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The aim of this study was to characterize the fluoroquinolone (FQ) resistance mechanism of Salmonella enterica serovar Typhi and Paratyphi A in Bangladesh. Salmonella Typhi isolates were classified into sequence type (ST) 1, ST2, and ST2209 and Salmonella Paratyphi A isolates were classified into ST85 and ST129. The most common STs of the FQ-nonsusceptible strain were ST1 (44.4%) and ST129 (66.6%). Thirty-nine percent of Salmonella Typhi isolates were multidrug resistant, and these were all ST1, which is the type prevalent in the Indian subcontinent. Although plasmid-mediated quinolone resistance genes were not detected in any of the tested strains, single and double mutations were identified in the quinolone resistance-determining region (QRDR). The most common QRDR mutation was GyrA_Ser83Phe (66.7% for Salmonella Typhi and 100% for Salmonella Paratyphi A). Treatment with an efflux pump inhibitor resulted in susceptibility of the strains to levofloxacin. All isolates demonstrated 100% susceptibility to ceftriaxone, azithromycin, and carbapenem. Our results suggest that mutations in gyrase A and enhancement of efflux pump activity are responsible for the resistance to FQs; in particular, the AcrAB-TolC efflux pump may be an important resistance factor for levofloxacin. To control the spread of FQ-nonsusceptible Salmonella Typhi, intensive surveillance in endemic areas, including Bangladesh, and effective infection control are necessary.

Typhoid fever is a major health problem in developing countries in spite of the use of antibiotics and the development of newer antibacterial drugs. Blood culture & serological tests (specially Widal test) which are invariably done in Bangladesh for typhoid fever diagnosis give unacceptable levels of false negative & false positive results respectively. This cross sectional study was done at Bangabandhu Sheikh Mujib Medical University from March 2013 to February 2014. In this study, a polymerase chain reaction-based technique (which has 100% specificity for Salmonella Typhi) was compared with blood culture and widal test among 80 clinically suspected cases of typhoid fever. PCR showed maximum positivity rate (70%) followed by widal test (43.75%) and blood culture (16.25%). PCR showed positive results for 17(48.6%) of 35 typhoid patients with negative results with blood culture and widal test. The results of the study revealed that PCR is rapid and reliable diagnostic technique for detection of S. Typhi in clinically suspected typhoid fever cases, as compared to most commonly done methods such as conventional blood culture, widal test applied.

Typhoid fever is one of the most common febrile illnesses encountered by the physicians in Bangladesh. Diagnosis is not difficult but has lately become a challenge due to changed clinical pattern of the disease, lack of adequate facilities for blood, stool, urine culture, excessive reliance on nonspecific Widal test and non availability of any reliable rapid diagnostic tests. Further, the indiscriminate and injudicious use of antibiotics for treating fever in undiagnosed febrile illnesses early has created problems to the physicians to reach to a diagnosis later on. This has also led to the emergence of high level resistance to many of the commonly used antibiotics in our country. Ciprofloxacin is often used empirically for treating the disease though there is already a high level resistance. In case the organism is in-vitro sensitive to ciprofloxacin but resistant to nalidixic acid, a much higher dose of drug is required to maintain the MIC which is 10 times higher than usual. Third generation cephalosporins (ceftriaxone and cefixime) are still the effective drugs for treating typhoid fever. The drug needs to be used in proper dose and duration to prevent emergence of resistance. Azithromycin though advocated by many as an alternative to ciprofloxacin in resistant cases, has recently lost its credibility due to emergence of resistance. We should not rely on Widal test in diagnosing typhoid fever. In a suspected case, the patient should not be prescribed any antibiotic without sending blood sample for culture sensitivity.

Serosurvillance of 650 children of clinically suspected dengue infection based on simple laboratory tests were evaluated to find out the early indicator for diagnosis of dengue infection. The study was conducted among the patients attending the Sir Salimullah Medical College (SSMC) and Mitford Hospital and Popular Diagnostic Center, Dhaka, during July 2002 to September 2002. Of these 650 suspected dengue cases, 294 were in the age group 1-5 years, 206 were in age group 6-10 years and 150 cases in age group 11-15 years, of which Seropositivity was found in 78 (26.53%), 60 (24.12%) and 65 (43.33%) cases respectively. Primary dengue IgM was positive in 123 (60.59%) cases and secondary dengue (IgG & IgM combined or IgG alone) was positive in 80 (39.41%) cases. Leucopenia was found in 90 (75%) cases and Thrombocytopenia was found in 95 (79.16%) cases in primary dengue cases. Similarly in secondary dengue cases TWBC and PLT was decreased in 60 (72.29%) and 65 (78.15%) cases respectively. Haemoconcentration was found in 40 (36.67%) cases of primary dengue and 13 (18%) cases in secondary dengue. Month wise distribution of dengue seropositivity shows that 10 (8.53%) cases was found in July, 175 (50.10%) cases in August and 78 (10.00%) cases in September. This study reveals that seropositivity is highest (43.33%), in the age group 11-15 years and incidence of dengue increased in the month of August. Leucopenia (WBC

Out of 350 acute respiratory tract infection (ARI) patients 110 (31.4%) were positive on culture. Among then (35.5%) yielded from upper respiratory tract infection (URI) and 64.5% yielded from lower respiratory tract infection (LRI). Predominant bacterial isolates from URI were Staph aureus (12.4%) and Strepto. pyogen (9.8%) whereas predominant agent from LRI were Strepto. pneumoniae (14.7%) and Haemophilus influenzae (8.6%). Capsular typing by polymerase chain reaction (PCR) and type specific antisera revealed that 64.7% of the isolates were type-b and rest were non-b. The most frequent resistance pattern of H. influenzae was found resistant to penicillin-ampicillin (64.7%) followed by SMX-TMP (14.7%) and tetracycline (5.9%). Among penicillin-ampicillin resistant strains, 81.8% were beta lectamase positive and 18.2% were beta lectamase negative. Among beta lectamase positive strains 66.7% were capsular type-b and 33.3% were non-b, had MICS < or = 8 microgram/ml. and < or = 4 microgram/ml. respectively. 5.9% strains of Strepto. pneumoniae was found resistant to SMX-TMP, 5.9% to penicillin-ampicillin and 2.9% to cephalexin. Common resistance pattern of Staph aureus was penicillin-ampicillin (60%), SMX-TMP (37.2%) and tetracycline-erythromycine-cephalexin (11.4%). Strepto. pyogen was found resistant to tetracycline in 12.2% cases and to SMX-TMP in 8.3% cases.

We studied 125 clinically suspected septicemic neonates (Patient) aged from 1 to 28 days and 25 healthy neonates (control) of comparable age and sexes. Cultures of blood were done and serum immunoglobulins (IgG, IgA) were estimated in all the subjects. Blood cultures were found positive in 45 (36%) patients. Preterm patients showed significantly higher number of positive blood cultures as compared to term patients. The mean serum IgG level in patients was found significantly lower than that of the controls. The serum IgG levels were also found significantly lower in 75 preterm as compared to 50 term, and in 45 blood culture positive patients as compared to 80 blood culture negative patients. On the other hand, the mean serum IgM level in patients was found significantly higher as compared to controls. Similarly, serum IgM levels were found higher in preterm patients as compared to term patients and in blood culture positive patients as compared to blood culture negative patients. No significant difference of mean serum IgA level was found among the subjects. It is evident from our study, that blood culture positive patients were mostly preterm, in whom transplacental passage of IgG is insufficient and due to low IgG level, preterm baby cannot counteract bacterial invasion and as such, suffer from septicemia more frequently. Septicemic neonates as a rule showed higher level of serum IgM due to synthesis by themselves in primary response to infection.

Children with protein energy malnutrition showed high deranged cellular immunity as evidenced by impairment of lymphocyte transformation after stimulation by phytohaemagglutination (PHA). The proliferative response (PR) to PHA measured by estimating incorporation of tritiated thymidine into newly synthesized DNA. In-vitro proliferative response to PHA was used as a marker for studying the functional characteristics of T lymphocytes of children with different categories of malnutrition. PHA response of peripheral blood lymphocytes obtained from different categories of severely malnourished children were significantly low compared to healthy control children (P < 0.01). The results indicate that cell mediated immunity was grossly depressed in severe malnutrition.

Indirect fluorescent antibody test (IFAT) was found to be 100% sensitive and 100% specific when tested with sera from 125 parasitologically proven kala-azar patients, 100 healthy controls and 50 sick control cases. Promastigotes of both L. enriettii and L. donovani as well as amastigotes of L. enriettii were found equally satisfactory as antigen for IFAT. From the results of the present study, it is concluded that IFAT is a highly sensitive as well as specific serological test for the diagnosis of kala-azar.

Cerebrospinal fluid from 260 children clinically diagnosed as meningitis were examined by Dm, culture, COA and CIE test. Dm revealed the presence of bacteria in 41 (15.8%) whereas culture showed growth of organism in 52 (20%) cases. COA and CIE test were done for the detection of antigen of H. influenzae, S. pneumoniae and N. meningitidis. Among the 3 methods viz. culture, COA and CIE test which were used for the detection of the above three organisms COA detected the maximum numbers (23.5%). COA test could detect antigen in both culture positive and culture negative CSF samples. COA test detected 100% of pneumococcal, 88.5% of H. influenzae and 66.7% of N. meningitidis antigens from CSF. Diagnosis by CIE in detecting H. influenzae and N. meningitidis antigens is inferior to culture and COA, whereas in detecting pneumococcal antigens CIE is superior to culture. So COA is a valuable, cheap, rapid and sensitive method for the diagnosis of meningitis caused by the above three organisms and when used along with culture 100% of cases can be diagnosed.