Bacteriological Assessment of Pneumonia Caused by Gram-Negative Bacteria in Patients Hospitalized in Intensive Care Unit.

The article presents the results of 11-year study (2005-2015) of Gram-negative bacteria responsible for pneumonia in 2033 mechanically ventilated patients hospitalized in Intensive Care Unit. Of 8796 biological samples, consisting mainly of bronchial aspirate (97.9 %), 2056 bacterial strains were isolated and subjected to identification. VITEK 2 was used to determine drug susceptibility (classified according to the EUCAST criteria). ESBL, MBL and KPC-producing strains were identified by means of phenotypic methods using appropriate discs. The findings were that the predominant bacteria responsible for infections consisted of Enterobacteriaceae (42.0 %), Acinetobacter baumannii (37.2 %), Pseudomonas aeruginosa (16.1 %), and Stenotrophomonas maltophila (4.7 %). We observed a rise in the number of bacteria causing pneumonia throughout the study period, especially in S. maltophila and Enterobacteriaceae ESBL (+). Gram-negative bacilli were 100 % susceptible to colistin, apart from naturally resistant strains such as Proteus mirabilis, Serratia marcescens, whereas Enterobacteriaceae ESBL (+) were susceptible to imipenem and meropenem. Acinetobacter baumannii strains exhibited the lowest drug susceptibility. In conclusion, we report an increase in the prevalence of pneumonia associated with Gram-negative bacteria in mechanically ventilated intensive care patients. Colistin remains the most effective drug against the majority of Gram-negative bacteria. Therapeutic problems are common in the course of treatment of Acinetobacter baumannii infections.

Prevalence of Neisseria meningitidis Carriage with Identification of Serogroups and Genogroups in Professional Soldiers.

The article presents the prevalence of Neisseria meningitidis carriage with the identification of sero- and genogroups in professional soldiers serving in the Polish Armed Forces. A total of 1246 soldiers from the 10th Armored Cavalry Brigade in Swietoszów, Poland were examined in the period January-February 2016. Microbiological tests were performed using standard methods (culture, incubation, microscopy, biochemical, and automated identification with VITEK cards). Neisseria meningitidis isolates from carriers were subjected to a slide agglutination test for the identification of serogroups, next bacterial DNA was isolated and genogroups were identified based on the results of PCR. Of the 1246 soldiers tested, 65 were found to be carriers of N. meningitidis. Serogroups of 36 isolates and genogroups of 56 meningococcal isolates were determined. The genogrouping identified the isolates as belonging to group B (n = 34; 52.3 %), E29 (n = 8; 12.3 %), C (n = 6; 9.2 %), Y (n = 6; 9.2 %), and W (n = 2; 3.1 %). The primers which were used did not make it possible to determine the genogroup of nine isolates. In conclusion, the overall carrier rate of N. meningitidis amounted to 5.2 %, with the serogroup B being predominant, which is similar to that reported in the general population in Poland and Central Europe.

Effectiveness of immunoprophylaxis in suppressing carriage of Neisseria meningitidis in the military environment.

Neisseria meningitidis, etiological factor of invasive meningococcal disease, is a human commensal that colonizes the nasopharynx. Colonization is usually asymptomatic, but it is a prerequisite for disease. Asymptomatic carriers are the major source of infection. In the present study, a survey of N. meningitidis carriage was conducted between January and March 2013 in a military unit in Poland. Single-time throat culture samples were collected from professional 559 soldiers (302 unvaccinated vs. 257 vaccinated individuals with the quadrivalent conjugate vaccine ACYW-135). Bacterial identification was performed with classic microbiological methods (culture, incubation, identification). Non-culture method (PCR) was used for confirmation of detected strains of N. meningitidis and determination of serogroups. We found 29 carriers in the group of unvaccinated soldiers (9.6 % of examined individuals) whereas among vaccinated soldiers only 3 persons were carriers of N. meningitidis (1.2 %). The most frequently identified serogroups among the carriers serving in the same military facility were serogroup B (28 %), followed by Y (25 %), and C (22 %). In conclusion, the initiation of mass vaccination with the quadrivalent conjugate vaccine ACYW-135 in the military environment seems an effective method of suppressing N. meningitidis carriage.

Etiological factors causing lower respiratory tract infections isolated from hospitalized patients.

Lower respiratory tract infections (LRTI) account for 20-30 % of all hospital-acquired contagions. They are characterized by high mortality of hospitalized patients. The most serious form of LRTI is pneumonia, and the most common etiological factors in such cases are bacteria. The article gives the analysis of bacterial flora samples obtained from lower respiratory tract of hospitalized patients. In vitro susceptibility of pathogens to selected antibiotics has also been assessed. We carried out a retrospective analysis of 1,171 bacterial strains isolated from 1,171 patients treated in clinics of the Military Institute of Medicine in Warsaw, Poland. In most cases the samples were collected from an endotracheal or tracheostomic tube (71.5 %) and from bronchoalveolar lavage (21.7 %). The most commonly isolated pathogens included Acinetobacter baumannii (35.8 %), Staphylococcus aureus (27.6 %), Klebsiella pneumoniae (19.4 %), and Pseudomonas aeruginosa (16.2 %). Multidrug-resistant gram-negative bacteria exhibited 100 % susceptibility to colistin only. Klebsiella pneumoniae ESBL+ and Acinetobacter baumannii were most susceptible to carbapenems, while Pseudomonas aeruginosa strains to ceftazidime. Methicillin-resistant Staphylococcus aureus were 100 % susceptible to vancomycin, linezolid, and tigecycline. In conclusion, identifying the etiological factors causing infections of the lower respiratory tract and determining their drug-susceptibility is of key importance in empirical treatment.