Resistance patterns among nosocomial pathogens: trends over the past few years

Hospital-acquired pneumonia: challenges and options for diagnosis and treatment

The management of hospital-acquired pneumonia (HAP) presents a major challenge for the clinician. The insensitivity of current diagnostic methods and the increasing prevalence of nosocomial pathogens with multiple antibiotic resistance complicate the issue. Use of mechanical ventilation and broad-spectrum antimicrobials in the intensive care setting predipose patients to acquire HAP more frequently with antimicrobial-resistant pathogens. Controversy exists regarding the patients in which invasive diagnostic testing is indicated; the timing of these procedures is another subject of debate. Proper empirical therapy is fundamental to a favourable outcome, and the selection of inappropriate agents to which pathogens are resistant contributes significantly to morbidity and mortality. In general, there is agreement on the requirement for a thorough knowledge of the local causative organisms and the pathogens' resistance profiles. A wide variety of antimicrobials can be used either as monotherapy or in combinations.

Aerobic Gram-negative Bacillary Pneumonia

Gram-negative bacilli (GNB) are a common cause of severe hospital-acquired pneumonia. Due to changes in the health care environment and selective antimicrobial pressure, these bacteria also are becoming a more common cause of pneumonia in venues outside of the traditional hospital setting and are increasingly resistant to antimicrobial agents. Risk factors for acquisition of GNB allow the clinician to efficiently identify patients who are likely to have pneumonia due to these pathogens. Available diagnostic techniques have a limited capacity to accurately detect GNB pulmonary infection. Yet, a pathogen specific diagnosis and knowledge of local resistance patterns are quintessential elements in formulating an effective treatment plan. This article reviews the epidemiologic characteristics, pathogenesis, and current management issues of GNB pneumonia.

Spectrum and antibiotic resistance of uropathogens from hospitalized patients with urinary tract infections: 1994-2000

During the period 1994-2000 all uropathogens cultured from urine of hospitalized urological patients were identified and susceptibility was tested against 11 antibacterials. Duplicated isolates were eliminated. There was no general trend of increased of resistance apart from E. coli to ciprofloxacin (10.4% in 2000). Vancomycin-resistant staphylococci or enterococci was not significant. The lowest overall rates of resistance were found with piperacillin/tazobactam followed by ciprofloxacin and trimethoprim/sulphamethoxazole. Ciprofloxacin was the best oral antibiotic for the empirical treatment of urinary tract infection (UTI) due to Gram-negative rods and ampicillin/sulbactam for the treatment of UTI with Gram-positive cocci.

Nosocomial and ventilator-associated pneumonias: developing country perspective

Nosocomial pneumonias are recognized as an important cause of morbidity and mortality in industrialized nations. Emerging data show that they play a similar role in the developing world. A host of extrinsic and intrinsic factors predispose individuals to the development of pneumonias, and a modification of some of these factors provides a low cost solution to prevention of pneumonias. The ideal modality for microbiologic diagnosis of pneumonia remains to be determined. Recent data suggest that there is no difference in outcome when noninvasive techniques are compared with invasive techniques. Antimicrobial resistance is a rapidly increasing problem globally, and combating this with appropriate antibiotic policies, close surveillance, and physician education is essential.

Prevention of nosocomial infections in the neonatal intensive care unit

Nosocomial infections are responsible for significant morbidity and late mortality among neonatal intensive care unit patients. The number of neonatal patients at risk for acquiring nosocomial infections is increasing because of the improved survival of very low birthweight infants and their need for invasive monitoring and supportive care. Effective strategies to prevent nosocomial infection must include continuous monitoring and surveillance of infection rates and distribution of pathogens; strategic nursery design and staffing; emphasis on handwashing compliance; minimizing central venous catheter use and contamination, and prudent use of antimicrobial agents. Educational programs and feedback to nursery personnel improve compliance with infection control programs.

Staphylococcus aureus mutants isolated via exposure to nonfluorinated quinolones: detection of known and unique mutations

The in vitro development of resistance to the new nonfluorinated quinolones (NFQs; PGE 9262932, PGE 4175997, and PGE 9509924) was investigated in Staphylococcus aureus. At concentrations two times the MIC, step 1 mutants were isolated more frequently with ciprofloxacin and trovafloxacin (9.1 x 10(-8) and 5.7 x 10(-9), respectively) than with the NFQs, gatifloxacin, or clinafloxacin (<5.7 x 10(-10)). Step 2 and step 3 mutants were selected via exposure of a step 1 mutant (selected with trovafloxacin) to four times the MICs of trovafloxacin and PGE 9262932. The step 1 mutant contained the known Ser80-Phe mutation in GrlA, and the step 2 and step 3 mutants contained the known Ser80-Phe and Ser84-Leu mutations in GrlA and GyrA, respectively. Compared to ciprofloxacin, the NFQs were 8-fold more potent against the parent and 16- to 128-fold more potent against the step 3 mutants. Mutants with high-level NFQ resistance (MIC, 32 microg/ml) were isolated by the spiral plater-based serial passage technique. DNA sequence analysis of three such mutants revealed the following mutations: (i) Ser84-Leu in GyrA and Glu84-Lys and His103-Tyr in GrlA; (ii) Ser-84Leu in GyrA, Ser52-Arg in GrlA, and Glu472-Val in GrlB; and (iii) Ser84-Leu in GyrA, Glu477-Val in GyrB, and Glu84-Lys and His103-Tyr in GrlA. Addition of the efflux pump inhibitor reserpine (10 microg/ml) resulted in 4- to 16-fold increases in the potencies of the NFQs against these mutants, whereas it resulted in 2-fold increases in the potencies of the NFQs against the parent.