A study on nosocomial pathogens in ICU with special reference to multiresistant Acinetobacter baumannii harbouring multiple plasmids.

BACKGROUND & OBJECTIVES: Antibiotic resistant bacterial nosocomial infections are a leading problem in intensive care units (ICU). Present investigation was undertaken to know antibiotic resistance in Acinetobacter baumannii and some other pathogens obtained from clinical samples from ICU causing nosocomial infections. Special emphasis was given on plasmid mediated transferable antibiotic resistance in Acinetobacter. METHODS: The clinical specimens obtained from ICU, were investigated to study distribution of nosocomial pathogens (272) and their antibiotic resistance profile. Acinetobacter isolates were identified by API2ONE system. Antimicrobial resistance was studied with minimum inhibitory concentration (MIC) by double dilution agar plate method. The plasmid profile of 26 antibiotic resistant isolates of Acinetobacter was studied. Curing of R-plasmids was determined in three antibiotic resistant plasmid containing A. baumannii isolates. Plasmid transfer was studied by transformation. RESULTS: Major infections found in ICU were due to Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes. The infection rate was maximum in urinary tract (44.4%) followed by wound infections (29.4%), pneumonia (10.7%) and bronchitis (7.4%). Acinetobacter isolates displayed high level of antibiotic resistance (up to 1024microg/ml) to most of antibiotics. More than 90 per cent isolates of Acinetobacter were resistant to a minimum of 23 antibiotics. Plasmid profile of Acinetobacter isolates showed presence of 1-4 plasmids. Ethidium bromide cured plasmids pUPI280, pUPI281, pUPI282 with curing efficiencies 20, 16 and 11 per cent respectively while acridine orange cured plasmids pUPI280, pUPI281 with curing efficiencies 7 and 18 per cent retrospectively. Transformation frequency of E. coli HB101 with pUPI281 was 4.3 x 10(4) transformants/microg plasmid DNA. INTERPRETATION & CONCLUSIONS: A. baumannii was found to be associated with urinary tract infections, respiratory tract infections, septicaemia, bacteraemia, meningitis and wound infections. A. baumannii displayed higher resistance to more number of antibiotics than other nosocomial pathogens from ICU. Antibiotic sensitivity of A. baumannii cured isolates confirmed plasmid borne nature of antibiotic resistance markers. Transfer of antibiotic resistant plasmids from Acinetobacter to other nosocomial pathogens can create complications in the treatment of the patient. Therefore, it is very important to target Acinetobacter which is associated with nosocomial infections.

Diagnosis and outcome of acute bacterial meningitis in early childhood.

OBJECTIVE: To estimate frequency of acute bacterial meningitis (ABM) in early childhood in hospital admissions, to describe clinical and diagnostic features, and to analyze mortality, complications and long term sequelae. DESIGN: Prospective study. SETTING: Pediatric wards and Rehabilitation Center of KEM Hospital, Pune. METHOD: Study subjects between the ages of 1 months to 5 years with ABM were recruited. Clinical details were recorded. CSF was analysed by routine biochemical methods, antigen detection tests (Latex agglutination LAT) and microbiological studies on special media. Management was as per standard protocols. Survivors were followed up long term with neurodevelopmental studies and rehabilitation programmes. RESULTS: In a study period of 2 years, 54 children (1.5% of all admissions) satisfied the criteria of ABM in early childhood; 78% were below one year and 52% were under the age of six months. Chief presentation was high fever, refusal of feeds, altered sensorium and seizures. Meningeal signs were present in only 26%. CSF C-reactive protein was positive in 41%, gram stain was positive in 67% LAT in 78% and cultures grew causative organisms in 50% of the cases. The final etiological diagnosis (as per LAT and/or cultures) were Streptococcus pneumoniae 39% Hemophilus influenzae type b 26% and others in 35% The others included one case of Neisseria meningitidis and 10 who were LAT negative and culture sterile. 39% patients developed acute neurological complications during the hospital course. 31% children with ABM died in hospital or at home soon after discharge. Six were lost to follow up. Of the 31 children, available for long term follow up (1-3 years), 14 (45%) had no sequelae. The remaining had significant neurodevelopmental handicaps ranging from isolated hearing loss to severe mental retardation with multiple disabilities. CONCLUSION: ABM in early childhood has a considerable mortality, morbidity and serious long term sequelae. Neurodevelopmental follow up and therapy should begin early. Etiological diagnosis can be enhanced by LAT and good culture media. H. influenzae b and S. pneumoniae account for more than 60% of ABM in early childhood.

Salmonella types and antibiotic susceptibility: a six months survey.

A total of 51 Salmonella strains were isolated during the six month period of May 1998 till October 1998. Of these, 41 (80.3%) were Salmonella typhi, 5 (9.8%) Salmonella pararyphi A,2 (3.9%) Salmonella worthington and 1 (1.9%) Salmonella senftenberg. The prevalent phage and biotype of Salmonella typhi was E1 (75%) and type 1 (90.2%) respectively. The commonest pattern of multiple drug resistance in Salmonella typhi was ACCoT and 92.5% of these belonged to phage E1. Out of the five Salmonella paratyphi A, one belonged to phage type 1 and the others were untypable. Similarly both the strains of Salmonella typhimurium were untypable. Thus the predominant isolate was Salmonella typhi and the commonest phage and biotype were E1 and biotype1 respectively.

Neonatal gram-negative bacteremia.

A 22 months prospective study of neonatal gram-negative bacteremia was undertaken in a 15 bed NICU to find out the incidence and antibiotic resistance patterns. Clinically suspected 1326 cases of neonatal sepsis were studied during this period. More than 25% of the cases were microbiologically positive for sepsis. Among 230 (67.2%) cases of gram-negative bacteremia, the predominant isolates were Pseudomonas aeruginosa (38.3%), Klebsiella pneumoniae (30.4%), Escherichia coli (15.6%) and Acinetobacter sp. (7.8%). Fifty-nine per cent of the neonates were born in hospital while 41% were from community and referral cases. Lower respiratory tract infection, umbilical sepsis, central intravenous line infection and infection following invasive procedures were the most commonly identified sources of septicemia. Prematurity and low birth weight were the main underlying conditions in 60% of the neonates. Total mortality was 32%. Increased mortality was mainly associated with neutropenia, nosocomial infection and inappropriate antibiotic therapy. Resistance was increasingly noted against many antibiotics. The isolates were predominantly resistant to extended spectrum cephalosporins (25%-75%), piperacillin (68%-78%), and gentamicin (23%-69%). The commonest microorganisms causing gram-negative bacteremia were Pseudomonas aeruginosa followed by Klebsiella pneumoniae. The community-acquired bacteremia was mainly due to E. coli. The proportion of preterm and low birth weight babies was significantly high, and the major contributing factor in total mortality. Sensitivity to different antibiotics conclusively proved that a combination of ampicillin + sulbactam with amikacin or ampicillin + sulbactam with ciprofloxacin is most effective.