ZIEHL-NEELSEN MICROSCOPY IN THE DIAGNOSIS OF TUBERCULOSIS IN SETTINGS OF HIGH HUMAN IMMUNODEFICIENCY VIRUS PREVALENCE.

OBJECTIVE: To determine the accuracy of Ziehl-Neelsen microscopy in the diagnosis of TB in setings of high HIV prevalence. DESIGN: Cross-sectional descriptive study. SETTING: Hospitals serving areas of high human immunodeficiency virus prevalence in western Kenya. The study was conducted between September 2007 and September 2009. RESULTS: In total, 341/872(39.1%) of the TB suspects were positive in ZN, 53.1% (181/341) of them culture positive. Only 3.8% (20/531) of the ZN smear negatives were culture positive. Of the 695 suspects evaluated for both Mycobacterium and HIV infection, 255 (36.7%) were ZN smear positive, 42.7% of them HIV positive. Out of the 440 ZN smear negatives, 37% were HIV positive. Similarly, 168 suspects were culture positive, 46.4% of them HIV positive. The HIV infection did not significantly reduce ZN smear positivity rate (P = 0.42) and culture sensitivity (P = 0.09). The ZN sensitivity and specificity were 88.1% and 79.7%, respectively. The predictive values were 58.0 (PPV), and 95.5% (NPV), respectively. However, the area under the ROC curve was 0.84, with 95% CI between 0.80-0.87 and P < 0.001). The ZN smear microscopy had a lesser ability to distinguish between TB and non-TB cases compared to culture. CONCLUSION: ZN microscopy causes a significant over-diagnosis of TB in settings of high HIV/AIDS prevalence. There is need for further studies on this subject taking into consideration the various confounding factors.

Modifiable factors associated with active pulmonary tuberculosis in a Kenyan prison.

OBJECTIVES: To establish modifiable factors associated with active pulmonary tuberculosis (PTB) among prisoners. DESIGN: Retrospective matched case-control study. SETTING: Nakuru GK prison in Kenya. SUBJECTS: A total of 144 subjects (48 cases and 96 controls) were recruited into the study. Cases were adult prisoners who had at least two initial sputum specimens being Acid Fast Bacilli-positive (AFB+) on direct smear microscopy and hence recruited to PTB WHO DOTS Programme. Controls were adults with no chronic cough and not on PTB treatment six months prior to the study. RESULTS: Independent factors significantly associated with active PTB disease were: self reported HIV+ status (OR=11; 95% CI = 2.42-47.77), evidence of BCG vaccination (OR = 0.20; 95% CI = 0.05-0.60), contact with PTB case (OR = 7.0; 95% CI = 1.17-38.23), unemployment (OR = 9.0; 95% CI = 1.84-43.97) and sharing linen (OR = 4.32; 95%CI = 1.08-17.29). CONCLUSIONS: Modifiable factors associated with active PTB in Nakuru G.K prison are: HIV status, BCG vaccination, PTB case contact, poverty and poor personal hygiene. We recommend HIV counselling and testing of all PTB patients, screening for TB upon prison entry and TB contact investigation and improving personal hygiene of prisoners.

Streptomycin and chloramphenicol resistance genes in Escherichia coli isolates from cattle, pigs, and chicken in Kenya.

The aims of this study were to determine the genetic basis of streptomycin and chloramphenicol resistance in 30 Escherichia coli isolates from food animals in Kenya and the role of plasmids in the spread of the resistance. Seven of the 29 streptomycin-resistant isolates harbored both the strA and strB genes. Twenty-one of isolates had the strA, strB, and aadA1 genes. The strA gene was disrupted by a functional trimethoprim gene, dfrA14 in 10 of the 21 isolates harboring the three streptomycin resistance genes. Physical linkage of intact strA and sul2 genes was found in two different plasmids from four isolates. Linkage of cassette-borne aadA1 and dfrA1 genes in class 1 integrons was found in two of the isolates. Chloramphenicol resistance was due to the gene catA1 in all the chloramphenicol resistant isolates. The strB, strA, and catA1 genes were transferable by conjugation and this points to the significance of conjugative resistance plasmids in the spread and persistence of streptomycin and chloramphenicol resistance in food animals in Kenya.

Antimicrobial resistance in Salmonella serotypes isolated from slaughter animals in Kenya.

OBJECTIVES: To isolate Salmonella from food animals and characterise the antimicrobial resistance of the isolates. DESIGN: A random sampling of slaughter animals was carried out. SETTING: Department of Public Health, Pharmacology and Toxicology, University of Nairobi, Kenya and Institute for Animal Breeding, Neustadt-Mariensee, Germany. SUBJECTS: Two hundred and eighty five samples, including faecal samples and carcass, cloacal and pharyngeal swab samples were analysed. RESULTS: Sixteen (5.6%) of 285 samples were positive for Salmonella. The prevalence of Salmonella on pig carcasses (19%) was higher than in faeces (8.6%). Three Salmonella enterica sub-species enterica serovars, namely Saintpaul (S. Saintpaul), Braenderup (S. Braenderup), and Heidelberg (S. Heidelberg), were identified, with S. Saintpaul being the predominant serovar. Antimicrobial resistance was found in 35.7% of all the isolates. The S. Heidelberg isolates were susceptible to all the antimicrobial agents tested. Multidrug resistance was found in 7.1% of the resistant Salmonella isolates. Plasmids were only detected in S. Heidelberg. Ampicillin resistance was based on expression of a bla(TEM) gene, while chloramphenicol, streptomycin, and tetracycline resistances were encoded by the genes catAl, strA, and tet(A), respectively. CONCLUSION: Pigs may serve as reservoirs of antimicrobial resistant Salmonella and slaughterhouse cross-contamination of pork may be a food safety risk. We recommended that slaughterhouse hygiene be improved to minimise contamination of pig carcasses.

The pharmacokinetics of a long-acting oxytetracycline formulation in healthy dogs and in dogs infected with Ehrlichia canis.

The pharmacokinetic properties of oxytetracycline were studied following a single injection of a long-acting formulation (20 mg/kg body weight) into the semimembranosus muscle of healthy dogs and of dogs that had been experimentally infected with Ehrlichia canis. The disposition curves of the long-acting oxytetracycline formulation before and after infection were best described by a bi-exponential decline after a first-order absorption. The mean maximum serum concentration (Cmax) following infection was significantly lower and the time taken to attain this concentration (tmax) was significantly shorter than that in the healthy dogs. The mean apparent elimination half-life (t(1/2) beta) was significantly increased following infection. The corresponding rate constant (beta) was significantly decreased. The absorption half-life (t(1/2) ab) was significantly decreased after infection. The volume of distribution at steady state (Vdss) increased significantly following infection. It was concluded that the pharmacokinetic behaviour of a long-acting oxytetracycline in dogs after intramuscular administration is characterized by a two-compartment model with a slow elimination phase. This could be due to flip-flop kinetics. The febrile reaction in experimental E. canis infection affected some pharmacokinetic parameters of oxytetracycline.

HIV co-infection with tuberculous and non-tuberculous mycobacteria in western Kenya: challenges in the diagnosis and management.

BACKGROUND: Tuberculosis (TB) and HIV co-infections have a global prevalence with devastating morbidity and massive mortality, Sub-Saharan Africa being the worst hit. OBJECTIVES: To evaluate the prevalence of TB-HIV co-infection and demonstrate the confusion caused by NTM and HIV/AIDS co-infection in TB diagnosis and treatment in western Kenya. METHODS: In a cross-sectional study carried out at 10 hospitals in western Kenya, sputa from consenting 872 TB suspects underwent microscopy, and culture on Lowenstein-Jensen and Mycobacteria Growth Index Tube media. Isolates were identified using the Hain's GenoType(®) Mycobacterium CM and GenoType(®) Mycobacterium AS kits. A total of 695 participants were screened for HIV using Uni-Gold™ test and positives confirmed with the enzyme linked immunosorbent assay. RESULTS: A total of 346 (39.7%) participants were diagnosed with TB. Out of the 346 TB cases, 263 (76%) were tested for HIV infection and 110 (41.8%) of these were sero-positive (co-infected). The female to male TB-HIV co-infection prevalence ratio (PR) was 1.35. This study reports isolation of non-tuberculous mycobacteria from TB suspects at a rate of 1.7%. CONCLUSION: A high TB-HIV co-infection rate was observed in this study. The NTM disease could be misdiagnosed and treated as TB in western Kenya.

An assessment of antimicrobial consumption in food producing animals in Kenya.

Antimicrobial agents are useful for control of bacterial infections in food animals and man. Their prudent use in these animals is important to control any possible development and transfer of resistance between animals and man. The objective of this study was to generate quantitative information to evaluate antimicrobial usage patterns by animal species, route of administration, antimicrobial class and type of use from 1995 to 1999 in Kenya. Theses data are essential for risk analysis and planning and can be helpful in interpreting resistance surveillance data, and evaluating the effectiveness of prudent use efforts and antimicrobial resistance mitigation strategies. Data on quantities of active substance classes were collected from the official records of the Pharmacy and Poisons Board of the Ministry of Health and analysed in MS Excel 2000 program. The mean antimicrobial consumption for the 5-year period was 14 594 +/- 1457 kg per year. This was distributed in the various antimicrobial classes as follows: 7975 kg (54.65%) of tetracyclines, 3103.96 kg (21.27%) of sulfonamides and 954.5 kg (6.56%) of aminoglycosides, 905 kg (6.20%) of beta-lactams, 94 kg (0.64%) of quinolones, 35 kg (0.24%) of macrolides and 24 kg (0.16%) of others (tiamulin). Mean consumption per year among the various food animals was: 10 989 +/- 357 kg in large animals (cattle, sheep, pigs and goats), 2906 +/- 127 kg in poultry alone and 699 +/- 427 kg in both large animals and poultry. These quantities represented 56.56% (8255 kg) consumption per year for parenteral use, 41.79% (6098 kg) for oral use and 1.65% (241 kg) for topical use (intramammary and eye ointments) in cattle. With respect to intended use in food producing animals, the mean consumption per year was: 13 178 kg (90.30%) for therapeutic use (ST), 4 kg (0.03%) for prophylactic treatment (PT) and 1411 +/- 246 kg (9.67%) was used both for therapeutic and prophylactic purposes (GPT). The study confirmed that antimicrobials are not used for growth promotion in Kenya. There was no specific trend in the quantities of active antimicrobial classes. This study has revealed that the tetracyclines, sulfonamides and trimethoprim, nitrofurans aminoglycosides, beta-lactams and the quinolones are the most commonly used drugs in food-producing animals in Kenya. Tetracyclines contributed approximately 55% of the total consumption, and there was an increasing trend in the consumption of quinolones from 1998.