventeen percent of CAP had mixed infection, especially S. pneumoniae with C. pneumoniae. The overall mortality rate was 7.3%, and nursing home residence, mechanical ventilation, malignancy, cardiovascular diseases, respiratory rate>30/min and hyponatraemia were significant independent risk factors for mortality by multivariate analysis (P<0.05). The current data provide relevant information about pathogen distribution and antimicrobial resistance of major pathogens of CAP as well as clinical outcomes of illness in Asian countries.

Nasopharyngeal carriage of Haemophilus influenzae.

OBJECTIVE: Nasopharyngeal colonization of Haemophilus influenzae (H. influenzae) in young children may be important in developing countries. METHOD: In this study, we screened school going children for carriage of H. influenzae. A total of 44 H. influenzae isolates out of a collection of 162 were characterized for biotypes, capsular serotypes and antibiotic resistance. RESULTS: A significant proportion of H. influenzae (25/44) isolates were serotype b. High antibiotic resistance was observed against commonly administered antibiotics like ampicillin (79%), chloramphenicol (20%), trimethoprim sulfamethoxazole (84%) and erythromycin (95%). Comparison of antibiotic resistance profile of nasopharyngeal isolates was observed to be correlated with those of H. influenzae from disease. CONCLUSION: Multidrug resistant nasopharyngeal H. influenzae in young healthy children may act as reservoir. Monitoring of antibiotic resistance among nasopharyngeal H. influenzae as a surrogate for invasive H. influenzae seems an attractive option.

Systemic bacterial infections in bone marrow transplant patients.

The clinical microbiology department at CMC&H, Vellore in conjunction with the haematology department carries out routine surveillance of patients admitted to the hematology department. Since 1994 in a sample population of 55 patients with various underlying clinical conditions who have had bone marrow transplant, sepsis was observed in 16 patients (29%). The predominant Gram negatives associated with sepsis were non-fermenting Gram negative bacilli and all the 5 Gram positives were coagulase negative staphylococci. These organisms were susceptible to most of the routinely used antimicrobial agents. Continued surveillance is needed to determine changing trends with respect to organisms causing systemic infections and their susceptibility to antimicrobials.

PCR-Enzyme immunoassay for detection of Streptococcus pneumoniae DNA in cerebrospinal fluid samples from patients with culture-negative meningitis.

A PCR-based assay was developed to amplify a conserved region of the pneumococcal autolysin gene. The amplified product was labelled with digoxigenin-labelled dUTP and was detected with a biotin-labelled probe in an enzyme immunoassay (EIA). The assay was initially tested with suspensions of various serotypes of Streptococcus pneumoniae and other gram-positive and gram-negative bacteria and was then applied to cerebrospinal fluid (CSF) specimens from patients with meningitis and those with other neurological disorders. The assay detected all the serotypes of S. pneumoniae tested, whereas all the other bacterial strains tested were negative. Seven of the 8 CSF specimens positive for pneumococcus by culture or latex agglutination (LA) were positive by PCR-EIA, whereas all 10 specimens positive for other organisms were negative. Among 11 patients with clinically diagnosed meningitis but with negative culture and LA results, 5 were positive by PCR-EIA. The assay was negative for all but one patient without meningitis; it was positive with the CSF from a child with immunodeficiency and pneumococcal abscesses on the scalp. PCR-EIA is a useful tool for the diagnosis of meningitis, especially when culture and LA are negative because of prior antibiotic treatment.

Unusual manifestations of salmonellosis--a surgical problem.

From January 1981 to December 1992, of 6250 cases of salmonellosis treated at the Christian Medical College and Hospital, Vellore, India, 100 patients with focal pyogenic infection caused by salmonellae required surgical intervention in addition to medical therapy. Thirty-one had involvement of the hepatobiliary system, and 10 more had other intra-abdominal infections. Involvement of bone and joint as well as soft tissue constituted 15% each. The site of infection in patients with soft tissue abscesses included skin (7), parotid (2), thyroid (2), breast (1) inguinal node (1), branchial sinus (1) and injection site (1). Three patients had arterial infections. Noteworthy among the cases of genital infections was one case of salmonella infection in a pre-existing hydrocele, and one case of epididymo-orchitis with a loculated salmonella infection. Salmonella infection in a pre-existing ovarian cyst was seen in a patient with endometriosis. The salmonella serotypes most frequently encountered were S. typhi (36) and S. typhimurium (36), followed by S. paratyphi A (15). The importance of recognition of these protean manifestations of salmonellosis in an endemic setting is discussed. The microbiological evaluation of properly obtained specimens is mandatory in such unusual pyogenic infections.

An outbreak of anthrax meningoencephalitis.

We report a common-source outbreak of anthrax meningoencephalitis in Chittoor district in Andhra Pradesh, southern India, in October 1990. The source of infection was the carcass of a sheep. Of 5 persons who skinned and cut up its meat for human consumption, 4 developed anthrax meningoencephalitis and one a malignant pustule. Another person who wrapped the meat in a cloth and carried it home on his head developed a malignant pustule on his forehead and also meningoencephalitis. All subjects with anthrax meningoencephalitis died, but the one with only a malignant pustule recovered. A large number of people who cooked or ate the cooked meat of the dead sheep remained well. The medical, public health and veterinary authorities were alerted and sheep, goats and cattle in the locality were immunized with anthrax vaccine. Although rules against consumption of meat of dead animals exist, their violation shows a lack of public awareness. Health education should be undertaken to correct this situation.

In vitro evaluation of newer beta-lactam antibiotics against gram negative bacilli isolated from neutropenic patients.

The in-vitro susceptibility pattern to newer beta lactams namely Ticer/Clav, Azlocillin, Piperacillin and Imipenem was determined with 50 clinical strains isolated from neutropenic patients with strains isolated from neutropenic patients with sepsis, with an objective of evolving a strategy for empirical antibiotic therapy for febrile neutropenic patients. The MIC90 value for Imipenem for the Gram negative bacilli tested, other than Pseudomonas was < 0.25 mcg/ml therapy revealing a high degree of susceptibility, while for Ps. aeruginosa and related species MIC50 and MIV90 values were 2.0 and 64.0 micrograms/ml respectively. A comparatively lower degree of susceptibility was found among Gram negative bacilli included in the study to ticar/clavu, azlocillin and piperacillin indicating a moderate degree of resistance to these antibiotics. The data from this study suggests that (i) Ureidopenicillins with an aminoglycoside should be effective therapy for proven Pseudomonas and other Gram negative sepsis in febrile neutropenic patients. (ii) Imipenem would be the antibiotic of choice in Gram negative bacterial sepsis in febrile neutropenic patients where the organism is resistant to cephalosporins and ureidopenicillins.

Transducer related Enterobacter cloacae sepsis in post-operative cardiothoracic patients.

The use of intra-arterial pressure monitoring devices in patients undergoing major cardiac surgery is on the increase. Here we document an outbreak of Enterobacter cloacae septicaemia among seven post-operative cardiothoracic patients. Detailed investigations revealed the source of this nosocomial problem to be contaminated transducer heads. The need to follow strict aseptic measures in handling intra-arterial devices is emphasized, in order to minimize the morbidity and mortality in otherwise low-risk post-operative patients.

Bilateral septic arthritis due to Salmonella enteritidis.

We present an unusual case of septic arthritis due to Salmonella enteritidis involving both knee joints of a 29-year-old man with Hodgkin's lymphoma. The role of ciprofloxacin in septic arthritis caused by Gram-negative bacilli is also reviewed.